Aside from the principal +3 oxidation state, which other oxidation states are frequently exhibited b

Question

Aside from the principal +3 oxidation state, which other oxidation states are frequently exhibited by lanthanoids, and why?

Professor PC Thomas Classes · Answer

Lanthanoids predominantly show the +3 state. However, +2 and +4 oxidation states are also exhibited when they lead to exceptionally stable empty ($f^0$), half-filled ($f^7$), or completely filled ($f^{14}$) subshells.