Bromine



35 krypton
I
General
Number bromine, Br, 35
halogens
Block p
Appearance gas/liquid: red-brown
solid: metallic luster
(1)  g·mol−1
Ar] 4s2 3d10 4p5
shell 2, 8, 18, 7
Physical properties
Phase liquid
r.t.) (Br2, liquid) 3.1028  g·cm−3
F)
F)
K, 10.34 MPa
kJ·mol−1
kJ·mol−1
Heat capacity (25 °C) (Br2)
75.69  J·mol−1·K−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 185 201 220 244 276 332
Atomic properties
Crystal structure orthorhombic
acidic oxide)
Electronegativity 2.96 (Pauling scale)
more) 1st:  1139.9  kJ·mol−1
2nd:  2103  kJ·mol−1
3rd:  3470  kJ·mol−1
Atomic radius 115  pm
Atomic radius (calc.) 94  pm
Covalent radius 114  pm
Van der Waals radius 185 pm
Miscellaneous
Magnetic ordering nonmagnetic
Electrical resistivity (20 °C) 7.8×1010  Ω·m
Thermal conductivity (300 K) 0.122  W·m−1·K−1
Speed of sound (20 °C) ? 206 m/s
CAS registry number 7726-95-6
Selected isotopes
Main article: Isotopes of bromine
iso NA half-life DM DE (MeV) DP
79Br 50.69% Br is neutrons
81Br 49.31% Br is neutrons
References

Bromine (iodine. Bromine vapours are corrosive toxic. Approximately 730,000,000 kg were produced in 1993.[4] The main applications for bromine are in fire retardants and fine chemicals.

History

Please help improve this article by expanding this section.
See talk page for details. Please remove this message once the section has been expanded.

Bromine was discovered by Joseph-Louis Gay-Lussac suggested the name bromine due to the characteristic smell of the vapors. Some also suggest that it may have been discovered by Bernard Courtois, the man who discovered iodine.

Isotopes

Main article: Isotopes of bromine
 Please help improve this article by expanding this section.
See talk page for details. Please remove this message once the section has been expanded.

Bromine has 2 stable isotopes: Br-79 (50.69%) and Br-81 (49.31%). At least another 23[5] isotopes are known to exist. Many of the bromine isotopes are fission products. Several of the heavier bromine isotopes from fission are delayed neutron emitters. All of the radioactive bromine isotopes are relatively short lived. The longest half life is the neutron deficient Br-77 at 2.376 days. The longest half life on the neutron rich side is Br-82 at 1.471 days. A number of the bromine isotopes exhibit metastable isomers. Stable Br-79 exhibits a radioactive isomer, with a half life of 4.86 seconds. It decays by isomeric transition to the stable ground state.

Notable characteristics

Bromine is the only liquid bleaching action.

Certain bromine-related compounds have been evaluated to have an ozone depletion potential or bioaccumulate in living organisms. As a result many industrial bromine compounds are no longer manufactured, are being restricted, or scheduled for phasing out.

Bromine is a powerful illumination.

Bromine has no known role in human health. Organobromine compounds do occur naturally, a famous example being Tyrian purple. Most organobromine compounds in nature arise via the action of vanadium bromoperoxidase.

Occurrence and production

See also Halide minerals.

  The diatomic compound Br2 does not occur naturally. Instead, bromine exists exclusively as bromide salts in diffuse amounts in crustal rock. Due to ppm), but at a lower concentration than chloride. Bromine may be economically recovered from bromide-rich brine wells and from the Dead Sea waters (up to 50000 ppm).

Approximately 500,000 metric tons (worth around US$350 million) of bromine are produced per year (2001) worldwide with the United States and Israel being the primary producers. Bromine production has increased sixfold since the 1960s. The largest bromine reserve in the United States is located in Columbia and Union County, Arkansas, U.S.[6] Israel's bromine reserves are contained in the waters of the Dead Sea. The bromide-rich brines are treated with chlorine gas, flushing through with air. In this treatment, bromide anion is oxidized to bromine by the chlorine gas.

2 Br− + Cl2 → 2 Cl− + Br2

Because of its commercial availability and long shelf-life, bromine is not typically prepared. Small amounts of bromine can however be generated through the reaction of solid sulfur dioxide (SO2).

NaBr (s) + H2SO4 (aq) → HBr (aq) + NaHSO4 (aq)
2 HBr (aq) + H2SO4 (aq) → Br2 (g) + SO2 (g) + 2 H2O (l)

Similar alternatives, such as the use of dilute substitution reaction to occur.

Compounds

 Please help improve this article by expanding this section.
See talk page for details. Please remove this message once the section has been expanded.
See also: Category:Bromine compounds

Organic chemistry

Organic compounds are brominated by either free radical reactions. For example hydrocarbons are brominated upon treatment with bromine in the presence of light.

Bromine, sometimes with a catalytic amount of carboxylic acids at the α-position. This method, the Hell-Volhard-Zelinsky reaction, is the basis of the commercial route to bromoacetic acid.

N-Bromosuccinimide is commonly used as a substitute for elemental bromine, being easier to handle, and reacting more mildly and thus more selectively.

Organic bromides are often preferable relative to the less reactive chlorides and more expensive iodide-containing reagent]]s. Thus, Grignard and organolithium compound are most often generated from the corresponding bromides.

Inorganic chemistry

Bromine is an oxidizer, and it will oxidize iodide ions to iodine, being itself reduced to bromide:

Br2 + 2 I− → 2 Br− + I2

Bromine will also oxidize metals and metaloids to the corresponding bromides. alkali metals.

Applications

A wide variety of organobromine compounds are used in industry. Some are prepared from bromine and others are prepared from hydrogen in bromine.[4]

Illustrative of the addition reaction[7] is the preparation of 1,2-Dibromoethane, the organobromine compound produced in the largest amounts:

C2H4 + Br2 → CH2BrCH2Br

Ethylene bromide is a additive in gasolines containing lead anti-engine knocking agents. It scavenges lead by forming volatile lead bromide, which is exhausted from the engine. This application has declined since the 1970's due to environmental regulations. Ethylene bromide is also used as a fumigant, but again this application is declining.

decabromodiphenyl ether, and vinyl bromide.

The bromides of calcium, sodium, and zinc account for a sizable part of the bromine market. These salts form dense solutions in water that are used as drilling fluids.

Miscellaneous uses:

Safety

Please help improve this article by expanding this section.
See talk page for details. Please remove this message once the section has been expanded.

Elemental bromine is toxic and causes burns. As an oxidizing agent, it is incompatible with most organic and inorganic compounds.

See also

References

  1. ^ Bromine: bromine(IV) oxide compound data. WebElements.com. Retrieved on 2007-12-10.
  2. ^ Bromine: bromine(III) fluoride compound data. WebElements.com. Retrieved on 2007-12-10.
  3. ^ Gemoll W, Vretska K: Griechisch-Deutsches Schul- und Handwörterbuch ("Greek-German dictionary"), 9th ed., published by öbvhpt, ISBN 3-209-00108-1
  4. ^ a b Jack F. Mills "Bromine" in Ullmann's Encyclopedia of Chemical Technology Wiley-VCH Verlag; Weinheim, 2002. DOI: 10.1002/14356007.a04_391
  5. ^ GE Nuclear Energy (1989). Chart of the Nuclides, 14th Edition. 
  6. ^ Bromine:An Important Arkansas Industry, Butler Center for Arkansas Studies
  7. ^ N. A. Khan, F. E. Deatherage, and J. B. Brown (1963). "Stearolic Acid". Org. Synth.; Coll. Vol. 4: 851. 
  • Los Alamos National Laboratory – Bromine
 v • d • e chemical elements

Hydrogen H2 | Nitrogen N2 | Oxygen O2 | Fluorine F2 | Chlorine Cl2 | Bromine Br2 | Iodine I2 | Astatine At2

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Bromine". A list of authors is available in Wikipedia.