Fluorine
Fluorine is an univalent poisonous gaseous halogen, it is pale
yellow-green and it is the most chemically reactive and electronegative
of all the elements. Fluorine readily forms compounds with most other
elements, even with the noble gases Krypton, Xenon and Radon. It is so
reactive that glass, metals, and even water, as well as other
substances, burn with a bright flame in a jet of Fluorine gas.
In aqueous solution, Fluorine commonly occurs as the fluoride ion F-.
Fluorides are compounds that combine fluoride with some positively
charged counterpart.
Applications
Atomic Fluorine and molecular Fluorine are used for plasma etching in
semiconductor manufacturing, flat panel display production and MEMs
fabrication.
Fluorine is indirectly used in the production of low friction plastics
such as teflon and in halons such as freon, in the production of
Uranium. FluorochlorohydroCarbons are used extensively in air
conditioning and in refrigeration.
Fluorides are often added to toothpaste and, somewhat controversially,
to municipal water supplies to prevent dental cavities. Fore more
information visit our page on
mineral water.
Fluorine in the environment
Annual world production of the mineral fluorite in around 4 million
tonnes, and there are around 120 million tonnes of mineral reserves. The
main mining areas for fluorite are China, Mexico and Western Europe.
Fluorine occurs naturally in the earth's
crust where it can be found in rocks, coal and clay. Fluorides are
released into the air in wind-blown soil. Fluorine is the 13th
most aboundant element in the Earth's crust: 950 ppm are contanined in
it. Soils contain approximatively 330 ppm of Fluorine, ranging from 150
to 400 ppm. Some solis can have as much as 1000 ppm and contaminated
solis have been found with 3500 ppm. Hydrogen fluorides can
be released into air through combustion processes in the industry.
Fluorides that are found in air will eventually drop onto land or
into water. When Fluorine is attached to very small particles it
can remain in the air for a long period of time.
In the atmosphere 0.6 ppb of Fluorine are present as salt spray and
organicoChloride compounds. Up to 50 ppb has been recorded in city
envIronments.
Small amounts of Fluorine are naturally
present in water, air, plants and animals. As a result humans are
exposed to Fluorine through food and drinking water and by
breathing air. Fluorine can be found in any kind of food in
relatively small quantities. Large quantities of Fluorine can be
found in tea and shellfish.
Fluorine is essential for the maintenance of solidity of our
bones. Fluorine can also protect us from dental decay, if it is
applied through toothpaste twice a day. If Fluorine is absorbed
too frequently, it can cause teeth decay,
osteoporosis and harm to
kidneys, bones, nerves and muscles.
Fluorine gas is released in the industries. This gas is very
dangerous, as it can cause death at very high concentrations. At
low concentrations it causes eye and nose irritations.
When Fluorine from the air ends up in water it will settle into
the sediment. When it ends up in soils, Fluorine will become
strongly attached to soil particles. In the environment Fluorine
cannot be destroyed; it can only change form.
Fluorine that is located in soils may accumulate in plants. The
amount of uptake by plants depends upon the type of plant and the
type of soil and the amount and type of Fluorine found in the
soil. With plants that are sensitive for Fluorine exposure even
low concentrations of Fluorine can cause leave damage and a
decline in growth. Too much fluoride, wheater taken in form the
soil by roots, or asdorbed from the atmosphere by the leaves,
retards the growth of plants and reduces crop yields. Those more
affected are corns and apricots.
Animals that eat Fluorine-containing plants may accumulate large
amounts of Fluorine in their bodies. Fluorine primarily
accumulates in bones. Consequently, animals that are exposed to
high concentrations of Fluorine suffer from dental decay and bone
degradation. Too much Fluorine can also cause the uptake of food
from the paunch to decline and it can disturb the development of
claws. Finally, it can cause low birth-weights.
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