Question

Explain why stability of +1 oxidation state progressively increases for the heavier elements of group 13 ?

Answer 1

This happens due to the 'inert pair effect'. As we go down the group, the size of the atom increases as d and f electrons are far away from the nucleus. This makes the s electrons more tightly bound to the nucleus due to which they are reluctant to take part in chemical reactions. They act as an inert pair of electrons and this leads to added stability of +1 oxidation state in group 13 elements. Instead of losing 3 electrons (2 from s orbital and 1 from p), they only tend to lose the p orbital electrons.