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 $[\text{Xe}]\,4f^7\,5d^1\,6s^2$. When Gd loses 3 electrons (one from the 6s orbital and two from the 5d and 6s orbitals), it becomes Gd$^{3+}$ with the electronic configuration $[\text{Xe}]\,4f^7$. This configuration does not match $4f^6$.

The electronic configuration of Sm (Samarium) is $[\text{Xe}]\,4f^6\,6s^2$. When Sm loses 2 electrons from the 6s orbital, 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 of these matches the required configuration.

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

Answer 2

Correct Answer:

Option 3: Sm²⁺

Explanation:

1. Gd³⁺ (Gadolinium(III) ion):

Gd: [Xe] 4f⁷ 5d¹ 6s²

Gd³⁺: [Xe] 4f⁷

2. Sm³⁺ (Samarium(III) ion):

Sm: [Xe] 4f⁶ 6s²

Sm³⁺: [Xe] 4f⁵

3. Sm²⁺ (Samarium(II) ion):

Sm: [Xe] 4f⁶ 6s²

Sm²⁺: [Xe] 4f⁶

4. Tb³⁺ (Terbium(III) ion):

Tb: [Xe] 4f⁹ 6s²

Tb³⁺: [Xe] 4f⁸

Therefore, Sm²⁺ has the 4f⁶ electronic configuration.