Bromine

Bromine (Br) is a chemical element with atomic number 35. It belongs to the group of halogens, which also includes fluorine, chlorine, and iodine. Bromine is the only halogen that is not a gas at room temperature, existing instead as a liquid. Its color is dark reddish-brown, and it gives off a vapor of the same color with a strong, sharp odor.

In its natural state, bromine exists primarily as a single element. It is most commonly found as bromide (Br⁻) dissolved in seawater, salt springs, and deep underground water. Industrial producers extract it from these sources by adding chlorine to the water to release the bromide.

Physical and chemical properties

Bromine exists as a two-atom molecule (Br₂). It evaporates readily at ordinary temperature. Like other halogens, it is highly reactive: it oxidizes metals by forming bromides. Bromine is less reactive than chlorine but more reactive than iodine. Liquid bromine can burn skin, and its vapor damages the eyes and respiratory system; therefore, protective equipment is required when handling it.

Uses

Bromine compounds are used in flame retardants made from plastics, electronic equipment, and textiles. They are also used in pharmaceuticals, pesticides, and chemicals for water treatment. Historically, silver bromide compounds were used in photographic film, and bromine was added to gasoline in motor vehicles in earlier decades.

Environment and regulation

Some bromine compounds, particularly those known as methyl bromide, damage the ozone layer. For this reason, international agreements on ozone protection have reduced their use, with certain applications banned. Additionally, bromine-based flame retardants are suspected of persisting in the environment, leading many countries to issue regulations restricting specific types.