Question

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

Answer 1

e (Z = 26)

\[\ce{Fe -> Fe^2+ + 2e^-}\]

\[\ce{Fe -> Fe^3+ + 3e^-}\]

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 the Aufbau principle. Half filled and completely filled d-orbitals are more stable than partially filled d-orbitals. So Fe³⁺ is more stable than Fe²⁺.