Alkali Metals
The group 1 elements — lithium through francium — which have a single valence s electron.
Formula / equation
ns¹
Unit
Dimensionless
In depth
Losing one electron gives a noble-gas configuration, so these metals are the most electropositive elements known, forming M⁺ ions in every compound. They are soft enough to cut with a knife, tarnish instantly in air, and react with water increasingly violently down the group.
Examples in the real world
Lithium fizzing in water, sodium melting into a ball, and potassium igniting the hydrogen it releases.