Hybridization
VSEPR Theory – Predicts molecular shape, but doesn’t relate covalent
bonding geometry to molecular orbitals.
Valence Bond Theory – Describes molecular geometry in terms of atomic
orbitals. States that a covalent bond occurs when:
The orbitals from 2 atoms overlap and a pair of electrons occupies the
region between the nuclei.
Central Ideas of VBT:
1. Opposing spins pair in a covalent bond.
2. Maximum overlap of orbitals occurs in a covalent bond.
3. Atomic orbitals hybridize (mix) in a covalent bond.
Rules for hybridizing atomic orbitals. (Look at the central atom only!)
Recall electron configurations: There is only 1 orbital in the s sublevel, 3
orbitals in the p sublevel, 5 orbitals in the d sublevel. We can mix up to 1 s
orbital, 3 p orbitals, and 5 d orbitals (but we won’t need that many)
1. The number of atomic orbitals mixed = the total number of hybridized
orbitals formed. This also = the number of electron groups around the
central atom.
2. The type of hybrid orbital formed depends on the atomic orbitals that
formed it. If you mix 1 s orbital and 1 p orbital, you get 2 sp hybrid orbitals.
3. All hybrid orbitals are degenerate. (Equal in energy)
Fill in the following chart:
Atomic Orbitals
Mixed
Hybrid orbitals
Formed
Shape of
molecule
2 sp hybrids
# of e- groups
around central
atom
2
1s + 1p
1s + 2p
3 sp2 hybrids
3
trigonal planar
bent angular
1s + 3p
4 sp3 hybrids
4
tetrahedral,
trigonal
pyramidal,
bent
linear