Fluorine is the chemical element of the periodic table of the elements that has the symbol F, atomic number 9 and atomic weight of 18.99840. It belongs to the halogen group and is the most electronegative of the periodic table; Is the only element that can oxidize oxygen.
The term "fluorine" was coined by André-Marie Ampère and Sir Humphry Davy in 1812 and derives from the first uses of fluorite as a fluxing agent (from the Latin word fluoro).
Fluorous salts are called fluorides.
Fluoride, due to its high reactivity, is not found free in nature, except in small traces within fluorescents subjected to beta and gamma irradiation  . It is combined with other elements and accounts for about 0.065% in mass of earth's crust. In nature, fluoride is commonly found as fluoride ion F-, especially fluorite and fluorapatitite.
Like all halogens, it is in its elemental state as a biatomic molecule, F2. Elemental fluoride at room temperature is a pale yellow, slightly heavier air, toxic, extremely aggressive and penetrating smell.
Fluoride has a unique natural isotope, the 19F. Artificially other radioactive isotopes with an atomic weight ranging from 17 to 22 were prepared, with a half-life ranging from 4 s for 22F to 110 minutes for 18F.
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