s-Block Elements
The elements of groups 1 and 2, plus helium, whose outermost electrons occupy an s orbital.
Formula / equation
ns¹ or ns²
Unit
Dimensionless
In depth
These are soft, low-melting, highly electropositive metals that form ionic compounds and are never found free in nature. Their low ionisation energies make them powerful reducing agents, and reactivity increases sharply down each group as the valence electron becomes easier to lose.
Examples in the real world
Sodium reacting vigorously with water; calcium forming CaO and CaCO₃ throughout the Earth's crust.