Br

Br is the chemical element bromine, symbol Br, and atomic number 35. It is a member of the halogen family (group 17) in period 4 of the periodic table. At room temperature bromine is a reddish-brown liquid, one of the few elements that is liquid under standard conditions, and it exists as diatomic molecules (Br2). It is dense, highly volatile, and has a pungent odor.

Bromine is highly reactive and corrosive. In chemistry it forms bromide ions (Br−) in many compounds and participates in a wide range of reactions, including oxidation and addition to organic substrates. It readily forms hydrogen bromide (HBr) when reacting with hydrogen and can form interhalogen compounds such as BrF and BrCl.

Occurrence and production: Bromine does not occur as a free element in nature; it is found primarily as bromide salts in seawater, brines, and certain mineral deposits. Commercial bromine is extracted from brine pools and salt deposits. Industrially, bromine is produced by oxidizing bromide in brine with chlorine or other oxidants and then purifying the product by distillation.

History and naming: Bromine was discovered in 1826 by Antoine-Jérôme Balard in Montpellier, France, from seawater. The name bromine derives from the Greek bromos, meaning stench, in reference to its strong odor.

Uses: Bromine and many brominated compounds are used in flame retardants, pharmaceuticals, dyes, and agricultural chemicals. Bromide chemistry played a significant historical role in photography through silver bromide emulsions.

Safety: Bromine is toxic and corrosive; exposure can irritate skin, eyes, and the respiratory tract. Handling requires appropriate safety precautions and ventilation. It is also an environmental hazard in concentrated forms.

Isotopes: Natural bromine has two stable isotopes, Br-79 and Br-81.