Molecular Orbital Theory

Molecular orbital theory was proposed by F. Hund and R.S. Mulliken in 1932. The basic idea of molecular orbital theory is that atomic orbitals of individual atoms combine to form molecular orbitals. The electrons in molecules are present in the molecular orbitals, which are associated with several nuclei. These molecular orbitals are filled in the same way as the atomic orbitals in atoms are filled.

Molecular orbitals are formed by the combination of atomic orbitals of bonded atoms. According to wave mechanics, the atomic orbitals can be expressed by wave functions (y). The wave functions represent the amplitude of the electron waves. These are obtained from the solutions of Schrodinger wave equation. Similarly, we can write Schrodinger wave equation for the whole molecule. However, it is very difficult to solve the wave equation for molecules. To overcome this problem, scientists have used an approximate method known as linear combination of atomic orbitals.