P Block Elements

Oxygen differs from other elements of group 16 (S, Se, Te, Po) due to its small size, high electronegativity, and absence of vacant d-orbitals. Its anomalous behaviour is as follows:

• (i) Atomicity: Oxygen exists as a diatomic molecule ( ), whereas other group members exist as polyatomic molecules such as , , etc.
• (ii) Oxidation state: Oxygen shows only two common oxidation states: (in most compounds) and (in peroxides). Other group members exhibit higher oxidation states like and due to the presence of d-orbitals.
• (iii) Magnetic property: Dioxygen ( ) is paramagnetic due to the presence of two unpaired electrons in antibonding molecular orbitals ( ). Other group members in molecular form are generally diamagnetic.
• (iv) Nature of hydrides: Water ( ) is a liquid at room temperature, has strong hydrogen bonding, and shows high boiling point. Hydrides of other group members (H S, H Se, H Te) are gases with weak intermolecular forces and much lower boiling points.

Final Answer:

Oxygen shows anomalous behaviour in all four aspects: It exists as diatomic , has limited oxidation states, is paramagnetic, and forms a unique hydrogen-bonded liquid hydride (water).