Q.What is inert pair effect?

The inert pair effect makes the ns² electrons of heavy p-block atoms reluctant to bond, favouring a lower oxidation state as we go down a group.

Explanation

In the p-block, as we move down a group, the effective nuclear charge experienced by the outermost ns electrons increases due to poor shielding by the intervening d- and f-electrons. Consequently, the ns² electron pair is held more tightly by the nucleus and becomes increasingly reluctant to participate in bond formation, while the np electrons are still available for bonding. This tendency of the ns² pair to remain non-bonding (as a lone pair) is called the inert pair effect.

Consequence

This makes the oxidation state that is 2 units less than the group oxidation state increasingly stable as we move down a group.

Examples

• Group 13: Tl⁺ is more stable than Tl³⁺ (unlike Al³⁺, which is the stable state for aluminium). …