Bonding in methane and orbital hybridization
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Bonding in Methane and Orbital Hybridization. Structure of Methane. tetrahedral bond angles = 109.5° bond distances = 110 pm but structure seems inconsistent with electron configuration of carbon. Electron configuration of carbon. only two unpaired electrons

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Bonding in methane and orbital hybridization l.jpg
Bonding in Methane andOrbital Hybridization


Structure of methane l.jpg
Structure of Methane

tetrahedral

bond angles = 109.5°

bond distances = 110 pm

but structure seems inconsistent withelectron configuration of carbon


Electron configuration of carbon l.jpg
Electron configuration of carbon

only two unpaired electrons

should form sbonds to only two hydrogen atoms

bonds should be at right angles to one another

2p

2s


Sp 3 orbital hybridization l.jpg
sp3 Orbital Hybridization

Promote an electron from the 2s to the 2p orbital

2p

2s


Sp 3 orbital hybridization5 l.jpg
sp3 Orbital Hybridization

2p

2p

2s

2s


Sp 3 orbital hybridization6 l.jpg
sp3 Orbital Hybridization

Mix together (hybridize) the 2s orbital and the three 2p orbitals

2p

2s


Sp 3 orbital hybridization7 l.jpg
sp3 Orbital Hybridization

4 equivalent half-filled orbitals are consistent with four bonds and tetrahedral geometry

2p

2 sp3

2s




Shape of sp 3 hybrid orbitals l.jpg
Shape of sp3 hybrid orbitals

take the s orbital and place it on top of the p orbital

p

+

+

s


Shape of sp 3 hybrid orbitals11 l.jpg

+

Shape of sp3 hybrid orbitals

reinforcement of electron wave in regions where sign is the same

destructive interference in regions of opposite sign

s + p

+


Shape of sp 3 hybrid orbitals12 l.jpg

Shape of sp3 hybrid orbitals

orbital shown is sp hybrid

analogous procedure using three s orbitals and one p orbital gives sp3 hybrid

shape of sp3 hybrid is similar

sp hybrid

+


Shape of sp 3 hybrid orbitals13 l.jpg

+

Shape of sp3 hybrid orbitals

hybrid orbital is not symmetrical

higher probability of finding an electron on one side of the nucleus than the other

leads to stronger bonds

sp hybrid


Slide14 l.jpg

+

The C—H s Bond in Methane

In-phase overlap of a half-filled 1s orbital of hydrogen with a half-filled sp3 hybrid orbital of carbon:

+

sp3

s

H

C

gives a s bond.

+

H—C s

C

H


Slide15 l.jpg

Justification for Orbital Hybridization

consistent with structure of methane

allows for formation of 4 bonds rather than 2

bonds involving sp3 hybrid orbitals are stronger than those involving s-s overlap or p-p overlap


Sp 3 hybridization and bonding in ethane l.jpg
sp3 Hybridization and Bonding in Ethane


Slide17 l.jpg

Structure of Ethane

tetrahedral geometry at each carbon

C—H bond distance = 110 pm

C—C bond distance = 153 pm

C2H6

CH3CH3


Slide18 l.jpg

The C—C s Bond in Ethane

In-phase overlap of half-filled sp3 hybridorbital of one carbon with half-filled sp3hybrid orbital of another.

Overlap is along internuclear axis to give a s bond.


Slide19 l.jpg

The C—C s Bond in Ethane

In-phase overlap of half-filled sp3 hybridorbital of one carbon with half-filled sp3hybrid orbital of another.

Overlap is along internuclear axis to give a s bond.


Sp 2 hybridization and bonding in ethylene l.jpg
sp2 Hybridization and Bonding in Ethylene


Structure of ethylene l.jpg
Structure of Ethylene

C2H4

H2C=CH2

planar

bond angles: close to 120°

bond distances: C—H = 110 pm C=C = 134 pm


Sp 2 orbital hybridization l.jpg
sp2 Orbital Hybridization

Promote an electron from the 2s to the 2p orbital

2p

2s


Sp 2 orbital hybridization23 l.jpg
sp2 Orbital Hybridization

2p

2p

2s

2s


Sp 2 orbital hybridization24 l.jpg
sp2 Orbital Hybridization

Mix together (hybridize) the 2s orbital and two of the three 2p orbitals

2p

2s


Sp 2 orbital hybridization25 l.jpg
sp2 Orbital Hybridization

3 equivalent half-filled sp2 hybrid orbitals plus 1 p orbital left unhybridized

2p

2 sp2

2s


Sp 2 orbital hybridization26 l.jpg
sp2 Orbital Hybridization

p

2 of the 3 sp2 orbitalsare involved in s bondsto hydrogens; the otheris involved in a s bondto carbon

2 sp2


Sp 2 orbital hybridization27 l.jpg

s

s

s

s

s

sp2 Orbital Hybridization

p

2 sp2


P bonding in ethylene l.jpg
p Bonding in Ethylene

the unhybridized p orbital of carbon is involved in p bondingto the other carbon

p

2 sp2


P bonding in ethylene29 l.jpg
p Bonding in Ethylene


P bonding in ethylene30 l.jpg
p Bonding in Ethylene


1 18 sp hybridization and bonding in acetylene l.jpg
1.18sp Hybridization and Bonding in Acetylene


Structure of acetylene l.jpg

HC

CH

Structure of Acetylene

C2H2

linear

bond angles: 180°

bond distances: C—H = 106 pm CC = 120 pm


Sp orbital hybridization l.jpg
spOrbital Hybridization

Promote an electron from the 2s to the 2p orbital

2p

2s


Sp orbital hybridization34 l.jpg
sp Orbital Hybridization

2p

2p

2s

2s


Sp orbital hybridization35 l.jpg
spOrbital Hybridization

Mix together (hybridize) the 2s orbital and one of the three 2p orbitals

2p

2s


Sp orbital hybridization36 l.jpg
sp Orbital Hybridization

2 equivalent half-filled sp hybrid orbitals plus 2 p orbitals left unhybridized

2p

2 p

2 sp

2s


Sp orbital hybridization37 l.jpg
sp Orbital Hybridization

2 p

1 of the 2 sp orbitalsis involved in a s bondto hydrogen; the otheris involved in a s bondto carbon

2 sp


Sp orbital hybridization38 l.jpg
sp Orbital Hybridization

s

2 p

s

2 sp

s


P bonding in acetylene l.jpg
p Bonding in Acetylene

the unhybridized p orbitals of carbon are involved in separatep bonds to the other carbon

2 p

2 sp


P bonding in acetylene40 l.jpg
p Bonding in Acetylene


P bonding in acetylene41 l.jpg
p Bonding in Acetylene


P bonding in acetylene42 l.jpg
p Bonding in Acetylene


Which theory of chemical bonding is best l.jpg
Which Theory ofChemical Bonding is Best?


Three models l.jpg
Three Models

Lewis

most familiar—easiest to apply

Valence-Bond (Orbital Hybridization)

provides more insight than Lewis model

ability to connect structure and reactivity to hybridization develops with practice

Molecular Orbital

potentially the most powerful method

but is the most abstract

requires the most experience to use effectively