Question

why does iron show a valency of 2 and 3 whereas zinc doesn't?

why are iron nails highly paramagnetic in nature?

Answer 1

Electronic configuration of Fe is 3d⁶ 4s² and electronic configuration of Zn is 3d¹⁰ 4s² .

Both Fe and Zn show +2 valency.

for +3 valency,

the 3rd electron will have to be removed from partially filled 3d orbital of Fe and a half filled 3d orbital will be produced with 5 electrons. Half filled orbital is more stable than partially filled orbitals thus Fe will show +3 valency frequently.

In case of +3 valency of Zn, the 3rd electron will be removed from fully filled 3d orbital which will require a large amount of energy as fully filled orbitals are very stable. Thus Zn does not show +3 oxidation state.