Iron (Fe) has a valency of 2. as per the number of electrons in the 4s orbital. Iron exists with a valency of 2, 3, 4, 5 in many compounds. Most stable ones are those with Iron in an oxidation state of 2 : Fe(II) or 3 : Fe(III).
In Fe²⁺ , the outermost orbital electrons are given out.
In Fe³⁺ , the 3d orbitals will have all 5 unpaired electrons.
Fe has an atomic number Z of 26. configuration is :
1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²
We find Iron in an oxidation state of 2 , in Ferrous Sulphate : Fe SO₄ , Ferrous oxide : Fe O
In an oxidation state of 3, in Ferric chloride Fe Cl₃ , Ferric oxide: Fe₂ O₃