Salient Features of Molecular Orbital (MO) Theory

• The electrons in a molecule are present in various molecular orbitals as the electrons of atoms are present in various atomic orbitals.

• Molecular orbitals are formed by the combination of atomic orbitals of comparable energy and proper symmetry.

• An electron in an atomic orbital is under the influence of only one nucleus while in a molecular orbital, it is under the influence of two or more nuclei depending upon the number of atoms in the molecule. Thus, an atomic orbital is mono-centric while a molecular orbital is polycentric.

• The number of molecular orbitals formed is equal to the number of combining atomic orbitals. When two atomic orbitals combine, two molecular orbitals are formed. One is called bonding molecular orbital and the other is called anti-bonding molecular orbital.

• The bonding MO has greater stability than anti-bonding MO as bonding MO has lower energy than anti-bonding MO.

• A molecular orbital gives the electron probability distribution around a group of nuclei in a molecule such as an atomic orbital that gives the electron probability distribution around a nucleus in an atom.

• The molecular orbitals are filled in the same way...