The p- Block Elements – Solutions

1) Discuss the pattern of variation in the oxidation states of I)B to Tl and ii) C to Pb.

Solution

i) The elements from B to Tl are group 13 elements. They exhibit both +1 to +3 oxidation states. The most stable oxidation state is +3. B and Al exhibit only +3 oxidation state, while Ga, In and Tl exhibit +3 and +1 oxidation states. But the stability of +1 oxidation state increases down the group from B to Tl, due to inert pair effect of ns²

ii) The elements from C to Pb are group 14 elements . They exhibit both +4 and +2 oxidation states. C and Si exhibit only +4 oxidation state. Germanium forms stable compounds in +4 oxidation state and forms compound in +2 oxidation state. Tin forms stable compounds in both +4 and +2 oxidation states. Lead forms stable compounds only in +2 oxidation state due to inert pair effect of ns² Therefore, in group 14 from C to Pb the stability of +4 oxidation state decreases and the stability of +2 oxidation state increases down the group.