Which member of the lanthanoid series is most well-known to exhibit a +4 oxidation state due to its

Question

Which member of the lanthanoid series is most well-known to exhibit a +4 oxidation state due to its stable empty f-shell configuration?

Professor PC Thomas Classes · Answer

Cerium (Z=58) has the configuration $[	ext{Xe}] 4f^1 5d^1 6s^2$. It can easily lose four electrons to achieve the highly stable noble gas configuration of Xenon ($f^0$), making the +4 state ($	ext{Ce}^{4+}$) quite stable.