Molecular Orbital Theory Summary

Molecular Orbital Theory Overview

• Explains molecular bonding beyond Lewis structures, VSEPR, and valence bond theory.

• Addresses discrepancies in oxygen molecule (O2) behavior and magnetic properties.

Key Concepts of Molecular Orbital Theory

• Accounts for paramagnetism in O2, which has unpaired electrons.

• Combines atomic orbitals to form delocalized molecular orbitals over the entire molecule.

Molecular Orbitals and Electron Behavior

• Electrons exist in regions called molecular orbitals, characterized by quantized energies.

• Molecular orbitals result from constructive (in-phase) or destructive (out-of-phase) interference of atomic orbital wave functions.

Bonding and Antibonding Orbitals

• Bonding Orbitals (σs, σpx, π): Lower energy, higher probability of electron density between nuclei.

• Antibonding Orbitals (σs, σpx, π*): Higher energy, features a node between nuclei leading to lower electron density.

Electron Filling and Spin

• Electrons fill bonding orbitals first before antibonding orbitals, similar to atomic orbitals.

• A molecular orbital is full with two electrons of opposite spins.

Formation of σ and π Orbitals

• σ Orbitals: Formed by end-to-end combination of s and p orbitals, leading to σ and σ* types.

• π Orbitals: Formed by side-by-side combination of p orbitals, creating π and π* types.

• Each set of p orbitals can produce distinct bonding and antibonding molecular orbitals, leading to multiple orbitals (σpx, σpx, πpy, πpy, πpz, π*pz).