Question

What is the trend in ionic radii of elements of first transition series when oxidation state changes from $+2$ to $+3$?

Answer 1

As the nuclear charge increases , the ionic radii decreases. This decrease is due to the fact that with the increase of nuclear charge, the incoming electrons enter the inner $(n-1)d$ orbitals. As a result, there is a gradual decrease in ionic radii when oxidation state changes from +2 to +3.