Q1(a). Occurrence of lithium

Answer in brief

The small, strongly polarising Li⁺ ion favours different mineral environments from the larger Na⁺ and K⁺ ions.

Key points

• Lithium has a much smaller ionic radius and greater charge density than sodium and potassium.
• Lithium is concentrated in minerals such as spodumene, LiAlSi₂O₆, and lepidolite. Its similarity to magnesium is an example of the diagonal relationship.
• Sodium and potassium commonly accumulate in soluble salts and evaporite deposits. Differences in crystal-site size and mineral partitioning help separate lithium from these alkali metals.