Bromine Element Facts

Bromine in sample-tube. (Photo by Greenhorn1)

Classification:	Bromine is a halogen and a nonmetal
Atomic weight:	79.904 g/mol
Density @ 20 oC:	3.122 g/cm3
Atomic volume:	23.5 cm3/mol

Ozone Depletion Above Antarctica:
The intensity of blue shows the severity of ozone depletion above Antarctica in September 2010. Atom for atom, bromine atoms are 40-100 times more destructive in the ozone layer than chlorine atoms. Reactions involving bromine are responsible for up to half of the loss of ozone above Antarctica. The largest source of ozone-depleting bromine is methyl bromide. Methyl bromide's main use is as a fumigant. About 30% of the bromine in the atmosphere comes from human activities, the rest is natural. ⁽⁷⁾
Photo: Nasa Ozone Hole Watch.

Discovery of Bromine

Bromine compounds have been used since ancient times.

In the first century A.D. Pliny describes one of the world's first chemical industries: dye factories making Tyrian purple. Tyrian purple (or royal purple) is an ancient purple dye obtained from a marine mollusk. A major component of the dye is the compound 6,6'-dibromoindigo. ⁽¹⁾

Three people are significant in the story of the element bromine's discovery.

First there's Justus von Liebig, one of most famous chemists of his time. Liebig could have been credited with the independent discovery of bromine, but he squandered the opportunity.

In 1825 a salt maker sent Liebig a sample of salt spring waters from the German town of Bad Kreuznach, asking for an analysis. The sample had a relatively high amount of bromine in it, which Liebig isolated. Without considering the substance too seriously, he concluded it was a compound of iodine and chlorine.

Only when bromine's existence had been announced did an anguished Liebig return to the red-brown liquid to study it closely. He then placed the bottle in his 'mistakes cupboard' to remind himself that preconceived ideas ruined his chance of discovering something new and to try not to make the same mistake again. ^{(2), (3), (4), (5)}

The next name in the story of bromine is Carl Lðwig (Loewig), who discovered bromine in 1825, while still a chemistry student at Heidelberg University.

Lðwig's home town was Bad Kreuznach, where Liebig's sample had come from. Lðwig had taken water from a salt spring in Bad Kreuznach and added chlorine to the liquid. He shook the solution with ether and found a red-brown substance dissolved in the ether. Lðwig evaporated the ether to leave a red-brown liquid: bromine.

His professor at Heidelberg asked Lðwig to prepare more of this substance for testing. By the time Lðwig had done this it was 1826 and a final name - Antoine Balard - had taken over the story of bromine's discovery.

In 1824 Antoine Balard, aged 21, was studying the plant life in a salt marsh in Montpellier, France. He became interested in salt deposits he saw and began investigating them.

He took brine (sea water in which salts have been concentrated by evaporation of water) and crystallized salt from it. He took the remaining liquid and saturated it with chlorine. He then distilled the solution to leave a dark red liquid. ^{(2), (3), (4), (5)}

Alert to the possibility that he had found something very interesting, Balard gave the French Academy of Science a sealed envelope containing his initial results in 1824. He finally published his results in 1826, providing evidence that the substance he had discovered was a new 'simple body' - i.e. an element, not a compound. ⁽³⁾

As first to publish, he became bromine's discoverer. Ironically, like Liebig, his first idea was that the substance was a compound of chlorine and iodine. ⁽³⁾

The French Academy named the new element after the Greek bromos for 'stench' ⁽⁶⁾ because bromine, quite simply, stinks.

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