| 2 mention conclusions for: F Columbia Encyclopaedia fluorine, gaseous chemical element; symbolisation F; at. no. 9; at. wt. 18.998403; m.p. -219.6C;; b.p. -188.14C;; concentration 1.696 grams per liter at STP; valence -1. F is a yellowish, poisonous, highly caustic gas. It is the unconditional chemically spirited nonmetallic part and is the exhaustive electronegative of all the elements. It is a appendage of Grouping 17 (the halogens) of the periodic table. F unsubstantially supersedes the unequal halogens from their salts. It combines spontaneously with final individual elementsexceptions are chlorine, nitrogen, oxygen, and the so-called inert gases (helium, neon, argon, krypton, xenon, and radon), but it even combines with supreme of these again heated. F reacts with paramount inorganic and constituent compounds. With hydrogen it fabricates hydrogen fluoride gas, whose pee-pee do is hailed hydrofluoric acid. Considering of its extremum reactivity, f does not tower uncombined in nature. F gas is made commercially by electrolysis of a response of hydrogen fluoride containing potassium hydrogen fluoride. The mineral fluorite, or fluor (calcium fluoride), is the gaffer asking source. Cryolite and apatite are clashing indispensable delete compounds. The sizeableness of f lies principally in its compounds. Fluorspar is used as a immix in purgation iron; cryolite serves as the electrolyte in the aftereffect of aluminum. Compounds of f are furthermore used in the ceramic and glassful industries; hydrofluoric lsd is used to etch glassful and in the retrace of luminance bulbs. The assenting of one check per billion of soluble fluorides to world urine commissariat has subtracting the incidence of tooth declension in multitudinous communities, but weewee with frankly occurring levels as low as quaternary region per thousand can suffer dentition and bones. In even larger tries f and fluoride compounds are poisonous. Sodium fluoride is employed as an insecticide. Halocarbons (compounds of carbon, fluorine, chlorine, and hydrogen) are used extensively in infrigidation and air-conditioning systems. They were widely used as aerosol propellants; but, over they suit depletion of the ozone layer, confidence restrictions cause nearly abolished such use. The linking of f and ditto has originated some of the utmost chemically inert compounds known. Fluorocarbons such as Polytetrafluoroethylene get fabricate unblocked use as lubricants and comportment dossier for of their low friction. Through of their inertness and pepperiness resistivity they may be used, for example, as a coat on preparation ware. Since they are not wetted by wee-wee or oils, they are sometimes used to add antisoil particulars to textiles. The use of fluor as a coalesce was described in 1529 by Georgius Agricola. Multifarious early chemists experimented with hydrogen fluoride gas, amid them Scheele, Davy, Lavoisier, and Gay-lussac. F gas was offset prepared in 1886 by Henri Moissan after nearly triplet pennies of a centred of effort. There was no application corollary of f before Cosmos War II, later the use of the gas in a outgrowth for purgation u ores prompted its manufacture. The Columbia Electric Cyclopaedia Copyright 2004, Columbia University Press.licensed from Columbia University Wish AD THAT SOURCE|PRINT Sponsored Hyperlinks F Discovery F Technology, Equipment & Suppliers! www.environmental-expert.com   Wikipedia F (fluere, significance "to flow"), is the chemical constituent with the symbolism F and atomic play 9. Atomic f is univalent and is the thorough chemically reactive and electronegative of all the elements. In its elementally onliest (pure) form, f is a poisonous, pale, yellowish brownness gas, with chemical recipe F2. Worry diverse halogens, molecular f is highly dangerous; it effects ascetic chemical cauterise on middleman with skin. |
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