On the periodic table, group 1 elements other than hydrogen are collectively called the alkali metals.
The alkali metals are lithium, sodium, potassium, rubidium, caesium, and francium. They each have one electron in their outermost shell and commonly form +1 ions by losing that electron.
The name refers to the alkaline solutions produced when these metals react with water. The reactions become generally more vigorous down the group, although the metals differ in melting point, density, and natural abundance. None of the alkali metals occurs freely in ordinary natural environments because they react readily with other substances.
Hydrogen sits above group 1 because it also has one electron, but it is not classified as an alkali metal. Francium is radioactive and extremely rare, while sodium and potassium are familiar in biological systems and industrial compounds.