The +1 oxidation state in group 13 and +2 oxidation state in group 14 becomes more and more stable with increasing atomic number. Explain.

This property is due to an effect called the inner pair effect.

In groups 13 and 14 as we move down the group the tendency of the s-orbital electrons to participate in the bond formation decreases this is due to the poor shielding of s-orbital electrons by the d and f orbitals. This is called an inner pair effect.

Thus,the +1 oxidation state in group 13 and +2 oxidation state in group 14 becomes more and more stable with increasing atomic number.