Discuss the pattern of oxidation from boron to thallium and also carbon to lead
(a).B and Tl : boron and aluminum show an oxidation state + 3 only because they don't exhibit inert pair effect due to absence of d- or f- orbitals . elements from Ga to Tl show two oxidation state e.g., +1 and +3 . the tendency to show +1 oxidation state increases down the group due to the inability of ns² electrons of valance shell to participate in bonding which is called inert pair effect. therefore, Tl+ is more stable than Tl3+ .
(b).Carbon and Silicon show an oxidation state of +4 only. in heavier members the tendency to show +2 oxidation state increases in the sequence Ge < Sn < Pb. it is due to the inability of ns² electrons of valance shell to participate in bonding (inert pair effect ).Ge forms stable compounds in +4state and only few compounds in +2 state. Sn forms compounds in both the oxidation states and lead compound in +2 oxidation state is more stable than +4 oxidation state.