The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation states of these elements.

(N/A) Lanthanoids primarily show a stable $+3$ oxidation state. They display a limited number of oxidation states because the energy gap between $4f$,$5d$,and $6s$ orbitals is quite large.
On the other hand,the energy difference between $5f$,$6d$,and $7s$ orbitals in actinoids is very small.
Consequently,actinoids exhibit a wide range of oxidation states.
For example,uranium $(U)$ and plutonium $(Pu)$ display $+3, +4, +5,$ and $+6$ oxidation states,while neptunium $(Np)$ displays $+3, +4, +5,$ and $+7$ oxidation states.