Lesson 4: Molecular Orbital Theory (MOT)
MOT is a more sophisticated theory that explains bonding in a different way, providing insights that VBT cannot, particularly for magnetic properties.
- Principles of MOT: In this theory, atomic orbitals combine to form an equal number of molecular orbitals (MOs). The MOs are classified as bonding MOs (lower energy, stabilize the molecule) and antibonding MOs (higher energy, destabilize the molecule).
- Bond Order: A key concept derived from MOT is bond order, which is calculated as half the difference between the number of electrons in bonding and antibonding MOs. A positive bond order indicates a stable bond.
- Magnetic Properties: MOT provides a perfect explanation for the magnetic properties of molecules. For example, it correctly predicts that oxygen (O$_2$) is paramagnetic (has unpaired electrons), a fact that VBT fails to explain. Students will learn how to write the electronic configuration of simple homonuclear diatomic molecules
