How is the variability in oxidation states of transition
metals different from that of the non-transition
metals? Illustrate with examples.
Answers
The non-transition elements also show variable oxidation states. However these differ from the variable oxidation states shown by transition elements. Variable oxidation states shown by transition elements can differ by one unit while the oxidation states shown by non-transition elements differ by 2 unit due to inert pair effect. For example, thallium exhibits oxidation states +1, +3 and lead exhibits +2, +4 oxidation states. Moreover, in case of transition elements of the same group, higher oxidation state is more stable for heavier elements. e.g., Mo (VI) and W (VI) are more stable than Cr (VI). In non-transition elements of p-block, lower oxidation state is more stable due to inert pair effect e.g., Pb2+ is more stable than Pb4+.
In case of transition elements, the variability in the oxidation state is due to participation of (n-1) d orbitals and ns orbitals.
The oxidation states differ by unity. Thus, V shows +2,+3,+4 and +5 oxidation states and Mn shows +2,+3,+4,+5,+6 and +7 oxidation states.
On the other hand, the variable oxidation states shown by some p block elements differ by two units. Thus, tin shows +2 and +4 oxidation state and indium shows +1 and +3 oxidation states.