Question

Manganese in the +2 oxidation state is more stable than +3 oxidation state where as iron is stable at +3
oxidation state than +2 oxidation state. Explain why?

Answer 1

DEAR STUDENT,
The electronic configuration of Mn is [Ar]3d⁵4s².
Mn²⁺ - [Ar]3d⁵ and Mn³⁺ - [Ar]3d⁴
Since half-filled d-orbital (3d⁵) has more stability and lower energy than 3d⁴, Mn²⁺ is more stable than Mn³⁺.
But in the case of iron, The electronic configuration of Fe is [Ar]3d⁶4s².
Fe²⁺ - [Ar]3d⁶ and Fe³⁺ - [Ar]3d⁵
Since the half-filled orbital is more stable, the +3 oxidation state of Fe is more stable than the +2 state.
REGARDS,