Question

Which is more stable? Fe³⁺ or Fe²⁺ – explain.

Answer 1

Fe (Z = 26) 

Fe → Fe2⁺ + 2e^- 

Fe → Fe³⁺ + 3e^-

Fe²⁺ [Number of electrons 24] 

Electronic configuration = [Ar]3d⁶ 

Fe³⁺ [Number of electrons 23] 

Electronic configuration = [Ar]3d⁵ 

Among Fe³⁺ and Fe²⁺ , Fe³⁺ is more stable due to half filled d-orbital. This can be explained by Aufbau principle. Half filled and completely filled d-orbitals are more stable than partially filled d-orbitals. So Fe³⁺ is more stable than Fe²⁺.