Bromine (from the Greek word bromos, meaning stench) has an atomic weight 79.909, atomic number 35, melting point - 7.2° C, and boiling point 58.78° C. As a gas it has a density of 7.59 g/1 and as a liquid 3.12 g/1 (20° C). The element was discovered by Balard in 1826 but not prepared in quantity until 1860. It is a member of the halogen group of elements. Bromine is found mainly in the bromide form, widely distributed and in relatively small proportions. Extractable bromides occur in the ocean and salt lakes, brines, or saline deposits left after these waters evaporated during earlier geological periods. The average bromide content of ocean water is 65 ppm by weight (about 308,000 tons of bromine per cubic mile of sea water). The Dead Sea is one of the richest commercial sources of bromine in the world (containing nearly 0.4 percent at the surface and up to 0.6 percent at deeper levels). In the United States, major sources of bromine are the brine wells in Arkansas, Ohio, and Michigan (bromide contents range from 0.2 percent to 0.4 percent).
Bromine is the only liquid nonmetallic element. It is a heavy, mobile, reddish-brown liquid that readily volatilizes at room temperature to a red vapor having a strong pungent odor. Its disagreeable odor strongly resembles chlorine and has a very irritating effect on the eyes and throat. Bromine is readily soluble in water or carbon disulfide, forming a red solution. It is less active than chlorine but more so than iodine. Bromine unites readily with many elements and has a bleaching action. The toxic action of bromine is similar to that of chlorine and can cause physiological damage to humans through inhalation and oral routes. It is an irritant to the mucous membranes of the eyes and upper respiratory tract. Severe exposures may result in pulmonary edema. Chronic exposure is similar to therapeutic ingestion of excessive bromides.
Bromine is considered a moderate fire hazard. As liquid or vapor, it can enter spontaneous chemical reactions with reducing materials. It is a very powerful oxidizer. Bromine is considered a highly dangerous material. Upon being heated, it emits highly toxic fumes. It will react with water or steam to produce toxic and corrosive fumes.
The most common inorganic bromides are sodium, potassium, ammonium, calcium, and magnesium bromides. Methyl and ethyl bromides are among the most common organic bromides. The inorganic bromides produce a number of toxic effects in humans: depression, emaciation, and in severe cases, psychoses and mental deterioration. Bromide rashes (called bromoderma) can occur especially on the facial area and resemble acne and furunculosis. This often occurs when bromide inhalation or administration is prolonged. Organic bromides such as methyl bromide and ethyl bromide are volatile liquids of relatively high toxicity. When any of the bromides are strongly heated, they emit highly toxic fumes.
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