Bromine was discovered in 1825 and 1826, independently by two chemists, Antoine Jerome Balard and Carl Jacob Lowig. Bromine is a hazardous gas. It is highly reactive and have various industrial uses.
History and Discovery
Bromine was discovered independently by in 1826 and 1825, respectively. Bromine was isolated from samples of spring water by Lowig, while Balard isolated bromine from seaweed ashes. The name bromine is a Greek word that means stench [1].
Bromine
| Periodic Table Classification | Group 17 Period 4 |
|---|---|
| State at 20C | Liquid |
| Color | Reddish-brown |
| Electron Configuration | [Ar] 3d10 4s2 4p5 |
| Electron Number | 35 |
| Proton Number | 35 |
| Electron Shell | 2, 8, 18, 7 |
| Density | 3.12 g.cm-3 at 20°C |
| Atomic number | 35 |
| Atomic Mass | 79.90 g.mol -1 |
| Electronegativity according to Pauling | 2.96 |
Occurrence
Bromine is not a very abundant element, it is less abundant in crust than chlorine and fluorine. Bromine is ranked as the forty-sixth abundant element in the earth’s crust. And is present in about 65 ppm on Earth. I Bromine is not found in free form in nature. it always exists in combined form with other metals. mostly it exists in the form of soluble crystalline mineral salts, that are colorless in nature. These salts resemble table salt. Bromine is quite abundant in oceans, primarily due to leaching from the minerals and ores. The Dead Sea is comprised of 0.4% bromide ions [2]. The largest producers of bromine are China, USA and Israel. And it is widely extracted from pools of brine.
Physical Characteristics
Bromine is liquid at room temperature. It is reddish brown in color. It has a very unpleasant, pungent and choking smell. It is the only non-metallic element that is present in liquid form at standard temperature and pressure. Bromine readily evaporates (very volatile) in the form of reddish colored gas. It is part of the halogen family and is the third lightest member of this group. It has properties that are intermediate between iodine and chlorine. Bromine is soluble in water and organic solvents.
Chemical Characteristics
Bromine is highly reactive element. It is more reactive than iodine and less reactive than chlorine. Bromine is a strong oxidizing agent. Bromine forms simple compounds with hydrogen bromide. Bromic acid is a strong acid. Bromine form oxides with oxygen, bromine monoxide and bromine dioxide, but they are quite unstable. Handling and transportation of bromine needs caution and should be stored in steel tanks with lining of lead. Organobromides are one of the most common organohalides present in the nature [3].
Significance and Uses
- Compounds of bromine are used as fire retardants.
- Bromine is used as catalyst in the manufacturing process of organic chemicals. Various organo-bromo compounds, such as dibromoethane was used in the manufacturing of leaded gasoline. Organo-bromine compounds are also used to make fire extinguishers, sanitizers and in water purification.
- Bromine is used in making photographic film.
- Bromoethane is used as pesticides to remove pests from houses (fumigation) and farms.
Health Hazards
Bromine in is elemental form is highly hazardous and corrosive. An exposure to a dose of 3 ppm bromine is considered dangerous to life and health. Inhalation of bromine gas can lead to irritation of nose and eyes. Prolonged exposure can cause shortness of breath, coughing and choking that can lead to death. Chronic exposure to bromine can lead to permanent damage to the lungs and increase the risks of bronchial infections. Direct skin contact to bromine gas can cause burns and blisters on skin. Bromide salts are quite toxic. Ingestion of these salts in large quantities can lead to a condition termed as bromism. Bromism is a neurotoxic disturbance caused by effect of bromine on brain and it causes psychosis and unconsciousness. However, in minute quantities, bromine is also an essential trace element. It is required by the body to carry out its normal functions, but only in small amount. Bromine is also essential for the primary producers of our ecosystem, i.e. algae.
Isotopes of Bromine
There are two naturally occurring isotopes of bromine, bromine-79 and bromine-81, having a relative abundance of 51% and 49%. There are twenty-four radioactive isotopes of bromine, with mass number ranging from 68-94. The most stable radioactive isotope of bromine is bromine-77 [4].
REFERENCES
[1]. Mary Elvira Weeks, The discovery of the elements. XVII. The halogen family., J. Chem. Educ., 1932, 9 (11), p1915
[2]. Greenwood and Earnshaw, pp. 795–6
[3]. A.G. Ruaws, Pharmacokinetics of Bromide Ion — An Overview., Ed Chem. Toxic., 1983, vol. 21, 4 p379
[4]. Audi, G.; Bersillon, O.; Blachot, J.; Wapstra, A. H. (2003). “The NUBASE evaluation of nuclear and decay properties” (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729….3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2011-07-20