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Atomic Number: 9
Atomic Symbol: F
Atomic Weight: 18.998403
Electron Configuration: [He]2s22p5
History
(L. and F. fluere, flow or flux) In 1529, Georigius Agricola
described the use of fluorspar as a flux, and as early as 1670 Schwandhard found
that glass was etched when exposed to fluorspar treated with acid. Scheele and
many later investigators, including Davy, Gay-Lussac, Lavoisier, and Thenard,
experimented with hydrofluoric acid, some experiments ending in tragedy.
The element was finally isolated in 1866 by Moissan after nearly
74 years of continuous effort.
Properties
Fluorine is the most electronegative and reactive of all elements. It
is a pale yellow, corrosive gas, which reacts with most organic and inorganic
substances. Finely divided metals, glass, ceramics, carbon, and even water burn
in fluorine with a bright flame.
Until World War II, there was no commercial production of
elemental fluorine. The nuclear bomb project and nuclear energy applications,
however, made it necessary to produce large quantities.
Uses
Fluorine and its compounds are used in producing uranium (from the
hexafluoride) and more than 100 commercial fluorochemicals, including many well
known high-temperature plastics. Hydrofluoric acid etches the glass of light
bulbs, etc. Fluorochlorohydrocarbons are extensively used in air conditioning
and refrigeration.
The presence of fluorine as a soluble fluoride in drinking water
to the extent of 2 ppm may cause mottled enamel in teeth, when used by children
acquiring permanent teeth; in smaller amounts, however, fluorides are added to
water supplies to prevent dental cavities.
Elemental fluorine has been studied as a rocket propellant as it
has an exceptionally high specific impulse value.
Compounds
One hypothesis says that fluorine can be substituted for hydrogen
wherever it occurs in organic compounds, which could lead to an astronomical
number of new fluorine compounds. Compounds of fluorine with rare gases have now
been confirmed in fluorides of xenon, radon, and krypton.
Handling
Elemental fluorine and the fluoride ion are highly toxic. The free
element has a characteristic pungent odor, detectable in concentrations as low
as 20 ppb, which is below the safe working level. The recommended maximum
allowable concentration for a daily 8-hour time-weighted exposure is 1 ppm.
Safe handling techniques enable the transport liquid fluorine by
the ton.
Sources: CRC Handbook of Chemistry and
Physics and the American Chemical Society.
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