Periodic Table -> Bromine


Bromine Details

Bromine Symbol: Br

Bromine Atomic Number: 35

Bromine Atomic Weight: 79.909

What is Bromine?

Bromine (atomic number 35, symbol Br) is a chemical element belonging to the halogen group. It is the only nonmetallic, liquid element and a reddish brown, mobile, volatile, and heavy liquid. The vapor irritates the throat and eyes and has an unpleasant, strong odor. Elemental bromine exists in a liquid form at room temperature and is toxic and corrosive. Its properties are similar to those of iodine and chlorine. Free bromine is not found it nature, and occurs in the form of soluble, colorless, crystalline halide salts.

Bromine was first isolated in the period 1825 - 1826 by the chemists Antoine Jerome and Carl Jacob Löwig, who were working independently. When the young student of chemistry Carl Löwig produced bromine, he showed it to his instructor Leopold Gmelin. The professor realized that the chemical was an unknown substance and asked Löwig to produce more of it so that it can be studied in detail. Holidays and exams delayed Löwig long enough for Antoine-Jérôme Balard, also a chemistry student, to publish a research paper on the new element. Antoine-Jérôme Balard was credited with bromine’s discovery and named the element after bromos, which is a Greek word for stench.

This element is rarer than around three fourths of the chemical elements in the earth’s crust. The bromide ion’s high solubility, however, has led to its accumulation in the oceans. Bromine is commercially extracted in China, Israel, and the United States from brine pools.

It should be noted that elemental bromine is a dangerous material, and in contact with the skin, it causes severe burns. Its vapor irritates the throat, nose, and eyes. In the US, most of the bromine was used to manufacture the chemical ethylene dibromide. Leaded gasolines that prevented lead compounds from accumulating in the engine contained it before the use of leaded gasolines was discontinued. Unleaded gasolines were then introduced, and the demand for bromine dropped considerably. Today, bromide is mostly used in the form of silver bromide, which has application in photography.

Bromine has other applications as well, as a flame retardant, pesticide, and gasoline additive. Bromine-based flame retardants have a growing commercial importance, and this is the most common use of bromine. The burning of brominated material generates hybrobromic acid, interfering in fire’s oxidation reaction. Hydroxy radicals and hydrogen oxygen react with the acid, forming free bromine atoms, which are less reactive radicals of bromine. Methyl bromide is a poisonous substance that was commonly used as a pesticide. Ethylene bromide had a similar application. Being ozone depletion agents, these volatile compounds are regulated today. Prior to the 1991 adoption of the Montreal protocol, bromide was used to control weeds, fungi, nematodes, and other soil-borne diseases. Similarly, due to environmental regulations, the use of bromide as a gasoline additive has declined since the 70s. Ethylene bromide was formerly used as an additive in gasolines that contained anti-engine knocking agents.

Compounds of bromide are also used in medicine. Potassium bromide, in particular, was used as a sedative in the 19th century and the beginning of the 20th century. As simple salts, bromides are used today as anticonvulsants in human and veterinary medicine, but their use differs between countries. Notably, the prolonged use of potassium bromide causes bromism, which is an uncommon disorder nowadays. In the past, bromism was responsible for five to ten percent of all psychiatric admissions.

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