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.

Explanation

In a transition series, the oxidation states which lead to noble gas or exactly half-filled or completely filled d-orbitals are more stable. For example, electronic configuration of Mn (Z = 25) is [Ar] `3d^(5)` `4s^(2)`. It shows oxidation states from +2 to +7 but Mn (II) is most stable because it has the half-filled configuration [Ar] `3d^(5)`.
Similarly, `Sc^(3+)` and `Zn^(2+)` are more stable because of noble gas configuration and completely filled configuration.
Sc = [Ar] `3d^(1)4s^(2),Sc^(3+)=[Ar],i.e.,` noble gas configuration
`Zn=[Ar]3d^(10)4s^(2),Zn^(2+)=[Ar]3d^(10)`, i.e., completely filled configuration.