• The electrons in an atom are found in atomic orbitals, the electrons in a molecule are found in molecular orbitals.
• The molecular orbitals are formed by the combination of atomic orbitals of comparable energies and proper symmetry.
• The BMO has lower energy and hence greater stability than the corresponding ABMO.
• The molecular orbitals are filled by electrons in accordance with Aufbau principle, Pauli’s exclusion principle, and the Hund’s rule.
