Question

Identify the ion having 4f\(^6\) electronic configuration.

• A. Gd\(^{3+}\)
• B. Sm\(^{3+}\)
• C. Sm\(^{2+}\)
• D. Tb\(^{3+}\)

Answer 1

The Correct Option is C

The electronic configuration of Gd (Gadolinium) is $[\text{Xe}]\,4f^7\,5d^1\,6s^2$. Upon losing 3 electrons, Gd becomes Gd$^{3+}$ with the electronic configuration $[\text{Xe}]\,4f^7$. This does not match $4f^6$.

The electronic configuration of Sm (Samarium) is $[\text{Xe}]\,4f^6\,6s^2$. When Sm loses 2 electrons, it becomes Sm$^{2+}$ with the configuration $[\text{Xe}]\,4f^6$. This matches the given $4f^6$ configuration.

The configuration of Sm$^{3+}$ is $[\text{Xe}]\,4f^5$, and that of Tb$^{3+}$ (Terbium) is $[\text{Xe}]\,4f^8$. Neither matches the required configuration.

Therefore, the ion with a $4f^6$ configuration is Sm$^{2+}$.