Explain the formation of molecular orbitals by linear combination of atomic orbitals (LCAO).

Explanation

The formation of molecular orbitals take place either by the addition or subtraction of wave functions of individual atomic orbitals. These are shown as below:
`sigma Psi_(MO)=Psi_(A)pmPsi_(B)`
Here, the two molecular orbitals `sigma` and `sigma^(**)` are formed as :
`{:(sigma= Psi_(A)+Psi_(B)),(sigma^(**)= Psi_(A)-Psi_(B)):}`
The molecular orbital `simga` formed by addition of atomic orbitals is called the bonding molecular orbital. The molecular orbital `sigma^(**)` formed by the subtraction of atomic orbitals is called antibonding molecular orbital.