上海交通大学：《大学化学》教学资源_加州理工课件学习_Series11HybridizationPart2

Hybridization 6 Reading:Gray:(4-7) oGC:(6.4)and(6.5) X1-1

Hybridization Part 2 Reading: Gray: (4-7) OGC: (6.4) and (6.5) XI-1

The Story so far: MO-LCAO works great for diatomic molecules! We can use hybridization of the central atom and MO-LCAO together to describe small polyatomic molecules. But... What about larger molecules? Does hybridization MO-LCAO enable us to describe more complicated molecules? X1-2

MO-LCAO works great for diatomic molecules! But... The Story so far: We can use hybridization of the central atom and MO-LCAO together to describe small polyatomic molecules. Does hybridization / MO-LCAO enable us to describe more complicated molecules? XI-2

Watson and Crick's Original DNA Model X-3

Watson and Crickʼs Original DNA Model XI-3

We'll take the challenge: C2H6 From VSEPR and Lewis dot structures,we know it looks like this: H H HC-C"H H H H H H H X1-4

Weʼll take the challenge: C2H6 From VSEPR and Lewis dot structures, we know it looks like this: H H H H H c c C C H H H H H H XI-4

H HC- Let's analyze one C at a time. H Look at the left C.- H Notice it has a steric number of four: 2 What other molecule had a steric number of four?CH4 This suggests we should hybridize our current C the same way. X1-5

C C H H H H H H C2H6 Look at the left C. Notice it has a steric number of four: What other molecule had a steric number of four? CH4 This suggests we should hybridize our current C the same way. Letʼs analyze one C at a time. H H H H H H 1 2 3 4 C H C XI-5

C2Ho H C H H sp3 hybridize the carbon: Sp3 Notice the Sp3 Sp3 tetrahedral shape. sp3 Add 3 hydrogens (using MO-LCAO) 1s Sp3 Sp3 Sp3 H 1s Sp3 1s X1-6

C2H6 sp3 hybridize the carbon: Add 3 hydrogens (using MO-LCAO) sp3 sp3 sp3 sp3 sp3 sp3 sp3 H H H C 1s 1s 1s sp3 Notice the tetrahedral shape. C C H H H H H H XI-6

C2H6 、H H-C-C H H H Do the same to the other side: Sp3 Sp3 Sp3 Sp3 Bring the two halves together: Success! X-7

C2H6 Do the same to the other side: Bring the two halves together: C C H H H H H H sp3 sp3 sp3 sp3 H H H C H C H H XI-7

C2H6 H. H H-C-C H H Notice that all the bonds formed are o bonds. Each is rotationally symmetrical about its axis. X-8

C2H6 Notice that all the bonds formed are σ bonds. Each is rotationally symmetrical about its axis. H H H C H C H H C C H H H H H H XI-8

Let's try another: C2Ha From VSEPR and Lewis dot structures,we know it looks like this: H ∠H C= H H H H H H H X1-9

Letʼs try another: C2H4 From VSEPR and Lewis dot structures, we know it looks like this: C C H H H H C H H C C C H H H H XI-9

C2Hg H C=C Let's analyze one C at a time. H Look at the left C.- Notice it has a steric H 20 number of three: What other molecule had a steric number of three?BH3 This suggests we should hybridize our current C the same way. X-10

Look at the left C. Notice it has a steric number of three: What other molecule had a steric number of three? BH3 This suggests we should hybridize our current C the same way. Letʼs analyze one C at a time. C C H H H H C2H4 B H H H C 1 2 3 C H H XI-10