Question

Explain briefly how +2 states become more and more stable in the first half of the first-row transition elements with increasing atomic numbers.

Answer 1

In the elements of the first half of the first row, with the removal of valance 4s electrons (+2 oxidation state) the 3d orbital gets gradually occupied. Since the number of empty d orbital decreases, the stability of the cations (M²⁺) increases from Sc²⁺ to Mn²⁺.