Molecular Orbital Theory and Bonding Concepts

Molecular Orbital Theory

Describes electron distribution and energy in molecules.

Valence Bond Theory Failure

Inadequate for explaining molecular properties like O2.

Bonding Orbitals

Lower energy orbitals formed from in-phase overlap.

Antibonding Orbitals

Higher energy orbitals from out-of-phase overlap.

Nonbonding Orbitals

Orbitals with energy equal to atomic orbitals.

Wave Function

Mathematical description of electron behavior in orbitals.

Schrödinger Wave Equation

Equation used to describe wave functions of electrons.

Constructive Interference

In-phase wave functions combine to lower energy.

Destructive Interference

Out-of-phase wave functions combine to higher energy.

Sigma Bonding Orbital

Formed by head-on overlap of atomic orbitals.

Nodal Plane

Region where probability of finding electron is zero.

Pi Molecular Orbitals

Formed by side-on overlap of p atomic orbitals.

Bond Order

Indicates number of bonds; higher means more stability.

Pauli Exclusion Principle

No two electrons can have identical quantum states.

Hund's Rule

Electrons occupy degenerate orbitals singly before pairing.

Aufbau Principle

Electrons fill lowest energy orbitals first.

Bond Energy

Energy required to break one mole of bonds.

Paramagnetic Molecules

Contain unpaired electrons in molecular orbitals.

Diamagnetic Species

Have no unpaired electrons in molecular orbitals.

Homonuclear Diatomic Molecules

Molecules composed of two identical atoms.

Energy Level Diagram

Visual representation of molecular orbital energies.

Overlap of 1s Orbitals

Produces bonding and antibonding molecular orbitals.

Overlap of 2pz Orbitals

Head-on overlap forms sigma orbitals.

Overlap of 2py Orbitals

Side-on overlap forms pi molecular orbitals.

Overlap of 2px Orbitals

Similar to 2py, produces bonding and antibonding p orbitals.