There are many elements in the periodic table that are known for their characteristics, the story behind its discovery, their utility and so on. However, the strange fact is that there is an element which is well recognised for its odour. The element is Bromine. Bromine is a chemical element with symbol Br and atomic number 35. In its elemental form, Bromine is a heavy, volatile, mobile, dangerous, reddish–brown liquid. Bromine does not occur freely in nature and is as colourless as table salt. Bromine is a rare element and is about three–quarters in the earth’s crust. But, the high solubility of bromide ion has caused its accumulation in the oceans. It is derived from the Greek word ‘bromos’, which means stench or smell. There is a red vapour of Bromine that has a strong unpleasant odour, which irritates the eyes and the throat.
Two different individuals were working towards discovering Bromine. In 1826, Antoine–Jerome Balard took the concentrated residue left after the brine had evaporated and passed chlorine gas into it. He deduced a new element by liberating an orange–red liquid and sent an account of his findings to the French Academy’s journal in Montpellier, France. Also a year earlier, Carl Lowig, a student at Heidelberg had produced a sample of Bromine from the waters of a natural spring near his home at Keruznach. He presented his sample to his professor who asked him to produce more of it. When Carl Lowig was producing its quantities, in the meanwhile, Antoine–Jerome Balard published his results and hence, became known as its discoverer.
Bromine is a rare element and is not available free in nature. It occurs in compounds present in sea water, natural brines and salt–lake evaporates. Mineral deposits of bromine are found in the United States in natural brine wells in Michigan and Arkansas. The estimated production of Bromine worldwide is around 330,000 tons per year.
Important characteristics of Bromine include:
- Bromine is a heavy, non–metallic reddish–brown liquid and is a member of the halogen group.
- It is corrosive and toxic and has similar characteristics between those of chlorine and iodine.
- It quickly vaporizes and has a foul odour at room temperature. This vapour is reddish in colour and irritates the eyes and the throat.
- Due to its toxicity, it can produce painful sores when spilled on skin.
- When mixed with water or carbon disulfide, Bromine forms a red solution.
- Bromine readily bonds with many other elements.
The isotopes of Bromine range from 67Br to 98Br, out of which, there are two stable naturally occurring isotopes namely 79Br and 81Br. Most of the isotopes are short–lived. However, 67Br has an unknown half–life. Most of the isotopes of Bromine are fission products. The heavier ones from the fission are delayed neutron emitters and are important to the controllability of a nuclear reactor. There are at least 23 radioisotopes known of Bromine and all of them are relatively short–lived.
Common uses of Bromine include:
- It is used in water purification for swimming pools and in the manufacture of ethylene dibromide.
- It is well used in bleaching, as a solvent, for organic synthesis, as an analytical reagent, as a fire retardant for plastic products, in pharmaceuticals and for shrink–proofing wool.
- It is used in many areas such as agricultural chemicals, dyestuffs, insecticides, chemical intermediates and flame–retardants.
- Dibromoethane is prepared with the help of Bromine, which is used as an anti–knock agent in combustion engines and to make bromide salts for photography
In a liquid state, Bromine is corrosive as its vapours are toxic to inhale and may irritate eyes and throat. Organic bromines are widely used as sprays to kill insects and pests and can be absorbed in the human body through skin, with food and during breathing. Bromine–containing contaminants may lead to malfunctioning of the nervous system and disturbances in genetic materials. Organs such as liver, kidneys, lungs and milt can be damaged due to organic bromines and they can cause stomach and gastrointestinal malfunctioning. Some forms of organic bromines which include ethylene bromine may even cause cancer.