bromine [key] [Gr.,=stench], volatile, liquid chemical element; symbol Br; at. no. 35; at. wt. 79.904; m.p. –7.2℃; b.p. 58.78℃; sp. gr. of liquid 3.12 at 20℃; density of vapor 7.14 grams per liter at STP; valence −1, +1, +3, +5, or +7. At ordinary temperatures bromine is a brownish-red liquid that gives off a similarly colored vapor with an offensive, suffocating odor. It is a member of the halogen family in Group 17 of the periodic table. It is the only nonmetallic element that is liquid under ordinary conditions. It is soluble in water to some extent; the aqueous solution, called bromine water, acts as an oxidizing agent. It is also soluble in alcohol, ether, and carbon disulfide. Bromine is less active chemically than chlorine or fluorine but is more active than iodine. It forms compounds similar to those of the other halogens (see bromide). Oxides of bromine are unstable, but two acids, hypobromous acid, HBrO, and bromic acid, HBrO3, are known with their salts. Hydrobromic acid is the aqueous solution of hydrogen bromide, HBr. Bromine does not occur uncombined in nature but is found in combination with other elements, notably sodium, potassium, magnesium, and silver. In compounds it is present in seawater, in mineral springs, and in common salt deposits, e.g., those at Stassfurt, Germany. It occurs in the United States, principally in Michigan, Ohio, and West Virginia. Bromine for commercial purposes is obtained by treating brines (from salt wells or seawater) with chlorine, which displaces the bromine. It is important in the preparation of organic compounds, such as ethylene dibromide, which is used in conjunction with an antiknock compound in gasoline. Bromine has a powerful corrosive action on the skin, destroying the tissue, and the vapor is strongly irritating to the eyes and the membranes of the nose and throat. The element was discovered in seawater by Antoine Jérôme Balard in 1826.
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