Hetero-Diatomics: HF Due to higher electronegativity of F than H, - - PowerPoint PPT Presentation

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Sep 20, 2022 356 likes •618 views

Hetero-Diatomics: HF Due to higher electronegativity of F than H, the electron distribution is lopsided Hetero-Diatomics: HCl For Cl 3p states close in energy to the 1s of H Hetero-Diatomics: HBr For Cl 4p states close (higher) in energy to the

SLIDE 1

Hetero-Diatomics: HF Due to higher electronegativity

f F than H, the electron

distribution is lopsided

SLIDE 2

Hetero-Diatomics: HCl For Cl 3p states close in energy to the 1s of H

SLIDE 3

Hetero-Diatomics: HBr For Cl 4p states close (higher) in energy to the 1s of H

SLIDE 4

Hetero-Diatomics: CO

SLIDE 5

Hybridization Linear combination of atomic orbitals within an atom leading to more effective bonding 2s 2pz 2px 2py 2px 2py α 2s-β 2pz α 2s+β 2pz The coefficients α and β depend on field strength

Hybridization is close to VBT approach. Use of experimental information All hybridized orbitals are equivalent and are ortho-normal to each other

SLIDE 6

Contribution from s=0.5; contribution from p=0.5 Have to normalize each hybridized orbital 2 equivalent hybrid orbitals

f the same energy and

shape (directions different)

Linear geometry with Hybridized atom at the center s and p orbital of the Same atom! Not same as S (overlap)

s+p (sp)Hybridization   = −  

1

1 2

s p

ψ ψ ψ   = +  

2

1 2

s p

ψ ψ ψ

SLIDE 7

s+p (sp)Hybridization

SLIDE 8

The other p-orbitals are available for π bonding s+p (sp)Hybridization

SLIDE 9

Molecular orbitals of BeH2

SLIDE 10

Molecular orbitals of BeH2

( ) ( ) ( ) ( )

* 4 2 3 1 1 * 2 2 1 1 1 3 2 4 1 1 1 2 2 1 1

A B A B A B A B

H H u Be s s H H g Be s s H H u Be s s H H g Be s s

pz s pz s

c c c c c c c c

σ σ σ σ

ϕ ψ ψ ψ ϕ ψ ψ ψ ϕ ψ ψ ψ ϕ ψ ψ ψ = − − = − + = + − = + +

SLIDE 11

Molecular orbitals & Hybridization in BeH2

g u σ σ

ϕ ϕ −

g u σ σ

ϕ ϕ +

( )

3 2 4 1 1

A B

H H u Be s s

pz

c c

σ

ϕ ψ ψ ψ = + −

( )

1 2 2 1 1

A B

H H g Be s s

s

c c

σ

ϕ ψ ψ ψ = + +

SLIDE 12

s+2p (sp2)Hybridization px and py can be combined with s to get three 3 equivalent hybrids at 120o to each other x y

30o 30o

x y

30o 30o

x y

30o 30o

+

x

s p − + cos(60) cos(30)

x y

s p p − − cos(60) cos(30)

x y

s p p

SLIDE 13

The other p-orbital are available for π bonding s+2p (sp2)Hybridization

1 2 3

1 2 3 3 1 1 1 3 2 6 1 1 1 3 2 6

s px py s px py s px py

ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ = + × + = + − = − −

SLIDE 14

s+2p (sp2)Hybridization

SLIDE 15

How to calculate the coefficients? Use orthogonality of hybrid orbitals and normalization conditions There is no unique solution

s+3p (sp3)Hybridization

1 2 3 4

1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2

s px py pz s px py pz s px py pz s px py pz

ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ = + + + = − − + = + − − = − + −

1 2 3 4

1 3 2 2 1 2 1 2 3 2 3 1 1 1 1 2 6 2 2 3 1 1 1 1 2 6 2 2 3

s px py pz s px py pz s px py pz s px py pz

ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ ψ = + × + × + = + + × − = − + − = − − −

SLIDE 16

s+3p (sp3)Hybridization No other p-orbital is available for π bonding

SLIDE 17

Asymmetrical Hybridization: Water Molecule Electronic Configuration of ‘O’ atom: 1s22s22pz22px12py1 104.5o φ φ = + = +

1 1 2 2 3 4

1 2 1 2

A B

H xO H yO

c s c p c s c p ψ ψ = + + = + +

1 1 2 3 2 4 5 6

( ) 2 2 2 ( ) 2 2 2

x y x y

O a s a p a p O a s a p a p ψ ψ = × + × + × = × − × + ×

1 2

( ) 0.45 2 0.71 2 0.55 2 ( ) 0.45 2 0.71 2 0.55 2

x y x y

O s p p O s p p

SLIDE 18

Asymmetrical Hybridization: Water Molecule Electronic Configuration of ‘O’ atom: 1s22s22pz22px12py1 Form bonds with two Hydrogen atoms Two lone pair electrons ψ ψ ψ ψ = × + × + × = × − × + × = × − × =

1 2 3 4

( ) 0.45 2 0.71 2 0.55 2 ( ) 0.45 2 0.71 2 0.55 2 ( ) 0.77 2 0.63 2 ( ) 2

x y x y y z

O s p p O s p p O s p O p

SLIDE 19

Asymmetrical Hybridization: Water Molecule Electronic Configuration of ‘O’ atom: 1s22s22pz22px12py1 Form bonds with two Hydrogen atoms Two lone pair electrons NOT Equivalent! ψ ψ ψ ψ = × + × + × = × − × + × = × − × =

1 2 3 4

( ) 0.45 2 0.71 2 0.55 2 ( ) 0.45 2 0.71 2 0.55 2 ( ) 0.77 2 0.63 2 ( ) 2

x y x y y z

O s p p O s p p O s p O p

SLIDE 20

Asymmetrical Hybridization: Water Molecule Electronic Configuration of ‘O’ atom: 1s22s22pz22px12py1 Form bonds with two Hydrogen atoms Two lone pair electrons NOT Equivalent! 104.5o ψ ψ = × − × + × = × − × − ×

3 4

( ) 0.55 2 0.45 2 0.71 2 ( ) 0.55 2 0.45 2 0.71 2

y z y z

O s p p O s p p ψ ψ ψ ψ = × + × + × = × − × + × = × − × =

1 2 3 4

( ) 0.45 2 0.71 2 0.55 2 ( ) 0.45 2 0.71 2 0.55 2 ( ) 0.77 2 0.63 2 ( ) 2

x y x y y z

O s p p O s p p O s p O p

SLIDE 21

Asymmetrical Hybridization: Water Molecule Form bonds with two Hydrogen atoms Lone pair electrons

Lone pair electrons have more ‘s’ character than the bonding orbitals

ψ ψ ψ ψ = × + × + × = × − × + × = × − × + × = × − × − ×

1 2 3 4

( ) 0.45 2 0.71 2 0.55 2 ( ) 0.45 2 0.71 2 0.55 2 ( ) 0.55 2 0.45 2 0.71 2 ( ) 0.55 2 0.45 2 0.71 2

x y x y y z y z

O s p p O s p p O s p p O s p p

SLIDE 22

Asymmetrical Hybridization: Water Molecule Bond pairs Lone pairs ψ ψ ψ ψ = × + × + × = × − × + × = × − × + × = × − × − ×

1 2 3 4

( ) 0.45 2 0.71 2 0.55 2 ( ) 0.45 2 0.71 2 0.55 2 ( ) 0.55 2 0.45 2 0.71 2 ( ) 0.55 2 0.45 2 0.71 2

x y x y y z y z

O s p p O s p p O s p p O s p p

0.0 0.5 1.0 θ =104.47

0.71 0.55 0.71 0.55

θ'=tan

1(0.55/0.71)

=37.76

SLIDE 23

s-p3-d2 & s-p3-d Hybridization Sp3d2 Octahedral Sp3d Trignoal bipyramidal

SLIDE 24

Hybridization and Geometry

SLIDE 25