Bromine

BROMINE, Br (from the Latin word "bromum" * EN: bromine; DE: Brom; FR: brome; ES: bromo; RU: бром) is the chemical element of the Group VII of the periodic table by Dmitry Mendeleev, the atomic number is 35, the atomic weight is 79.904; it belongs to halogens. The natural bromine consists of the two stable isotopes 79Br (50.56%) and 81Br (49.44%). Bromine has been discovered by the French chemist Antoine Jerome Balard during the 1826.

Under the usual conditions, bromine is the liquid with the pungent unpleasant odour, dark purple under the reflected light, dark-red within the passing light; the temperature of the boiling point is 58.8 degrees Celsius; the temperature of the melting point is 7.2 degrees Celsius, the density of the liquid bromine is 3102 kilograms per cubic metre (at the temperature of 25 degrees Celsius), the specific atomic heat capacity is 36.034 kilojoules per kilogram-kelvin. The solid bromine is of the bright red colour with the metallic lustre; the density is approximately 3400 kilograms per cubic metre (at the temperature of -7.2 degrees Celsius); the specific atomic heat capacity is 23.464 kilojoules per kilogram-kelvin. Bromine is diatomic in the solid, liquid, and gaseous states. The molecular bromine is diamagnetic. Bromine is soluble within alcohol, ether, and other organic solvents, and is limitedly soluble within water. The major oxidation states are -1 (bromides) and +5 (bromates). Bromine is the strong oxidant; under the usual conditions, it does not react with oxygen. The dry bromine reacts with Al, K, Sb; the humid bromine reacts with Fe, Zn, Bi, Na, and thus is forming bromates. There are known several unstable compounds of bromine with halogens. Bromine is toxic.

Bromine is the scattered element, mainly within the magmatic rocks and within halides, its elemental content within the Earth's crust is 4.10% (by mass). It has not been found in the free form within nature. As the consequence of the high solubility of its compounds, the minerals of bromine are rare (see the "Natural halides" article). Bromine accumulates itself mostly within the marine water (up to 75% of the total content within the Earth's crust), within the underground and surface brines. Within the cycle of bromine within the nature, the important role belongs to the living organisms, which are concentrating it within the compounds, which are produced, and to the ground surface evaporation within the hydrosphere, within which there are concentrated the industrial clusters of bromine (the deposits of the deep horizons, the brines of the Syvash, Kara-Bogaz-Gol, and other lakes). The high content of bromine is noted within the layers of bischofite within the Lower Volga region, and within the depositions of the potassium salts.

They produce bromine and its compounds from the underground and lacustrine brines, and from the lye of the potassium production; there are used the salty waters of the petroleum drilled wells, and the marine water. There are known several methods for the obtainment of bromine: the sublimation by the water steam, the blowing by the air, the extraction by the solvents, and others. Within the USSR, they use the method for the aerial desorption of bromine. The worldwide production of bromine (without the socialistic countries) is 320 thousand tonnes (1978). Among the main producing countries are the USA (approximately 200 thousand tonnes), Great Britain (30 thousand tonnes), Israel (21 thousand tonnes), France (16 thousand tonnes), Japan (12 thousand tonnes). They use the compounds of bromine for the production of the anti-knock substances for the motor fuels, within the agriculture for the fight against the pests of plants, within the pharmaceutics, for the fire extinguishing substances, within the photographic craft, and so on.