| Discovery date | 1826 |
| Discovered by | Antoine-Jérôme Balard in Montpellier, France and Carl Löwig in Heidelberg, Germany |
| Origin of the name | The name comes from the Greek 'bromos' meaning stench. |
| Allotropes |
|
Br
Bromine
35
79.904
| Group | 17 | Melting point | −7.2°C, 19°F, 266 K |
| Period | 4 | Boiling point | 58.8°C, 137.8°F, 332 K |
| Block | p | Density (g cm−3) | 3.1028 |
| Atomic number | 35 | Relative atomic mass | 79.904 |
| State at 20°C | Liquid | Key isotopes | 79Br |
| Electron configuration | [Ar] 3d104s24p5 | CAS number | 7726-95-6 |
| ChemSpider ID | 4514586 | ChemSpider is a free chemical structure database | |
Image explanation
The image intends to reflect the rich colour, liquidity and aromatic nature of the element.
Appearance
Bromine is a deep-red, oily liquid with a sharp smell. It is toxic.
Uses
Bromine is used in many areas such as agricultural chemicals, dyestuffs, insecticides, pharmaceuticals and chemical intermediates. Some uses are being phased out for environmental reasons, but new uses continue to be found.
Bromine compounds can be used as flame retardants. They are added to furniture foam, plastic casings for electronics and textiles to make them less flammable. However, the use of bromine as a flame retardant has been phased out in the USA because of toxicity concerns.
Organobromides are used in halon fire extinguishers that are used to fight fires in places like museums, aeroplanes and tanks. Silver bromide is a chemical used in film photography.
Before leaded fuels were phased out, bromine was used to prepare 1,2-di-bromoethane, which was an anti-knock agent.
Biological role
Bromine is present in small amounts, as bromide, in all living things. However, it has no known biological role in humans. Bromine has an irritating effect on the eyes and throat, and produces painful sores when in contact with the skin.
Natural abundance
Bromine is extracted by electrolysis from natural bromine-rich brine deposits in the USA, Israel and China. It was the first element to be extracted from seawater, but this is now only economically viable at the Dead Sea, Israel, which is particularly rich in bromide (up to 0.5%).
Antoine-Jérôme Balard discovered bromine while investigating some salty water from Montpellier, France. He took the concentrated residue which remained after most of the brine had evaporated and passed chlorine gas into it. In so doing he liberated an orange-red liquid which he deduced was a new element. He sent an account of his findings to the French Academy’s journal in 1826.
A year earlier, a student at Heidelberg, Carl Löwig, had brought his professor a sample of bromine which he had produced from the waters of a natural spring near his home at Keruznach. He was asked to produce more of it, and while he was doing so Balard published his results and so became known at its discoverer.
| Atomic radius, non-bonded (Å) | 1.85 | Covalent radius (Å) | 1.17 |
| Electron affinity (kJ mol−1) | 324.537 |
Electronegativity (Pauling scale) |
2.96 |
|
Ionisation energies (kJ mol−1) |
1st
1139.859
2nd
2083.215
3rd
3473
4th
4563.8
5th
5760.2
6th
8548.6
7th
9938
8th
18602.4
|
||
|
| Common oxidation states | 7, 5, 3, 1, -1 | ||||
| Isotopes | Isotope | Atomic mass | Natural abundance (%) | Half life | Mode of decay |
| 79Br | 78.918 | 50.69 | - | - | |
| 81Br | 80.916 | 49.31 | - | - | |
|
|
|
Specific heat capacity (J kg−1 K−1) |
474 | Young's modulus (GPa) | Unknown | |||||||||||
| Shear modulus (GPa) | Unknown | Bulk modulus (GPa) | 1.9 | |||||||||||
| Vapour pressure | ||||||||||||||
| Temperature (K) |
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| Pressure (Pa) |
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| Listen to Bromine Podcast |
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Transcript :
Chemistry in its element: bromine(Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello, welcome to Chemistry in its element where this week we're sniffing out the chemical that is named after the Greek word for stench and this substance has certainly kicked up a stink in its own right in its time because it makes holes in the ozone layer. But it's not all bad as it's also given us drugs, insecticides and fire extinguishers and to tell the story of element number 35, here's chemist and author John Emsley. John Emsley Fifty years ago bromine was produced on a massive scale and turned into lots of useful compounds. Photography relied on the light-sensitivity of silver bromide, doctors prescribed potassium bromide as a tranquiliser, leaded petrol needed dibromomethane to ensure the lead was removed via the exhaust gases, bromomethane was widely used to fumigate soil and storage facilities, and fire extinguishers contained volatile organobromine compounds. Today these uses have all but disappeared. World production of liquid bromine once exceeded 300,000 tonnes per year, of which a significant part was produced by a plant on the coast of Anglesey in Wales, which closed in 2004. This extracted the element from sea water, which contains 65 p.p.m. of bromide, and was done by using chlorine gas to convert the bromide to bromine which was then removed by blowing air through the water. The bromine story began with 24-year-old student Antoine-Jérôme Balard. He found that the salt residues left by evaporating brine from Montpellier, France, gave an oily red liquid when treated with acid. He realised this was a new element and reported it to the French Academy, who confirmed his discovery. When they realised it was chemically similar to chlorine and iodine they proposed the name bromine, based on the Greek word bromos meaning stench. While some uses of bromine have declined because the products made from it are no longer needed, others have been discouraged because of the damage this element could cause to the ozone layer. Volatile organobromine compounds are capable of surviving in the atmosphere long enough to reach the upper ozone layer where their bromine atoms are 50 times more damaging than the chlorine atoms - which are the main threat, coming as they did from the widely used chlorofluorocarbons, the CFCs. The Montreal Protocol which outlawed the CFCs sought also to ban the use of all volatile organobromines by 2010, and this restriction especially applied to the fumigant bromomethane and compounds such as CBrClF2 which were in fire extinguishers for electrical fires or those in confined spaces. Bromomethane was a particular cause for concern but banning it has proved impossible because it has some uses for which alternatives have not been found. Often referred to as methyl bromide, CH3Br (boiling point 3.5oC), this has been widely employed to kill pests in the soil, in storage facilities, and to treat wood before it is exported. In the soil it kills nematodes, insects, bacteria, mites and fungi which threaten crops such as seed crops, lettuce, strawberries, grapes, and flowers such as carnations and chrysanthemums. In fact bromomethane is not quite so threatening as it first appears. Environmental research uncovered the unexpected result that half the bromomethane sprayed on soil never evaporates into the air because it is consumed by bacteria. Nor are man-made organobromines the main source of these compounds in the atmosphere. Marine plankton and algae release around half a million tonnes of various bromomethanes a year and in particularly tribromomethane (aka bromoform, CHBr3). Even more surprising has been the discovery that something in the oceans is making pentabromodiphenyl ether. This has been used as a fire-retardant, and when in 2005 it was found to be present in whale blubber it was at first thought to be the man-made variety. However, the carbon atoms it contained had detectable amounts of 14C meaning that they were of recent origin, whereas the fire retardant is made entirely from fossil resources and contains no 14C. Another complex bromine compound from the sea is the purple dye once used for clothes worn by the Roman Emperors. Tyrian purple as it was called was extracted from the Mediterranean mollusc Murex brandaris and this molecule contains two bromine atoms and is 6,6'-dibromoindigo. Even when it appears benign as bromide ions in water, this element can still pose a threat to health. Ozonising drinking water in order to sterilise it converts any bromide to bromate (BrO3-) which is a suspected carcinogen and so must not exceed 10 p.p.b. And some reservoirs in California where this has been exceeded have had to be drained because of it. Once so beneficial, bromine now appears to cause nothing but trouble. Yet in ways unseen, such as in the pharmaceutical industries, it still continues to be used to provide intermediates in the manufacture of live-saving drugs. Chris Smith John Emsley unlocking the secrets of the brown element Bromine. You can find out more about some of John's other favourite elements in a series he has written for the RSC's Education in Chemistry and that's online at rsc.org/education. Next time on Chemistry in its element Nobel prize winning chemist Kary Mullis explains why a soul of iron is essential. Kary Mullis For the human brain, iron is essential yet deadly. Carbon, sulfur, nitrogen, calcium, magnesium, sodium, maybe ten other elements are also involved in life, but none of them have the power of iron to move electrons around, and none of them have the power to totally destroy the whole system. Iron does. Chris Smith And you can catch Kary Mullis ironing out the wrinkles in metabolism's most important element on next week's Chemistry in its Element. I'm Chris Smith, thank you for listening, see you next time. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements. (End promo)
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Visual Elements images and videos
© Murray Robertson 1998-2017.
W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.
John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.
Derived in part from material provided by the British Geological Survey © NERC.
Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.
Produced by The Naked Scientists.
Created by video journalist Brady Haran working with chemists at The University of Nottingham.
© Murray Robertson 1998-2017.
Data
W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.
Uses and properties
John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.
Supply risk data
Derived in part from material provided by the British Geological Survey © NERC.
History text
Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.
Podcasts
Produced by The Naked Scientists.
Periodic Table of Videos
Created by video journalist Brady Haran working with chemists at The University of Nottingham.
