4162. Fluorine

Nomenclature

CAS number: 7782-41-4

Description and references

F; at. wt 18.9984032; at. no. 9; valence 1. A halogen, Group VIIA (17). Does not exist as elemental state, F, in nature. Occurs as diatomic molecule, F2. Occurrence in earth's crust 0.065% by wt. Naturally occurring isotope (mass number): 19 (100%). Know artificial radioactive isotopes; 15-17, 18 (longest-lived known isotope, T 109.77 min, β+ emitter), 20-27. Primary commercial source is fluorite, or fluorspar; other important sources are cryolite, and fluorapatite. Discovered in 1771 by Scheele. Isolated in 1886 by electrolyzing a soln of potassium fluoride in anhydr hydrogen fluoride at 23°, using platinum-iridium electrodes: H. Moissan, Compt. Rend. 102, 1543 (1886); 103, 202, 256. Toxicity data: Keplinger, Suissa, Am. Ind. Hyg. Assoc. J. 29, 10 (1968). Reviews: Finger, “Fluorine Resources and Fluorine Utilization” in Advances in Fluorine Chemistry vol. 2, M. Stacey et al., Eds. (Butterworths, London, 1961) pp 35-54; A. J. Rudge, The Manufacture and Use of Fluorine and its Compounds (Oxford University Press, 1962); T. A. O'Donnell, “Fluorine” in Comprehensive Inorganic Chemistry vol. 2, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 1009-1106; G. Shia in Kirk-Othmer Encyclopedia of Chemical Technology vol. 11 (Wiley-Interscience, New York, 4th ed., 1994) pp 241-267. Review of toxicology and human exposure: Toxicological Profile for Fluorides, Hydrogen Fluoride and Fluorine (PB2004-100002, 2003) 404 pp. Book: Fluorine: The First Hundred Years (1886-1986), R. E. Banks et al., Eds. (Elsevier Sequoia, Laussanne, 1986) 404 pp.

Properties

Pale yellow, diatomic gas with sharp penetrating odor. mp 219.61° (53.54 K); bp 188.13° (85.02 K); d (liq, 188.13°) 1.5127; vapor pressure data: Hu et al., J. Am. Chem. Soc. 75, 5642 (1953); White et al., ibid. 76, 2584 (1954). Crit temp: 129°; crit pressure: 55 atm. Poisonous, oxidizer, corrosive. Most chemically reactive element; most powerful oxidizing agent, higher oxidation potential than ozone; most electronegative element; E° (calc) F/F 2.9 V. F-F bond weaker than Cl-Cl and Br-Br bonds; enthalpy of dissociation: 37.7 kcal. Reacts vigorously with most oxidizable substances at room temp, frequently with ignition. Combines directly or indirectly, to form fluorides with all the elements except helium, neon and argon. Dec water, giving hydrofluoric acid, HF, oxygen fluoride, OF2, hydrogen peroxide, oxygen and ozone. Reacts with nitric acid, forming the explosive gas, fluorine nitrate, NO3F; with sulfuric acid, giving fluorosulfuric acid, HFSO3. Yields the metal fluorides, water, oxygen and oxygen fluoride when made to react with metal hydroxides in the cold. Reacts violently with organic compds, usually with disintegration of the molecule. Under controlled conditions, however, hydrocarbon vapors may be fluorinated with elemental fluorine. Solid fluorine explodes when brought in contact with liquid hydrogen. Under ordinary conditions it does not react directly with oxygen, nor does it react with oxides of sodium, potassium or calcium. LC50 (1 hr) inhalation by rats, mice, guinea pigs: 185, 150, 170 ppm (by vol) (Keplinger, Suissa).

Caution

Potential symptoms of overexposure are irritation of eyes, nose and respiratory system; laryngeal spasms, bronchial spasms; pulmonary edema; eye and skin burns. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 146. Chronic ingestion of high concentrations from water supply can cause mottled enamel of teeth and osteosclerosis. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section III, pp 185-193.

Use

In manuf of UF6 for nuclear power generation, of SF6 for dielectrics, of fluorinating and metal fluoride compounds.