chapter 3: bonding fundamentals (MO theory & hybridization)

What is the difference between σ and π bonds?

• σ bonds: head-on overlap, single bonds only

• π bonds: side-by-side p orbital overlap, require unhybridized p orbitals

All single bonds are σ. Double = 1 σ + 1 π. Triple = 1 σ + 2 π.

What does Molecular Orbital (MO) theory explain?

MO theory explains bonding as a combination of atomic orbitals forming bonding and antibonding orbitals. Two atomic orbitals always form two molecular orbitals.

Why does hybridization exist?

Hybridization explains observed molecular geometry by mixing atomic orbitals into equivalent hybrid orbitals. The number of hybrid orbitals equals the number of orbitals mixed. This links geometry, bonding, and orbital theory.

How do hybridization, geometry, and bonding connect?

sp³: 4 groups → tetrahedral → 109.5° → no π bonds

sp²: 3 groups → trigonal planar → 120° → 1 π bond

sp: 2 groups → linear → 180° → 2 π bonds