Question

why transition elements exhibit variable oxidation state

Answer 1

Transition elements show variable state oxidation in their compounds.
Reason of variable oxidation state is that there is a very small energy difference in between (n-1)d and ns-orbitals.
As a result ,electrons of (n-1)d orbitals as well as ns-orbitals take part in bond formation.


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Answer 2

Answer : The electrons present in 'ns' and (n-1)d orbitals can take part in the bond formation due to similar energies.

Explanation :

Transition elements are the elements which lie between 's' and 'p' block elements. The valence electrons of these elements enter d-orbital. Their general electronic configuration is: $(n-1)d^{1-10}ns^{0-2}$ where n is the outermost shell.

These elements show variable oxidation state because their valence electrons in two different sets of orbitals, that is (n-1)d and ns.

As, the difference in energy of these orbitals is very little, so both the energy levels can be used for bond formation. Thus, these elements have variable oxidation states.