Alkali Metal Definition (Chemistry)

Alkali Metal Definition (Chemistry)

An alkali metal is any of the elements found in Group IA of the periodic table (the first column). Alkali metals are very reactive chemical species which readily lose their one valence electron to form ionic compounds with nonmetals. All elements in the alkali metal group occur in nature.

List of Alkali Metals

The alkali metals are:

  • Lithium (Li)
  • Sodium (Na)
  • Potassium (K)
  • Rubidium (Rb)
  • Cesium (Cs)
  • Francium (Fr)

The IUPAC excludes hydrogen (H) as an alkali metal because it occurs as a gas under ordinary temperatures and pressures. However, hydrogen displays many of the properties associated with elements in the group and does become an alkali metal under extremely high pressure.

Alkali Metal Properties

The alkali metals are all soft, shiny, reactive metals. Although they are soft enough to cut with a knife, exposing a bright surface, the metals react with water and air to quickly tarnish. The pure metals are stored in an inert atmosphere or under oil to prevent oxidation. All of the metals react vigorously with water, with the energy of the reaction increasing as you move down the periodic table. None of the alkali metals exists free in nature. They are found as salts. All of the metals form crystals with the body-centered cubic structure.


  • Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
  • Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.