Chemistry - f-block Question with Solution | TestHub

Question Explanation:

Find the stable oxidation states of Eu and Tb.

Concept:

This question is based on electronic configuration and oxidation states

Solution:

The stability of an ion's oxidation state is often related to achieving a completely empty, half-filled, or completely filled f-subshell. Europium (Eu) can attain a stable half-filled 4f⁷ configuration by exhibiting a +2 oxidation state. Terbium (Tb) can attain a stable half-filled 4f⁷ configuration by exhibiting a +4 oxidation state.

Eu (Z = 63) has the electronic configuration

$[Xe]4f^{7}6s^2$. Losing two electrons gives

Eu²⁺: $[Xe]4f^7$, which is a stable half-filled configuration. Tb (Z = 65) has the electronic configuration

$[Xe]4f^{9}6s^2$. Losing four electrons gives

Tb⁴⁺: $[Xe]4f^7$, which is also a stable half-filled configuration.