Valence Bond Theory

1
Valence Bond Theory
A covalent bond forms when two half-filled
orbitals overlap.
H
H
H2
2
Electron Configuration of C



3
Electron Promotion
90o
4
Methane
109o
5
Hybridization
A theoretical process involving the mixing of
orbitals to create a new set of orbitals. It
only occurs when an atom forms a covalent bond.
These hybrid orbitals are 109o apart.

6
Bonding in Methane
7
Ethene
120o
8
sp2 hybridization
120o
9
Bonding in Ethene
sp2 hybrid orbitals
sigma (s) bonds ? end-to-end overlap of orbitals
unhybridized p orbitals
pi (?) bond ? side-by-side overlap of orbitals
10
Acetylene
180o
11
sp hybridization
180o
12
Bonding in Acetylene
unhybridized p orbitals
sp hybrid orbitals
pi bond
sigma bond
sigma bond
pi bond