Bromine

Bromine, ₃₅Br
	Liquid and gas bromine inside transparent cube
Bromine
Pronunciation	/ˈbroʊmiːn, -mɪn, -maɪn/ (BROH-meen, -⁠min, -⁠myne)
Appearance	reddish-brown
Standard atomic weight Ar°(Br)
	[79.901, 79.907]; 79.904±0.003 (abridged);
Bromine in the periodic table
	selenium ← bromine → krypton
Atomic number (Z)	35
Group	group 17 (halogens)
Period	period 4
Block	p-block
Electron configuration	[Ar] 3d10 4s2 4p5
Electrons per shell	2, 8, 18, 7
Physical properties
Phase at STP	liquid
Melting point	(Br2) 265.8 K (−7.2 °C, 19 °F)
Boiling point	(Br2) 332.0 K (58.8 °C, 137.8 °F)
Density (near r.t.)	Br2, liquid: 3.1028 g/cm3
Triple point	265.90 K, 5.8 kPa
Critical point	588 K, 10.34 MPa
Heat of fusion	(Br2) 10.571 kJ/mol
Heat of vaporisation	(Br2) 29.96 kJ/mol
Molar heat capacity	(Br2) 75.69 J/(mol·K)
Atomic properties
Oxidation states	−1, 0, +1, +2, +3, +4, +5, +7 (a strongly acidic oxide)
Electronegativity	Pauling scale: 2.96
Ionisation energies	1st: 1139.9 kJ/mol ; 2nd: 2103 kJ/mol ; 3rd: 3470 kJ/mol ; ;
Atomic radius	empirical: 120 pm
Covalent radius	120±3 pm
Van der Waals radius	185 pm
	Spectral lines of bromine
Other properties
Natural occurrence	primordial
Crystal structure	orthorhombic (oS8)
Lattice constants	a = 674.30 pm; b = 466.85 pm; c = 870.02 pm (at triple point: 269.60 K)
Thermal conductivity	0.122 W/(m⋅K)
Electrical resistivity	7.8×1010 Ω⋅m (at 20 °C)
Magnetic ordering	diamagnetic
Molar magnetic susceptibility	−56.4×10−6 cm3/mol
Speed of sound	206 m/s (at 20 °C)
CAS Number	7726-95-6
History
Discovery and first isolation	Antoine Jérôme Balard and Carl Jacob Löwig (1825)
Isotopes of bromine v; e;
	Category: Bromine; view; talk; edit; \| references

Bromine is a chemical element; it has symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig (in 1825) and Antoine Jérôme Balard (in 1826), its name was derived from the Ancient Greek βρῶμος (bromos) meaning "stench", referring to its sharp and pungent smell.

Elemental bromine is very reactive and thus does not occur as a free element in nature. Instead, it can be isolated from colourless soluble crystalline mineral halide salts analogous to table salt, a property it shares with the other halogens. While it is rather rare in the Earth's crust, the high solubility of the bromide ion (Br⁻) has caused its accumulation in the oceans. Commercially the element is easily extracted from brine evaporation ponds, mostly in the United States and Israel. The mass of bromine in the oceans is about one three-hundredth that of chlorine.

At standard conditions for temperature and pressure it is a liquid; the only other element that is liquid under these conditions is mercury. At high temperatures, organobromine compounds readily dissociate to yield free bromine atoms, a process that stops free radical chemical chain reactions. This effect makes organobromine compounds useful as fire retardants, and more than half the bromine produced worldwide each year is put to this purpose. The same property causes ultraviolet sunlight to dissociate volatile organobromine compounds in the atmosphere to yield free bromine atoms, causing ozone depletion. As a result, many organobromine compounds—such as the pesticide methyl bromide—are no longer used. Bromine compounds are still used in well drilling fluids, in photographic film, and as an intermediate in the manufacture of organic chemicals.

Large amounts of bromide salts are toxic from the action of soluble bromide ions, causing bromism. However, bromine is beneficial for human eosinophils,^[9] and is an essential trace element for collagen development in all animals.^[10] Hundreds of known organobromine compounds are generated by terrestrial and marine plants and animals, and some serve important biological roles.^[11] As a pharmaceutical, the simple bromide ion (Br⁻) has inhibitory effects on the central nervous system, and bromide salts were once a major medical sedative, before replacement by shorter-acting drugs. They retain niche uses as antiepileptics.

^ "Standard Atomic Weights: Bromine". CIAAW. 2011.
^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ ^a ^b Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.121. ISBN 1-4398-5511-0.
^ Br(II) is known to occur in bromine monoxide radical; see Kinetics of the bromine monoxide radical + bromine monoxide radical reaction
^ Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
^ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
^ Cite error: The named reference pmid2538427 was invoked but never defined (see the help page).
^ Cite error: The named reference pmid24906154 was invoked but never defined (see the help page).
^ Cite error: The named reference Gribble99 was invoked but never defined (see the help page).

[1] "Standard Atomic Weights: Bromine". CIAAW. 2011.

[CIAAW2021-2] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[b92-3] Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.121. ISBN 1-4398-5511-0.

[4] Br(II) is known to occur in bromine monoxide radical; see Kinetics of the bromine monoxide radical + bromine monoxide radical reaction

[Arblaster_2018-5] Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.

[6] Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.

[7] Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.

[NUBASE2020-8] Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[pmid2538427-9] Cite error: The named reference pmid2538427 was invoked but never defined (see the help page).

[pmid24906154-10] Cite error: The named reference pmid24906154 was invoked but never defined (see the help page).

[Gribble99-11] Cite error: The named reference Gribble99 was invoked but never defined (see the help page).

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