Question

Give reason in group $16$, the stability of +6 oxidation state decreases and that of $+4$ oxidation state increases down the group.

Answer 1

• Group 16 elements have $n{s}^{2}n{p}^4$ electronic configuration.
• Hence they would be expected to have a maximum oxidation state of +6 but the heavy elements show a lower oxidation state, i.e., +4.
• This is due to inert pair effect due to which s-electrons remain paired and do not participate in bond formation.
• This happens because the s-orbitals held close to the nucleus, therefore the electrons present in s-orbitals held strongly by nucleus because of large electrostatic force.
• Since the energy required to unpair these s-electrons is high, hence the electrons remain paired.
  
• Hence, the stability of +6 oxidation state decreases and that of +4 oxidation state increases down the group.