Question

Diamagnetic Lanthanoid ions are:

• A. Nd\(^{3+}\) and Eu\(^{3+}\)
• B. Nd\(^{3+}\) and Ce\(^{4+}\)
• C. La\(^{3+}\) and Ce\(^{4+}\)
• D. Lu\(^{3+}\) and Eu\(^{3+}\)

Answer 1

The Correct Option is C

To determine which lanthanoid ions are diamagnetic, we need to understand the electronic configuration of these ions. An ion is diamagnetic if all of its electrons are paired because paired electrons create no net magnetic field.

Understanding the Properties of Lanthanoid Ions

• La³⁺: Lanthanum (La) in the +3 oxidation state has the configuration [Xe]. This means all orbitals are filled up to xenon's configuration, which makes the electron configuration complete, resulting in no unpaired electrons. Hence, La³⁺ is diamagnetic.
• Ce⁴⁺: Cerium (Ce) in the +4 oxidation state has the configuration [Xe]. Similar to La³⁺, this configuration implies that Ce⁴⁺ is also diamagnetic, as it does not possess unpaired electrons.
• Nd³⁺ and Eu³⁺: These ions have unpaired electrons in their configurations, making them paramagnetic.
• Lu³⁺: Lutetium (Lu) in the +3 state has its f-orbital fully filled ([Xe]4f¹⁴5d⁰6s⁰), thus resulting in no unpaired electrons. However, since it's not given in the correct option pair, it does not affect the answer.

Conclusion

Based on the above analysis, the correct option is:

La³⁺ and Ce⁴⁺

because both ions have fully paired electrons and exhibit diamagnetic properties.

 

Answer 2

Step 1. Understand Diamagnetism: Diamagnetic species have all electrons paired, which means the ions should have no unpaired electrons in their electron configuration.

Step 2. Examine Electron Configurations: Ce⁴⁺: [Xe] 4f⁰ - All electrons are paired, hence diamagnetic. La³⁺: [Xe] - Also has no unpaired electrons, hence diamagnetic.

Step 3. Conclusion: La³⁺ and Ce⁴⁺ are both diamagnetic as they lack unpaired electrons.