Why is it that the s-block elements never occur free in nature? What are their usual modes of occurrence and how are they generally prepared?

Explanation

The element belonging to s- block in periodic table (i.e. alkali and alkaline earth metals) are highely reactive because of their low ionisation enthalpy. They are highely electropositive forming positive ion. So, they are never found in free state.
They are widely distributed in nature in the combined state. They occur in the earth's crust in the form of oxides, chlorides, silicates and carbonates.
Generally elements of group 1,2 and `AI` metals are prepared by the electroylsis of fused solution.
For example:
i. `NaCI rarr underset(("Cathode"))(Na^(o+)) + underset(("Anode"))(CI^(Theta))`
At cathode: `Na^(o+) +e^(Theta) rarr Na`
At anode: `2CI^(Theta) rarr CI_(2) +2e^(Theta)`
ii. `KOH hArr K^(o+) +overset(Theta)(OH)`
At cathode: `K^(o+) +e^(Theta) rarr K`
At cathode: `4overset(Theta)(OH) rarr 2H_(2)O +O_(2) +4e^(Theta)`
These metals are highely reactive and therefore cannot be extracted by the usual methods, because they are strong reducing agents.