(N/A) Compared to lanthanoids,actinoids exhibit a greater range of oxidation states because the $5f$,$6d$,and $7s$ energy levels are of comparable energies.
In actinoids,the $5f$ orbitals extend further from the nucleus than the $4f$ orbitals in lanthanoids,allowing them to participate in chemical bonding,whereas $4f$ orbitals are shielded by outer electrons.
Actinoids generally show a $(+3)$ oxidation state.
The elements in the first half of the series frequently exhibit higher oxidation states. For example,the maximum oxidation state increases from $(+4)$ in $Th$ to $(+5)$,$(+6)$,and $(+7)$ in $Pa$,$U$,and $Np$ respectively,but decreases in the succeeding elements.
Actinoids resemble lanthanoids in having more compounds in the $(+3)$ state than in the $(+4)$ state. However,both $(+3)$ and $(+4)$ ions tend to hydrolyze.
| Element | Oxidation States |
| :--- | :--- |
| $Ac$ | $3$ |
| $Th$ | $3, 4$ |
| $Pa$ | $3, 4, 5$ |
| $U$ | $3, 4, 5, 6$ |
| $Np$ | $3, 4, 5, 6, 7$ |
| $Pu$ | $3, 4, 5, 6, 7$ |
| $Am$ | $3, 4, 5, 6$ |
| $Cm$ | $3, 4$ |
| $Bk$ | $3, 4$ |
| $Cf$ | $3$ |
| $Es$ | $3$ |
| $Fm$ | $3$ |
| $Md$ | $3$ |
| $No$ | $3$ |
| $Lr$ | $3$ |