Question

Give three differences between Lanthanoids and Actinoids.

Hint:

Actinoid contraction is greater than Lanthanoid contraction due to poorer shielding by 5f electrons compared to 4f electrons.

Answer 1

1. Oxidation States: Lanthanoids show +3 as the dominant oxidation state, with occasional +2 or +4. Actinoids show a wider range of oxidation states (+3, +4, +5, +6, +7) due to comparable energies of 5f, 6d, and 7s shells.
2. Binding Energy: 4f electrons (Lanthanoids) have higher binding energy and are more deeply buried. 5f electrons (Actinoids) have lower binding energy and are more available for bonding (covalent character).
3. Radioactivity: Only Promethium is radioactive among Lanthanoids. All Actinoids are radioactive.