Question

Distinguish between lanthanides and actinides.

Hint:

Focus on orbital filling and radioactivity to distinguish lanthanides from actinides effectively.

Answer 1

Lanthanides and actinides are f-block elements, but they differ as follows:
1. **Electronic Configuration:**
- Lanthanides: Electrons fill the 4f orbitals ([Xe] 4f\(^{1-14}\) 5d\(^{0-1}\) 6s\(^2\)).
- Actinides: Electrons fill the 5f orbitals ([Rn] 5f\(^{1-14}\) 6d\(^{0-1}\) 7s\(^2\)).
2. **Radioactivity:**
- Lanthanides: Mostly non-radioactive (except promethium).
- Actinides: All are radioactive due to unstable nuclei.
3. **Oxidation States:**
- Lanthanides: Predominantly +3, rarely +2 or +4.
- Actinides: Show variable oxidation states (e.g., +3 to +6 for uranium).
4. **Chemical Reactivity:**
- Lanthanides: Less reactive, similar to group 2 metals.
- Actinides: More reactive, form complexes easily due to higher charge density.