Question

To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your
answer with examples.

Answer 1

The elements in the first-half of the transition series exhibit many oxidation states with Mn
exhibiting maximum number of oxidation states (+2 to +7). The stability of +2 oxidation state increases with the increase in atomic number. This happens as more electrons are getting filled in the d-orbital. However, Sc does not show +2 oxidation state. Its electronic configuration is 4s² 3d¹. It loses all the three electrons to form Sc3+. ⁺³ oxidation state of Sc is very stable as by losing all three electrons, it attains stable noble gas configuration, [Ar]. Ti (+ 4) and V(+5) are very stable for the same reason. For Mn, +2 oxidation state is very stable as after losing two electrons, its d-orbital is exactly half-filled, [Ar] 3d^5.