Explain about the oxidation state of Lanthanoids.

Explanation

(i) The common oxidation state of lanthanoids is +3. In addition to that some of the lanthanoids also show either +2 or +4 oxidation states.
(ii) `Gd^(3+)` and `Lu^(3+)` ions have extra stability, it is due to half filled and completely filled f-orbitals.
(iii) Cerium and terbium attain `4f^(7)` and `4f^(14)` configurations respectively in the +4 oxidation states.
(iv) `Eu^(2+)` and `Yb^(2+)` ions have exactly half filled and completely filled f orbitals.
(v) Lu shows only +3 oxidation state.
(vi) Ce, Pr, Nd, Tb and Dy exhibit +3 and +4 oxidation states.
(vii) Nd, Sm, Eu, Tm, Yb exhibit +2 oxidation states also.