Question

Name the members of the lanthanoid series which exhibit +4 oxidation state and those
which exhibit +2 oxidation state. Try to correlate this type of behavior with the electronic
configurations of these elements.

Answer 1

The lanthanides that exhibit +2 and +4 states are shown in the given table. The atomic numbers of the elements are given in the parenthesis.

+2	+4
Nd (60)	Ce (58)
Sm (62)	Pr (59)
Eu (63)	Nd (60)
Tm (69)	Tb (65)
Yb (70)	Dy (66)

Ce after forming Ce⁴⁺ attains a stable electronic configuration of [Xe].
Tb after forming Tb⁴⁺ attains a stable electronic configuration of [Xe] 4f⁷.
Eu after forming Eu²⁺ attains a stable electronic configuration of [Xe] 4f⁷.
Yb after forming Yb²⁺ attains a stable electronic configuration of [Xe] 4f^14.