Question

Explain the terms
(i) Bonding molecular orbitals
(ii) Antibonding molecular orbitals
(iii) Non-bonding molecular orbitals

Answer 1

Hint: Whenever molecules are going to form from atoms, then the atomic orbitals of atoms interact with each other and form molecular orbitals. Molecular orbitals are mainly of two types. Those are Bonding molecular orbitals, and Antibonding molecular orbitals. The non-bonding one doesn’t take part in the chemical bonding.

Complete step by step answer:
(i) Bonding molecular orbital:
-The bonding orbital which is formed by the interaction of orbitals of the atoms with same symmetry.
-The formed molecular orbital is called the bonding orbital, and its energy is lower than that of the atomic orbitals of the atoms.
-Electrons spend most of their time between the nuclei of two atoms placed into the bonding orbitals. Entering of an electron into the bonding orbital stabilizes the molecule. -Electrons will enter according to the energy levels of the molecular orbitals.
-Electrons enter first into the lower energy molecular orbitals called bonding molecular orbital and then they enter into the higher energy molecular orbitals.
-The structure of the bonding molecular orbital is as follows.

(ii) Antibonding molecular orbitals:
-Antibonding molecular orbitals are the molecular orbitals where the interactions lack in symmetry happens due to overlap of the orbitals of the atoms and leads to lessening in electron density between the nuclei of the atoms and upsurge in density away from the atoms.
-Electrons that occupy most of the time outside the nuclei of the atoms are placed into the antibonding molecular orbitals. Equally, entering of electrons into the antibonding molecular orbitals will reduce the stability of the molecule.

(iii) Non-bonding molecular orbitals:
-Non-bonding molecular orbitals are molecular orbitals in which addition or removal of electrons does not affect the energy of the molecule.
-The electron density in non-bonding molecular orbitals is focused in one atom and the electron has the same energy in the molecule as that of atom.

Note: Always remember that the energies of Antibonding molecular orbitals are always higher than bonding molecular orbitals due to the destructive overlapping that leads to the formation of the antibonding molecular orbital. The destructive overlapping takes place when the waves interact with each other in out of phase i.e. the amplitude of the resultant wave decreases resulting in higher energy while the constructive overlapping which is observed in the formation of bonding molecular orbitals takes place when the waves interact with each other in the same phase i.e. the amplitude of the resultant wave increases resulting in lower energy.