Fluorine << FLOO uh reen >> is a chemical element. At ordinary temperatures, it is a pale yellow gas. Fluorine combines with other elements more readily than does any other element. Compounds that contain fluorine are called fluorides.
The principal source of fluorine is the mineral fluorite, also called fluorspar. Fluorite consists of the compound calcium fluoride. Steelmakers use fluorite to purify steel. Chemical companies treat fluorite with sulfuric acid to produce hydrogen fluoride. Hydrogen fluoride is used to make aluminum and to produce compounds called chlorofluorocarbons (see Chlorofluorocarbon). Small amounts of fluorides applied to the teeth greatly reduce tooth decay. For this reason, fluorides are added to toothpaste, and many communities add fluorides to their drinking water.
Fluorine is the lightest of the elements known as halogens (see Halogen). It has the chemical symbol F. Fluorine’s atomic number (number of protons in its nucleus) is 9. Its relative atomic mass is 18.9984032. An element’s relative atomic mass equals its mass (amount of matter) divided by 1/12 of the mass of carbon 12, the most abundant form of carbon. Fluorine may be condensed to a liquid that boils at –188.14 °C and freezes at –219.62 °C. Fluorine was first isolated in 1886 by the French chemist Henri Moissan.
For information on the position of fluorine on the periodic table, see the article Periodic table. See also Element, Chemical (table); Fluoridation.
