Discuss the pattern of variation in the oxidation states of (i) B to Tl, (ii) C to Pb

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p-blockelements

#1

(i) Element Oxidation state
Boron (B) + 3
Aluminium (Al) + 3
Gallium (Ga) +3 +1
Indium (In) +3 +1
Thallium (Tl) +3 +1 1
The eledronic configaration of all the above elements. As we go down the group the 2 electrons present in s-orbital prefer to remain paired, i.e., they do not take part in bond formation. Such a pair of elctrons is called Inert-Pair and this effect is called Inert-Pair Effect
Therefore as we go down the group 13, the

    1. Oxidation state becomes increasingly more
      dominant, (ii) Element Oxidation state
      Carbon © + 4
      Silicon (Si) + 4
      Germanium (Ge) + 4 (+2)
      Tin (Sn) + 4 + 2
      Lead (Pb) (+4) + 2 1

It is again due to inert-pair effect.
As we go down the group electrons prefer to remain paired, i.e., they do not take part in bond formation. Therefore the heavier elements of the group show increasingly + 2 oxidation state.