Fluorine "F" is the chemical element with atomic number 9. At standard pressure and temperature,
fluorine is a pale yellow gas composed of diatomic molecules, F2.
Fluorine is the most electronegative element and is extremely reactive,
requiring great care in handling. It has a single stable isotope, fluorine-19.
In stars, fluorine is rare compared to other light elements. In
Earth's crust, fluorine is the thirteenth most abundant element. Fluorine's
most important mineral, fluorite, was first
formally described in 1530, in the context of smelting. The mineral's
name derives from the Latin verb " fluo",
which means "flow", because fluorite was added to metal ores to lower
their melting points. Suggested as a chemical element in 1811, fluorine was
named after the source mineral, but resisted many attempts to isolate the
element. In 1886, French chemist Henri Moissan succeeded. His method of electrolysis remains the industrial production
method for fluorine gas. The main use of elemental fluorine, uranium
enrichment, was developed during the Manhattan
Project.
Because of the difficulty in making elemental fluorine, most
fluorine used in commerce is never converted to free fluorine. Instead, hydrofluoric
acid is the key intermediate for the $16 billion per year global fluorite-chemical industry. The fluorides of low charged metals are ionic compounds (salts); those of high charged metals
are volatile molecular compounds. The largest uses of
inorganic fluorides are steel making and aluminium refining.
Organic fluorine compounds tend
to have high chemical and thermal stability. The largest commercial use is in refrigerant gases. Although traditional chlorofluorocarbons (CFCs) are widely banned, the replacement
gases still contain fluorine. Polytetrafluoroethylene (Teflon) is the most important fluoropolymer and is used in electrical insulation,
chemical-resistant parts, stadium roofs, and cookware. A growing fraction of
modern pharmaceuticals contain fluorine; Lipitor and Prozac are prominent examples. While a few
plants and bacteria synthesize organofluorine poisons, fluorine has no
metabolic role in mammals. The fluoride ion, when directly applied to teeth,
reduces decay and for this reason is used in toothpaste and municipal water fluoridation.
