NEETChemistryd and f Block Elements
Among the lanthanoids, Europium readily forms stable Eu²⁺ ions in solid compounds and in solution. Which of the following best explains the stability of this specific oxidation state?
Options
- AThe Eu²⁺ ion attains a fully-filled 4f¹⁴ subshell.
- BThe removal of two electrons leaves behind a noble gas core.
- CThe resulting ion possesses a 4f⁶ 5d¹ configuration.
- DThe formation of the ion results in an exactly half-filled 4f⁷ subshell.
Correct answer
D. The formation of the ion results in an exactly half-filled 4f⁷ subshell.
Step-by-step solution
The atomic number of Europium (Eu) is 63 . The ground state electronic configuration of Eu is [Xe] 4f⁷ 6s² . When it loses two electrons to form the Eu²⁺ ion, the electrons are removed from the outermost 6s orbital. The electronic configuration of Eu²⁺ becomes [Xe] 4f⁷ . This configuration features a half-filled f -subshell, which imparts extra stability to the +2 oxidation state. Thus, the stability of Eu²⁺ is due to the acquisition of a half-filled 4f⁷ configuration. Answer: The formation of the ion results in an