Among lanthanoids, Ln (III) compounds are predominant. However, occasionally in solutions or in solid compounds, +2 and +4 ions are also obtained.

Explanation

`+2` and `+4` oxidation states are shown by those elements which by losing 2 or 4 electrons acquire a stable configureation of `f^(0), f^(7) ` or `f^(14)` , e.g., `Eu^(2+)` is `[Xe] 4f^(7), Yb^(2+)` is `[Xe4f^(14) , Ce^(4+) ` is `[Xe]4f^(0)` and `Tb^(4+)` is `[Xe]4f^(7)`