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About Bromine

Bromine Bohr

Bromine was discovered independently by two young chemists: Carl Jacob Löwig in 1825 and Antoine Balard in 1826. Balard extracted the bromine from seaweed ash, using a procedure that was in common use at the time to obtain iodine. Löwig was experimenting with a concentrate from a mineral water spring in his hometown, which he saturated with chlorine and then extracted using ether. After allowing the ether to evaporate, a foul-smelling brown liquid remained, and Löwig presented this liquid as proof of his skills in order to obtain his first position in an academic chemistry lab. Balard was actually the first to published his results, and it was after his results were confirmed by senior chemists that the name bromine, derived from the Greek word for “stench,” was given to the new element.

The earliest significant commercial use of bromine was in photography, starting in the mid-nineteenth century. Silver bromide, like other silver halides, is a light-sensitive crystal, and may be used alone or along with silver chloride to produce film capable of recording an image when exposed to light. Shortly after bromine came into use for photography, potassium and sodium bromides came into use as anticonvulsants and sedatives; however the toxicity of these compounds led them to be largely replaced as other drugs became available. Occasionally, potassium bromide is still used as an epilepsy treatment in veterinary medicine. The toxicity of some bromine compounds was deliberately exploited for use in chemical warfare during First World War. Like many more familiar chlorine-based chemical warfare agents, compounds such as xylyl bromide cause severe irritation to skin and mucous membranes, leading to pain, tearing, respiratory distress, and sometimes chemical burns.

In modern usage, inorganic bromine compounds are primarily found in just a few areas beyond film photography. Calcium, sodium, and zinc bromides are all used in drilling fluids in oil and natural gas mining. Bromine gas, hydrogen bromide, or other simple bromine compounds can be used to reduce mercury pollution from coal power plants; either the coal or the gases produced during combustion are treated with bromine agents which bind the mercury. Like chlorine, bromine can be used in the maintenance of swimming pools and spas. It is usually produced as needed for this use from a bromide and hydrogen peroxide. Bromine may also be used for drinking water disinfection, though in this usage it is typically supplied in the form of a polybrominated resin cartridge that is inserted into water treatment systems.

Bromine is also important in organic synthesis. In this usage, the original source of bromine is an inorganic compound--bromine gas or hydrogen bromide--but except in cases where hydrogen bromide acts solely as a catalyst, ultimately the bromine is incorporated into an organic bromide compound. These compounds often serve as intermediate reagents in multistep synthesis of complex organic molecules such as pharmaceuticals. One notable class of such reagents are Grignard reagents, magnesium halides attached to carbon compounds. Additionally, some organobromine compounds are themselves end products used in a variety of applications.

Synthetic organobromine compounds are used as pharmaceuticals, dyes, flame retardants, and pesticides. Bromated pharmaceuticals are far less common than organofluorine or organochlorine drugs, but nonetheless several such drugs are in current use as vasodilators, sedatives, chemotherapeutics, and antiseptics. The earliest bromine dye in use was actually a natural organobromine produced by a family of sea snails. This dye, Tyrian purple, was prized for being colorfast despite weathering and sunlight, and its scarcity made objects dyed with it luxuries and status symbols in ancient times. Today, bromine-substituted dyes are used in commercial textile coloring as well as in analytical chemistry as pH indicators and in molecular biology to bind to and visualize DNA. The use of organobromine flame retardants and pesticides is widespread but controversial, as many of these compounds are known to breakdown extremely slowly, and therefore they act as persistent organic pollutants. The persistence of these compounds is of particular concern because many are ozone depleting agents, and some are known to be toxic to humans or have the potential to act as hormone-disruptors.

Bromine is recovered from naturally bromine-rich brines which are frequently found in underground rock formations. The bromine can be recovered from these brines by treating them with chlorine gas. Additionally, bromine can be recovered as a byproduct of organic synthesis reactants using brominated reagents, or from incineration of bromine-containing plastics.


Bromates Bromides
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Bromine is the only liquid halogen. Bromide compounds are formed when a metallic cation binds with a charged (- 1) bromine (Br) anion to form a bromide salt of that metal. Metallic bromides are marketed under the trade name AE Bromides™. Most metal bromide compounds are water soluble for uses in water treatment, chemical analysis and in ultra high purity for certain crystal growth applications. Bromide in an aqueous solution can be detected by adding carbon disulfide (CS2) and chlorine. Bromides were first prepared and used as a sedative, which is why overused platitudes or phrases are sometimes called bromides.

Bromine Properties

Bromine Element SymbolBromine is a Block P, Group 17, Period 4 element. Its electron configuration is [Ar]4s23d104p5. The bromine atom has a radius of 102 pm and its Van der Waals radius is 183 pm. Bromine Bohr ModelIn its elemental form, CAS 7726-95-6, bromine has a red-brown appearance. Bromine does not occur by itself in nature, it is found as colorless soluble crystalline minerals--halide salts. Bromine was discovered and first isolated by Antoine Jérôme Balard and Carl Jacob Löwig in 1826 and 1825, respectively.

Symbol: Br
Atomic Number: 35
Atomic Weight: 79.9
Element Category: halogen
Group, Period, Block: 17 (halogens), 4, p
Color: red-brown
Other Names: Brom, Brome, Bromo
Melting Point: -7.2°C, 19.04°F, 265.95 K
Boiling Point: 58.8°C, 137.84°F, 331.95 K
Density: (Br2, liquid) 3.1028 g·cm3
Liquid Density @ Melting Point: N/A
Density @ 20°C: 3.122 g/cm3
Density of Solid: 4050 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: 265.90 K, 5.8 kPa
Critical Point: 588 K, 10.34 MPa
Heat of Fusion (kJ·mol-1): 10.8
Heat of Vaporization (kJ·mol-1): 30.5
Heat of Atomization (kJ·mol-1): 117.943
Thermal Conductivity: 0.122 W·m-1·K-1
Thermal Expansion: N/A
Electrical Resistivity: (20 °C) 7.8×1010 µΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 75.69 J·mol-1·K-1
Young's Modulus: N/A
Shear Modulus: N/A
Bulk Modulus: N/A
Poisson Ratio: N/A
Mohs Hardness: N/A
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: (20°C) 206 m·s-1
Pauling Electronegativity: 2.96
Sanderson Electronegativity: 3.22
Allred Rochow Electronegativity: 2.74
Mulliken-Jaffe Electronegativity: 2.95 (14.3% s orbital)
Allen Electronegativity: 2.685
Pauling Electropositivity: 1.04
Reflectivity (%): N/A
Refractive Index: 1.001132
Electrons: 35
Protons: 35
Neutrons: 45
Electron Configuration: [Ar]4s23d104p5
Atomic Radius: 120 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 120±3 pm
Covalent Radius (Å): 1.17
Van der Waals Radius: 183 pm
Oxidation States: 7, 5, 4, 3, 1, -1 (strongly acidic oxide)
Phase: liquid
Crystal Structure: orthorhombic
Magnetic Ordering: diamagnetic
Electron Affinity (kJ·mol-1) 324.577
1st Ionization Energy: 1139.9 kJ·mol-1
2nd Ionization Energy: 2103 kJ·mol-1
3rd Ionization Energy: 3470 kJ·mol-1
CAS Number: 7726-95-6
EC Number: 231-778-1
MDL Number: MFCD00010896
Beilstein Number: N/A
SMILES Identifier: [Br]
InChI Identifier: InChI=1S/Br
PubChem CID: 24408
ChemSpider ID: 4514586
Earth - Total: 106 ppb
Mercury - Total: 1.2 ppb 
Venus - Total: 111 ppb
Earth - Seawater (Oceans), ppb by weight: 67300
Earth - Seawater (Oceans), ppb by atoms: 5210
Earth -  Crust (Crustal Rocks), ppb by weight: 3000
Earth -  Crust (Crustal Rocks), ppb by atoms: 780
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: 20
Stream, ppb by atoms: 0.3
Meterorite (Carbonaceous), ppb by weight: 1200
Meterorite (Carbonaceous), ppb by atoms: 230
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: N/A
Universe, ppb by atom: N/A
Discovered By: Antoine Jérôme Balard and Leopold Gmelin
Discovery Date: 1825
First Isolation: Antoine Jérôme Balard and Leopold Gmelin (1825)

Health, Safety & Transportation Information for Bromine

Bromine is corrosive and toxic. Bromine information, including technical data, safety data and its high purity properties, research, applications and other useful facts are specified in other tabs. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity and thermal properties are included. For additional information please see the Bromides Information Center. The below information applies to elemental (metallic) Bromine.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H314-H330-H400
Hazard Codes T+,C,N
Risk Codes 26-35-50
Safety Precautions 7/9-26-45-61
RTECS Number EF9100000
Transport Information UN 1744 8/PG 1
WGK Germany 2
Globally Harmonized System of
Classification and Labelling (GHS)
Corrosion-Corrosive to metals Environment-Hazardous to the aquatic environment Skull and Crossbones-Acute Toxicity

Bromine Isotopes

Bromine (Br) has two stable isotopes: 79Br and 81Br.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
66Br 66 N/A p to 65Se N/A N/A N/A -
67Br 66.96479(54)# N/A p to 66Se 1/2-# N/A 535.54 -
68Br 67.95852(38)# <1.2 µs p to 67Se 3+# N/A 549.21 -
69Br 68.95011(11)# <24 ns p to 68Se 1/2-# N/A 564.74 -
70Br 69.94479(33)# 79.1(8) ms EC to 70Se 0+# N/A 578.41 -
71Br 70.93874(61) 21.4(6) s EC to 71Se (5/2)- N/A 592.08 -
72Br 71.93664(6) 78.6(24) s EC to 72Se 1+ N/A 602.02 -
73Br 72.93169(5) 3.4(2) min EC to 73Se 1/2- N/A 614.76 -
74Br 73.929891(16) 25.4(3) min EC to 74Se (0-) N/A 624.7 -
75Br 74.925776(15) 96.7(13) min EC to 75Se 3/2- 0.75 636.5 -
76Br 75.924541(10) 16.2(2) h EC to 76Se 1- 0.54821 645.51 -
77Br 76.921379(3) 57.036(6) h EC to 77Se 3/2- N/A 656.39 -
78Br 77.921146(4) 6.46(4) min EC to 78Se; ß- to 78Kr 1+ 0.1 664.47 -
79Br 78.9183371(22) STABLE - 3/2- 2.106399 675.34 50.69
80Br 79.9185293(22) 17.68(2) min EC to 80Se; ß- to 80Kr 1+ 0.514 683.42 -
81Br 80.9162906(21) STABLE - 3/2- 2.27056 693.36 49.31
82Br 81.9168041(21) 35.282(7) h ß- to 82Kr 5- 1.627 701.44 -
83Br 82.915180(5) 2.40(2) h ß- to 83Kr 3/2- N/A 710.45 -
84Br 83.916479(16) 31.80(8) min ß- to 84Kr 2- N/A 717.6 -
85Br 84.915608(21) 2.90(6) min ß- to 85Kr 3/2- N/A 726.61 -
86Br 85.918798(12) 55.1(4) s ß- to 86Kr (2-) N/A 731.89 -
87Br 86.920711(19) 55.65(13) s ß- to 87Kr; ß- + n to 86Kr 3/2- N/A 738.11 -
88Br 87.92407(4) 16.29(6) s ß- to 88Kr; ß- + n to 86Kr (2-) N/A 742.46 -
89Br 88.92639(6) 4.40(3) s ß- to 89Kr; ß- + n to 88Kr (3/2-,5/2-) N/A 748.67 -
90Br 89.93063(8) 1.91(1) s ß- to 90Kr; ß- + n to 89Kr N/A N/A 753.03 -
91Br 90.93397(8) 541(5) ms ß- to 91Kr; ß- + n to 90Kr 3/2-# N/A 758.31 -
92Br 91.93926(5) 0.343(15) s ß- to 92Kr; ß- + n to 91Kr (2-) N/A 760.8 -
93Br 92.94305(32)# 102(10) ms ß- to 93Kr; ß- + n to 92Kr 3/2-# N/A 765.15 -
94Br 93.94868(43)# 70(20) ms ß- to 94Kr; ß- + n to 93Kr N/A N/A 768.57 -
95Br 94.95287(54)# 50# ms [>300 ns] Unknown 3/2-# N/A 772.92 -
96Br 95.95853(75)# 20# ms [>300 ns] Unknown N/A N/A 775.41 -
97Br 96.96280(86)# 10# ms [>300 ns] Unknown 3/2-# N/A 779.76 -