Question

Explain anomalous behaviour of oxygen in group 16 with respect to:
i. Atomicity
ii. Magnetic property
iii. Oxidation state

Hint:

Oxygen’s anomalies stem from its small size, high electronegativity, and lack of d-orbitals.

Answer 1

i. Atomicity: Oxygen exists as a diatomic gas (\( \text{O}_2 \)), whereas other group 16 elements (S, Se, Te) form polyatomic structures (e.g., S\(_8\)) due to stronger tendency for catenation.
ii. Magnetic Property: O\(_2\) is paramagnetic due to two unpaired electrons in its molecular orbitals (\( \pi^*_{2p} \)), while others like S\(_8\) are diamagnetic.
iii. Oxidation State: Oxygen commonly shows -2 (e.g., H\(_2\)O), rarely +2 (e.g., OF\(_2\)) due to high electronegativity. Others (S, Se, Te) show +4, +6 due to d-orbital availability.