How is the variability in oxidation states of transition metals different from that of the non transition metals? Illustrate with examples.
The variability in oxidation states of transition metals differs from that of non-transition metals in two main ways:
Firstly, in transition elements, the oxidation states differ from each other by unity (one) due to incomplete filling of d orbitals. For example, vanadium exhibits oxidation states of V(II), V(III), V(IV), and V(V), which differ by one unit successively. In contrast, the oxidation states of non-transition elements normally differ by a unit of two.
Secondly, in the d-block, higher oxidation states are more stable for heavier members. For instance, in Group 6, Mo(VI) and W(VI) are more stable than Cr(VI). This is opposite to the p-block where lower oxidation states are favoured by heavier members due to the inert pair effect.
Explanation
The textbook clearly states that transition metals have oxidation states differing by unity (e.g., V shows +2, +3, +4, +5) due to incomplete d orbital filling, while non-transition metals have oxidation states differing by two. Additionally, the context highlights that in d-block, heavier members favour higher oxidation states (opposite to p-block behaviour), illustrated by Mo(VI) and W(VI) being more stable than Cr(VI).