Bromine
Contents
Background
| Previous Element: Selenium Next Element: Krypton |
| |
| Physical Properties | ||
|---|---|---|
| Color | red-brown | |
| Phase at Room Temp. | liquid | |
| Density (g/cm3) | 3.1 | |
| Hardness (Mohs) | --- | |
|
Melting Point (K) |
266 | |
|
Boiling Point (K) |
332.7 | |
| Heat of Fusion (kJ/mol) | 10.8 | |
| Heat of Vaporization (kJ/mol) | 29.6 | |
| Heat of Atomization (kJ/mol) | 112 | |
| Thermal Conductivity (J/m sec K) | 0.12 | |
| Electrical Conductivity (1/mohm cm) | 0 | |
| Source | Seawater, brines | |
| Atomic Properties | ||
| Electron Configuration | [Ar]4s23d104p5 | |
|
Number of Isotopes |
40 (2 natural) | |
| Electron Affinity (kJ/mol) | 324.7 | |
| First Ionization Energy (kJ/mol) | 1139.9 | |
| Second Ionization Energy (kJ/mol) | 2103.4 | |
| Third Ionization Energy (kJ/mol) | 3473.4 | |
| Electronegativity | 2.96 | |
| Polarizability (Å3) | 3.1 | |
| Atomic Weight | 79.9 | |
| Atomic Volume (cm3/mol) | 25.8 | |
| Ionic Radius2- (pm) | --- | |
| Ionic Radius1- (pm) | 182 | |
| Atomic Radius (pm) | 114 | |
| Ionic Radius1+ (pm) | --- | |
| Ionic Radius2+ (pm) | --- | |
| Ionic Radius3+ (pm) | --- | |
| Common Oxidation Numbers | -1, +1, +3, +5 | |
| Other Oxid. Numbers | +4, +7 | |
| Abundance | ||
| In Earth's Crust (mg/kg) | 2.4×100 | |
| In Earth's Ocean (mg/L) | 6.73×101 | |
| In Human Body (%) | 0.0004% | |
| Regulatory / Health | ||
| CAS Number | 7726-95-6 | |
| OSHA Permissible Exposure Limit (PEL) | TWA: 0.1 ppm | |
| OSHA PEL Vacated 1989 | TWA: 0.1 ppm STEL: 0.3 ppm | |
|
NIOSH Recommended Exposure Limit (REL) |
TWA: 0.1 ppm STEL: 0.3 ppm IDHL: 3.0 ppm | |
|
Sources: |
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Bromine is a reddish-brown fuming liquid at room temperature, one of only a few elements which is liquid. Bromine liquid has a very strong, irritating odor, and is reactive and rather poisonous. Its atomic number is 35 and chemical symbol is Br.
Bromine is one of the four halogen elements, which are chemically related and show a systematic progression of physical and chemical properties. The other halogens are: fluorine, an extremely reactive gas; chlorine, a reactive, heavy gas; iodine, a relatively inactive solid; and astatine.
Name
Bromine compounds were in use long before bromine was identified and isolated. A purple excretion from certain mollusks was long ago used to make purple dye known as "Tyrian purple." It is now known that this excretion is a bromine compound.
Elemental bromine was discovered in 1826, by German and French scientists working independently. Important quantities of bromine were not isolated until 1860. Bromine was named from the Greek word bromos which means stench, a reference to its very strong odor.
Sources
It is no exaggeration to say that world bromine resources are unlimited. Seawater contains 65 parts per million (ppm) bromine, which translates into 100 trillion tons of elemental bromine! In addition, approximately 1 billion tons of bromine is believed to be in the water of the Dead Sea in Israel. Underground brines in Poland, the United States and elsewhere contain millions of additional tons.
A few bromine minerals have been identified, but none are important in commerce, because bromine compounds (bromides) are usually highly soluble in water, and tend to remain in solution in oceanic or underground brines.
The United States and Israel are the world’s leading producers of elemental bromine. In the U.S., several companies produce nearly one-half of the world’s bromine supply from deep brine wells located adjacent to oil fields in Arkansas and, to a lesser degree, in Michigan. Israel produces approximately 40% of the world’s supply from brines in the Dead Sea. The remaining comes from nine other countries, including some where bromine is extracted from seawater.
Significant amounts of bromine are recovered by recycling the chemical sodium bromide.
Uses
Bromine and bromine compounds are used for a number of very different applications. Some bromine compounds are effective flame retardants, and nearly one-half of the bromine consumed annually is used in flame retardants for household and industrial applications. The agriculture industry uses bromine in pesticides. Bromine compounds are also used in oil-well drilling fluids, sanitary preparations, and an assortment of other applications including water purification chemicals, fumigants, dyes, medicines, and inorganic bromides (AgBr, silver bromide) used in films and photographic processes.
While pure liquid or vaporous bromine are poisonous, most bromides are not especially harmful in small amounts.
Substitutes and Alternative Sources
Chlorine and iodine can be used in place of bromine for water purification processes and other sanitation applications. A number of different alcohols (methanol, ethanol, etc.) can be used in place of ethylene dibromide in gasoline. As digital photography and printing grows, there will be a reduced need for silver bromide to make film.
There is literally more bromine available cheaply than could ever be consumed at current rates, for many decades to come.
Further Reading
- Common Minerals and Their Uses, Mineral Information Institute.
- More than 170 Mineral Photographs, Mineral Information Institute.
