Bromine (from Greek: βρῶμος, brómos, meaning "stench (of he-goats)") is a chemical element with the symbol Br, and atomic number of 35. It is in the halogen group (17). The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826. Elemental bromine is a fuming red-brown liquid at room temperature, corrosive and toxic, with properties between those of chlorine and iodine. Free bromine does not occur in nature, but occurs as colorless soluble crystalline mineral halide salts, analogous to table salt.

Bromine is rarer than about three-quarters of elements in the Earth's crust; however, the high solubility of bromide ion has caused its accumulation in the oceans, and commercially the element is easily extracted from brine pools, mostly in the United States, Israel and China. About 556,000 tonnes were produced in 2007, an amount similar to the far more abundant element magnesium.

At high temperatures, organobromine compounds are easily converted to free bromine atoms, a process which acts to terminate free radical chemical chain reactions. This makes such compounds useful fire retardants and this is bromine's primary industrial use, consuming more than half of world production of the element. The same property allows volatile organobromine compounds, under the action of sunlight, to form free bromine atoms in the atmosphere which are highly effective in ozone depletion. This unwanted side-effect has caused many common volatile brominated organics like methyl bromide, a pesticide that was formerly a large industrial bromine consumer, to be abandoned. Remaining uses of bromine compounds are in well-drilling fluids, as an intermediate in manufacture of organic chemicals, and in film photography.

Bromine has no essential function in mammals, though it is preferentially used over chloride by one antiparasitic enzyme in the human immune system. Organobromides are needed and produced enzymatically from bromide by some lower life forms in the sea, particularly algae, and the ash of seaweed was one source of bromine's discovery. As a pharmaceutical, simple bromide ion, Br–, has inhibitory effects on the central nervous system, and bromide salts were once a major medical sedative, before being replaced by shorter-acting drugs. They retain niche uses as antiepileptics.

Read more about BromineHistory, Occurrence, Production, Applications, Biological Role, Safety

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Bromine Monochloride
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... See also List of highly toxic gases Elemental bromine is toxic and causes burns ... Care needs to be taken when transporting bromine it is commonly carried in steel tanks lined with lead, supported by strong metal frames ... When certain ionic compounds containing bromine are mixed with potassium permanganate (KMnO4) and an acidic substance, they will form a pale brown cloud of bromine gas ...
Bromine Dioxide - Reactions
... Bromine dioxide is formed when an electrical current is passed through a mixture of bromine and oxygen gases at low temperature and pressure ... Bromine dioxide can also be formed by the treatment of bromine gas with ozone in trichlorofluoromethane at −50 °C ... When mixed with a base, bromine dioxide gives the bromide and bromate anions 6 BrO2 + 6 NaOH → NaBr + 5 NaBrO3 + 3 H2O ...