Alkali Metal Definition

Chemistry Glossary Definition of Alkali Metal

The first column of the periodic table contains the alkali metals.
The first column of the periodic table contains the alkali metals. davidf / Getty Images

Alkali metals are any of the elements found in Group IA of the periodic table (the first column). Alkali metals are very reactive chemical species that 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:

The International Union of Pure and Applied Chemistry (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

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 and quickly tarnish, so 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, forming crystals with the body-centered cubic structure.

Sources

  • Greenwood, Norman, and Alan Earnshaw. Chemistry of the Elements. 2nd ed., Butterworth- Heinemann, 1997.
  • Lide, D. R., editor. CRC Handbook of Chemistry and Physics. 86th ed., CRC Press, 2005.