Question

Explain trivalent ion fe3+ ion os more stable than th divalent ion fe2+

Answer 1

Half-filled and fully-filled orbitals are extra stable, because of their symmetry. Fe 3+ has d5 configuration, which is half filled. Fe 2+ has d6 configuration and neighter half filled nor full filled, partiall filled, which is less symmetric than  d5 configuration. So Fe3+ ion are more stable than Fe2+.