Bromine

Bromine [bʁoːm] (ancient Greek βρῶμος brōmos "stench") is a chemical element with the element symbol Br and atomic number 35. In the periodic table, it is in the 7th main group, or the 17th IUPAC group, and thus belongs to the halogens together with fluorine, chlorine, iodine, astatine and tenness. Elemental bromine exists in liquid form under standard conditions (temperature = 0 °C and pressure = 1 atm) in the form of the diatomic molecule Br2. Bromine and mercury are the only natural elements that are liquid under standard conditions.

In nature, bromine does not occur elementally, but only in various compounds. The most important compounds are the bromides, in which bromine occurs in the form of the anion Br-. The best known bromides are sodium bromide and potassium bromide. Bromides are a component of seawater and have some biological functions.

Discovery

Bromine was extracted from seaweed in the salt marshes near Montpellier in 1826 by the French chemist Antoine-Jérôme Balard, who recognized it as a previously unknown substance.

Already two years before Balard, the German chemist Justus von Liebig unknowingly produced elemental bromine in 1824. He had been commissioned to analyse the brines of Salzhausen, as the town was planning a spa. While examining these brines, Liebig found a new substance, which he interpreted as iodine chloride. Thirteen years later he admitted that his careless analysis had deprived him of the discovery of a new element. Liebig wrote of this, "I know a chemist who, when he was at Kreuznach, examined the mother liquors of the salt works." He then went on to describe his misfortune, concluding with the words, "Since that time he has put forward no theories unless they have been supported and confirmed by undoubted experiments; and I can report that he has not done badly at that."

Karl Löwig also worked on bromine, which he had already obtained before 1825 by introducing chlorine into Kreuznach brine water, but Balard beat him to the publication of his discovery.

Industrial production began in 1860, and Joseph Louis Gay-Lussac suggested the name "bromine" (Greek for "goat stench of animals") because of its pungent odor.

Justus Liebig was the first to isolate elemental bromine

Occurrence

Bromine occurs in the form of bromides, the salts of hydrobromic acid. In terms of quantity, the largest deposits are found as dissolved bromides in seawater. Deposits of natural salt deposits (rock and potash salts) also contain small amounts of potassium bromide and potassium bromate. Bromine can also occur in the atmosphere in the form of molecular bromine and bromine oxide and can significantly affect atmospheric ozone chemistry, being transported over long distances. During the polar spring, larger concentrations (>10ppt) of BrO regularly destroy almost all tropospheric ozone. These events can also be observed by satellites using the DOAS method. In tropical regions with high bioactivity, strong emissions of halogenated hydrocarbons have been observed, which can ultimately contribute to the formation of BrO and ozone destruction through photolysis.

Bromine is essential for animals in trace amounts. Bromide acts as a cofactor in a metabolic reaction that is necessary for building the collagen IV matrix in connective tissue.