1
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remember last time we were talking about

2
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remember last time we were talking about

3
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remember last time we were talking about
metallic bonding metals

4
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metallic bonding metals

5
00:00:17,690 --> 00:00:25,580
metallic bonding metals
solids

6
00:00:25,580 --> 00:00:25,590

7
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now as we have seen before we have

8
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now as we have seen before we have

9
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now as we have seen before we have
defined the metallic bonding attraction

10
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defined the metallic bonding attraction

11
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defined the metallic bonding attraction
between the electron cloud which moves

12
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between the electron cloud which moves

13
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between the electron cloud which moves
freely in the solid metal and the

14
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freely in the solid metal and the

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freely in the solid metal and the
positively charged metal ions we simply

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positively charged metal ions we simply

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positively charged metal ions we simply
imagine a metal as if the positively

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imagine a metal as if the positively

19
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imagine a metal as if the positively
charged metal ions are put into an

20
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charged metal ions are put into an

21
00:00:58,979 --> 00:01:02,299
charged metal ions are put into an
electron see now these electrons II or

22
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electron see now these electrons II or

23
00:01:02,309 --> 00:01:04,280
electron see now these electrons II or
electron cloud you can call it are

24
00:01:04,280 --> 00:01:04,290
electron cloud you can call it are

25
00:01:04,290 --> 00:01:07,330
electron cloud you can call it are
actually the valence electrons off the

26
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actually the valence electrons off the

27
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actually the valence electrons off the
metal atom so a net attraction between

28
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metal atom so a net attraction between

29
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metal atom so a net attraction between
the this electron cloud and the

30
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the this electron cloud and the

31
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the this electron cloud and the
positively charged metal atom simply

32
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positively charged metal atom simply

33
00:01:17,689 --> 00:01:20,240
positively charged metal atom simply
holds the metal together and we call

34
00:01:20,240 --> 00:01:20,250
holds the metal together and we call

35
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holds the metal together and we call
that metallic bonding now again as we

36
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that metallic bonding now again as we

37
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that metallic bonding now again as we
said last time this happens because the

38
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said last time this happens because the

39
00:01:25,470 --> 00:01:29,330
said last time this happens because the
metals do not have enough electron

40
00:01:29,330 --> 00:01:29,340
metals do not have enough electron

41
00:01:29,340 --> 00:01:32,870
metals do not have enough electron
valence electrons to make the electron

42
00:01:32,870 --> 00:01:32,880
valence electrons to make the electron

43
00:01:32,880 --> 00:01:35,139
valence electrons to make the electron
configuration as the noble gas electron

44
00:01:35,139 --> 00:01:35,149
configuration as the noble gas electron

45
00:01:35,149 --> 00:01:38,149
configuration as the noble gas electron
configuration by Charon making bonds

46
00:01:38,149 --> 00:01:38,159
configuration by Charon making bonds

47
00:01:38,159 --> 00:01:42,020
configuration by Charon making bonds
like for bonds or with the surrounding

48
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like for bonds or with the surrounding

49
00:01:42,030 --> 00:01:46,090
like for bonds or with the surrounding
metal atoms therefore they get together

50
00:01:46,090 --> 00:01:46,100
metal atoms therefore they get together

51
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metal atoms therefore they get together
to form an electron called electron C

52
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to form an electron called electron C

53
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to form an electron called electron C
and the positively charged metal ions

54
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and the positively charged metal ions

55
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and the positively charged metal ions
there that's how we simply consider and

56
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there that's how we simply consider and

57
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there that's how we simply consider and
imagine the metal atom but as I said

58
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imagine the metal atom but as I said

59
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imagine the metal atom but as I said
last time there are some problems with

60
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last time there are some problems with

61
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last time there are some problems with
this model because when you consider for

62
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this model because when you consider for

63
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this model because when you consider for
example the transition metal atoms 3 d 4

64
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example the transition metal atoms 3 d 4

65
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example the transition metal atoms 3 d 4
D first transition metal atoms second

66
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D first transition metal atoms second

67
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D first transition metal atoms second
and so on the metal bond strength which

68
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and so on the metal bond strength which

69
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and so on the metal bond strength which
is indicated by the melting points of

70
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is indicated by the melting points of

71
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is indicated by the melting points of
the metals for example one property

72
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the metals for example one property

73
00:02:23,900 --> 00:02:27,110
the metals for example one property
increases as the number of electrons D

74
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increases as the number of electrons D

75
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increases as the number of electrons D
electron increases then when we reach to

76
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electron increases then when we reach to

77
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electron increases then when we reach to
the middle it becomes maximum the

78
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the middle it becomes maximum the

79
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the middle it becomes maximum the
strongest metal metallic bonding

80
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strongest metal metallic bonding

81
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strongest metal metallic bonding
actually and then as the number of

82
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actually and then as the number of

83
00:02:37,980 --> 00:02:40,030
actually and then as the number of
electron increases

84
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electron increases

85
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electron increases
the metallic bond decreases again

86
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the metallic bond decreases again

87
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the metallic bond decreases again
actually as the number of electrons

88
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actually as the number of electrons

89
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actually as the number of electrons
increases that will provide more

90
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increases that will provide more

91
00:02:47,700 --> 00:02:49,690
increases that will provide more
abundant with the other metals and

92
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abundant with the other metals and

93
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abundant with the other metals and
should make the metallic bond and

94
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should make the metallic bond and

95
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should make the metallic bond and
stronger but it

96
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stronger but it

97
00:02:53,599 --> 00:02:56,539
stronger but it
that doesn't happen actually as I said

98
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that doesn't happen actually as I said

99
00:02:56,549 --> 00:02:58,879
that doesn't happen actually as I said
experimentally so there is another model

100
00:02:58,879 --> 00:02:58,889
experimentally so there is another model

101
00:02:58,889 --> 00:03:02,690
experimentally so there is another model
that we can explain the metallic

102
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that we can explain the metallic

103
00:03:02,700 --> 00:03:04,520
that we can explain the metallic
properties and the electronic structure

104
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properties and the electronic structure

105
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properties and the electronic structure
of the metals electronic structure of

106
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of the metals electronic structure of

107
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of the metals electronic structure of
the metals and this can be consider

108
00:03:09,289 --> 00:03:09,299
the metals and this can be consider

109
00:03:09,299 --> 00:03:11,809
the metals and this can be consider
again as based on the molecular orbital

110
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again as based on the molecular orbital

111
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again as based on the molecular orbital
theory now how let me try to explain now

112
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theory now how let me try to explain now

113
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theory now how let me try to explain now
remember again we usually talked about

114
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remember again we usually talked about

115
00:03:19,500 --> 00:03:23,089
remember again we usually talked about
the molecular orbital energy diagrams or

116
00:03:23,089 --> 00:03:23,099
the molecular orbital energy diagrams or

117
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the molecular orbital energy diagrams or
the electronic structure of the

118
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the electronic structure of the

119
00:03:24,629 --> 00:03:30,409
the electronic structure of the
molecules based on by molecular diatomic

120
00:03:30,409 --> 00:03:30,419
molecules based on by molecular diatomic

121
00:03:30,419 --> 00:03:34,039
molecules based on by molecular diatomic
molecules right made of two atoms and we

122
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molecules right made of two atoms and we

123
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molecules right made of two atoms and we
combined the atomic orbitals to form the

124
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combined the atomic orbitals to form the

125
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combined the atomic orbitals to form the
molecular orbitals now remember again

126
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molecular orbitals now remember again

127
00:03:41,669 --> 00:03:43,879
molecular orbitals now remember again
that the number of molecular orbitals

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that the number of molecular orbitals

129
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that the number of molecular orbitals
are always equal to the number of atomic

130
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are always equal to the number of atomic

131
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are always equal to the number of atomic
orbitals that we linearly combine if

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orbitals that we linearly combine if

133
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orbitals that we linearly combine if
they combine to we get two molecular

134
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they combine to we get two molecular

135
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they combine to we get two molecular
orbitals and one of those is the

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orbitals and one of those is the

137
00:03:54,299 --> 00:03:56,270
orbitals and one of those is the
abundant lower energy the other one is

138
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abundant lower energy the other one is

139
00:03:56,280 --> 00:03:59,210
abundant lower energy the other one is
anti-bonding again higher energy and

140
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anti-bonding again higher energy and

141
00:03:59,220 --> 00:04:01,610
anti-bonding again higher energy and
then the electrons valence electrons

142
00:04:01,610 --> 00:04:01,620
then the electrons valence electrons

143
00:04:01,620 --> 00:04:03,319
then the electrons valence electrons
actually goes into these molecular

144
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actually goes into these molecular

145
00:04:03,329 --> 00:04:05,929
actually goes into these molecular
orbitals first we start filling them the

146
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orbitals first we start filling them the

147
00:04:05,939 --> 00:04:07,520
orbitals first we start filling them the
lowest energy bonding and the

148
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lowest energy bonding and the

149
00:04:07,530 --> 00:04:13,240
lowest energy bonding and the
antibonding and we also define a simply

150
00:04:13,240 --> 00:04:13,250
antibonding and we also define a simply

151
00:04:13,250 --> 00:04:16,939
antibonding and we also define a simply
bond order as the number of electrons in

152
00:04:16,939 --> 00:04:16,949
bond order as the number of electrons in

153
00:04:16,949 --> 00:04:18,949
bond order as the number of electrons in
the bonded molecular orbital minus the

154
00:04:18,949 --> 00:04:18,959
the bonded molecular orbital minus the

155
00:04:18,959 --> 00:04:20,300
the bonded molecular orbital minus the
number of electrons an anti-bonding

156
00:04:20,300 --> 00:04:20,310
number of electrons an anti-bonding

157
00:04:20,310 --> 00:04:24,890
number of electrons an anti-bonding
divided by two and this actually gave us

158
00:04:24,890 --> 00:04:24,900
divided by two and this actually gave us

159
00:04:24,900 --> 00:04:26,689
divided by two and this actually gave us
informations about the bond strength

160
00:04:26,689 --> 00:04:26,699
informations about the bond strength

161
00:04:26,699 --> 00:04:30,140
informations about the bond strength
between those two atoms actually which

162
00:04:30,140 --> 00:04:30,150
between those two atoms actually which

163
00:04:30,150 --> 00:04:33,409
between those two atoms actually which
form the molecule now again we said the

164
00:04:33,409 --> 00:04:33,419
form the molecule now again we said the

165
00:04:33,419 --> 00:04:34,939
form the molecule now again we said the
molecular orbitals are very similar to

166
00:04:34,939 --> 00:04:34,949
molecular orbitals are very similar to

167
00:04:34,949 --> 00:04:37,610
molecular orbitals are very similar to
the atomic orbitals but they cover all

168
00:04:37,610 --> 00:04:37,620
the atomic orbitals but they cover all

169
00:04:37,620 --> 00:04:43,310
the atomic orbitals but they cover all
over the molecule so the electron which

170
00:04:43,310 --> 00:04:43,320
over the molecule so the electron which

171
00:04:43,320 --> 00:04:45,589
over the molecule so the electron which
is in a molecular orbital means that

172
00:04:45,589 --> 00:04:45,599
is in a molecular orbital means that

173
00:04:45,599 --> 00:04:49,070
is in a molecular orbital means that
move around all atoms in the molecule in

174
00:04:49,070 --> 00:04:49,080
move around all atoms in the molecule in

175
00:04:49,080 --> 00:04:51,019
move around all atoms in the molecule in
the molecule free to move because it

176
00:04:51,019 --> 00:04:51,029
the molecule free to move because it

177
00:04:51,029 --> 00:04:52,180
the molecule free to move because it
orbitals is that big

178
00:04:52,180 --> 00:04:52,190
orbitals is that big

179
00:04:52,190 --> 00:04:55,240
orbitals is that big
and again molecular orbital's just takes

180
00:04:55,240 --> 00:04:55,250
and again molecular orbital's just takes

181
00:04:55,250 --> 00:04:57,250
and again molecular orbital's just takes
two electrons just the same as the

182
00:04:57,250 --> 00:04:57,260
two electrons just the same as the

183
00:04:57,260 --> 00:04:59,380
two electrons just the same as the
atomic orbitals we can put two electrons

184
00:04:59,380 --> 00:04:59,390
atomic orbitals we can put two electrons

185
00:04:59,390 --> 00:05:01,660
atomic orbitals we can put two electrons
in one molecular orbital and they should

186
00:05:01,660 --> 00:05:01,670
in one molecular orbital and they should

187
00:05:01,670 --> 00:05:06,210
in one molecular orbital and they should
be in spin paired opposite and spin now

188
00:05:06,210 --> 00:05:06,220
be in spin paired opposite and spin now

189
00:05:06,220 --> 00:05:09,780
be in spin paired opposite and spin now
let's simply consider the lithium

190
00:05:09,780 --> 00:05:09,790
let's simply consider the lithium

191
00:05:09,790 --> 00:05:13,090
let's simply consider the lithium
molecule like we have done before so

192
00:05:13,090 --> 00:05:13,100
molecule like we have done before so

193
00:05:13,100 --> 00:05:14,890
molecule like we have done before so
when we consider in lithium molecule

194
00:05:14,890 --> 00:05:14,900
when we consider in lithium molecule

195
00:05:14,900 --> 00:05:18,360
when we consider in lithium molecule
remember the lithium three electron

196
00:05:18,360 --> 00:05:18,370
remember the lithium three electron

197
00:05:18,370 --> 00:05:24,060
remember the lithium three electron
configuration is 1s2 2s1 it has 1s

198
00:05:24,060 --> 00:05:24,070
configuration is 1s2 2s1 it has 1s

199
00:05:24,070 --> 00:05:27,040
configuration is 1s2 2s1 it has 1s
electron as valence electrons so again

200
00:05:27,040 --> 00:05:27,050
electron as valence electrons so again

201
00:05:27,050 --> 00:05:30,940
electron as valence electrons so again
these two s orbitals actually from one

202
00:05:30,940 --> 00:05:30,950
these two s orbitals actually from one

203
00:05:30,950 --> 00:05:32,950
these two s orbitals actually from one
lithium and from the other lithium

204
00:05:32,950 --> 00:05:32,960
lithium and from the other lithium

205
00:05:32,960 --> 00:05:35,350
lithium and from the other lithium
combine to form bonding molecular

206
00:05:35,350 --> 00:05:35,360
combine to form bonding molecular

207
00:05:35,360 --> 00:05:37,720
combine to form bonding molecular
orbitals and antibonding molecular

208
00:05:37,720 --> 00:05:37,730
orbitals and antibonding molecular

209
00:05:37,730 --> 00:05:40,120
orbitals and antibonding molecular
orbitals and the bonding molecular

210
00:05:40,120 --> 00:05:40,130
orbitals and the bonding molecular

211
00:05:40,130 --> 00:05:43,140
orbitals and the bonding molecular
orbitals is Sigma type remember

212
00:05:43,140 --> 00:05:43,150
orbitals is Sigma type remember

213
00:05:43,150 --> 00:05:45,490
orbitals is Sigma type remember
anti-bonding is also Sigma type and

214
00:05:45,490 --> 00:05:45,500
anti-bonding is also Sigma type and

215
00:05:45,500 --> 00:05:48,580
anti-bonding is also Sigma type and
since we only have two electrons one

216
00:05:48,580 --> 00:05:48,590
since we only have two electrons one

217
00:05:48,590 --> 00:05:50,680
since we only have two electrons one
from each lithium valence electrons that

218
00:05:50,680 --> 00:05:50,690
from each lithium valence electrons that

219
00:05:50,690 --> 00:05:53,800
from each lithium valence electrons that
go into the bonding molecular orbital so

220
00:05:53,800 --> 00:05:53,810
go into the bonding molecular orbital so

221
00:05:53,810 --> 00:05:57,220
go into the bonding molecular orbital so
the lithium in fact the electronic

222
00:05:57,220 --> 00:05:57,230
the lithium in fact the electronic

223
00:05:57,230 --> 00:05:58,450
the lithium in fact the electronic
structure if you write down the

224
00:05:58,450 --> 00:05:58,460
structure if you write down the

225
00:05:58,460 --> 00:06:00,220
structure if you write down the
electronic structure that will be like

226
00:06:00,220 --> 00:06:00,230
electronic structure that will be like

227
00:06:00,230 --> 00:06:06,220
electronic structure that will be like
Sigma 1s two electrons there and then we

228
00:06:06,220 --> 00:06:06,230
Sigma 1s two electrons there and then we

229
00:06:06,230 --> 00:06:08,680
Sigma 1s two electrons there and then we
have the core electrons which is

230
00:06:08,680 --> 00:06:08,690
have the core electrons which is

231
00:06:08,690 --> 00:06:11,560
have the core electrons which is
involves this one s but forget about

232
00:06:11,560 --> 00:06:11,570
involves this one s but forget about

233
00:06:11,570 --> 00:06:14,850
involves this one s but forget about
that just take the valence electrons now

234
00:06:14,850 --> 00:06:14,860
that just take the valence electrons now

235
00:06:14,860 --> 00:06:18,640
that just take the valence electrons now
they are simply indicated as here this

236
00:06:18,640 --> 00:06:18,650
they are simply indicated as here this

237
00:06:18,650 --> 00:06:21,550
they are simply indicated as here this
is the bonding molecular orbital okay

238
00:06:21,550 --> 00:06:21,560
is the bonding molecular orbital okay

239
00:06:21,560 --> 00:06:23,830
is the bonding molecular orbital okay
this is the bonding molecular orbital

240
00:06:23,830 --> 00:06:23,840
this is the bonding molecular orbital

241
00:06:23,840 --> 00:06:26,110
this is the bonding molecular orbital
this is the shape again an electron goes

242
00:06:26,110 --> 00:06:26,120
this is the shape again an electron goes

243
00:06:26,120 --> 00:06:27,790
this is the shape again an electron goes
here in this bonding molecular orbital

244
00:06:27,790 --> 00:06:27,800
here in this bonding molecular orbital

245
00:06:27,800 --> 00:06:30,340
here in this bonding molecular orbital
they move all around the molecule which

246
00:06:30,340 --> 00:06:30,350
they move all around the molecule which

247
00:06:30,350 --> 00:06:32,110
they move all around the molecule which
is made off from two lithium atoms in

248
00:06:32,110 --> 00:06:32,120
is made off from two lithium atoms in

249
00:06:32,120 --> 00:06:33,760
is made off from two lithium atoms in
this case and this is the anti-bonding

250
00:06:33,760 --> 00:06:33,770
this case and this is the anti-bonding

251
00:06:33,770 --> 00:06:36,400
this case and this is the anti-bonding
molecular orbital where we have a nodal

252
00:06:36,400 --> 00:06:36,410
molecular orbital where we have a nodal

253
00:06:36,410 --> 00:06:39,340
molecular orbital where we have a nodal
plane sort of between the two atoms and

254
00:06:39,340 --> 00:06:39,350
plane sort of between the two atoms and

255
00:06:39,350 --> 00:06:41,830
plane sort of between the two atoms and
the electrons are more there as we said

256
00:06:41,830 --> 00:06:41,840
the electrons are more there as we said

257
00:06:41,840 --> 00:06:44,380
the electrons are more there as we said
again more electron is in abundant

258
00:06:44,380 --> 00:06:44,390
again more electron is in abundant

259
00:06:44,390 --> 00:06:46,150
again more electron is in abundant
molecular orbital in a molecule means

260
00:06:46,150 --> 00:06:46,160
molecular orbital in a molecule means

261
00:06:46,160 --> 00:06:48,430
molecular orbital in a molecule means
that the more stable the molecule

262
00:06:48,430 --> 00:06:48,440
that the more stable the molecule

263
00:06:48,440 --> 00:06:50,710
that the more stable the molecule
because the bond order will increase now

264
00:06:50,710 --> 00:06:50,720
because the bond order will increase now

265
00:06:50,720 --> 00:06:54,490
because the bond order will increase now
what happens if I don't if I take for

266
00:06:54,490 --> 00:06:54,500
what happens if I don't if I take for

267
00:06:54,500 --> 00:06:59,770
what happens if I don't if I take for
example for lithium atoms right now

268
00:06:59,770 --> 00:06:59,780
example for lithium atoms right now

269
00:06:59,780 --> 00:07:01,990
example for lithium atoms right now
these four lithium atoms can be again as

270
00:07:01,990 --> 00:07:02,000
these four lithium atoms can be again as

271
00:07:02,000 --> 00:07:05,640
these four lithium atoms can be again as
follow we can think about this as one

272
00:07:05,640 --> 00:07:05,650
follow we can think about this as one

273
00:07:05,650 --> 00:07:07,830
follow we can think about this as one
lithium and other lithium and another

274
00:07:07,830 --> 00:07:07,840
lithium and other lithium and another

275
00:07:07,840 --> 00:07:10,140
lithium and other lithium and another
lithium and another lithium here all

276
00:07:10,140 --> 00:07:10,150
lithium and another lithium here all

277
00:07:10,150 --> 00:07:13,379
lithium and another lithium here all
same distances away from each other or

278
00:07:13,379 --> 00:07:13,389
same distances away from each other or

279
00:07:13,389 --> 00:07:15,270
same distances away from each other or
you can think about this as one lithium

280
00:07:15,270 --> 00:07:15,280
you can think about this as one lithium

281
00:07:15,280 --> 00:07:17,490
you can think about this as one lithium
here one leave him there they're very

282
00:07:17,490 --> 00:07:17,500
here one leave him there they're very

283
00:07:17,500 --> 00:07:20,330
here one leave him there they're very
the same distance again and in this case

284
00:07:20,330 --> 00:07:20,340
the same distance again and in this case

285
00:07:20,340 --> 00:07:24,120
the same distance again and in this case
again if we consider the molecular

286
00:07:24,120 --> 00:07:24,130
again if we consider the molecular

287
00:07:24,130 --> 00:07:28,469
again if we consider the molecular
orbitals we will have four atomic

288
00:07:28,469 --> 00:07:28,479
orbitals we will have four atomic

289
00:07:28,479 --> 00:07:31,290
orbitals we will have four atomic
orbitals to combine these are actually

290
00:07:31,290 --> 00:07:31,300
orbitals to combine these are actually

291
00:07:31,300 --> 00:07:33,870
orbitals to combine these are actually
2's orbitals right and when they combine

292
00:07:33,870 --> 00:07:33,880
2's orbitals right and when they combine

293
00:07:33,880 --> 00:07:36,930
2's orbitals right and when they combine
they will form for molecular orbitals

294
00:07:36,930 --> 00:07:36,940
they will form for molecular orbitals

295
00:07:36,940 --> 00:07:38,909
they will form for molecular orbitals
now where are these molecular orbitals

296
00:07:38,909 --> 00:07:38,919
now where are these molecular orbitals

297
00:07:38,919 --> 00:07:41,340
now where are these molecular orbitals
these molecular orbiters will be one

298
00:07:41,340 --> 00:07:41,350
these molecular orbiters will be one

299
00:07:41,350 --> 00:07:44,010
these molecular orbiters will be one
will be the abundant the lowest again

300
00:07:44,010 --> 00:07:44,020
will be the abundant the lowest again

301
00:07:44,020 --> 00:07:46,080
will be the abundant the lowest again
and now the second one will be little

302
00:07:46,080 --> 00:07:46,090
and now the second one will be little

303
00:07:46,090 --> 00:07:46,920
and now the second one will be little
higher

304
00:07:46,920 --> 00:07:46,930
higher

305
00:07:46,930 --> 00:07:50,219
higher
over here and then than the third one

306
00:07:50,219 --> 00:07:50,229
over here and then than the third one

307
00:07:50,229 --> 00:07:52,350
over here and then than the third one
and the fourth one and so on right like

308
00:07:52,350 --> 00:07:52,360
and the fourth one and so on right like

309
00:07:52,360 --> 00:07:58,980
and the fourth one and so on right like
this now if I simply increase the number

310
00:07:58,980 --> 00:07:58,990
this now if I simply increase the number

311
00:07:58,990 --> 00:08:02,360
this now if I simply increase the number
of lithium atoms and then go to the

312
00:08:02,360 --> 00:08:02,370
of lithium atoms and then go to the

313
00:08:02,370 --> 00:08:07,080
of lithium atoms and then go to the
lithium atom infinite number of lithium

314
00:08:07,080 --> 00:08:07,090
lithium atom infinite number of lithium

315
00:08:07,090 --> 00:08:09,420
lithium atom infinite number of lithium
atoms this can be again in three

316
00:08:09,420 --> 00:08:09,430
atoms this can be again in three

317
00:08:09,430 --> 00:08:13,830
atoms this can be again in three
dimensions now again you can think about

318
00:08:13,830 --> 00:08:13,840
dimensions now again you can think about

319
00:08:13,840 --> 00:08:16,279
dimensions now again you can think about
the molecular orbitals that will form

320
00:08:16,279 --> 00:08:16,289
the molecular orbitals that will form

321
00:08:16,289 --> 00:08:18,839
the molecular orbitals that will form
how many molecular orbitals will form

322
00:08:18,839 --> 00:08:18,849
how many molecular orbitals will form

323
00:08:18,849 --> 00:08:21,149
how many molecular orbitals will form
there's going to be actually if they're

324
00:08:21,149 --> 00:08:21,159
there's going to be actually if they're

325
00:08:21,159 --> 00:08:23,370
there's going to be actually if they're
infinite as the number of lithium atom

326
00:08:23,370 --> 00:08:23,380
infinite as the number of lithium atom

327
00:08:23,380 --> 00:08:25,770
infinite as the number of lithium atom
goes to infinite that means that the

328
00:08:25,770 --> 00:08:25,780
goes to infinite that means that the

329
00:08:25,780 --> 00:08:27,510
goes to infinite that means that the
number of molecular orbitals will will

330
00:08:27,510 --> 00:08:27,520
number of molecular orbitals will will

331
00:08:27,520 --> 00:08:31,320
number of molecular orbitals will will
go to the infinite two now what does

332
00:08:31,320 --> 00:08:31,330
go to the infinite two now what does

333
00:08:31,330 --> 00:08:33,060
go to the infinite two now what does
that mean that means half of those

334
00:08:33,060 --> 00:08:33,070
that mean that means half of those

335
00:08:33,070 --> 00:08:36,089
that mean that means half of those
molecular orbiters will be bonding half

336
00:08:36,089 --> 00:08:36,099
molecular orbiters will be bonding half

337
00:08:36,099 --> 00:08:39,240
molecular orbiters will be bonding half
will be anti-bonding but when you have

338
00:08:39,240 --> 00:08:39,250
will be anti-bonding but when you have

339
00:08:39,250 --> 00:08:41,459
will be anti-bonding but when you have
that much molecular orbital actually

340
00:08:41,459 --> 00:08:41,469
that much molecular orbital actually

341
00:08:41,469 --> 00:08:44,370
that much molecular orbital actually
what really happens that the energy

342
00:08:44,370 --> 00:08:44,380
what really happens that the energy

343
00:08:44,380 --> 00:08:46,170
what really happens that the energy
differences like between the molecular

344
00:08:46,170 --> 00:08:46,180
differences like between the molecular

345
00:08:46,180 --> 00:08:52,050
differences like between the molecular
orbitals becomes almost zero right

346
00:08:52,050 --> 00:08:52,060
orbitals becomes almost zero right

347
00:08:52,060 --> 00:08:54,650
orbitals becomes almost zero right
almost zero so that means there is

348
00:08:54,650 --> 00:08:54,660
almost zero so that means there is

349
00:08:54,660 --> 00:08:57,360
almost zero so that means there is
molecular orbital here molecular orbital

350
00:08:57,360 --> 00:08:57,370
molecular orbital here molecular orbital

351
00:08:57,370 --> 00:08:59,160
molecular orbital here molecular orbital
very close to that molecular orbital

352
00:08:59,160 --> 00:08:59,170
very close to that molecular orbital

353
00:08:59,170 --> 00:09:02,190
very close to that molecular orbital
here here here infinite almost number of

354
00:09:02,190 --> 00:09:02,200
here here here infinite almost number of

355
00:09:02,200 --> 00:09:05,790
here here here infinite almost number of
molecular orbitals now again when you

356
00:09:05,790 --> 00:09:05,800
molecular orbitals now again when you

357
00:09:05,800 --> 00:09:07,350
molecular orbitals now again when you
have those infinite molecular orbiters

358
00:09:07,350 --> 00:09:07,360
have those infinite molecular orbiters

359
00:09:07,360 --> 00:09:10,590
have those infinite molecular orbiters
and Delirium infinite case again as I

360
00:09:10,590 --> 00:09:10,600
and Delirium infinite case again as I

361
00:09:10,600 --> 00:09:12,300
and Delirium infinite case again as I
should say the number of n goes to

362
00:09:12,300 --> 00:09:12,310
should say the number of n goes to

363
00:09:12,310 --> 00:09:14,550
should say the number of n goes to
infinity that probably put it that way

364
00:09:14,550 --> 00:09:14,560
infinity that probably put it that way

365
00:09:14,560 --> 00:09:17,340
infinity that probably put it that way
can't have infinite but that's like

366
00:09:17,340 --> 00:09:17,350
can't have infinite but that's like

367
00:09:17,350 --> 00:09:19,000
can't have infinite but that's like
we're talking about a piece of

368
00:09:19,000 --> 00:09:19,010
we're talking about a piece of

369
00:09:19,010 --> 00:09:24,100
we're talking about a piece of
lithium metal a piece of just solid

370
00:09:24,100 --> 00:09:24,110
lithium metal a piece of just solid

371
00:09:24,110 --> 00:09:26,950
lithium metal a piece of just solid
material right there in you can you can

372
00:09:26,950 --> 00:09:26,960
material right there in you can you can

373
00:09:26,960 --> 00:09:28,810
material right there in you can you can
say the end goes to infinite their

374
00:09:28,810 --> 00:09:28,820
say the end goes to infinite their

375
00:09:28,820 --> 00:09:31,330
say the end goes to infinite their
number of lithium atoms now there's

376
00:09:31,330 --> 00:09:31,340
number of lithium atoms now there's

377
00:09:31,340 --> 00:09:34,150
number of lithium atoms now there's
going to be like two n that means twice

378
00:09:34,150 --> 00:09:34,160
going to be like two n that means twice

379
00:09:34,160 --> 00:09:37,180
going to be like two n that means twice
as much as the number of lithium atoms

380
00:09:37,180 --> 00:09:37,190
as much as the number of lithium atoms

381
00:09:37,190 --> 00:09:39,970
as much as the number of lithium atoms
with the molecular orbiters here bonding

382
00:09:39,970 --> 00:09:39,980
with the molecular orbiters here bonding

383
00:09:39,980 --> 00:09:41,800
with the molecular orbiters here bonding
and anti-bonding but they're very close

384
00:09:41,800 --> 00:09:41,810
and anti-bonding but they're very close

385
00:09:41,810 --> 00:09:43,630
and anti-bonding but they're very close
is energy you can't really separate

386
00:09:43,630 --> 00:09:43,640
is energy you can't really separate

387
00:09:43,640 --> 00:09:46,330
is energy you can't really separate
those so you fill those electrons what

388
00:09:46,330 --> 00:09:46,340
those so you fill those electrons what

389
00:09:46,340 --> 00:09:48,610
those so you fill those electrons what
happens it will fill up to the middle

390
00:09:48,610 --> 00:09:48,620
happens it will fill up to the middle

391
00:09:48,620 --> 00:09:52,500
happens it will fill up to the middle
right here because when we combine n

392
00:09:52,500 --> 00:09:52,510
right here because when we combine n

393
00:09:52,510 --> 00:09:56,620
right here because when we combine n
lithium atoms you will form in molecular

394
00:09:56,620 --> 00:09:56,630
lithium atoms you will form in molecular

395
00:09:56,630 --> 00:10:00,540
lithium atoms you will form in molecular
orbitals but you will have actually n

396
00:10:00,540 --> 00:10:00,550
orbitals but you will have actually n

397
00:10:00,550 --> 00:10:03,610
orbitals but you will have actually n
electrons since you put two electrons in

398
00:10:03,610 --> 00:10:03,620
electrons since you put two electrons in

399
00:10:03,620 --> 00:10:05,320
electrons since you put two electrons in
one lip molecular orbital that means

400
00:10:05,320 --> 00:10:05,330
one lip molecular orbital that means

401
00:10:05,330 --> 00:10:08,050
one lip molecular orbital that means
half of the molecular orbitals will be

402
00:10:08,050 --> 00:10:08,060
half of the molecular orbitals will be

403
00:10:08,060 --> 00:10:12,520
half of the molecular orbitals will be
full half will be empty now this series

404
00:10:12,520 --> 00:10:12,530
full half will be empty now this series

405
00:10:12,530 --> 00:10:14,650
full half will be empty now this series
of molecular orbitals this is the

406
00:10:14,650 --> 00:10:14,660
of molecular orbitals this is the

407
00:10:14,660 --> 00:10:16,330
of molecular orbitals this is the
highest energy this is the lowest energy

408
00:10:16,330 --> 00:10:16,340
highest energy this is the lowest energy

409
00:10:16,340 --> 00:10:17,670
highest energy this is the lowest energy
again

410
00:10:17,670 --> 00:10:17,680
again

411
00:10:17,680 --> 00:10:21,490
again
this is again in metal metallic solid

412
00:10:21,490 --> 00:10:21,500
this is again in metal metallic solid

413
00:10:21,500 --> 00:10:23,500
this is again in metal metallic solid
actually and you feel the electrons

414
00:10:23,500 --> 00:10:23,510
actually and you feel the electrons

415
00:10:23,510 --> 00:10:28,870
actually and you feel the electrons
there is this is called bend right this

416
00:10:28,870 --> 00:10:28,880
there is this is called bend right this

417
00:10:28,880 --> 00:10:31,510
there is this is called bend right this
series of molecular orbitals which are

418
00:10:31,510 --> 00:10:31,520
series of molecular orbitals which are

419
00:10:31,520 --> 00:10:36,190
series of molecular orbitals which are
very very closely spaced between this

420
00:10:36,190 --> 00:10:36,200
very very closely spaced between this

421
00:10:36,200 --> 00:10:38,620
very very closely spaced between this
energy and that energy is called bend

422
00:10:38,620 --> 00:10:38,630
energy and that energy is called bend

423
00:10:38,630 --> 00:10:39,340
energy and that energy is called bend
again

424
00:10:39,340 --> 00:10:39,350
again

425
00:10:39,350 --> 00:10:41,890
again
now the electrical conductivity can

426
00:10:41,890 --> 00:10:41,900
now the electrical conductivity can

427
00:10:41,900 --> 00:10:45,580
now the electrical conductivity can
easily be explained here because when

428
00:10:45,580 --> 00:10:45,590
easily be explained here because when

429
00:10:45,590 --> 00:10:49,060
easily be explained here because when
simply these electrons here filled with

430
00:10:49,060 --> 00:10:49,070
simply these electrons here filled with

431
00:10:49,070 --> 00:10:50,980
simply these electrons here filled with
the molecular orbitals and filled

432
00:10:50,980 --> 00:10:50,990
the molecular orbitals and filled

433
00:10:50,990 --> 00:10:53,590
the molecular orbitals and filled
molecular orbitals electrons absorb

434
00:10:53,590 --> 00:10:53,600
molecular orbitals electrons absorb

435
00:10:53,600 --> 00:10:57,130
molecular orbitals electrons absorb
energy from the light or from other

436
00:10:57,130 --> 00:10:57,140
energy from the light or from other

437
00:10:57,140 --> 00:10:59,320
energy from the light or from other
sources they will be excited to the

438
00:10:59,320 --> 00:10:59,330
sources they will be excited to the

439
00:10:59,330 --> 00:11:02,560
sources they will be excited to the
higher molecular orbitals so I will have

440
00:11:02,560 --> 00:11:02,570
higher molecular orbitals so I will have

441
00:11:02,570 --> 00:11:04,360
higher molecular orbitals so I will have
molecular orbitals here which are

442
00:11:04,360 --> 00:11:04,370
molecular orbitals here which are

443
00:11:04,370 --> 00:11:07,840
molecular orbitals here which are
partially filled now those partially

444
00:11:07,840 --> 00:11:07,850
partially filled now those partially

445
00:11:07,850 --> 00:11:10,750
partially filled now those partially
filled molecular orbitals that means one

446
00:11:10,750 --> 00:11:10,760
filled molecular orbitals that means one

447
00:11:10,760 --> 00:11:13,260
filled molecular orbitals that means one
electron in one molecular orbital will

448
00:11:13,260 --> 00:11:13,270
electron in one molecular orbital will

449
00:11:13,270 --> 00:11:17,080
electron in one molecular orbital will
function to carry the electrical charge

450
00:11:17,080 --> 00:11:17,090
function to carry the electrical charge

451
00:11:17,090 --> 00:11:20,050
function to carry the electrical charge
through the metal lithium that means

452
00:11:20,050 --> 00:11:20,060
through the metal lithium that means

453
00:11:20,060 --> 00:11:21,880
through the metal lithium that means
that the electron in those molecular

454
00:11:21,880 --> 00:11:21,890
that the electron in those molecular

455
00:11:21,890 --> 00:11:24,370
that the electron in those molecular
orbitals can move from one end of the

456
00:11:24,370 --> 00:11:24,380
orbitals can move from one end of the

457
00:11:24,380 --> 00:11:26,800
orbitals can move from one end of the
metal to the other man and and that will

458
00:11:26,800 --> 00:11:26,810
metal to the other man and and that will

459
00:11:26,810 --> 00:11:29,080
metal to the other man and and that will
carry the electrical charge right that's

460
00:11:29,080 --> 00:11:29,090
carry the electrical charge right that's

461
00:11:29,090 --> 00:11:31,570
carry the electrical charge right that's
how we explain that now on the other

462
00:11:31,570 --> 00:11:31,580
how we explain that now on the other

463
00:11:31,580 --> 00:11:33,220
how we explain that now on the other
side again with

464
00:11:33,220 --> 00:11:33,230
side again with

465
00:11:33,230 --> 00:11:36,730
side again with
Bend approach the more electrons we have

466
00:11:36,730 --> 00:11:36,740
Bend approach the more electrons we have

467
00:11:36,740 --> 00:11:39,160
Bend approach the more electrons we have
in the bonding molecular orbitals and

468
00:11:39,160 --> 00:11:39,170
in the bonding molecular orbitals and

469
00:11:39,170 --> 00:11:40,990
in the bonding molecular orbitals and
less electron in the anti-bonding

470
00:11:40,990 --> 00:11:41,000
less electron in the anti-bonding

471
00:11:41,000 --> 00:11:42,610
less electron in the anti-bonding
molecular orbiters you can think about

472
00:11:42,610 --> 00:11:42,620
molecular orbiters you can think about

473
00:11:42,620 --> 00:11:45,130
molecular orbiters you can think about
this these are sort of anti bonding then

474
00:11:45,130 --> 00:11:45,140
this these are sort of anti bonding then

475
00:11:45,140 --> 00:11:47,440
this these are sort of anti bonding then
the more stable will be the metal and

476
00:11:47,440 --> 00:11:47,450
the more stable will be the metal and

477
00:11:47,450 --> 00:11:50,050
the more stable will be the metal and
higher will be the melting point this is

478
00:11:50,050 --> 00:11:50,060
higher will be the melting point this is

479
00:11:50,060 --> 00:11:53,740
higher will be the melting point this is
simple lithium atom case right now what

480
00:11:53,740 --> 00:11:53,750
simple lithium atom case right now what

481
00:11:53,750 --> 00:11:56,920
simple lithium atom case right now what
happens if I have transition metals

482
00:11:56,920 --> 00:11:56,930
happens if I have transition metals

483
00:11:56,930 --> 00:12:00,880
happens if I have transition metals
which have D orbitals S orbitals and P

484
00:12:00,880 --> 00:12:00,890
which have D orbitals S orbitals and P

485
00:12:00,890 --> 00:12:04,900
which have D orbitals S orbitals and P
orbitals as valence orbitals for example

486
00:12:04,900 --> 00:12:04,910
orbitals as valence orbitals for example

487
00:12:04,910 --> 00:12:07,390
orbitals as valence orbitals for example
3d transitions we have four s orbitals

488
00:12:07,390 --> 00:12:07,400
3d transitions we have four s orbitals

489
00:12:07,400 --> 00:12:10,660
3d transitions we have four s orbitals
lower energy here three D orbitals there

490
00:12:10,660 --> 00:12:10,670
lower energy here three D orbitals there

491
00:12:10,670 --> 00:12:13,090
lower energy here three D orbitals there
and then 4s orbital there actually

492
00:12:13,090 --> 00:12:13,100
and then 4s orbital there actually

493
00:12:13,100 --> 00:12:15,580
and then 4s orbital there actually
remember the energy of these 4s and

494
00:12:15,580 --> 00:12:15,590
remember the energy of these 4s and

495
00:12:15,590 --> 00:12:18,250
remember the energy of these 4s and
three D changes as we fill out that but

496
00:12:18,250 --> 00:12:18,260
three D changes as we fill out that but

497
00:12:18,260 --> 00:12:20,290
three D changes as we fill out that but
think about this again as follow we have

498
00:12:20,290 --> 00:12:20,300
think about this again as follow we have

499
00:12:20,300 --> 00:12:24,610
think about this again as follow we have
four s + 3 d + 4 P now we can think

500
00:12:24,610 --> 00:12:24,620
four s + 3 d + 4 P now we can think

501
00:12:24,620 --> 00:12:28,720
four s + 3 d + 4 P now we can think
about exactly the same way we thought

502
00:12:28,720 --> 00:12:28,730
about exactly the same way we thought

503
00:12:28,730 --> 00:12:33,190
about exactly the same way we thought
about the lithium metal now all the four

504
00:12:33,190 --> 00:12:33,200
about the lithium metal now all the four

505
00:12:33,200 --> 00:12:36,100
about the lithium metal now all the four
s orbitals from each metal atom will

506
00:12:36,100 --> 00:12:36,110
s orbitals from each metal atom will

507
00:12:36,110 --> 00:12:39,760
s orbitals from each metal atom will
combine to form and molecular orbitals

508
00:12:39,760 --> 00:12:39,770
combine to form and molecular orbitals

509
00:12:39,770 --> 00:12:43,570
combine to form and molecular orbitals
as n goes to infinity they will simply

510
00:12:43,570 --> 00:12:43,580
as n goes to infinity they will simply

511
00:12:43,580 --> 00:12:47,410
as n goes to infinity they will simply
spend an energy range and that will be

512
00:12:47,410 --> 00:12:47,420
spend an energy range and that will be

513
00:12:47,420 --> 00:12:51,730
spend an energy range and that will be
from here to here and this is called the

514
00:12:51,730 --> 00:12:51,740
from here to here and this is called the

515
00:12:51,740 --> 00:12:55,180
from here to here and this is called the
s Bend this is again the series of

516
00:12:55,180 --> 00:12:55,190
s Bend this is again the series of

517
00:12:55,190 --> 00:12:57,610
s Bend this is again the series of
molecular orbitals which are very

518
00:12:57,610 --> 00:12:57,620
molecular orbitals which are very

519
00:12:57,620 --> 00:13:01,330
molecular orbitals which are very
closely spaced energy wise and they're

520
00:13:01,330 --> 00:13:01,340
closely spaced energy wise and they're

521
00:13:01,340 --> 00:13:03,970
closely spaced energy wise and they're
made up from four s linear combinations

522
00:13:03,970 --> 00:13:03,980
made up from four s linear combinations

523
00:13:03,980 --> 00:13:06,280
made up from four s linear combinations
of the four s orbitals like that then

524
00:13:06,280 --> 00:13:06,290
of the four s orbitals like that then

525
00:13:06,290 --> 00:13:09,730
of the four s orbitals like that then
the D orbitals five of those D orbitals

526
00:13:09,730 --> 00:13:09,740
the D orbitals five of those D orbitals

527
00:13:09,740 --> 00:13:12,220
the D orbitals five of those D orbitals
from each metal atom they will also

528
00:13:12,220 --> 00:13:12,230
from each metal atom they will also

529
00:13:12,230 --> 00:13:14,470
from each metal atom they will also
linearly combine to form molecular

530
00:13:14,470 --> 00:13:14,480
linearly combine to form molecular

531
00:13:14,480 --> 00:13:17,770
linearly combine to form molecular
orbitals and since the end goes to

532
00:13:17,770 --> 00:13:17,780
orbitals and since the end goes to

533
00:13:17,780 --> 00:13:20,350
orbitals and since the end goes to
infinite these molecular orbitals which

534
00:13:20,350 --> 00:13:20,360
infinite these molecular orbitals which

535
00:13:20,360 --> 00:13:22,600
infinite these molecular orbitals which
simply obtain from the linear

536
00:13:22,600 --> 00:13:22,610
simply obtain from the linear

537
00:13:22,610 --> 00:13:26,140
simply obtain from the linear
combinations of the D orbitals will have

538
00:13:26,140 --> 00:13:26,150
combinations of the D orbitals will have

539
00:13:26,150 --> 00:13:28,420
combinations of the D orbitals will have
a band like this and this is simply

540
00:13:28,420 --> 00:13:28,430
a band like this and this is simply

541
00:13:28,430 --> 00:13:31,660
a band like this and this is simply
called 3d band this is called for air

542
00:13:31,660 --> 00:13:31,670
called 3d band this is called for air

543
00:13:31,670 --> 00:13:34,930
called 3d band this is called for air
spend now then the p orbitals here

544
00:13:34,930 --> 00:13:34,940
spend now then the p orbitals here

545
00:13:34,940 --> 00:13:37,780
spend now then the p orbitals here
they will also combine linearly to form

546
00:13:37,780 --> 00:13:37,790
they will also combine linearly to form

547
00:13:37,790 --> 00:13:39,310
they will also combine linearly to form
molecular orbitals exactly the same

548
00:13:39,310 --> 00:13:39,320
molecular orbitals exactly the same

549
00:13:39,320 --> 00:13:43,180
molecular orbitals exactly the same
fashion as the 4s and 3b and they will

550
00:13:43,180 --> 00:13:43,190
fashion as the 4s and 3b and they will

551
00:13:43,190 --> 00:13:45,620
fashion as the 4s and 3b and they will
simply have a band

552
00:13:45,620 --> 00:13:45,630
simply have a band

553
00:13:45,630 --> 00:13:47,630
simply have a band
here we call that P bet what does that

554
00:13:47,630 --> 00:13:47,640
here we call that P bet what does that

555
00:13:47,640 --> 00:13:50,470
here we call that P bet what does that
bank means that means series of

556
00:13:50,470 --> 00:13:50,480
bank means that means series of

557
00:13:50,480 --> 00:13:53,630
bank means that means series of
molecular orbitals very large number of

558
00:13:53,630 --> 00:13:53,640
molecular orbitals very large number of

559
00:13:53,640 --> 00:13:55,970
molecular orbitals very large number of
molecular orbitals spaced very very

560
00:13:55,970 --> 00:13:55,980
molecular orbitals spaced very very

561
00:13:55,980 --> 00:13:58,520
molecular orbitals spaced very very
closely and energy wise now once you

562
00:13:58,520 --> 00:13:58,530
closely and energy wise now once you

563
00:13:58,530 --> 00:14:01,880
closely and energy wise now once you
have these separate bands s Bank P band

564
00:14:01,880 --> 00:14:01,890
have these separate bands s Bank P band

565
00:14:01,890 --> 00:14:04,780
have these separate bands s Bank P band
and D band in this energy scale actually

566
00:14:04,780 --> 00:14:04,790
and D band in this energy scale actually

567
00:14:04,790 --> 00:14:07,370
and D band in this energy scale actually
the relative energies with respect to

568
00:14:07,370 --> 00:14:07,380
the relative energies with respect to

569
00:14:07,380 --> 00:14:09,620
the relative energies with respect to
each other as shown here then we will

570
00:14:09,620 --> 00:14:09,630
each other as shown here then we will

571
00:14:09,630 --> 00:14:11,540
each other as shown here then we will
take the electrons this is actually the

572
00:14:11,540 --> 00:14:11,550
take the electrons this is actually the

573
00:14:11,550 --> 00:14:14,990
take the electrons this is actually the
nickel right twenty-eight atomic number

574
00:14:14,990 --> 00:14:15,000
nickel right twenty-eight atomic number

575
00:14:15,000 --> 00:14:17,210
nickel right twenty-eight atomic number
and we take these electrons here and

576
00:14:17,210 --> 00:14:17,220
and we take these electrons here and

577
00:14:17,220 --> 00:14:19,580
and we take these electrons here and
then we start filling them from the

578
00:14:19,580 --> 00:14:19,590
then we start filling them from the

579
00:14:19,590 --> 00:14:21,980
then we start filling them from the
lowest energy molecular orbital which is

580
00:14:21,980 --> 00:14:21,990
lowest energy molecular orbital which is

581
00:14:21,990 --> 00:14:24,200
lowest energy molecular orbital which is
in the S band and then continuing over

582
00:14:24,200 --> 00:14:24,210
in the S band and then continuing over

583
00:14:24,210 --> 00:14:26,240
in the S band and then continuing over
here when we reach to the here then we

584
00:14:26,240 --> 00:14:26,250
here when we reach to the here then we

585
00:14:26,250 --> 00:14:29,840
here when we reach to the here then we
fuel SMD together like this okay and

586
00:14:29,840 --> 00:14:29,850
fuel SMD together like this okay and

587
00:14:29,850 --> 00:14:32,960
fuel SMD together like this okay and
then when we reach here the P we simply

588
00:14:32,960 --> 00:14:32,970
then when we reach here the P we simply

589
00:14:32,970 --> 00:14:35,750
then when we reach here the P we simply
start fill-in s P and D this looks like

590
00:14:35,750 --> 00:14:35,760
start fill-in s P and D this looks like

591
00:14:35,760 --> 00:14:38,810
start fill-in s P and D this looks like
you know pouring water here and as the

592
00:14:38,810 --> 00:14:38,820
you know pouring water here and as the

593
00:14:38,820 --> 00:14:40,520
you know pouring water here and as the
water reaches to this region then the

594
00:14:40,520 --> 00:14:40,530
water reaches to this region then the

595
00:14:40,530 --> 00:14:42,590
water reaches to this region then the
water goes over here and as it reaches

596
00:14:42,590 --> 00:14:42,600
water goes over here and as it reaches

597
00:14:42,600 --> 00:14:45,590
water goes over here and as it reaches
to that level it goes to here here and

598
00:14:45,590 --> 00:14:45,600
to that level it goes to here here and

599
00:14:45,600 --> 00:14:45,980
to that level it goes to here here and
here

600
00:14:45,980 --> 00:14:45,990
here

601
00:14:45,990 --> 00:14:48,920
here
that means we fill out the electrons in

602
00:14:48,920 --> 00:14:48,930
that means we fill out the electrons in

603
00:14:48,930 --> 00:14:51,520
that means we fill out the electrons in
these bands like this this is the

604
00:14:51,520 --> 00:14:51,530
these bands like this this is the

605
00:14:51,530 --> 00:14:54,380
these bands like this this is the
electronic structure of the nickel atom

606
00:14:54,380 --> 00:14:54,390
electronic structure of the nickel atom

607
00:14:54,390 --> 00:14:58,460
electronic structure of the nickel atom
you have three bands now again here we

608
00:14:58,460 --> 00:14:58,470
you have three bands now again here we

609
00:14:58,470 --> 00:15:00,980
you have three bands now again here we
have empty molecular orbitals here we

610
00:15:00,980 --> 00:15:00,990
have empty molecular orbitals here we

611
00:15:00,990 --> 00:15:03,140
have empty molecular orbitals here we
have empty molecular orbitals and here

612
00:15:03,140 --> 00:15:03,150
have empty molecular orbitals and here

613
00:15:03,150 --> 00:15:04,700
have empty molecular orbitals and here
also we have empty molecular orbitals

614
00:15:04,700 --> 00:15:04,710
also we have empty molecular orbitals

615
00:15:04,710 --> 00:15:07,850
also we have empty molecular orbitals
any electron excited to these level

616
00:15:07,850 --> 00:15:07,860
any electron excited to these level

617
00:15:07,860 --> 00:15:11,630
any electron excited to these level
actually is simply will provide the

618
00:15:11,630 --> 00:15:11,640
actually is simply will provide the

619
00:15:11,640 --> 00:15:14,060
actually is simply will provide the
electrical conductivity actually this

620
00:15:14,060 --> 00:15:14,070
electrical conductivity actually this

621
00:15:14,070 --> 00:15:17,990
electrical conductivity actually this
part fill part of the as we will see

622
00:15:17,990 --> 00:15:18,000
part fill part of the as we will see

623
00:15:18,000 --> 00:15:20,150
part fill part of the as we will see
bends are called the valence band and

624
00:15:20,150 --> 00:15:20,160
bends are called the valence band and

625
00:15:20,160 --> 00:15:22,160
bends are called the valence band and
the empty part is called the conduction

626
00:15:22,160 --> 00:15:22,170
the empty part is called the conduction

627
00:15:22,170 --> 00:15:24,980
the empty part is called the conduction
band again that means the electrons in

628
00:15:24,980 --> 00:15:24,990
band again that means the electrons in

629
00:15:24,990 --> 00:15:28,210
band again that means the electrons in
the conduction band are the ones that

630
00:15:28,210 --> 00:15:28,220
the conduction band are the ones that

631
00:15:28,220 --> 00:15:31,070
the conduction band are the ones that
conducts carry the electrical charge and

632
00:15:31,070 --> 00:15:31,080
conducts carry the electrical charge and

633
00:15:31,080 --> 00:15:34,490
conducts carry the electrical charge and
make the metal atom conductor okay this

634
00:15:34,490 --> 00:15:34,500
make the metal atom conductor okay this

635
00:15:34,500 --> 00:15:37,220
make the metal atom conductor okay this
is the approach again molecular orbital

636
00:15:37,220 --> 00:15:37,230
is the approach again molecular orbital

637
00:15:37,230 --> 00:15:40,160
is the approach again molecular orbital
approach to explain the metallic

638
00:15:40,160 --> 00:15:40,170
approach to explain the metallic

639
00:15:40,170 --> 00:15:42,770
approach to explain the metallic
properties and it does better than the

640
00:15:42,770 --> 00:15:42,780
properties and it does better than the

641
00:15:42,780 --> 00:15:45,680
properties and it does better than the
other electron and electron C and the

642
00:15:45,680 --> 00:15:45,690
other electron and electron C and the

643
00:15:45,690 --> 00:15:50,540
other electron and electron C and the
positively charged metal ions okay now

644
00:15:50,540 --> 00:15:50,550
positively charged metal ions okay now

645
00:15:50,550 --> 00:15:52,430
positively charged metal ions okay now
the next we will talk about the ionic

646
00:15:52,430 --> 00:15:52,440
the next we will talk about the ionic

647
00:15:52,440 --> 00:15:55,340
the next we will talk about the ionic
solids now ionic solids remember are the

648
00:15:55,340 --> 00:15:55,350
solids now ionic solids remember are the

649
00:15:55,350 --> 00:15:57,890
solids now ionic solids remember are the
solids made of positive and negatively

650
00:15:57,890 --> 00:15:57,900
solids made of positive and negatively

651
00:15:57,900 --> 00:15:59,060
solids made of positive and negatively
charged ions

652
00:15:59,060 --> 00:15:59,070
charged ions

653
00:15:59,070 --> 00:16:01,370
charged ions
and they are crystalline structures and

654
00:16:01,370 --> 00:16:01,380
and they are crystalline structures and

655
00:16:01,380 --> 00:16:04,550
and they are crystalline structures and
again the distances very regular pattern

656
00:16:04,550 --> 00:16:04,560
again the distances very regular pattern

657
00:16:04,560 --> 00:16:06,350
again the distances very regular pattern
they have a legislative irregular

658
00:16:06,350 --> 00:16:06,360
they have a legislative irregular

659
00:16:06,360 --> 00:16:08,480
they have a legislative irregular
pattern and they have a unit cell just

660
00:16:08,480 --> 00:16:08,490
pattern and they have a unit cell just

661
00:16:08,490 --> 00:16:11,630
pattern and they have a unit cell just
like other crystalline solids now the

662
00:16:11,630 --> 00:16:11,640
like other crystalline solids now the

663
00:16:11,640 --> 00:16:14,930
like other crystalline solids now the
easiest way to imagine the ionic solids

664
00:16:14,930 --> 00:16:14,940
easiest way to imagine the ionic solids

665
00:16:14,940 --> 00:16:17,840
easiest way to imagine the ionic solids
would be as follow now in this case we

666
00:16:17,840 --> 00:16:17,850
would be as follow now in this case we

667
00:16:17,850 --> 00:16:19,790
would be as follow now in this case we
have positive and negative charges and

668
00:16:19,790 --> 00:16:19,800
have positive and negative charges and

669
00:16:19,800 --> 00:16:22,070
have positive and negative charges and
remember again the attractions of

670
00:16:22,070 --> 00:16:22,080
remember again the attractions of

671
00:16:22,080 --> 00:16:23,960
remember again the attractions of
positive and negative charges results

672
00:16:23,960 --> 00:16:23,970
positive and negative charges results

673
00:16:23,970 --> 00:16:28,370
positive and negative charges results
the ionic bent and that is the one keeps

674
00:16:28,370 --> 00:16:28,380
the ionic bent and that is the one keeps

675
00:16:28,380 --> 00:16:30,680
the ionic bent and that is the one keeps
the solid ionic solid together and they

676
00:16:30,680 --> 00:16:30,690
the solid ionic solid together and they

677
00:16:30,690 --> 00:16:32,630
the solid ionic solid together and they
are very hard there are properties of

678
00:16:32,630 --> 00:16:32,640
are very hard there are properties of

679
00:16:32,640 --> 00:16:35,330
are very hard there are properties of
those do not conduct the electricity and

680
00:16:35,330 --> 00:16:35,340
those do not conduct the electricity and

681
00:16:35,340 --> 00:16:39,710
those do not conduct the electricity and
so on but we can imagine the structure

682
00:16:39,710 --> 00:16:39,720
so on but we can imagine the structure

683
00:16:39,720 --> 00:16:43,610
so on but we can imagine the structure
of an ionic lattice as follow usually

684
00:16:43,610 --> 00:16:43,620
of an ionic lattice as follow usually

685
00:16:43,620 --> 00:16:45,980
of an ionic lattice as follow usually
one of the ion is bigger than the other

686
00:16:45,980 --> 00:16:45,990
one of the ion is bigger than the other

687
00:16:45,990 --> 00:16:48,020
one of the ion is bigger than the other
and that is usually the negative

688
00:16:48,020 --> 00:16:48,030
and that is usually the negative

689
00:16:48,030 --> 00:16:50,420
and that is usually the negative
negatively charged ion right you can

690
00:16:50,420 --> 00:16:50,430
negatively charged ion right you can

691
00:16:50,430 --> 00:16:52,430
negatively charged ion right you can
imagine that the larger ion or

692
00:16:52,430 --> 00:16:52,440
imagine that the larger ion or

693
00:16:52,440 --> 00:16:56,770
imagine that the larger ion or
negatively charged ion will form a

694
00:16:56,770 --> 00:16:56,780
negatively charged ion will form a

695
00:16:56,780 --> 00:17:01,420
negatively charged ion will form a
close-packed lattice that means

696
00:17:01,420 --> 00:17:01,430
close-packed lattice that means

697
00:17:01,430 --> 00:17:03,770
close-packed lattice that means
hexagonal lattice exactly with a

698
00:17:03,770 --> 00:17:03,780
hexagonal lattice exactly with a

699
00:17:03,780 --> 00:17:05,960
hexagonal lattice exactly with a
hexagonal unit cell or cubic close

700
00:17:05,960 --> 00:17:05,970
hexagonal unit cell or cubic close

701
00:17:05,970 --> 00:17:08,600
hexagonal unit cell or cubic close
packing which have the face and the

702
00:17:08,600 --> 00:17:08,610
packing which have the face and the

703
00:17:08,610 --> 00:17:13,720
packing which have the face and the
cubic unit cell and then the other iron

704
00:17:13,720 --> 00:17:13,730
cubic unit cell and then the other iron

705
00:17:13,730 --> 00:17:17,000
cubic unit cell and then the other iron
smaller ion usually the positively

706
00:17:17,000 --> 00:17:17,010
smaller ion usually the positively

707
00:17:17,010 --> 00:17:21,710
smaller ion usually the positively
charged ion will fill into the holes now

708
00:17:21,710 --> 00:17:21,720
charged ion will fill into the holes now

709
00:17:21,720 --> 00:17:23,780
charged ion will fill into the holes now
remember what kind of holes we had in

710
00:17:23,780 --> 00:17:23,790
remember what kind of holes we had in

711
00:17:23,790 --> 00:17:26,000
remember what kind of holes we had in
the close back in structures we had

712
00:17:26,000 --> 00:17:26,010
the close back in structures we had

713
00:17:26,010 --> 00:17:28,520
the close back in structures we had
remember last time I try to show you

714
00:17:28,520 --> 00:17:28,530
remember last time I try to show you

715
00:17:28,530 --> 00:17:33,200
remember last time I try to show you
that the holes between four metal atoms

716
00:17:33,200 --> 00:17:33,210
that the holes between four metal atoms

717
00:17:33,210 --> 00:17:36,410
that the holes between four metal atoms
we call that tetrahedral holes and the

718
00:17:36,410 --> 00:17:36,420
we call that tetrahedral holes and the

719
00:17:36,420 --> 00:17:38,810
we call that tetrahedral holes and the
holes that is between six metal atoms

720
00:17:38,810 --> 00:17:38,820
holes that is between six metal atoms

721
00:17:38,820 --> 00:17:41,570
holes that is between six metal atoms
and that is called the octahedral holes

722
00:17:41,570 --> 00:17:41,580
and that is called the octahedral holes

723
00:17:41,580 --> 00:17:44,180
and that is called the octahedral holes
and the octahedral holes are always

724
00:17:44,180 --> 00:17:44,190
and the octahedral holes are always

725
00:17:44,190 --> 00:17:47,000
and the octahedral holes are always
larger than the tetrahedral holes and we

726
00:17:47,000 --> 00:17:47,010
larger than the tetrahedral holes and we

727
00:17:47,010 --> 00:17:50,330
larger than the tetrahedral holes and we
also said that the number of tetrahedral

728
00:17:50,330 --> 00:17:50,340
also said that the number of tetrahedral

729
00:17:50,340 --> 00:17:53,660
also said that the number of tetrahedral
holes is equal to two times the number

730
00:17:53,660 --> 00:17:53,670
holes is equal to two times the number

731
00:17:53,670 --> 00:17:57,470
holes is equal to two times the number
of metal metal atoms that form that

732
00:17:57,470 --> 00:17:57,480
of metal metal atoms that form that

733
00:17:57,480 --> 00:17:59,270
of metal metal atoms that form that
lattice and the number of octahedral

734
00:17:59,270 --> 00:17:59,280
lattice and the number of octahedral

735
00:17:59,280 --> 00:18:01,400
lattice and the number of octahedral
holes are equal to the number of metal

736
00:18:01,400 --> 00:18:01,410
holes are equal to the number of metal

737
00:18:01,410 --> 00:18:03,950
holes are equal to the number of metal
atoms as a matter of fact so this is how

738
00:18:03,950 --> 00:18:03,960
atoms as a matter of fact so this is how

739
00:18:03,960 --> 00:18:06,890
atoms as a matter of fact so this is how
we can imagine that now with this for

740
00:18:06,890 --> 00:18:06,900
we can imagine that now with this for

741
00:18:06,900 --> 00:18:07,870
we can imagine that now with this for
example

742
00:18:07,870 --> 00:18:07,880
example

743
00:18:07,880 --> 00:18:13,470
example
let's see if I concede here

744
00:18:13,470 --> 00:18:13,480

745
00:18:13,480 --> 00:18:18,340
we can consider for example the sodium

746
00:18:18,340 --> 00:18:18,350
we can consider for example the sodium

747
00:18:18,350 --> 00:18:23,020
we can consider for example the sodium
chloride structure like over here like

748
00:18:23,020 --> 00:18:23,030
chloride structure like over here like

749
00:18:23,030 --> 00:18:24,700
chloride structure like over here like
this let's consider this sodium chloride

750
00:18:24,700 --> 00:18:24,710
this let's consider this sodium chloride

751
00:18:24,710 --> 00:18:26,830
this let's consider this sodium chloride
structure now sodium chloride you have

752
00:18:26,830 --> 00:18:26,840
structure now sodium chloride you have

753
00:18:26,840 --> 00:18:32,080
structure now sodium chloride you have
sodium plus ions and you have chloride

754
00:18:32,080 --> 00:18:32,090
sodium plus ions and you have chloride

755
00:18:32,090 --> 00:18:34,210
sodium plus ions and you have chloride
ions this is definitely much larger than

756
00:18:34,210 --> 00:18:34,220
ions this is definitely much larger than

757
00:18:34,220 --> 00:18:36,670
ions this is definitely much larger than
the sodium chloride ion is much larger

758
00:18:36,670 --> 00:18:36,680
the sodium chloride ion is much larger

759
00:18:36,680 --> 00:18:38,860
the sodium chloride ion is much larger
sodium are smaller so we can think about

760
00:18:38,860 --> 00:18:38,870
sodium are smaller so we can think about

761
00:18:38,870 --> 00:18:43,330
sodium are smaller so we can think about
that the chloride ion forms the cubic

762
00:18:43,330 --> 00:18:43,340
that the chloride ion forms the cubic

763
00:18:43,340 --> 00:18:47,020
that the chloride ion forms the cubic
close packing lattice which have

764
00:18:47,020 --> 00:18:47,030
close packing lattice which have

765
00:18:47,030 --> 00:18:49,390
close packing lattice which have
actually phase centered cubic

766
00:18:49,390 --> 00:18:49,400
actually phase centered cubic

767
00:18:49,400 --> 00:18:52,570
actually phase centered cubic
no yes face centered cubic unit cell

768
00:18:52,570 --> 00:18:52,580
no yes face centered cubic unit cell

769
00:18:52,580 --> 00:18:55,120
no yes face centered cubic unit cell
considering the chloride ions chloride

770
00:18:55,120 --> 00:18:55,130
considering the chloride ions chloride

771
00:18:55,130 --> 00:19:00,760
considering the chloride ions chloride
ions and then the sodium atoms fill into

772
00:19:00,760 --> 00:19:00,770
ions and then the sodium atoms fill into

773
00:19:00,770 --> 00:19:05,440
ions and then the sodium atoms fill into
the octahedral holes fill to the

774
00:19:05,440 --> 00:19:05,450
the octahedral holes fill to the

775
00:19:05,450 --> 00:19:06,460
the octahedral holes fill to the
octahedral holes

776
00:19:06,460 --> 00:19:06,470
octahedral holes

777
00:19:06,470 --> 00:19:10,000
octahedral holes
now remember number of octahedral holes

778
00:19:10,000 --> 00:19:10,010
now remember number of octahedral holes

779
00:19:10,010 --> 00:19:12,730
now remember number of octahedral holes
always equal to the number of atoms that

780
00:19:12,730 --> 00:19:12,740
always equal to the number of atoms that

781
00:19:12,740 --> 00:19:15,250
always equal to the number of atoms that
form the lattice close packed lattice

782
00:19:15,250 --> 00:19:15,260
form the lattice close packed lattice

783
00:19:15,260 --> 00:19:18,130
form the lattice close packed lattice
that means in this case all of the

784
00:19:18,130 --> 00:19:18,140
that means in this case all of the

785
00:19:18,140 --> 00:19:23,350
that means in this case all of the
octahedral holes will be full in a

786
00:19:23,350 --> 00:19:23,360
octahedral holes will be full in a

787
00:19:23,360 --> 00:19:25,810
octahedral holes will be full in a
sodium chloride right all of the

788
00:19:25,810 --> 00:19:25,820
sodium chloride right all of the

789
00:19:25,820 --> 00:19:27,400
sodium chloride right all of the
octahedral was full because the number

790
00:19:27,400 --> 00:19:27,410
octahedral was full because the number

791
00:19:27,410 --> 00:19:29,020
octahedral was full because the number
of octahedral holes equal to the number

792
00:19:29,020 --> 00:19:29,030
of octahedral holes equal to the number

793
00:19:29,030 --> 00:19:31,419
of octahedral holes equal to the number
of atoms that form the letters in this

794
00:19:31,419 --> 00:19:31,429
of atoms that form the letters in this

795
00:19:31,429 --> 00:19:33,430
of atoms that form the letters in this
case the number of atoms actually ions

796
00:19:33,430 --> 00:19:33,440
case the number of atoms actually ions

797
00:19:33,440 --> 00:19:36,790
case the number of atoms actually ions
which is the chloride ions is the one

798
00:19:36,790 --> 00:19:36,800
which is the chloride ions is the one

799
00:19:36,800 --> 00:19:38,830
which is the chloride ions is the one
that formed lattice so that simply means

800
00:19:38,830 --> 00:19:38,840
that formed lattice so that simply means

801
00:19:38,840 --> 00:19:42,669
that formed lattice so that simply means
that one chloride and one sodium ratio

802
00:19:42,669 --> 00:19:42,679
that one chloride and one sodium ratio

803
00:19:42,679 --> 00:19:44,230
that one chloride and one sodium ratio
comes out for the sodium chloride

804
00:19:44,230 --> 00:19:44,240
comes out for the sodium chloride

805
00:19:44,240 --> 00:19:48,250
comes out for the sodium chloride
structure now then if you consider the

806
00:19:48,250 --> 00:19:48,260
structure now then if you consider the

807
00:19:48,260 --> 00:19:50,620
structure now then if you consider the
zinc sulfide again again the zinc

808
00:19:50,620 --> 00:19:50,630
zinc sulfide again again the zinc

809
00:19:50,630 --> 00:19:55,000
zinc sulfide again again the zinc
sulfide we have zinc two plus and the

810
00:19:55,000 --> 00:19:55,010
sulfide we have zinc two plus and the

811
00:19:55,010 --> 00:19:57,370
sulfide we have zinc two plus and the
sulfide 2 minus ions here

812
00:19:57,370 --> 00:19:57,380
sulfide 2 minus ions here

813
00:19:57,380 --> 00:20:00,850
sulfide 2 minus ions here
here again the sulfide is much bigger

814
00:20:00,850 --> 00:20:00,860
here again the sulfide is much bigger

815
00:20:00,860 --> 00:20:04,360
here again the sulfide is much bigger
than the zinc two plus ion so the zinc

816
00:20:04,360 --> 00:20:04,370
than the zinc two plus ion so the zinc

817
00:20:04,370 --> 00:20:07,750
than the zinc two plus ion so the zinc
actually sulfide ion actually will form

818
00:20:07,750 --> 00:20:07,760
actually sulfide ion actually will form

819
00:20:07,760 --> 00:20:14,350
actually sulfide ion actually will form
the closed pack structure and the zinc 2

820
00:20:14,350 --> 00:20:14,360
the closed pack structure and the zinc 2

821
00:20:14,360 --> 00:20:17,620
the closed pack structure and the zinc 2
plus cation will fill in the detector he

822
00:20:17,620 --> 00:20:17,630
plus cation will fill in the detector he

823
00:20:17,630 --> 00:20:22,150
plus cation will fill in the detector he
drew holes right now this way again you

824
00:20:22,150 --> 00:20:22,160
drew holes right now this way again you

825
00:20:22,160 --> 00:20:26,250
drew holes right now this way again you
see in nature try to

826
00:20:26,250 --> 00:20:26,260
see in nature try to

827
00:20:26,260 --> 00:20:31,180
see in nature try to
use the space with the maximum

828
00:20:31,180 --> 00:20:31,190
use the space with the maximum

829
00:20:31,190 --> 00:20:32,950
use the space with the maximum
efficiency to get the highest density

830
00:20:32,950 --> 00:20:32,960
efficiency to get the highest density

831
00:20:32,960 --> 00:20:36,039
efficiency to get the highest density
right so this way you know the the empty

832
00:20:36,039 --> 00:20:36,049
right so this way you know the the empty

833
00:20:36,049 --> 00:20:38,080
right so this way you know the the empty
spaces between the atoms are also

834
00:20:38,080 --> 00:20:38,090
spaces between the atoms are also

835
00:20:38,090 --> 00:20:40,860
spaces between the atoms are also
partially fueled and that is the

836
00:20:40,860 --> 00:20:40,870
partially fueled and that is the

837
00:20:40,870 --> 00:20:43,330
partially fueled and that is the
structure of the zinc sulfide this is

838
00:20:43,330 --> 00:20:43,340
structure of the zinc sulfide this is

839
00:20:43,340 --> 00:20:46,029
structure of the zinc sulfide this is
called zinc blende actually zinc sulfide

840
00:20:46,029 --> 00:20:46,039
called zinc blende actually zinc sulfide

841
00:20:46,039 --> 00:20:51,610
called zinc blende actually zinc sulfide
now let's think about this way let's

842
00:20:51,610 --> 00:20:51,620
now let's think about this way let's

843
00:20:51,620 --> 00:20:53,470
now let's think about this way let's
assume that the sodium chloride

844
00:20:53,470 --> 00:20:53,480
assume that the sodium chloride

845
00:20:53,480 --> 00:20:57,039
assume that the sodium chloride
structure chlorides forming the cubic

846
00:20:57,039 --> 00:20:57,049
structure chlorides forming the cubic

847
00:20:57,049 --> 00:20:59,460
structure chlorides forming the cubic
close pack structure that means that the

848
00:20:59,460 --> 00:20:59,470
close pack structure that means that the

849
00:20:59,470 --> 00:21:02,560
close pack structure that means that the
unit cell with respect to the chloride

850
00:21:02,560 --> 00:21:02,570
unit cell with respect to the chloride

851
00:21:02,570 --> 00:21:05,769
unit cell with respect to the chloride
ion is face centered cubic so how many

852
00:21:05,769 --> 00:21:05,779
ion is face centered cubic so how many

853
00:21:05,779 --> 00:21:09,159
ion is face centered cubic so how many
unit cell belongs to it lets ability

854
00:21:09,159 --> 00:21:09,169
unit cell belongs to it lets ability

855
00:21:09,169 --> 00:21:11,680
unit cell belongs to it lets ability
this way how many chloride ions belongs

856
00:21:11,680 --> 00:21:11,690
this way how many chloride ions belongs

857
00:21:11,690 --> 00:21:19,659
this way how many chloride ions belongs
to one unit cell only chloride ion how

858
00:21:19,659 --> 00:21:19,669
to one unit cell only chloride ion how

859
00:21:19,669 --> 00:21:23,230
to one unit cell only chloride ion how
many four because it is face centered

860
00:21:23,230 --> 00:21:23,240
many four because it is face centered

861
00:21:23,240 --> 00:21:25,480
many four because it is face centered
cubic with respect to the chloride

862
00:21:25,480 --> 00:21:25,490
cubic with respect to the chloride

863
00:21:25,490 --> 00:21:27,430
cubic with respect to the chloride
remember the face centered cubic has

864
00:21:27,430 --> 00:21:27,440
remember the face centered cubic has

865
00:21:27,440 --> 00:21:31,299
remember the face centered cubic has
four atoms or four atoms make one face

866
00:21:31,299 --> 00:21:31,309
four atoms or four atoms make one face

867
00:21:31,309 --> 00:21:33,310
four atoms or four atoms make one face
centered cubic now let me ask you this

868
00:21:33,310 --> 00:21:33,320
centered cubic now let me ask you this

869
00:21:33,320 --> 00:21:37,629
centered cubic now let me ask you this
how many octahedral holes will be

870
00:21:37,629 --> 00:21:37,639
how many octahedral holes will be

871
00:21:37,639 --> 00:21:42,730
how many octahedral holes will be
present in one unit cell for exactly

872
00:21:42,730 --> 00:21:42,740
present in one unit cell for exactly

873
00:21:42,740 --> 00:21:44,019
present in one unit cell for exactly
because we said that the number of

874
00:21:44,019 --> 00:21:44,029
because we said that the number of

875
00:21:44,029 --> 00:21:45,700
because we said that the number of
updater laws equals the number of atoms

876
00:21:45,700 --> 00:21:45,710
updater laws equals the number of atoms

877
00:21:45,710 --> 00:21:48,690
updater laws equals the number of atoms
that form the letters for chloride for

878
00:21:48,690 --> 00:21:48,700
that form the letters for chloride for

879
00:21:48,700 --> 00:21:52,330
that form the letters for chloride for
Octavia laws so now when you have all

880
00:21:52,330 --> 00:21:52,340
Octavia laws so now when you have all

881
00:21:52,340 --> 00:21:55,779
Octavia laws so now when you have all
the octahedral holes are full with

882
00:21:55,779 --> 00:21:55,789
the octahedral holes are full with

883
00:21:55,789 --> 00:21:58,899
the octahedral holes are full with
sodium ion that means in one unit cell

884
00:21:58,899 --> 00:21:58,909
sodium ion that means in one unit cell

885
00:21:58,909 --> 00:22:03,879
sodium ion that means in one unit cell
how many sodium ion for so the unit cell

886
00:22:03,879 --> 00:22:03,889
how many sodium ion for so the unit cell

887
00:22:03,889 --> 00:22:08,560
how many sodium ion for so the unit cell
of sodium chloride contains four

888
00:22:08,560 --> 00:22:08,570
of sodium chloride contains four

889
00:22:08,570 --> 00:22:12,970
of sodium chloride contains four
chloride and for sodium ion right but

890
00:22:12,970 --> 00:22:12,980
chloride and for sodium ion right but

891
00:22:12,980 --> 00:22:15,490
chloride and for sodium ion right but
remember the ionic compounds do not have

892
00:22:15,490 --> 00:22:15,500
remember the ionic compounds do not have

893
00:22:15,500 --> 00:22:17,500
remember the ionic compounds do not have
molecules so the formula of those

894
00:22:17,500 --> 00:22:17,510
molecules so the formula of those

895
00:22:17,510 --> 00:22:19,000
molecules so the formula of those
compounds are not called molecular

896
00:22:19,000 --> 00:22:19,010
compounds are not called molecular

897
00:22:19,010 --> 00:22:21,009
compounds are not called molecular
formula but they are called the unit

898
00:22:21,009 --> 00:22:21,019
formula but they are called the unit

899
00:22:21,019 --> 00:22:24,720
formula but they are called the unit
formula so the actually the sodium

900
00:22:24,720 --> 00:22:24,730
formula so the actually the sodium

901
00:22:24,730 --> 00:22:28,389
formula so the actually the sodium
chloride lattice will be represented as

902
00:22:28,389 --> 00:22:28,399
chloride lattice will be represented as

903
00:22:28,399 --> 00:22:32,200
chloride lattice will be represented as
sodium for chloride for but the simplest

904
00:22:32,200 --> 00:22:32,210
sodium for chloride for but the simplest

905
00:22:32,210 --> 00:22:33,820
sodium for chloride for but the simplest
form of that one stood in one chloride

906
00:22:33,820 --> 00:22:33,830
form of that one stood in one chloride

907
00:22:33,830 --> 00:22:35,710
form of that one stood in one chloride
that is the formula of the sodium

908
00:22:35,710 --> 00:22:35,720
that is the formula of the sodium

909
00:22:35,720 --> 00:22:39,170
that is the formula of the sodium
chloride now in the case of zinc

910
00:22:39,170 --> 00:22:39,180
chloride now in the case of zinc

911
00:22:39,180 --> 00:22:43,490
chloride now in the case of zinc
sulphide actually how many tetrahedral

912
00:22:43,490 --> 00:22:43,500
sulphide actually how many tetrahedral

913
00:22:43,500 --> 00:22:45,380
sulphide actually how many tetrahedral
holes it's difficult to see it here but

914
00:22:45,380 --> 00:22:45,390
holes it's difficult to see it here but

915
00:22:45,390 --> 00:22:47,420
holes it's difficult to see it here but
there is actually tetrahedral holes

916
00:22:47,420 --> 00:22:47,430
there is actually tetrahedral holes

917
00:22:47,430 --> 00:22:48,110
there is actually tetrahedral holes
there

918
00:22:48,110 --> 00:22:48,120
there

919
00:22:48,120 --> 00:22:51,200
there
how many tetrahedral holes will be exact

920
00:22:51,200 --> 00:22:51,210
how many tetrahedral holes will be exact

921
00:22:51,210 --> 00:22:54,560
how many tetrahedral holes will be exact
zinc sulphide if the sulphide forms the

922
00:22:54,560 --> 00:22:54,570
zinc sulphide if the sulphide forms the

923
00:22:54,570 --> 00:23:00,440
zinc sulphide if the sulphide forms the
face centered cubic unit cell eight

924
00:23:00,440 --> 00:23:00,450
face centered cubic unit cell eight

925
00:23:00,450 --> 00:23:03,230
face centered cubic unit cell eight
right because the number of tetrahedral

926
00:23:03,230 --> 00:23:03,240
right because the number of tetrahedral

927
00:23:03,240 --> 00:23:05,000
right because the number of tetrahedral
holes is two times as the number of

928
00:23:05,000 --> 00:23:05,010
holes is two times as the number of

929
00:23:05,010 --> 00:23:08,450
holes is two times as the number of
spheres that we knew packing so eight

930
00:23:08,450 --> 00:23:08,460
spheres that we knew packing so eight

931
00:23:08,460 --> 00:23:13,030
spheres that we knew packing so eight
but in this case these eight actually

932
00:23:13,030 --> 00:23:13,040
but in this case these eight actually

933
00:23:13,040 --> 00:23:17,330
but in this case these eight actually
tetrahedral holes in this unit cell in

934
00:23:17,330 --> 00:23:17,340
tetrahedral holes in this unit cell in

935
00:23:17,340 --> 00:23:20,900
tetrahedral holes in this unit cell in
this cube are at this corner that corner

936
00:23:20,900 --> 00:23:20,910
this cube are at this corner that corner

937
00:23:20,910 --> 00:23:22,850
this cube are at this corner that corner
not exactly corner but some somewhere

938
00:23:22,850 --> 00:23:22,860
not exactly corner but some somewhere

939
00:23:22,860 --> 00:23:26,300
not exactly corner but some somewhere
inside over here here here here there

940
00:23:26,300 --> 00:23:26,310
inside over here here here here there

941
00:23:26,310 --> 00:23:28,850
inside over here here here here there
and then also form or below there eight

942
00:23:28,850 --> 00:23:28,860
and then also form or below there eight

943
00:23:28,860 --> 00:23:32,720
and then also form or below there eight
but in the zinc sulphide only half of

944
00:23:32,720 --> 00:23:32,730
but in the zinc sulphide only half of

945
00:23:32,730 --> 00:23:36,800
but in the zinc sulphide only half of
those tetrahedral holes are full with

946
00:23:36,800 --> 00:23:36,810
those tetrahedral holes are full with

947
00:23:36,810 --> 00:23:39,110
those tetrahedral holes are full with
zinc two plus iron the other half is

948
00:23:39,110 --> 00:23:39,120
zinc two plus iron the other half is

949
00:23:39,120 --> 00:23:41,720
zinc two plus iron the other half is
empty why because the formula actually

950
00:23:41,720 --> 00:23:41,730
empty why because the formula actually

951
00:23:41,730 --> 00:23:45,620
empty why because the formula actually
the ratio of the zinc two plus ion to

952
00:23:45,620 --> 00:23:45,630
the ratio of the zinc two plus ion to

953
00:23:45,630 --> 00:23:49,220
the ratio of the zinc two plus ion to
the sulfide has to be one right from the

954
00:23:49,220 --> 00:23:49,230
the sulfide has to be one right from the

955
00:23:49,230 --> 00:23:52,030
the sulfide has to be one right from the
formula so only half of that is full and

956
00:23:52,030 --> 00:23:52,040
formula so only half of that is full and

957
00:23:52,040 --> 00:23:55,220
formula so only half of that is full and
with the zinc sulfide now the question

958
00:23:55,220 --> 00:23:55,230
with the zinc sulfide now the question

959
00:23:55,230 --> 00:24:00,190
with the zinc sulfide now the question
here is what determines where the

960
00:24:00,190 --> 00:24:00,200
here is what determines where the

961
00:24:00,200 --> 00:24:03,530
here is what determines where the
smaller cation will go octahedral or

962
00:24:03,530 --> 00:24:03,540
smaller cation will go octahedral or

963
00:24:03,540 --> 00:24:10,000
smaller cation will go octahedral or
tetrahedral for example in a case of the

964
00:24:10,000 --> 00:24:10,010

965
00:24:10,010 --> 00:24:12,830
sodium chloride structure we said the

966
00:24:12,830 --> 00:24:12,840
sodium chloride structure we said the

967
00:24:12,840 --> 00:24:15,890
sodium chloride structure we said the
sodium plus goes into the octahedral

968
00:24:15,890 --> 00:24:15,900
sodium plus goes into the octahedral

969
00:24:15,900 --> 00:24:17,900
sodium plus goes into the octahedral
holes fills the octahedral holes but the

970
00:24:17,900 --> 00:24:17,910
holes fills the octahedral holes but the

971
00:24:17,910 --> 00:24:19,610
holes fills the octahedral holes but the
zinc sulphide goes in a tetrahedral

972
00:24:19,610 --> 00:24:19,620
zinc sulphide goes in a tetrahedral

973
00:24:19,620 --> 00:24:23,180
zinc sulphide goes in a tetrahedral
holes and the factor which determines

974
00:24:23,180 --> 00:24:23,190
holes and the factor which determines

975
00:24:23,190 --> 00:24:29,120
holes and the factor which determines
that is the size ratio of positive and

976
00:24:29,120 --> 00:24:29,130
that is the size ratio of positive and

977
00:24:29,130 --> 00:24:35,830
that is the size ratio of positive and
negatively charged ions if actually R +

978
00:24:35,830 --> 00:24:35,840
negatively charged ions if actually R +

979
00:24:35,840 --> 00:24:40,190
negatively charged ions if actually R +
/ r minus that means radius of the

980
00:24:40,190 --> 00:24:40,200
/ r minus that means radius of the

981
00:24:40,200 --> 00:24:43,250
/ r minus that means radius of the
positively charged smaller to the radius

982
00:24:43,250 --> 00:24:43,260
positively charged smaller to the radius

983
00:24:43,260 --> 00:24:47,180
positively charged smaller to the radius
of the negatively charged is about equal

984
00:24:47,180 --> 00:24:47,190
of the negatively charged is about equal

985
00:24:47,190 --> 00:24:50,360
of the negatively charged is about equal
to or less than I should probably say

986
00:24:50,360 --> 00:24:50,370
to or less than I should probably say

987
00:24:50,370 --> 00:24:52,180
to or less than I should probably say
two point

988
00:24:52,180 --> 00:24:52,190
two point

989
00:24:52,190 --> 00:24:59,200
two point
two-five then the iron will go into the

990
00:24:59,200 --> 00:24:59,210
two-five then the iron will go into the

991
00:24:59,210 --> 00:25:04,610
two-five then the iron will go into the
tetrahedral holes right now when it goes

992
00:25:04,610 --> 00:25:04,620
tetrahedral holes right now when it goes

993
00:25:04,620 --> 00:25:06,320
tetrahedral holes right now when it goes
into the tetrahedral holes what really

994
00:25:06,320 --> 00:25:06,330
into the tetrahedral holes what really

995
00:25:06,330 --> 00:25:08,690
into the tetrahedral holes what really
happens in that case it doesn't leave

996
00:25:08,690 --> 00:25:08,700
happens in that case it doesn't leave

997
00:25:08,700 --> 00:25:10,280
happens in that case it doesn't leave
really disturb the close-packed

998
00:25:10,280 --> 00:25:10,290
really disturb the close-packed

999
00:25:10,290 --> 00:25:13,280
really disturb the close-packed
structure it doesn't push away the other

1000
00:25:13,280 --> 00:25:13,290
structure it doesn't push away the other

1001
00:25:13,290 --> 00:25:15,530
structure it doesn't push away the other
atoms for example chloride ions if it is

1002
00:25:15,530 --> 00:25:15,540
atoms for example chloride ions if it is

1003
00:25:15,540 --> 00:25:17,750
atoms for example chloride ions if it is
exactly equal to that but in the case of

1004
00:25:17,750 --> 00:25:17,760
exactly equal to that but in the case of

1005
00:25:17,760 --> 00:25:21,350
exactly equal to that but in the case of
sodium this ratio is bigger than that

1006
00:25:21,350 --> 00:25:21,360
sodium this ratio is bigger than that

1007
00:25:21,360 --> 00:25:24,020
sodium this ratio is bigger than that
what does that means that means that in

1008
00:25:24,020 --> 00:25:24,030
what does that means that means that in

1009
00:25:24,030 --> 00:25:31,549
what does that means that means that in
this structure over here if I ever find

1010
00:25:31,549 --> 00:25:31,559
this structure over here if I ever find

1011
00:25:31,559 --> 00:25:34,700
this structure over here if I ever find
my okay in this structure over here that

1012
00:25:34,700 --> 00:25:34,710
my okay in this structure over here that

1013
00:25:34,710 --> 00:25:38,510
my okay in this structure over here that
means that chloride ions I'm not

1014
00:25:38,510 --> 00:25:38,520
means that chloride ions I'm not

1015
00:25:38,520 --> 00:25:40,660
means that chloride ions I'm not
touching each other

1016
00:25:40,660 --> 00:25:40,670
touching each other

1017
00:25:40,670 --> 00:25:43,100
touching each other
remember in close packed structure all

1018
00:25:43,100 --> 00:25:43,110
remember in close packed structure all

1019
00:25:43,110 --> 00:25:45,140
remember in close packed structure all
the spheres has to touch the each other

1020
00:25:45,140 --> 00:25:45,150
the spheres has to touch the each other

1021
00:25:45,150 --> 00:25:47,660
the spheres has to touch the each other
right why doesn't touch each other

1022
00:25:47,660 --> 00:25:47,670
right why doesn't touch each other

1023
00:25:47,670 --> 00:25:50,150
right why doesn't touch each other
because when the sodium goes into the

1024
00:25:50,150 --> 00:25:50,160
because when the sodium goes into the

1025
00:25:50,160 --> 00:25:53,120
because when the sodium goes into the
octahedral holes that ratio is a little

1026
00:25:53,120 --> 00:25:53,130
octahedral holes that ratio is a little

1027
00:25:53,130 --> 00:25:55,669
octahedral holes that ratio is a little
bit bigger than that and what that

1028
00:25:55,669 --> 00:25:55,679
bit bigger than that and what that

1029
00:25:55,679 --> 00:25:58,430
bit bigger than that and what that
happen that makes that push the chloride

1030
00:25:58,430 --> 00:25:58,440
happen that makes that push the chloride

1031
00:25:58,440 --> 00:26:00,740
happen that makes that push the chloride
ions a little bit away from each other

1032
00:26:00,740 --> 00:26:00,750
ions a little bit away from each other

1033
00:26:00,750 --> 00:26:06,140
ions a little bit away from each other
right but still you know pretty good

1034
00:26:06,140 --> 00:26:06,150
right but still you know pretty good

1035
00:26:06,150 --> 00:26:08,270
right but still you know pretty good
efficiency of packing there considering

1036
00:26:08,270 --> 00:26:08,280
efficiency of packing there considering

1037
00:26:08,280 --> 00:26:11,210
efficiency of packing there considering
that the empty holes are fueled by the

1038
00:26:11,210 --> 00:26:11,220
that the empty holes are fueled by the

1039
00:26:11,220 --> 00:26:14,299
that the empty holes are fueled by the
sodium plus ion again now if the ratio

1040
00:26:14,299 --> 00:26:14,309
sodium plus ion again now if the ratio

1041
00:26:14,309 --> 00:26:20,419
sodium plus ion again now if the ratio
of a plus a minus is greater than or

1042
00:26:20,419 --> 00:26:20,429
of a plus a minus is greater than or

1043
00:26:20,429 --> 00:26:25,690
of a plus a minus is greater than or
about somewhere about like 0.41

1044
00:26:25,690 --> 00:26:25,700
about somewhere about like 0.41

1045
00:26:25,700 --> 00:26:28,160
about somewhere about like 0.41
somewhere about there I can't remember

1046
00:26:28,160 --> 00:26:28,170
somewhere about there I can't remember

1047
00:26:28,170 --> 00:26:30,740
somewhere about there I can't remember
exactly for - I think this is somewhere

1048
00:26:30,740 --> 00:26:30,750
exactly for - I think this is somewhere

1049
00:26:30,750 --> 00:26:34,490
exactly for - I think this is somewhere
now if the this ratio is bigger than

1050
00:26:34,490 --> 00:26:34,500
now if the this ratio is bigger than

1051
00:26:34,500 --> 00:26:37,280
now if the this ratio is bigger than
that then it goes into the tetrahedral

1052
00:26:37,280 --> 00:26:37,290
that then it goes into the tetrahedral

1053
00:26:37,290 --> 00:26:40,990
that then it goes into the tetrahedral
holes no sorry

1054
00:26:40,990 --> 00:26:41,000
holes no sorry

1055
00:26:41,000 --> 00:26:44,900
holes no sorry
octahedral goes octahedrons okay I guess

1056
00:26:44,900 --> 00:26:44,910
octahedral goes octahedrons okay I guess

1057
00:26:44,910 --> 00:26:48,740
octahedral goes octahedrons okay I guess
we have simply confused here with the

1058
00:26:48,740 --> 00:26:48,750
we have simply confused here with the

1059
00:26:48,750 --> 00:26:50,780
we have simply confused here with the
sodium chloride and zinc sulphide

1060
00:26:50,780 --> 00:26:50,790
sodium chloride and zinc sulphide

1061
00:26:50,790 --> 00:26:54,380
sodium chloride and zinc sulphide
structure now this is for tetrahedral

1062
00:26:54,380 --> 00:26:54,390
structure now this is for tetrahedral

1063
00:26:54,390 --> 00:26:58,040
structure now this is for tetrahedral
hole this is for octahedral hole so that

1064
00:26:58,040 --> 00:26:58,050
hole this is for octahedral hole so that

1065
00:26:58,050 --> 00:27:01,970
hole this is for octahedral hole so that
means that this ratio is for the zinc

1066
00:27:01,970 --> 00:27:01,980
means that this ratio is for the zinc

1067
00:27:01,980 --> 00:27:05,420
means that this ratio is for the zinc
sulphide that is zinc over sulfide ratio

1068
00:27:05,420 --> 00:27:05,430
sulphide that is zinc over sulfide ratio

1069
00:27:05,430 --> 00:27:08,080
sulphide that is zinc over sulfide ratio
actually bigger than that and that's

1070
00:27:08,080 --> 00:27:08,090
actually bigger than that and that's

1071
00:27:08,090 --> 00:27:10,100
actually bigger than that and that's
sulfides are not touching each other

1072
00:27:10,100 --> 00:27:10,110
sulfides are not touching each other

1073
00:27:10,110 --> 00:27:12,950
sulfides are not touching each other
because that ratio is bigger now this is

1074
00:27:12,950 --> 00:27:12,960
because that ratio is bigger now this is

1075
00:27:12,960 --> 00:27:16,280
because that ratio is bigger now this is
for the sodium chloride cases because

1076
00:27:16,280 --> 00:27:16,290
for the sodium chloride cases because

1077
00:27:16,290 --> 00:27:18,890
for the sodium chloride cases because
the ratio is bigger than that and the

1078
00:27:18,890 --> 00:27:18,900
the ratio is bigger than that and the

1079
00:27:18,900 --> 00:27:21,170
the ratio is bigger than that and the
sodium goes into the octahedral holes

1080
00:27:21,170 --> 00:27:21,180
sodium goes into the octahedral holes

1081
00:27:21,180 --> 00:27:23,990
sodium goes into the octahedral holes
here zinc 2 plus goes into T 2 8 rolls

1082
00:27:23,990 --> 00:27:24,000
here zinc 2 plus goes into T 2 8 rolls

1083
00:27:24,000 --> 00:27:27,170
here zinc 2 plus goes into T 2 8 rolls
zinc 2 plus is smaller than sodium plus

1084
00:27:27,170 --> 00:27:27,180
zinc 2 plus is smaller than sodium plus

1085
00:27:27,180 --> 00:27:30,080
zinc 2 plus is smaller than sodium plus
actually right and the sulfide is big -

1086
00:27:30,080 --> 00:27:30,090
actually right and the sulfide is big -

1087
00:27:30,090 --> 00:27:33,290
actually right and the sulfide is big -
2 - sulfide is pretty big bigger than

1088
00:27:33,290 --> 00:27:33,300
2 - sulfide is pretty big bigger than

1089
00:27:33,300 --> 00:27:35,720
2 - sulfide is pretty big bigger than
the chloride and so on so this is how we

1090
00:27:35,720 --> 00:27:35,730
the chloride and so on so this is how we

1091
00:27:35,730 --> 00:27:40,549
the chloride and so on so this is how we
can imagine the ionic structures ionic

1092
00:27:40,549 --> 00:27:40,559
can imagine the ionic structures ionic

1093
00:27:40,559 --> 00:27:44,150
can imagine the ionic structures ionic
solid actually and we can calculate and

1094
00:27:44,150 --> 00:27:44,160
solid actually and we can calculate and

1095
00:27:44,160 --> 00:27:49,250
solid actually and we can calculate and
the number of ions that belong to one

1096
00:27:49,250 --> 00:27:49,260
the number of ions that belong to one

1097
00:27:49,260 --> 00:27:52,730
the number of ions that belong to one
unit cell let's for example take that

1098
00:27:52,730 --> 00:27:52,740
unit cell let's for example take that

1099
00:27:52,740 --> 00:27:55,640
unit cell let's for example take that
for sodium chloride now this is the

1100
00:27:55,640 --> 00:27:55,650
for sodium chloride now this is the

1101
00:27:55,650 --> 00:27:57,560
for sodium chloride now this is the
sodium chloride now sodium chloride

1102
00:27:57,560 --> 00:27:57,570
sodium chloride now sodium chloride

1103
00:27:57,570 --> 00:28:01,460
sodium chloride now sodium chloride
structure is as again as follow chloride

1104
00:28:01,460 --> 00:28:01,470
structure is as again as follow chloride

1105
00:28:01,470 --> 00:28:06,140
structure is as again as follow chloride
forms the face centered unit cell cubic

1106
00:28:06,140 --> 00:28:06,150
forms the face centered unit cell cubic

1107
00:28:06,150 --> 00:28:10,930
forms the face centered unit cell cubic
unit cell and the sodium goes into the

1108
00:28:10,930 --> 00:28:10,940
unit cell and the sodium goes into the

1109
00:28:10,940 --> 00:28:14,390
unit cell and the sodium goes into the
octahedral holes but now the octahedral

1110
00:28:14,390 --> 00:28:14,400
octahedral holes but now the octahedral

1111
00:28:14,400 --> 00:28:16,370
octahedral holes but now the octahedral
holes are here one is in the middle

1112
00:28:16,370 --> 00:28:16,380
holes are here one is in the middle

1113
00:28:16,380 --> 00:28:20,030
holes are here one is in the middle
right there in the middle of this unit

1114
00:28:20,030 --> 00:28:20,040
right there in the middle of this unit

1115
00:28:20,040 --> 00:28:22,280
right there in the middle of this unit
cell face centered cubic unit cell and

1116
00:28:22,280 --> 00:28:22,290
cell face centered cubic unit cell and

1117
00:28:22,290 --> 00:28:25,280
cell face centered cubic unit cell and
now the other one is here in the middle

1118
00:28:25,280 --> 00:28:25,290
now the other one is here in the middle

1119
00:28:25,290 --> 00:28:27,830
now the other one is here in the middle
of edge and this is in the middle of

1120
00:28:27,830 --> 00:28:27,840
of edge and this is in the middle of

1121
00:28:27,840 --> 00:28:29,810
of edge and this is in the middle of
edge and so on all on the middle of

1122
00:28:29,810 --> 00:28:29,820
edge and so on all on the middle of

1123
00:28:29,820 --> 00:28:35,950
edge and so on all on the middle of
edges so if I calculate the number of

1124
00:28:35,950 --> 00:28:35,960
edges so if I calculate the number of

1125
00:28:35,960 --> 00:28:39,830
edges so if I calculate the number of
chloride in sodium chloride unit cell

1126
00:28:39,830 --> 00:28:39,840
chloride in sodium chloride unit cell

1127
00:28:39,840 --> 00:28:48,100
chloride in sodium chloride unit cell
let's say unit cell so again I have

1128
00:28:48,100 --> 00:28:48,110

1129
00:28:48,110 --> 00:28:51,410
chloride cases that say chloride - iron

1130
00:28:51,410 --> 00:28:51,420
chloride cases that say chloride - iron

1131
00:28:51,420 --> 00:28:55,669
chloride cases that say chloride - iron
1 over 8 times 8 form the corner this is

1132
00:28:55,669 --> 00:28:55,679
1 over 8 times 8 form the corner this is

1133
00:28:55,679 --> 00:29:01,840
1 over 8 times 8 form the corner this is
one from there and the again 1 over 2

1134
00:29:01,840 --> 00:29:01,850
one from there and the again 1 over 2

1135
00:29:01,850 --> 00:29:05,630
one from there and the again 1 over 2
times 6 middle of faces this is equal to

1136
00:29:05,630 --> 00:29:05,640
times 6 middle of faces this is equal to

1137
00:29:05,640 --> 00:29:10,340
times 6 middle of faces this is equal to
3 so we have simply four chloride ions

1138
00:29:10,340 --> 00:29:10,350
3 so we have simply four chloride ions

1139
00:29:10,350 --> 00:29:13,220
3 so we have simply four chloride ions
if I simply take now the sodium eye and

1140
00:29:13,220 --> 00:29:13,230
if I simply take now the sodium eye and

1141
00:29:13,230 --> 00:29:15,500
if I simply take now the sodium eye and
calculate the number of sodium ion per

1142
00:29:15,500 --> 00:29:15,510
calculate the number of sodium ion per

1143
00:29:15,510 --> 00:29:19,330
calculate the number of sodium ion per
unit cell that would be again as follow

1144
00:29:19,330 --> 00:29:19,340
unit cell that would be again as follow

1145
00:29:19,340 --> 00:29:23,030
unit cell that would be again as follow
one will be from the center that belongs

1146
00:29:23,030 --> 00:29:23,040
one will be from the center that belongs

1147
00:29:23,040 --> 00:29:26,000
one will be from the center that belongs
to this unit cell which is right in the

1148
00:29:26,000 --> 00:29:26,010
to this unit cell which is right in the

1149
00:29:26,010 --> 00:29:28,810
to this unit cell which is right in the
middle of here there in octahedral holes

1150
00:29:28,810 --> 00:29:28,820
middle of here there in octahedral holes

1151
00:29:28,820 --> 00:29:34,990
middle of here there in octahedral holes
one sodium octahedral hole Center and

1152
00:29:34,990 --> 00:29:35,000
one sodium octahedral hole Center and

1153
00:29:35,000 --> 00:29:43,450
one sodium octahedral hole Center and
then we have simply one at the middle of

1154
00:29:43,450 --> 00:29:43,460
then we have simply one at the middle of

1155
00:29:43,460 --> 00:29:49,730
then we have simply one at the middle of
edges now the edge will be shared by how

1156
00:29:49,730 --> 00:29:49,740
edges now the edge will be shared by how

1157
00:29:49,740 --> 00:29:51,920
edges now the edge will be shared by how
many unit cell how many coop in three

1158
00:29:51,920 --> 00:29:51,930
many unit cell how many coop in three

1159
00:29:51,930 --> 00:30:03,880
many unit cell how many coop in three
dimension edge like this how many no

1160
00:30:03,880 --> 00:30:03,890
dimension edge like this how many no

1161
00:30:03,890 --> 00:30:07,130
dimension edge like this how many no
four right because this edge will be

1162
00:30:07,130 --> 00:30:07,140
four right because this edge will be

1163
00:30:07,140 --> 00:30:11,180
four right because this edge will be
shared by unit cell here by unit cell

1164
00:30:11,180 --> 00:30:11,190
shared by unit cell here by unit cell

1165
00:30:11,190 --> 00:30:14,750
shared by unit cell here by unit cell
here and up here and up there right four

1166
00:30:14,750 --> 00:30:14,760
here and up here and up there right four

1167
00:30:14,760 --> 00:30:19,670
here and up here and up there right four
so I have simply from the edges I will

1168
00:30:19,670 --> 00:30:19,680
so I have simply from the edges I will

1169
00:30:19,680 --> 00:30:24,250
so I have simply from the edges I will
have 1 over 4 and how many edge we have

1170
00:30:24,250 --> 00:30:24,260
have 1 over 4 and how many edge we have

1171
00:30:24,260 --> 00:30:26,420
have 1 over 4 and how many edge we have
12 right

1172
00:30:26,420 --> 00:30:26,430
12 right

1173
00:30:26,430 --> 00:30:30,010
12 right
and that times 12 and that makes three

1174
00:30:30,010 --> 00:30:30,020
and that times 12 and that makes three

1175
00:30:30,020 --> 00:30:34,610
and that times 12 and that makes three
sodium these are the edges here so if I

1176
00:30:34,610 --> 00:30:34,620
sodium these are the edges here so if I

1177
00:30:34,620 --> 00:30:38,780
sodium these are the edges here so if I
simply add them up I have 4 so again you

1178
00:30:38,780 --> 00:30:38,790
simply add them up I have 4 so again you

1179
00:30:38,790 --> 00:30:41,780
simply add them up I have 4 so again you
see in one unit cell sodium chloride I

1180
00:30:41,780 --> 00:30:41,790
see in one unit cell sodium chloride I

1181
00:30:41,790 --> 00:30:46,430
see in one unit cell sodium chloride I
have 4 chlorides and for sodium atom

1182
00:30:46,430 --> 00:30:46,440
have 4 chlorides and for sodium atom

1183
00:30:46,440 --> 00:30:48,620
have 4 chlorides and for sodium atom
actually if I would like to represent

1184
00:30:48,620 --> 00:30:48,630
actually if I would like to represent

1185
00:30:48,630 --> 00:30:50,480
actually if I would like to represent
the formula of a unit cell and sodium

1186
00:30:50,480 --> 00:30:50,490
the formula of a unit cell and sodium

1187
00:30:50,490 --> 00:30:52,490
the formula of a unit cell and sodium
chloride structure will be sodium for

1188
00:30:52,490 --> 00:30:52,500
chloride structure will be sodium for

1189
00:30:52,500 --> 00:30:56,480
chloride structure will be sodium for
chloride for right like this now zinc

1190
00:30:56,480 --> 00:30:56,490
chloride for right like this now zinc

1191
00:30:56,490 --> 00:30:59,210
chloride for right like this now zinc
sulphide cases we can also calculate

1192
00:30:59,210 --> 00:30:59,220
sulphide cases we can also calculate

1193
00:30:59,220 --> 00:31:01,670
sulphide cases we can also calculate
that but tetrahedral holes in this case

1194
00:31:01,670 --> 00:31:01,680
that but tetrahedral holes in this case

1195
00:31:01,680 --> 00:31:04,640
that but tetrahedral holes in this case
are all inside of this and there are 4

1196
00:31:04,640 --> 00:31:04,650
are all inside of this and there are 4

1197
00:31:04,650 --> 00:31:12,260
are all inside of this and there are 4
sulfides and 4 actually zinc 2 plus and

1198
00:31:12,260 --> 00:31:12,270
sulfides and 4 actually zinc 2 plus and

1199
00:31:12,270 --> 00:31:16,480
sulfides and 4 actually zinc 2 plus and
the formula again 1 zinc and 1 sulfide

1200
00:31:16,480 --> 00:31:16,490
the formula again 1 zinc and 1 sulfide

1201
00:31:16,490 --> 00:31:18,820
the formula again 1 zinc and 1 sulfide
ok

1202
00:31:18,820 --> 00:31:18,830
ok

1203
00:31:18,830 --> 00:31:23,090
ok
now you see the ratio of the positive to

1204
00:31:23,090 --> 00:31:23,100
now you see the ratio of the positive to

1205
00:31:23,100 --> 00:31:25,490
now you see the ratio of the positive to
the negative charges now this is the

1206
00:31:25,490 --> 00:31:25,500
the negative charges now this is the

1207
00:31:25,500 --> 00:31:29,750
the negative charges now this is the
sodium chloride and the ratio is 0.6 T 9

1208
00:31:29,750 --> 00:31:29,760
sodium chloride and the ratio is 0.6 T 9

1209
00:31:29,760 --> 00:31:32,080
sodium chloride and the ratio is 0.6 T 9
so it has to be what

1210
00:31:32,080 --> 00:31:32,090
so it has to be what

1211
00:31:32,090 --> 00:31:34,870
so it has to be what
not to disturb the close packing

1212
00:31:34,870 --> 00:31:34,880
not to disturb the close packing

1213
00:31:34,880 --> 00:31:37,060
not to disturb the close packing
structure this has to be point four

1214
00:31:37,060 --> 00:31:37,070
structure this has to be point four

1215
00:31:37,070 --> 00:31:40,000
structure this has to be point four
right but it is much higher than point

1216
00:31:40,000 --> 00:31:40,010
right but it is much higher than point

1217
00:31:40,010 --> 00:31:42,159
right but it is much higher than point
four actually what does that means the

1218
00:31:42,159 --> 00:31:42,169
four actually what does that means the

1219
00:31:42,169 --> 00:31:44,799
four actually what does that means the
chlorides are pushed away and this one

1220
00:31:44,799 --> 00:31:44,809
chlorides are pushed away and this one

1221
00:31:44,809 --> 00:31:48,100
chlorides are pushed away and this one
is point 52 now that is also much larger

1222
00:31:48,100 --> 00:31:48,110
is point 52 now that is also much larger

1223
00:31:48,110 --> 00:31:50,860
is point 52 now that is also much larger
than point two twenty five right and

1224
00:31:50,860 --> 00:31:50,870
than point two twenty five right and

1225
00:31:50,870 --> 00:31:53,169
than point two twenty five right and
that means that the sulfides are also

1226
00:31:53,169 --> 00:31:53,179
that means that the sulfides are also

1227
00:31:53,179 --> 00:31:55,570
that means that the sulfides are also
pushed away by the zinc two-plus iron

1228
00:31:55,570 --> 00:31:55,580
pushed away by the zinc two-plus iron

1229
00:31:55,580 --> 00:31:57,640
pushed away by the zinc two-plus iron
when it fills into the tetrahedral holes

1230
00:31:57,640 --> 00:31:57,650
when it fills into the tetrahedral holes

1231
00:31:57,650 --> 00:31:59,830
when it fills into the tetrahedral holes
you can think about that now how about

1232
00:31:59,830 --> 00:31:59,840
you can think about that now how about

1233
00:31:59,840 --> 00:32:00,700
you can think about that now how about
this one

1234
00:32:00,700 --> 00:32:00,710
this one

1235
00:32:00,710 --> 00:32:03,039
this one
now this one is the cesium chloride

1236
00:32:03,039 --> 00:32:03,049
now this one is the cesium chloride

1237
00:32:03,049 --> 00:32:07,750
now this one is the cesium chloride
structure and that is not a closed pack

1238
00:32:07,750 --> 00:32:07,760
structure and that is not a closed pack

1239
00:32:07,760 --> 00:32:10,899
structure and that is not a closed pack
structure again with respect to the

1240
00:32:10,899 --> 00:32:10,909
structure again with respect to the

1241
00:32:10,909 --> 00:32:13,149
structure again with respect to the
chlorides or with with respect to the

1242
00:32:13,149 --> 00:32:13,159
chlorides or with with respect to the

1243
00:32:13,159 --> 00:32:16,860
chlorides or with with respect to the
cesium's it is different actually so the

1244
00:32:16,860 --> 00:32:16,870
cesium's it is different actually so the

1245
00:32:16,870 --> 00:32:19,690
cesium's it is different actually so the
lattice cesium chloride lattice will not

1246
00:32:19,690 --> 00:32:19,700
lattice cesium chloride lattice will not

1247
00:32:19,700 --> 00:32:22,539
lattice cesium chloride lattice will not
be a closed pack lattice but these two

1248
00:32:22,539 --> 00:32:22,549
be a closed pack lattice but these two

1249
00:32:22,549 --> 00:32:24,610
be a closed pack lattice but these two
can be considered as a closed pack rat

1250
00:32:24,610 --> 00:32:24,620
can be considered as a closed pack rat

1251
00:32:24,620 --> 00:32:27,850
can be considered as a closed pack rat
lattice with respect to the negatively

1252
00:32:27,850 --> 00:32:27,860
lattice with respect to the negatively

1253
00:32:27,860 --> 00:32:30,269
lattice with respect to the negatively
charged ions as a matter of fact now

1254
00:32:30,269 --> 00:32:30,279
charged ions as a matter of fact now

1255
00:32:30,279 --> 00:32:33,190
charged ions as a matter of fact now
here again we have a cube of chloride

1256
00:32:33,190 --> 00:32:33,200
here again we have a cube of chloride

1257
00:32:33,200 --> 00:32:34,840
here again we have a cube of chloride
the chlorides are on the corner of a

1258
00:32:34,840 --> 00:32:34,850
the chlorides are on the corner of a

1259
00:32:34,850 --> 00:32:37,360
the chlorides are on the corner of a
cube simple cubic unit cell which refers

1260
00:32:37,360 --> 00:32:37,370
cube simple cubic unit cell which refers

1261
00:32:37,370 --> 00:32:39,940
cube simple cubic unit cell which refers
to the chloride ion cesium is in the

1262
00:32:39,940 --> 00:32:39,950
to the chloride ion cesium is in the

1263
00:32:39,950 --> 00:32:42,820
to the chloride ion cesium is in the
center now cesium plus actually is much

1264
00:32:42,820 --> 00:32:42,830
center now cesium plus actually is much

1265
00:32:42,830 --> 00:32:46,000
center now cesium plus actually is much
larger than the sodium and and this this

1266
00:32:46,000 --> 00:32:46,010
larger than the sodium and and this this

1267
00:32:46,010 --> 00:32:50,320
larger than the sodium and and this this
this hole which is called cubic hole but

1268
00:32:50,320 --> 00:32:50,330
this hole which is called cubic hole but

1269
00:32:50,330 --> 00:32:53,649
this hole which is called cubic hole but
that's not present in the close packed

1270
00:32:53,649 --> 00:32:53,659
that's not present in the close packed

1271
00:32:53,659 --> 00:32:56,799
that's not present in the close packed
structures but in cesium chloride

1272
00:32:56,799 --> 00:32:56,809
structures but in cesium chloride

1273
00:32:56,809 --> 00:33:00,580
structures but in cesium chloride
structure we say the chloride ion forms

1274
00:33:00,580 --> 00:33:00,590
structure we say the chloride ion forms

1275
00:33:00,590 --> 00:33:05,529
structure we say the chloride ion forms
the simple cubic lattice and the cesium

1276
00:33:05,529 --> 00:33:05,539
the simple cubic lattice and the cesium

1277
00:33:05,539 --> 00:33:09,870
the simple cubic lattice and the cesium
two plus ion fills in two cubic holes

1278
00:33:09,870 --> 00:33:09,880
two plus ion fills in two cubic holes

1279
00:33:09,880 --> 00:33:12,639
two plus ion fills in two cubic holes
cubicles in that case cubicles between

1280
00:33:12,639 --> 00:33:12,649
cubicles in that case cubicles between

1281
00:33:12,649 --> 00:33:15,789
cubicles in that case cubicles between
eight Spears here right in the middle of

1282
00:33:15,789 --> 00:33:15,799
eight Spears here right in the middle of

1283
00:33:15,799 --> 00:33:21,460
eight Spears here right in the middle of
that okay now the next is we talked

1284
00:33:21,460 --> 00:33:21,470
that okay now the next is we talked

1285
00:33:21,470 --> 00:33:25,090
that okay now the next is we talked
about the again metallic solids and X is

1286
00:33:25,090 --> 00:33:25,100
about the again metallic solids and X is

1287
00:33:25,100 --> 00:33:27,130
about the again metallic solids and X is
the molecular solids we talk about ionic

1288
00:33:27,130 --> 00:33:27,140
the molecular solids we talk about ionic

1289
00:33:27,140 --> 00:33:29,049
the molecular solids we talk about ionic
solids now the molecular solids

1290
00:33:29,049 --> 00:33:29,059
solids now the molecular solids

1291
00:33:29,059 --> 00:33:32,110
solids now the molecular solids
molecular solids remember the attraction

1292
00:33:32,110 --> 00:33:32,120
molecular solids remember the attraction

1293
00:33:32,120 --> 00:33:35,500
molecular solids remember the attraction
forces between the molecules in the

1294
00:33:35,500 --> 00:33:35,510
forces between the molecules in the

1295
00:33:35,510 --> 00:33:38,889
forces between the molecules in the
solids are London forces actually

1296
00:33:38,889 --> 00:33:38,899
solids are London forces actually

1297
00:33:38,899 --> 00:33:42,250
solids are London forces actually
hydrogen bonding dipole-dipole type

1298
00:33:42,250 --> 00:33:42,260
hydrogen bonding dipole-dipole type

1299
00:33:42,260 --> 00:33:44,600
hydrogen bonding dipole-dipole type
forces and they are usually

1300
00:33:44,600 --> 00:33:44,610
forces and they are usually

1301
00:33:44,610 --> 00:33:47,660
forces and they are usually
weaker as we said before and that simply

1302
00:33:47,660 --> 00:33:47,670
weaker as we said before and that simply

1303
00:33:47,670 --> 00:33:49,370
weaker as we said before and that simply
means that the molecular solids are

1304
00:33:49,370 --> 00:33:49,380
means that the molecular solids are

1305
00:33:49,380 --> 00:33:52,520
means that the molecular solids are
usually soft and the melting points are

1306
00:33:52,520 --> 00:33:52,530
usually soft and the melting points are

1307
00:33:52,530 --> 00:33:56,419
usually soft and the melting points are
lower than the ionic solids for example

1308
00:33:56,419 --> 00:33:56,429
lower than the ionic solids for example

1309
00:33:56,429 --> 00:33:59,930
lower than the ionic solids for example
now you see again in the molecular

1310
00:33:59,930 --> 00:33:59,940
now you see again in the molecular

1311
00:33:59,940 --> 00:34:04,039
now you see again in the molecular
solids the lattice points or the units

1312
00:34:04,039 --> 00:34:04,049
solids the lattice points or the units

1313
00:34:04,049 --> 00:34:08,570
solids the lattice points or the units
actually are molecules right molecules

1314
00:34:08,570 --> 00:34:08,580
actually are molecules right molecules

1315
00:34:08,580 --> 00:34:13,040
actually are molecules right molecules
so the attractions are the as I said

1316
00:34:13,040 --> 00:34:13,050
so the attractions are the as I said

1317
00:34:13,050 --> 00:34:14,930
so the attractions are the as I said
intermolecular forces that we have

1318
00:34:14,930 --> 00:34:14,940
intermolecular forces that we have

1319
00:34:14,940 --> 00:34:18,230
intermolecular forces that we have
talked about before and they are pretty

1320
00:34:18,230 --> 00:34:18,240
talked about before and they are pretty

1321
00:34:18,240 --> 00:34:22,849
talked about before and they are pretty
weak but we should simply consider the

1322
00:34:22,849 --> 00:34:22,859
weak but we should simply consider the

1323
00:34:22,859 --> 00:34:28,129
weak but we should simply consider the
shape of the molecules particularly when

1324
00:34:28,129 --> 00:34:28,139
shape of the molecules particularly when

1325
00:34:28,139 --> 00:34:31,280
shape of the molecules particularly when
we account for the intermolecular forces

1326
00:34:31,280 --> 00:34:31,290
we account for the intermolecular forces

1327
00:34:31,290 --> 00:34:34,010
we account for the intermolecular forces
compare the intermolecular forces for

1328
00:34:34,010 --> 00:34:34,020
compare the intermolecular forces for

1329
00:34:34,020 --> 00:34:36,129
compare the intermolecular forces for
example if you look at this benzene

1330
00:34:36,129 --> 00:34:36,139
example if you look at this benzene

1331
00:34:36,139 --> 00:34:42,190
example if you look at this benzene
toluene and phenol now this is nonpolar

1332
00:34:42,190 --> 00:34:42,200
toluene and phenol now this is nonpolar

1333
00:34:42,200 --> 00:34:45,460
toluene and phenol now this is nonpolar
molecule so the only force that

1334
00:34:45,460 --> 00:34:45,470
molecule so the only force that

1335
00:34:45,470 --> 00:34:48,560
molecule so the only force that
effective here holding that is London

1336
00:34:48,560 --> 00:34:48,570
effective here holding that is London

1337
00:34:48,570 --> 00:34:51,500
effective here holding that is London
forces right or dispersion forces same

1338
00:34:51,500 --> 00:34:51,510
forces right or dispersion forces same

1339
00:34:51,510 --> 00:34:54,639
forces right or dispersion forces same
things and this one is also nonpolar

1340
00:34:54,639 --> 00:34:54,649
things and this one is also nonpolar

1341
00:34:54,649 --> 00:34:56,899
things and this one is also nonpolar
again not polar tahleen

1342
00:34:56,899 --> 00:34:56,909
again not polar tahleen

1343
00:34:56,909 --> 00:34:59,920
again not polar tahleen
very similar here also dispersion forces

1344
00:34:59,920 --> 00:34:59,930
very similar here also dispersion forces

1345
00:34:59,930 --> 00:35:04,099
very similar here also dispersion forces
now this one here is phenol we have

1346
00:35:04,099 --> 00:35:04,109
now this one here is phenol we have

1347
00:35:04,109 --> 00:35:06,500
now this one here is phenol we have
dispersion forces we have hydrogen

1348
00:35:06,500 --> 00:35:06,510
dispersion forces we have hydrogen

1349
00:35:06,510 --> 00:35:09,200
dispersion forces we have hydrogen
bonding and we also have dipole-dipole

1350
00:35:09,200 --> 00:35:09,210
bonding and we also have dipole-dipole

1351
00:35:09,210 --> 00:35:11,990
bonding and we also have dipole-dipole
this is also polar molecule so when you

1352
00:35:11,990 --> 00:35:12,000
this is also polar molecule so when you

1353
00:35:12,000 --> 00:35:15,050
this is also polar molecule so when you
compare the mountain points five benzene

1354
00:35:15,050 --> 00:35:15,060
compare the mountain points five benzene

1355
00:35:15,060 --> 00:35:20,390
compare the mountain points five benzene
and 95 toluene and 43 phenol much higher

1356
00:35:20,390 --> 00:35:20,400
and 95 toluene and 43 phenol much higher

1357
00:35:20,400 --> 00:35:23,390
and 95 toluene and 43 phenol much higher
so this simply shows the intermolecular

1358
00:35:23,390 --> 00:35:23,400
so this simply shows the intermolecular

1359
00:35:23,400 --> 00:35:27,590
so this simply shows the intermolecular
force is much stronger in phenol and

1360
00:35:27,590 --> 00:35:27,600
force is much stronger in phenol and

1361
00:35:27,600 --> 00:35:30,500
force is much stronger in phenol and
then benzene and toluene but if we

1362
00:35:30,500 --> 00:35:30,510
then benzene and toluene but if we

1363
00:35:30,510 --> 00:35:33,250
then benzene and toluene but if we
consider only the dispersion forces

1364
00:35:33,250 --> 00:35:33,260
consider only the dispersion forces

1365
00:35:33,260 --> 00:35:36,710
consider only the dispersion forces
toluene which have higher molecular

1366
00:35:36,710 --> 00:35:36,720
toluene which have higher molecular

1367
00:35:36,720 --> 00:35:39,740
toluene which have higher molecular
weight than benzene should have a

1368
00:35:39,740 --> 00:35:39,750
weight than benzene should have a

1369
00:35:39,750 --> 00:35:42,230
weight than benzene should have a
stronger dispersion forces right

1370
00:35:42,230 --> 00:35:42,240
stronger dispersion forces right

1371
00:35:42,240 --> 00:35:44,630
stronger dispersion forces right
remember the special forces increases

1372
00:35:44,630 --> 00:35:44,640
remember the special forces increases

1373
00:35:44,640 --> 00:35:46,310
remember the special forces increases
with increase in molecular weight now

1374
00:35:46,310 --> 00:35:46,320
with increase in molecular weight now

1375
00:35:46,320 --> 00:35:49,520
with increase in molecular weight now
the reason here is because the packing

1376
00:35:49,520 --> 00:35:49,530
the reason here is because the packing

1377
00:35:49,530 --> 00:35:51,260
the reason here is because the packing
of the Tholian

1378
00:35:51,260 --> 00:35:51,270
of the Tholian

1379
00:35:51,270 --> 00:35:56,210
of the Tholian
in the solid is not the same as benzene

1380
00:35:56,210 --> 00:35:56,220
in the solid is not the same as benzene

1381
00:35:56,220 --> 00:35:57,880
in the solid is not the same as benzene
so the

1382
00:35:57,880 --> 00:35:57,890
so the

1383
00:35:57,890 --> 00:36:00,460
so the
distances between two toluene molecules

1384
00:36:00,460 --> 00:36:00,470
distances between two toluene molecules

1385
00:36:00,470 --> 00:36:02,860
distances between two toluene molecules
is much larger than the distances

1386
00:36:02,860 --> 00:36:02,870
is much larger than the distances

1387
00:36:02,870 --> 00:36:04,150
is much larger than the distances
between two benzene

1388
00:36:04,150 --> 00:36:04,160
between two benzene

1389
00:36:04,160 --> 00:36:06,610
between two benzene
so the intermolecular forces which are

1390
00:36:06,610 --> 00:36:06,620
so the intermolecular forces which are

1391
00:36:06,620 --> 00:36:09,580
so the intermolecular forces which are
effective in short distances is more

1392
00:36:09,580 --> 00:36:09,590
effective in short distances is more

1393
00:36:09,590 --> 00:36:12,070
effective in short distances is more
effective in benzene than Tolley in for

1394
00:36:12,070 --> 00:36:12,080
effective in benzene than Tolley in for

1395
00:36:12,080 --> 00:36:14,350
effective in benzene than Tolley in for
example when it comes to the liquid you

1396
00:36:14,350 --> 00:36:14,360
example when it comes to the liquid you

1397
00:36:14,360 --> 00:36:16,030
example when it comes to the liquid you
see again in the boiling point of

1398
00:36:16,030 --> 00:36:16,040
see again in the boiling point of

1399
00:36:16,040 --> 00:36:19,090
see again in the boiling point of
liquids benzene is 80 Tolley in 11 and

1400
00:36:19,090 --> 00:36:19,100
liquids benzene is 80 Tolley in 11 and

1401
00:36:19,100 --> 00:36:22,690
liquids benzene is 80 Tolley in 11 and
phenol is 182 because here the molecules

1402
00:36:22,690 --> 00:36:22,700
phenol is 182 because here the molecules

1403
00:36:22,700 --> 00:36:24,820
phenol is 182 because here the molecules
are simply moving around than directly

1404
00:36:24,820 --> 00:36:24,830
are simply moving around than directly

1405
00:36:24,830 --> 00:36:27,730
are simply moving around than directly
we can compare the intermolecular forces

1406
00:36:27,730 --> 00:36:27,740
we can compare the intermolecular forces

1407
00:36:27,740 --> 00:36:31,930
we can compare the intermolecular forces
with the molecular weight of the liquid

1408
00:36:31,930 --> 00:36:31,940
with the molecular weight of the liquid

1409
00:36:31,940 --> 00:36:37,650
with the molecular weight of the liquid
in fact where liquid molecules

1410
00:36:37,650 --> 00:36:37,660

1411
00:36:37,660 --> 00:36:41,650
now our covalent Network solids is

1412
00:36:41,650 --> 00:36:41,660
now our covalent Network solids is

1413
00:36:41,660 --> 00:36:45,460
now our covalent Network solids is
another type of solids and we said that

1414
00:36:45,460 --> 00:36:45,470
another type of solids and we said that

1415
00:36:45,470 --> 00:36:48,490
another type of solids and we said that
the covalent Network solids are hold

1416
00:36:48,490 --> 00:36:48,500
the covalent Network solids are hold

1417
00:36:48,500 --> 00:36:51,940
the covalent Network solids are hold
together by covalent bonds covalent

1418
00:36:51,940 --> 00:36:51,950
together by covalent bonds covalent

1419
00:36:51,950 --> 00:36:54,070
together by covalent bonds covalent
bonds and these covalent bonds are very

1420
00:36:54,070 --> 00:36:54,080
bonds and these covalent bonds are very

1421
00:36:54,080 --> 00:36:58,300
bonds and these covalent bonds are very
very strong and therefore the solids has

1422
00:36:58,300 --> 00:36:58,310
very strong and therefore the solids has

1423
00:36:58,310 --> 00:37:00,850
very strong and therefore the solids has
very very high melting point and very

1424
00:37:00,850 --> 00:37:00,860
very very high melting point and very

1425
00:37:00,860 --> 00:37:06,640
very very high melting point and very
strong again and the example is one

1426
00:37:06,640 --> 00:37:06,650
strong again and the example is one

1427
00:37:06,650 --> 00:37:10,990
strong again and the example is one
example is diamond now in diamonds is

1428
00:37:10,990 --> 00:37:11,000
example is diamond now in diamonds is

1429
00:37:11,000 --> 00:37:15,430
example is diamond now in diamonds is
carbon but it is structure is like this

1430
00:37:15,430 --> 00:37:15,440
carbon but it is structure is like this

1431
00:37:15,440 --> 00:37:19,810
carbon but it is structure is like this
and every carbon is bonded to four other

1432
00:37:19,810 --> 00:37:19,820
and every carbon is bonded to four other

1433
00:37:19,820 --> 00:37:23,140
and every carbon is bonded to four other
carbons around with a covalent bond

1434
00:37:23,140 --> 00:37:23,150
carbons around with a covalent bond

1435
00:37:23,150 --> 00:37:25,090
carbons around with a covalent bond
that's a very very strong bond and

1436
00:37:25,090 --> 00:37:25,100
that's a very very strong bond and

1437
00:37:25,100 --> 00:37:27,990
that's a very very strong bond and
actually the diamond is known as the

1438
00:37:27,990 --> 00:37:28,000
actually the diamond is known as the

1439
00:37:28,000 --> 00:37:32,920
actually the diamond is known as the
hardest solids hardest solid and and the

1440
00:37:32,920 --> 00:37:32,930
hardest solids hardest solid and and the

1441
00:37:32,930 --> 00:37:35,080
hardest solids hardest solid and and the
melting point of the diamond diamond is

1442
00:37:35,080 --> 00:37:35,090
melting point of the diamond diamond is

1443
00:37:35,090 --> 00:37:39,040
melting point of the diamond diamond is
about 3500 very very high and that means

1444
00:37:39,040 --> 00:37:39,050
about 3500 very very high and that means

1445
00:37:39,050 --> 00:37:42,010
about 3500 very very high and that means
that the attraction forces holding the

1446
00:37:42,010 --> 00:37:42,020
that the attraction forces holding the

1447
00:37:42,020 --> 00:37:45,130
that the attraction forces holding the
solid together are very very strong they

1448
00:37:45,130 --> 00:37:45,140
solid together are very very strong they

1449
00:37:45,140 --> 00:37:49,740
solid together are very very strong they
are actually covalent bonds again now

1450
00:37:49,740 --> 00:37:49,750
are actually covalent bonds again now

1451
00:37:49,750 --> 00:37:53,920
are actually covalent bonds again now
graphite is another Network solids again

1452
00:37:53,920 --> 00:37:53,930
graphite is another Network solids again

1453
00:37:53,930 --> 00:37:57,760
graphite is another Network solids again
we have the graphite layer actually the

1454
00:37:57,760 --> 00:37:57,770
we have the graphite layer actually the

1455
00:37:57,770 --> 00:37:59,530
we have the graphite layer actually the
carbon layers here these are all

1456
00:37:59,530 --> 00:37:59,540
carbon layers here these are all

1457
00:37:59,540 --> 00:38:02,920
carbon layers here these are all
hexagons and all of these carbons are

1458
00:38:02,920 --> 00:38:02,930
hexagons and all of these carbons are

1459
00:38:02,930 --> 00:38:06,460
hexagons and all of these carbons are
sp2 hybridization and we have a covalent

1460
00:38:06,460 --> 00:38:06,470
sp2 hybridization and we have a covalent

1461
00:38:06,470 --> 00:38:10,900
sp2 hybridization and we have a covalent
bond within the plane here one layer of

1462
00:38:10,900 --> 00:38:10,910
bond within the plane here one layer of

1463
00:38:10,910 --> 00:38:11,760
bond within the plane here one layer of
graphite

1464
00:38:11,760 --> 00:38:11,770
graphite

1465
00:38:11,770 --> 00:38:15,140
graphite
but between the layers we have actually

1466
00:38:15,140 --> 00:38:15,150
but between the layers we have actually

1467
00:38:15,150 --> 00:38:18,480
but between the layers we have actually
dispersion forces dipoles and other

1468
00:38:18,480 --> 00:38:18,490
dispersion forces dipoles and other

1469
00:38:18,490 --> 00:38:20,640
dispersion forces dipoles and other
intermolecular forces as a matter of

1470
00:38:20,640 --> 00:38:20,650
intermolecular forces as a matter of

1471
00:38:20,650 --> 00:38:23,550
intermolecular forces as a matter of
fact this is another network solids now

1472
00:38:23,550 --> 00:38:23,560
fact this is another network solids now

1473
00:38:23,560 --> 00:38:27,330
fact this is another network solids now
the silicon dioxide the glass actually

1474
00:38:27,330 --> 00:38:27,340
the silicon dioxide the glass actually

1475
00:38:27,340 --> 00:38:30,210
the silicon dioxide the glass actually
the crystalline silicon dioxide is

1476
00:38:30,210 --> 00:38:30,220
the crystalline silicon dioxide is

1477
00:38:30,220 --> 00:38:32,010
the crystalline silicon dioxide is
called quartz quartz is crystalline

1478
00:38:32,010 --> 00:38:32,020
called quartz quartz is crystalline

1479
00:38:32,020 --> 00:38:34,170
called quartz quartz is crystalline
normal glass is not crystalline but

1480
00:38:34,170 --> 00:38:34,180
normal glass is not crystalline but

1481
00:38:34,180 --> 00:38:36,990
normal glass is not crystalline but
amorphous that is also covalent Network

1482
00:38:36,990 --> 00:38:37,000
amorphous that is also covalent Network

1483
00:38:37,000 --> 00:38:41,520
amorphous that is also covalent Network
solids because the all atoms in three

1484
00:38:41,520 --> 00:38:41,530
solids because the all atoms in three

1485
00:38:41,530 --> 00:38:43,890
solids because the all atoms in three
dimensional lattice are bonded to each

1486
00:38:43,890 --> 00:38:43,900
dimensional lattice are bonded to each

1487
00:38:43,900 --> 00:38:46,530
dimensional lattice are bonded to each
other by covalent bond or force of

1488
00:38:46,530 --> 00:38:46,540
other by covalent bond or force of

1489
00:38:46,540 --> 00:38:48,210
other by covalent bond or force of
attractions are actually covalent bond

1490
00:38:48,210 --> 00:38:48,220
attractions are actually covalent bond

1491
00:38:48,220 --> 00:38:54,840
attractions are actually covalent bond
very very strong now uh let's look at

1492
00:38:54,840 --> 00:38:54,850
very very strong now uh let's look at

1493
00:38:54,850 --> 00:39:01,800
very very strong now uh let's look at
the semiconductors now remember we said

1494
00:39:01,800 --> 00:39:01,810
the semiconductors now remember we said

1495
00:39:01,810 --> 00:39:07,440
the semiconductors now remember we said
that the elements can be class elements

1496
00:39:07,440 --> 00:39:07,450
that the elements can be class elements

1497
00:39:07,450 --> 00:39:08,910
that the elements can be class elements
in the periodic table can be classified

1498
00:39:08,910 --> 00:39:08,920
in the periodic table can be classified

1499
00:39:08,920 --> 00:39:16,040
in the periodic table can be classified
as metals non-metals and metalloids and

1500
00:39:16,040 --> 00:39:16,050
as metals non-metals and metalloids and

1501
00:39:16,050 --> 00:39:18,420
as metals non-metals and metalloids and
the metals have high electrical

1502
00:39:18,420 --> 00:39:18,430
the metals have high electrical

1503
00:39:18,430 --> 00:39:21,000
the metals have high electrical
conductivity actually their conductor a

1504
00:39:21,000 --> 00:39:21,010
conductivity actually their conductor a

1505
00:39:21,010 --> 00:39:22,470
conductivity actually their conductor a
good electrical conductor heat

1506
00:39:22,470 --> 00:39:22,480
good electrical conductor heat

1507
00:39:22,480 --> 00:39:26,220
good electrical conductor heat
conductors and the nonmetals are not

1508
00:39:26,220 --> 00:39:26,230
conductors and the nonmetals are not

1509
00:39:26,230 --> 00:39:27,840
conductors and the nonmetals are not
conductors they do not conduct

1510
00:39:27,840 --> 00:39:27,850
conductors they do not conduct

1511
00:39:27,850 --> 00:39:30,110
conductors they do not conduct
electricity they do not conduct heat

1512
00:39:30,110 --> 00:39:30,120
electricity they do not conduct heat

1513
00:39:30,120 --> 00:39:33,720
electricity they do not conduct heat
again but there are also in the periodic

1514
00:39:33,720 --> 00:39:33,730
again but there are also in the periodic

1515
00:39:33,730 --> 00:39:36,750
again but there are also in the periodic
table remember sort of elements between

1516
00:39:36,750 --> 00:39:36,760
table remember sort of elements between

1517
00:39:36,760 --> 00:39:40,260
table remember sort of elements between
the metal region and nonmetal region and

1518
00:39:40,260 --> 00:39:40,270
the metal region and nonmetal region and

1519
00:39:40,270 --> 00:39:44,310
the metal region and nonmetal region and
those are called metalloids so the

1520
00:39:44,310 --> 00:39:44,320
those are called metalloids so the

1521
00:39:44,320 --> 00:39:47,970
those are called metalloids so the
properties of those are between the

1522
00:39:47,970 --> 00:39:47,980
properties of those are between the

1523
00:39:47,980 --> 00:39:50,790
properties of those are between the
metals and intermediate between metals

1524
00:39:50,790 --> 00:39:50,800
metals and intermediate between metals

1525
00:39:50,800 --> 00:39:53,070
metals and intermediate between metals
and nonmetals that simply means that

1526
00:39:53,070 --> 00:39:53,080
and nonmetals that simply means that

1527
00:39:53,080 --> 00:39:56,250
and nonmetals that simply means that
their electrical conductance is not zero

1528
00:39:56,250 --> 00:39:56,260
their electrical conductance is not zero

1529
00:39:56,260 --> 00:39:59,730
their electrical conductance is not zero
but as not as high as metals at all but

1530
00:39:59,730 --> 00:39:59,740
but as not as high as metals at all but

1531
00:39:59,740 --> 00:40:02,430
but as not as high as metals at all but
they're still conductors and they are

1532
00:40:02,430 --> 00:40:02,440
they're still conductors and they are

1533
00:40:02,440 --> 00:40:04,500
they're still conductors and they are
called semiconductors we call them

1534
00:40:04,500 --> 00:40:04,510
called semiconductors we call them

1535
00:40:04,510 --> 00:40:07,440
called semiconductors we call them
actually semiconductors now let's let's

1536
00:40:07,440 --> 00:40:07,450
actually semiconductors now let's let's

1537
00:40:07,450 --> 00:40:14,480
actually semiconductors now let's let's
look at the semiconductors now the

1538
00:40:14,480 --> 00:40:14,490
look at the semiconductors now the

1539
00:40:14,490 --> 00:40:18,060
look at the semiconductors now the
element semiconductors are actually

1540
00:40:18,060 --> 00:40:18,070
element semiconductors are actually

1541
00:40:18,070 --> 00:40:24,300
element semiconductors are actually
silicon germanium tin that is for a

1542
00:40:24,300 --> 00:40:24,310
silicon germanium tin that is for a

1543
00:40:24,310 --> 00:40:25,080
silicon germanium tin that is for a
group

1544
00:40:25,080 --> 00:40:25,090
group

1545
00:40:25,090 --> 00:40:28,650
group
where we have the diamond like structure

1546
00:40:28,650 --> 00:40:28,660
where we have the diamond like structure

1547
00:40:28,660 --> 00:40:31,400
where we have the diamond like structure
diamond like structure that means every

1548
00:40:31,400 --> 00:40:31,410
diamond like structure that means every

1549
00:40:31,410 --> 00:40:33,750
diamond like structure that means every
silicon for example is bonded to other

1550
00:40:33,750 --> 00:40:33,760
silicon for example is bonded to other

1551
00:40:33,760 --> 00:40:38,670
silicon for example is bonded to other
four silicones and every germanium

1552
00:40:38,670 --> 00:40:38,680
four silicones and every germanium

1553
00:40:38,680 --> 00:40:41,690
four silicones and every germanium
actually has bonded to four and so on

1554
00:40:41,690 --> 00:40:41,700
actually has bonded to four and so on

1555
00:40:41,700 --> 00:40:51,270
actually has bonded to four and so on
now when we consider the electronic

1556
00:40:51,270 --> 00:40:51,280
now when we consider the electronic

1557
00:40:51,280 --> 00:40:56,090
now when we consider the electronic
structure of semiconductors for example

1558
00:40:56,090 --> 00:40:56,100
structure of semiconductors for example

1559
00:40:56,100 --> 00:41:01,020
structure of semiconductors for example
we can think of as the diamond or just

1560
00:41:01,020 --> 00:41:01,030
we can think of as the diamond or just

1561
00:41:01,030 --> 00:41:03,930
we can think of as the diamond or just
the silicon like we can think about that

1562
00:41:03,930 --> 00:41:03,940
the silicon like we can think about that

1563
00:41:03,940 --> 00:41:06,330
the silicon like we can think about that
as again diamonds in a chronic structure

1564
00:41:06,330 --> 00:41:06,340
as again diamonds in a chronic structure

1565
00:41:06,340 --> 00:41:15,630
as again diamonds in a chronic structure
or the silicon again now the bent theory

1566
00:41:15,630 --> 00:41:15,640
or the silicon again now the bent theory

1567
00:41:15,640 --> 00:41:21,680
or the silicon again now the bent theory
still applies to those semiconductor

1568
00:41:21,680 --> 00:41:21,690
still applies to those semiconductor

1569
00:41:21,690 --> 00:41:25,770
still applies to those semiconductor
substances again as follow now take for

1570
00:41:25,770 --> 00:41:25,780
substances again as follow now take for

1571
00:41:25,780 --> 00:41:29,820
substances again as follow now take for
example think about the carbon and then

1572
00:41:29,820 --> 00:41:29,830
example think about the carbon and then

1573
00:41:29,830 --> 00:41:32,370
example think about the carbon and then
think about the electronic structure of

1574
00:41:32,370 --> 00:41:32,380
think about the electronic structure of

1575
00:41:32,380 --> 00:41:37,470
think about the electronic structure of
diamond now the carbon has two electrons

1576
00:41:37,470 --> 00:41:37,480
diamond now the carbon has two electrons

1577
00:41:37,480 --> 00:41:41,250
diamond now the carbon has two electrons
in S orbitals and four carbon this is

1578
00:41:41,250 --> 00:41:41,260
in S orbitals and four carbon this is

1579
00:41:41,260 --> 00:41:45,030
in S orbitals and four carbon this is
two as for silicon it is 3 S 4 s it goes

1580
00:41:45,030 --> 00:41:45,040
two as for silicon it is 3 S 4 s it goes

1581
00:41:45,040 --> 00:41:48,090
two as for silicon it is 3 S 4 s it goes
down like this and then it has P orbit

1582
00:41:48,090 --> 00:41:48,100
down like this and then it has P orbit

1583
00:41:48,100 --> 00:41:50,700
down like this and then it has P orbit
at P electron electrons in AP orbital

1584
00:41:50,700 --> 00:41:50,710
at P electron electrons in AP orbital

1585
00:41:50,710 --> 00:41:53,310
at P electron electrons in AP orbital
two of those four valence electrons and

1586
00:41:53,310 --> 00:41:53,320
two of those four valence electrons and

1587
00:41:53,320 --> 00:41:57,660
two of those four valence electrons and
four valence electrons again will make

1588
00:41:57,660 --> 00:41:57,670
four valence electrons again will make

1589
00:41:57,670 --> 00:42:01,710
four valence electrons again will make
for bond here like this and then we have

1590
00:42:01,710 --> 00:42:01,720
for bond here like this and then we have

1591
00:42:01,720 --> 00:42:04,110
for bond here like this and then we have
the network solids covalent Network

1592
00:42:04,110 --> 00:42:04,120
the network solids covalent Network

1593
00:42:04,120 --> 00:42:08,610
the network solids covalent Network
solids now this s orbitals from each

1594
00:42:08,610 --> 00:42:08,620
solids now this s orbitals from each

1595
00:42:08,620 --> 00:42:12,650
solids now this s orbitals from each
carbon will combine to form molecular

1596
00:42:12,650 --> 00:42:12,660
carbon will combine to form molecular

1597
00:42:12,660 --> 00:42:15,180
carbon will combine to form molecular
orbitals like this bonding molecular

1598
00:42:15,180 --> 00:42:15,190
orbitals like this bonding molecular

1599
00:42:15,190 --> 00:42:17,130
orbitals like this bonding molecular
orbitals and antibiotic molecular

1600
00:42:17,130 --> 00:42:17,140
orbitals and antibiotic molecular

1601
00:42:17,140 --> 00:42:21,300
orbitals and antibiotic molecular
orbitals these P orbitals three of those

1602
00:42:21,300 --> 00:42:21,310
orbitals these P orbitals three of those

1603
00:42:21,310 --> 00:42:24,330
orbitals these P orbitals three of those
will combine to form bonding and

1604
00:42:24,330 --> 00:42:24,340
will combine to form bonding and

1605
00:42:24,340 --> 00:42:30,360
will combine to form bonding and
anti-bonding over here but as the number

1606
00:42:30,360 --> 00:42:30,370
anti-bonding over here but as the number

1607
00:42:30,370 --> 00:42:35,490
anti-bonding over here but as the number
of carbon atom increases then the

1608
00:42:35,490 --> 00:42:35,500
of carbon atom increases then the

1609
00:42:35,500 --> 00:42:38,350
of carbon atom increases then the
molecular orbitals here increases

1610
00:42:38,350 --> 00:42:38,360
molecular orbitals here increases

1611
00:42:38,360 --> 00:42:41,770
molecular orbitals here increases
and that means that they will be placed

1612
00:42:41,770 --> 00:42:41,780
and that means that they will be placed

1613
00:42:41,780 --> 00:42:46,450
and that means that they will be placed
very close in energy like this just like

1614
00:42:46,450 --> 00:42:46,460
very close in energy like this just like

1615
00:42:46,460 --> 00:42:51,610
very close in energy like this just like
a band in the metals remember any metals

1616
00:42:51,610 --> 00:42:51,620
a band in the metals remember any metals

1617
00:42:51,620 --> 00:42:56,380
a band in the metals remember any metals
so we have actually series of molecular

1618
00:42:56,380 --> 00:42:56,390
so we have actually series of molecular

1619
00:42:56,390 --> 00:43:00,280
so we have actually series of molecular
orbitals here in this band and what are

1620
00:43:00,280 --> 00:43:00,290
orbitals here in this band and what are

1621
00:43:00,290 --> 00:43:02,350
orbitals here in this band and what are
these actually these are some of them

1622
00:43:02,350 --> 00:43:02,360
these actually these are some of them

1623
00:43:02,360 --> 00:43:06,850
these actually these are some of them
are s resulted from the linear

1624
00:43:06,850 --> 00:43:06,860
are s resulted from the linear

1625
00:43:06,860 --> 00:43:09,490
are s resulted from the linear
combinations of s orbitals and some are

1626
00:43:09,490 --> 00:43:09,500
combinations of s orbitals and some are

1627
00:43:09,500 --> 00:43:11,170
combinations of s orbitals and some are
resulted from the linear combination of

1628
00:43:11,170 --> 00:43:11,180
resulted from the linear combination of

1629
00:43:11,180 --> 00:43:14,520
resulted from the linear combination of
P orbitals on the carbon and

1630
00:43:14,520 --> 00:43:14,530
P orbitals on the carbon and

1631
00:43:14,530 --> 00:43:17,050
P orbitals on the carbon and
correspondent if we have simply here

1632
00:43:17,050 --> 00:43:17,060
correspondent if we have simply here

1633
00:43:17,060 --> 00:43:21,520
correspondent if we have simply here
like n molecular orbitals as the number

1634
00:43:21,520 --> 00:43:21,530
like n molecular orbitals as the number

1635
00:43:21,530 --> 00:43:24,210
like n molecular orbitals as the number
of carbon atoms goes to infinite in fact

1636
00:43:24,210 --> 00:43:24,220
of carbon atoms goes to infinite in fact

1637
00:43:24,220 --> 00:43:27,550
of carbon atoms goes to infinite in fact
then we also have n anti bonding

1638
00:43:27,550 --> 00:43:27,560
then we also have n anti bonding

1639
00:43:27,560 --> 00:43:30,370
then we also have n anti bonding
molecular orbitals here now if you

1640
00:43:30,370 --> 00:43:30,380
molecular orbitals here now if you

1641
00:43:30,380 --> 00:43:32,470
molecular orbitals here now if you
simply take the valence electrons and

1642
00:43:32,470 --> 00:43:32,480
simply take the valence electrons and

1643
00:43:32,480 --> 00:43:35,920
simply take the valence electrons and
start filling them out here you will

1644
00:43:35,920 --> 00:43:35,930
start filling them out here you will

1645
00:43:35,930 --> 00:43:38,710
start filling them out here you will
fill out all of the bonding molecular

1646
00:43:38,710 --> 00:43:38,720
fill out all of the bonding molecular

1647
00:43:38,720 --> 00:43:43,530
fill out all of the bonding molecular
orbitals and this will be the empty

1648
00:43:43,530 --> 00:43:43,540
orbitals and this will be the empty

1649
00:43:43,540 --> 00:43:45,910
orbitals and this will be the empty
non-bonding molecular which is empty so

1650
00:43:45,910 --> 00:43:45,920
non-bonding molecular which is empty so

1651
00:43:45,920 --> 00:43:49,390
non-bonding molecular which is empty so
we have a bent here which is full of

1652
00:43:49,390 --> 00:43:49,400
we have a bent here which is full of

1653
00:43:49,400 --> 00:43:52,420
we have a bent here which is full of
electrons that means every molecular

1654
00:43:52,420 --> 00:43:52,430
electrons that means every molecular

1655
00:43:52,430 --> 00:43:55,150
electrons that means every molecular
orbital I can accommodate two electrons

1656
00:43:55,150 --> 00:43:55,160
orbital I can accommodate two electrons

1657
00:43:55,160 --> 00:43:57,970
orbital I can accommodate two electrons
there made full and here there is no

1658
00:43:57,970 --> 00:43:57,980
there made full and here there is no

1659
00:43:57,980 --> 00:44:04,150
there made full and here there is no
electrons now this mo diagram or bent

1660
00:44:04,150 --> 00:44:04,160
electrons now this mo diagram or bent

1661
00:44:04,160 --> 00:44:08,230
electrons now this mo diagram or bent
structure will apply for carbon silicon

1662
00:44:08,230 --> 00:44:08,240
structure will apply for carbon silicon

1663
00:44:08,240 --> 00:44:11,350
structure will apply for carbon silicon
germanium and tin they are all in the

1664
00:44:11,350 --> 00:44:11,360
germanium and tin they are all in the

1665
00:44:11,360 --> 00:44:12,850
germanium and tin they are all in the
same group they have four valence

1666
00:44:12,850 --> 00:44:12,860
same group they have four valence

1667
00:44:12,860 --> 00:44:16,060
same group they have four valence
electrons now this energy difference

1668
00:44:16,060 --> 00:44:16,070
electrons now this energy difference

1669
00:44:16,070 --> 00:44:19,630
electrons now this energy difference
here between the filled molecular

1670
00:44:19,630 --> 00:44:19,640
here between the filled molecular

1671
00:44:19,640 --> 00:44:22,210
here between the filled molecular
orbitals filled bent which we call it

1672
00:44:22,210 --> 00:44:22,220
orbitals filled bent which we call it

1673
00:44:22,220 --> 00:44:26,440
orbitals filled bent which we call it
valence band and the empty molecular

1674
00:44:26,440 --> 00:44:26,450
valence band and the empty molecular

1675
00:44:26,450 --> 00:44:29,530
valence band and the empty molecular
orbitals and that is the empty band this

1676
00:44:29,530 --> 00:44:29,540
orbitals and that is the empty band this

1677
00:44:29,540 --> 00:44:31,330
orbitals and that is the empty band this
one is called conduction band this one

1678
00:44:31,330 --> 00:44:31,340
one is called conduction band this one

1679
00:44:31,340 --> 00:44:37,390
one is called conduction band this one
is called valence band right now the

1680
00:44:37,390 --> 00:44:37,400
is called valence band right now the

1681
00:44:37,400 --> 00:44:47,470
is called valence band right now the
energy gap here for carbon it is

1682
00:44:47,470 --> 00:44:47,480

1683
00:44:47,480 --> 00:45:02,080
let me give you the exact values yes for

1684
00:45:02,080 --> 00:45:02,090
let me give you the exact values yes for

1685
00:45:02,090 --> 00:45:11,700
let me give you the exact values yes for
carbon carbon actually diamond it is 5.5

1686
00:45:11,700 --> 00:45:11,710

1687
00:45:11,710 --> 00:45:20,580
now diamond and let's call this eg

1688
00:45:20,580 --> 00:45:20,590
now diamond and let's call this eg

1689
00:45:20,590 --> 00:45:23,170
now diamond and let's call this eg
energy difference between valence band

1690
00:45:23,170 --> 00:45:23,180
energy difference between valence band

1691
00:45:23,180 --> 00:45:27,850
energy difference between valence band
and conduction band diamond it is 5

1692
00:45:27,850 --> 00:45:27,860
and conduction band diamond it is 5

1693
00:45:27,860 --> 00:45:35,380
and conduction band diamond it is 5
point 5 electron volt for silicon it is

1694
00:45:35,380 --> 00:45:35,390
point 5 electron volt for silicon it is

1695
00:45:35,390 --> 00:45:39,840
point 5 electron volt for silicon it is
1 point 1 1 electron volt for germanium

1696
00:45:39,840 --> 00:45:39,850
1 point 1 1 electron volt for germanium

1697
00:45:39,850 --> 00:45:47,130
1 point 1 1 electron volt for germanium
and it is point 67 electron volts and

1698
00:45:47,130 --> 00:45:47,140
and it is point 67 electron volts and

1699
00:45:47,140 --> 00:45:50,890
and it is point 67 electron volts and
for tin SM tin

1700
00:45:50,890 --> 00:45:50,900
for tin SM tin

1701
00:45:50,900 --> 00:45:56,560
for tin SM tin
this is 0.08 electron volt and for lead

1702
00:45:56,560 --> 00:45:56,570
this is 0.08 electron volt and for lead

1703
00:45:56,570 --> 00:45:59,650
this is 0.08 electron volt and for lead
let is in the last one their LED and

1704
00:45:59,650 --> 00:45:59,660
let is in the last one their LED and

1705
00:45:59,660 --> 00:46:10,320
let is in the last one their LED and
this is actually 0 okay now the energy

1706
00:46:10,320 --> 00:46:10,330
this is actually 0 okay now the energy

1707
00:46:10,330 --> 00:46:13,630
this is actually 0 okay now the energy
that corresponds the energy of the

1708
00:46:13,630 --> 00:46:13,640
that corresponds the energy of the

1709
00:46:13,640 --> 00:46:17,080
that corresponds the energy of the
visible light that means the energy

1710
00:46:17,080 --> 00:46:17,090
visible light that means the energy

1711
00:46:17,090 --> 00:46:20,590
visible light that means the energy
carried by photons visible photons but

1712
00:46:20,590 --> 00:46:20,600
carried by photons visible photons but

1713
00:46:20,600 --> 00:46:22,420
carried by photons visible photons but
remember this is going to be like one

1714
00:46:22,420 --> 00:46:22,430
remember this is going to be like one

1715
00:46:22,430 --> 00:46:28,120
remember this is going to be like one
mole molar wise or no in this case

1716
00:46:28,120 --> 00:46:28,130
mole molar wise or no in this case

1717
00:46:28,130 --> 00:46:34,300
mole molar wise or no in this case
single photons energy of the visible

1718
00:46:34,300 --> 00:46:34,310
single photons energy of the visible

1719
00:46:34,310 --> 00:46:38,680
single photons energy of the visible
light photons is about 3 electron volt

1720
00:46:38,680 --> 00:46:38,690
light photons is about 3 electron volt

1721
00:46:38,690 --> 00:46:45,100
light photons is about 3 electron volt
less than 3 electron volt right and that

1722
00:46:45,100 --> 00:46:45,110
less than 3 electron volt right and that

1723
00:46:45,110 --> 00:46:49,090
less than 3 electron volt right and that
means that actually you can excite the

1724
00:46:49,090 --> 00:46:49,100
means that actually you can excite the

1725
00:46:49,100 --> 00:46:51,970
means that actually you can excite the
electron from the valence band by

1726
00:46:51,970 --> 00:46:51,980
electron from the valence band by

1727
00:46:51,980 --> 00:46:54,910
electron from the valence band by
electromagnetic radiation if you give

1728
00:46:54,910 --> 00:46:54,920
electromagnetic radiation if you give

1729
00:46:54,920 --> 00:46:57,640
electromagnetic radiation if you give
enough energy energy that means if the

1730
00:46:57,640 --> 00:46:57,650
enough energy energy that means if the

1731
00:46:57,650 --> 00:47:00,319
enough energy energy that means if the
energy of the photons is equal to

1732
00:47:00,319 --> 00:47:00,329
energy of the photons is equal to

1733
00:47:00,329 --> 00:47:03,319
energy of the photons is equal to
the eg the bandgap here which is called

1734
00:47:03,319 --> 00:47:03,329
the eg the bandgap here which is called

1735
00:47:03,329 --> 00:47:07,429
the eg the bandgap here which is called
the bandgap now for the carbon it is not

1736
00:47:07,429 --> 00:47:07,439
the bandgap now for the carbon it is not

1737
00:47:07,439 --> 00:47:10,009
the bandgap now for the carbon it is not
possible to excite electron from the

1738
00:47:10,009 --> 00:47:10,019
possible to excite electron from the

1739
00:47:10,019 --> 00:47:12,219
possible to excite electron from the
valence band to the conduction band by

1740
00:47:12,219 --> 00:47:12,229
valence band to the conduction band by

1741
00:47:12,229 --> 00:47:15,889
valence band to the conduction band by
visible light right because the energy

1742
00:47:15,889 --> 00:47:15,899
visible light right because the energy

1743
00:47:15,899 --> 00:47:17,359
visible light right because the energy
of the visible light photon is not

1744
00:47:17,359 --> 00:47:17,369
of the visible light photon is not

1745
00:47:17,369 --> 00:47:20,149
of the visible light photon is not
enough for that is less than that but

1746
00:47:20,149 --> 00:47:20,159
enough for that is less than that but

1747
00:47:20,159 --> 00:47:24,349
enough for that is less than that but
for the silicon in fact you can excite

1748
00:47:24,349 --> 00:47:24,359
for the silicon in fact you can excite

1749
00:47:24,359 --> 00:47:27,049
for the silicon in fact you can excite
the electron from the valence band to

1750
00:47:27,049 --> 00:47:27,059
the electron from the valence band to

1751
00:47:27,059 --> 00:47:30,139
the electron from the valence band to
the conduction band by the visible light

1752
00:47:30,139 --> 00:47:30,149
the conduction band by the visible light

1753
00:47:30,149 --> 00:47:33,079
the conduction band by the visible light
actually and when you excite the

1754
00:47:33,079 --> 00:47:33,089
actually and when you excite the

1755
00:47:33,089 --> 00:47:35,989
actually and when you excite the
electron from the valence band to the

1756
00:47:35,989 --> 00:47:35,999
electron from the valence band to the

1757
00:47:35,999 --> 00:47:39,079
electron from the valence band to the
conduction band you create partially

1758
00:47:39,079 --> 00:47:39,089
conduction band you create partially

1759
00:47:39,089 --> 00:47:42,279
conduction band you create partially
filled molecular orbitals right

1760
00:47:42,279 --> 00:47:42,289
filled molecular orbitals right

1761
00:47:42,289 --> 00:47:44,539
filled molecular orbitals right
partially filled molecular orbitals

1762
00:47:44,539 --> 00:47:44,549
partially filled molecular orbitals

1763
00:47:44,549 --> 00:47:47,359
partially filled molecular orbitals
now those partially filled molecular

1764
00:47:47,359 --> 00:47:47,369
now those partially filled molecular

1765
00:47:47,369 --> 00:47:51,019
now those partially filled molecular
orbitals will provide the electrical

1766
00:47:51,019 --> 00:47:51,029
orbitals will provide the electrical

1767
00:47:51,029 --> 00:47:53,659
orbitals will provide the electrical
conductivity to that substance actually

1768
00:47:53,659 --> 00:47:53,669
conductivity to that substance actually

1769
00:47:53,669 --> 00:47:59,329
conductivity to that substance actually
the electrical conductivity will be

1770
00:47:59,329 --> 00:47:59,339
the electrical conductivity will be

1771
00:47:59,339 --> 00:48:03,259
the electrical conductivity will be
obtained by the partially filled or due

1772
00:48:03,259 --> 00:48:03,269
obtained by the partially filled or due

1773
00:48:03,269 --> 00:48:04,969
obtained by the partially filled or due
to the actually due to the partially

1774
00:48:04,969 --> 00:48:04,979
to the actually due to the partially

1775
00:48:04,979 --> 00:48:08,149
to the actually due to the partially
filled molecular orbitals that means one

1776
00:48:08,149 --> 00:48:08,159
filled molecular orbitals that means one

1777
00:48:08,159 --> 00:48:09,739
filled molecular orbitals that means one
molecular object contains one electron

1778
00:48:09,739 --> 00:48:09,749
molecular object contains one electron

1779
00:48:09,749 --> 00:48:13,249
molecular object contains one electron
now how many electrons not much but

1780
00:48:13,249 --> 00:48:13,259
now how many electrons not much but

1781
00:48:13,259 --> 00:48:17,629
now how many electrons not much but
there enough to give some conductivity

1782
00:48:17,629 --> 00:48:17,639
there enough to give some conductivity

1783
00:48:17,639 --> 00:48:22,149
there enough to give some conductivity
to the silicon right not as much as

1784
00:48:22,149 --> 00:48:22,159
to the silicon right not as much as

1785
00:48:22,159 --> 00:48:25,459
to the silicon right not as much as
metal much less than that but not as

1786
00:48:25,459 --> 00:48:25,469
metal much less than that but not as

1787
00:48:25,469 --> 00:48:27,199
metal much less than that but not as
much as non metal nonmetal case is

1788
00:48:27,199 --> 00:48:27,209
much as non metal nonmetal case is

1789
00:48:27,209 --> 00:48:29,949
much as non metal nonmetal case is
almost zero now if you go to the

1790
00:48:29,949 --> 00:48:29,959
almost zero now if you go to the

1791
00:48:29,959 --> 00:48:32,149
almost zero now if you go to the
germanium you see the band gap is

1792
00:48:32,149 --> 00:48:32,159
germanium you see the band gap is

1793
00:48:32,159 --> 00:48:34,009
germanium you see the band gap is
smaller that means there will be better

1794
00:48:34,009 --> 00:48:34,019
smaller that means there will be better

1795
00:48:34,019 --> 00:48:37,069
smaller that means there will be better
electrical conductance here tin is much

1796
00:48:37,069 --> 00:48:37,079
electrical conductance here tin is much

1797
00:48:37,079 --> 00:48:39,469
electrical conductance here tin is much
better team actually almost like metal

1798
00:48:39,469 --> 00:48:39,479
better team actually almost like metal

1799
00:48:39,479 --> 00:48:43,429
better team actually almost like metal
the lead is metal because there's no

1800
00:48:43,429 --> 00:48:43,439
the lead is metal because there's no

1801
00:48:43,439 --> 00:48:46,339
the lead is metal because there's no
energy gap between the full valence band

1802
00:48:46,339 --> 00:48:46,349
energy gap between the full valence band

1803
00:48:46,349 --> 00:48:48,279
energy gap between the full valence band
and the conduction band there now

1804
00:48:48,279 --> 00:48:48,289
and the conduction band there now

1805
00:48:48,289 --> 00:48:51,399
and the conduction band there now
actually the more electron goes there

1806
00:48:51,399 --> 00:48:51,409
actually the more electron goes there

1807
00:48:51,409 --> 00:48:53,959
actually the more electron goes there
that means the more will be the

1808
00:48:53,959 --> 00:48:53,969
that means the more will be the

1809
00:48:53,969 --> 00:48:56,389
that means the more will be the
electrical conductance of the substance

1810
00:48:56,389 --> 00:48:56,399
electrical conductance of the substance

1811
00:48:56,399 --> 00:48:59,799
electrical conductance of the substance
that semiconductors so this is how the

1812
00:48:59,799 --> 00:48:59,809
that semiconductors so this is how the

1813
00:48:59,809 --> 00:49:04,489
that semiconductors so this is how the
semiconductor become conductors actually

1814
00:49:04,489 --> 00:49:04,499
semiconductor become conductors actually

1815
00:49:04,499 --> 00:49:07,009
semiconductor become conductors actually
right it's exciting the electron from

1816
00:49:07,009 --> 00:49:07,019
right it's exciting the electron from

1817
00:49:07,019 --> 00:49:08,659
right it's exciting the electron from
the valence band to the conduction band

1818
00:49:08,659 --> 00:49:08,669
the valence band to the conduction band

1819
00:49:08,669 --> 00:49:10,909
the valence band to the conduction band
and having that partially filled band

1820
00:49:10,909 --> 00:49:10,919
and having that partially filled band

1821
00:49:10,919 --> 00:49:13,230
and having that partially filled band
provides the electrical conductivity

1822
00:49:13,230 --> 00:49:13,240
provides the electrical conductivity

1823
00:49:13,240 --> 00:49:18,420
provides the electrical conductivity
why's the electrical conductivity but

1824
00:49:18,420 --> 00:49:18,430
why's the electrical conductivity but

1825
00:49:18,430 --> 00:49:22,050
why's the electrical conductivity but
now here is the point the main

1826
00:49:22,050 --> 00:49:22,060
now here is the point the main

1827
00:49:22,060 --> 00:49:25,980
now here is the point the main
difference between the semiconductors

1828
00:49:25,980 --> 00:49:25,990
difference between the semiconductors

1829
00:49:25,990 --> 00:49:31,350
difference between the semiconductors
and the metals semiconductor if you

1830
00:49:31,350 --> 00:49:31,360
and the metals semiconductor if you

1831
00:49:31,360 --> 00:49:32,880
and the metals semiconductor if you
increase the temperature of the

1832
00:49:32,880 --> 00:49:32,890
increase the temperature of the

1833
00:49:32,890 --> 00:49:35,460
increase the temperature of the
semiconductor electrical conductivity

1834
00:49:35,460 --> 00:49:35,470
semiconductor electrical conductivity

1835
00:49:35,470 --> 00:49:39,210
semiconductor electrical conductivity
increases but if you increase the metal

1836
00:49:39,210 --> 00:49:39,220
increases but if you increase the metal

1837
00:49:39,220 --> 00:49:41,700
increases but if you increase the metal
temperature electrical conductivity of

1838
00:49:41,700 --> 00:49:41,710
temperature electrical conductivity of

1839
00:49:41,710 --> 00:49:45,960
temperature electrical conductivity of
metal decreases and how as follows this

1840
00:49:45,960 --> 00:49:45,970
metal decreases and how as follows this

1841
00:49:45,970 --> 00:49:47,760
metal decreases and how as follows this
is explained as follow for the

1842
00:49:47,760 --> 00:49:47,770
is explained as follow for the

1843
00:49:47,770 --> 00:49:49,620
is explained as follow for the
semiconductor increase in the

1844
00:49:49,620 --> 00:49:49,630
semiconductor increase in the

1845
00:49:49,630 --> 00:49:52,230
semiconductor increase in the
temperature means that we increase the

1846
00:49:52,230 --> 00:49:52,240
temperature means that we increase the

1847
00:49:52,240 --> 00:49:53,820
temperature means that we increase the
number of electrons that are excited in

1848
00:49:53,820 --> 00:49:53,830
number of electrons that are excited in

1849
00:49:53,830 --> 00:49:55,830
number of electrons that are excited in
the conduction band because that is also

1850
00:49:55,830 --> 00:49:55,840
the conduction band because that is also

1851
00:49:55,840 --> 00:49:58,170
the conduction band because that is also
temperature energy actually like higher

1852
00:49:58,170 --> 00:49:58,180
temperature energy actually like higher

1853
00:49:58,180 --> 00:50:00,240
temperature energy actually like higher
temperature and that means more

1854
00:50:00,240 --> 00:50:00,250
temperature and that means more

1855
00:50:00,250 --> 00:50:02,820
temperature and that means more
electrons in the conduction band means

1856
00:50:02,820 --> 00:50:02,830
electrons in the conduction band means

1857
00:50:02,830 --> 00:50:05,250
electrons in the conduction band means
higher electrical conductivity so

1858
00:50:05,250 --> 00:50:05,260
higher electrical conductivity so

1859
00:50:05,260 --> 00:50:06,600
higher electrical conductivity so
increasing the temperature increases the

1860
00:50:06,600 --> 00:50:06,610
increasing the temperature increases the

1861
00:50:06,610 --> 00:50:09,000
increasing the temperature increases the
electric conductivity but for the metal

1862
00:50:09,000 --> 00:50:09,010
electric conductivity but for the metal

1863
00:50:09,010 --> 00:50:12,540
electric conductivity but for the metal
actually in fact since when we have zero

1864
00:50:12,540 --> 00:50:12,550
actually in fact since when we have zero

1865
00:50:12,550 --> 00:50:15,109
actually in fact since when we have zero
gap there increase in the temperature

1866
00:50:15,109 --> 00:50:15,119
gap there increase in the temperature

1867
00:50:15,119 --> 00:50:17,550
gap there increase in the temperature
increases the vibrational motions of the

1868
00:50:17,550 --> 00:50:17,560
increases the vibrational motions of the

1869
00:50:17,560 --> 00:50:19,560
increases the vibrational motions of the
metal in the lattice and that increase

1870
00:50:19,560 --> 00:50:19,570
metal in the lattice and that increase

1871
00:50:19,570 --> 00:50:20,910
metal in the lattice and that increase
in the vibrational motion sometimes

1872
00:50:20,910 --> 00:50:20,920
in the vibrational motion sometimes

1873
00:50:20,920 --> 00:50:23,550
in the vibrational motion sometimes
breaks the molecular orbital which goes

1874
00:50:23,550 --> 00:50:23,560
breaks the molecular orbital which goes

1875
00:50:23,560 --> 00:50:25,410
breaks the molecular orbital which goes
from one end to the other end because

1876
00:50:25,410 --> 00:50:25,420
from one end to the other end because

1877
00:50:25,420 --> 00:50:27,570
from one end to the other end because
you change the distances between the

1878
00:50:27,570 --> 00:50:27,580
you change the distances between the

1879
00:50:27,580 --> 00:50:30,120
you change the distances between the
metal metal atoms and that decreases the

1880
00:50:30,120 --> 00:50:30,130
metal metal atoms and that decreases the

1881
00:50:30,130 --> 00:50:33,240
metal metal atoms and that decreases the
electrical conductivity of the metal so

1882
00:50:33,240 --> 00:50:33,250
electrical conductivity of the metal so

1883
00:50:33,250 --> 00:50:35,970
electrical conductivity of the metal so
we say that the metal conductivity

1884
00:50:35,970 --> 00:50:35,980
we say that the metal conductivity

1885
00:50:35,980 --> 00:50:37,950
we say that the metal conductivity
decreases with increase in temperature

1886
00:50:37,950 --> 00:50:37,960
decreases with increase in temperature

1887
00:50:37,960 --> 00:50:41,040
decreases with increase in temperature
but semiconductor conductivity increases

1888
00:50:41,040 --> 00:50:41,050
but semiconductor conductivity increases

1889
00:50:41,050 --> 00:50:44,660
but semiconductor conductivity increases
with increase in temperature okay

1890
00:50:44,660 --> 00:50:44,670
with increase in temperature okay

1891
00:50:44,670 --> 00:50:48,720
with increase in temperature okay
question so let's have a break and come

1892
00:50:48,720 --> 00:50:48,730
question so let's have a break and come

1893
00:50:48,730 --> 00:50:52,020
question so let's have a break and come
back after 10 minutes let's