Bonding and Antibonding Molecular Orbitals

In the case of bonding molecular orbital, the attraction of both the nuclei for both the electrons is increased. This results in lowering of energy. In the case of antibonding molecular orbital, the electrons try to go away from the nuclei and this corresponds to repulsive state.

The energy of this orbital will be higher. The relative energies of bonding and antibonding molecular orbitals along with atomic orbitals can be represented as shown in the figure given below.

fig 1.10 - Relative energies of s1s and s*1s molecular orbitals

Thus, the bonding molecular orbital is stabilized relative to the energy of the isolated atoms and antibonding molecular orbital is destabilized relative to the individual atoms. Further, it may be noted that the bonding molecular orbital is stabilized to the same extent as the antibonding molecular orbital is destabilized.