BROMINE

The chemical element bromine is a liquid with a powerful, unpleasant odor. Its symbol is Br; its atomic number 35; and its atomic weight 79.904. In its elemental state it is a deep-red color, so dark as to appear almost black. It is a nonmetal appearing on the periodic chart of the elements as a member of family VIIa, the HALOGENS. Bromine is similar chemically to chlorine and combines directly with many elements and compounds, but it does so less energetically. Bromine reacts with most metals, explosively with potassium and vigorously with aluminum, but magnesium, nickel, and lead are un-reactive with it. In some cases, as with iron and zinc, moisture must be present to initiate the reaction, and in other cases, as with sodium, an elevated temperature must be attained. The reaction of bromine with organic compounds is called bromination. Bromine commonly adds across the bond of unsaturated hydrocarbons and reacts with the ring structure of phenol by substitution for hydrogen atoms. Bromine is an oxidizing agent. It hydrolyzes slightly in aqueous solution, producing hydrobromic acid (HBr) and hypobromous acid (HBrO). The hypobromous acid is unstable, resulting in the production of oxygen, which accounts for the bleaching capability of bromine water. In a freezing mixture of saturated bromine in water, deposits of red crystals of bromine hydrate will form. It is commonly used as a form of sanitizer using bromine salts as base and is most popular in spas and hot tubs, where hotter water temperatures melt chlorine tablets too fast and deposit too high of levels of sanitizer, bromine stands out as a residual base for sanitary water. Occasionally, it is used in place of chlorine in pool sanitation, it is effective, but the more expensive price, is a deterrent.