![]() Fluorides may be taken up from soil and accumulate in plants or they may be deposited on the upper parts of the plants. In water, fluorides attach to aluminum in freshwater and calcium and magnesium in seawater and settle into the sediment. Fluorine gas reacts with most organic and inorganic substances with metals, it forms fluorides and with water, it forms hydrofluoric acid.įluorine remains persistent in the environment. Fluorine combines with other chemicals in minerals forming primarily fluorspar, fluorapatite, and cryolite. Fluorides released into the atmosphere from volcanoes, power plants, and high-temperature processes are hydrogen fluoride gas or attached to very small particles. Both hydrogen fluoride and particulate fluorides are transported in the atmosphere and deposited on land or in water. It reacts at room temperature or elevated temperatures with all almost all elements. Fluorine is the most reactive of all the elements and is a strong oxidizer primarily because of its high electronegativity. It has one stable isotope with a valence of −1. As with the other halogens, fluorine occurs as a diatomic molecule, F 2, in its elemental form. ![]() It has an atomic number of 9 and a density of 1.5127 g cm −3 at −188.13 ☌. This group includes chloride, bromine, iodine, and astatine. Kapp Jr., in Encyclopedia of Toxicology (Third Edition), 2014 Environmental Behavior, Fate and Routes and Pathwaysįluorine is the lightest element of Group 17 of the periodic table called halogens. The isotope 211At is assayed by counting the alpha-particles or X-rays resulting from its nuclear decay. Further extractions are carried out to obtain the purified product. Alternatively, the target is dissolved in perchloric acid containing a little iodine, the Bi is removed by precipitation with phosphate, and the aqueous solution of AtI is used as is or the AtI is extracted into an organic solvent such as carbon tetrachloride or chloroform. It is removed from the target by distillation in a stream of nitrogen at a temperature of 200 to 600 ☌ and purified by redistillation. The isotope 211At has a half-life of 7.2 h and decays either by electron capture (59%) or by alpha-emission (41%). This isotope is prepared by the alpha-bombardment of 209Bi using energies in the range of 26 to 28 MeV. The chemistry of astatine is usually studied using 211At. Although the identification of some astatine compounds can be made directly by mass spectrometry, most investigations of the chemistry of this element have been carried out by tracer techniques using extremely dilute solutions (10 −8 M or less). The short half-lives of even the longest-lived isotopes make it extremely difficult to obtain weighable amounts of the element. With no stable or long-lived isotopes, it must be synthesized artificially through nuclear reactions. ![]() ![]() Marianna Anderson Busch, in Encyclopedia of Physical Science and Technology (Third Edition), 2003 VIII Astatine VIII.A Preparation, Isolation, and PurificationĪstatine is the heaviest member of the halogen family. ![]()
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