Inert pair effect is defined as
The non-participation of the two s electrons in bonding due to the high energy needed for unpairing them.
The inert pair theory was proposed by Sidgwick. He along with Powell accounted for the shapes of several molecules and correlated the shapes with some of their physical properties.
Example of Inert Pair Effect
The inert pair effect among group 4 and group 5 elements. Sn2+ and Pb2+ and Sb3+ and Bi3+ which are the lower oxidation states of the elements are formed because of the inert pair effect. When the s electrons remain paired the oxidation state is lower than the characteristic oxidation state of the group.
Difference between Inert Pair Effect and Shielding Effect
|Inert pair effect||Shielding effect|
|The effect explains that reluctance of s-electrons in the valence shell to participate in the bonding.||The effect describes the balance between the attraction between the electrons on valence electrons and the repulsion from the inner electrons.|
|The inert pair effect helps in understanding when common ions of Pb do not follow the octet rule.||The shielding effect explains why electrons from the valence shell can be removed easily.|