Question

Why actinides shows wide range of oxidation states?

Answer 1

Actinides show a variety of oxidation states from +3 to +6. This is due to the very small energy gap between 5f, 6d and 7s sub shells. The principaloxidation states are +3 and +4 and +3oxidation state is the most stable. ... The distributions of oxidation states inactinides are uneven.

Answer 2

Because they are bigger, the outermost shell is further away from the nucleus. that means the ionization energy is lower for the corresponding oxidation state compared to lanthanides.