selenium – bromine – krypton Cl Br I       Full table
General
Name, Symbol, Number	bromine, Br, 35
Series	halogens
Group, Period, Block	17 (VIIA), 4, p
Density, Hardness	3119 kg/m3 (300 K), NA
Appearance	Gas: red-brown solid: metallic luster
Atomic properties
Atomic weight	79.904 amu
Atomic radius (calc.)	115 (94) pm
Covalent radius	114 pm
van der Waals radius	185 pm
Electron configuration	[Ar]3d10 4s24p5
e- 's per energy level	2, 8, 18, 7
Oxidation states (Oxide)	±1,5 (strong acid)
Crystal structure	orthorhombic
Physical properties
State of matter	solid at STP, liquid at room temp (nonmagnetic)
Melting point	265.8 K (19 °F)
Boiling point	332 K (138 °F)
Molar volume	19.78 ×10-6 m3/mol
Heat of vaporization	15.438 kJ/mol
Heat of fusion	5.286 kJ/mol
Vapor pressure	5800 Pa at 280.1 K
Speed of sound	206 m/s at 293.15 K
Miscellaneous
Electronegativity	2.96 (Pauling scale)
Specific heat capacity	480 J/(kg*K)
Electrical conductivity	no data
Thermal conductivity	0.122 W/(m*K)
1st ionization potential	1139.9 kJ/mol
2nd ionization potential	2103 kJ/mol
3rd ionization potential	3470 kJ/mol
4th ionization potential	4560 kJ/mol
5th ionization potential	5760 kJ/mol
6th ionization potential	8550 kJ/mol
7th ionization potential	9940 kJ/mol
8th ionization potential	18600 kJ/mol
SI units & STP are used except where noted.

Bromine is a chemical element in the periodic table that has the symbol Br and atomic number 35. A halogen element, bromine is a red volatile liquid at room temperature which has a reactivity between chlorine and iodine. This element is harmful to human tissue in a liquid state and its vapour irritates eyes and throat.

Notable characteristics

Bromine is the only liquid nonmetallic element at room temperature. It is a heavy, mobile, reddish-brown liquid, that evaporates easily at standard temperature and pressures in a red vapor (its color resembles nitrogen dioxide) that has a strong disagreeable odor. A halogen, bromine resembles chlorine chemically but is less active (it is more active than iodine however). Bromine is very soluble in water or carbon disulfide (forming a red solution). It bonds easily with many elements and has a strong bleaching action.

Bromine is highly reactive and is a powerful oxidizing agent in the presence of water. It reacts vigorously with amines, alkenes and phenols as well as aliphatic and aromatic hydrocarbons, ketones and acids (these are brominated by either addition or substitution). With many of the metals and elements, anhydrous bromine is less reactive than wet bromine; however, dry bromine reacts vigorously with aluminium, titanium, mercury as well as alkaline earth and alkaline metals.

Applications

Elemental bromine is used to manufacture a wide variety of bromine compounds used in industry and agriculture. Traditionally the largest use of bromine was in the production of 1,2-Dibromoethane which in turn was used as a gasoline anti-knock agent for leaded gasolines before they were largely phased out due to environmental considerations.

Bromine is also used in making fumigants, flameproofing agents, water purification compounds, dyes, medicinals, sanitizes, inorganic bromides for photography, etc.

Bromine is used to make brominated vegetable oil, which is used as an emulsifier in many citrus-flavored soft drinks.

History

Bromine (Gr. bromos for stench) was discovered by Antoine Balard at salt marshes of Montpellier in 1826 but was not produced in quantity until 1860.

Occurrence

Bromine occs in nature as bromide salts in very diffuse amounts in crustal rock. Due to leaching bromide salts have accumulated in sea water (85 ppm), and may be economically recovered from brine wells and the Dead Sea (up to 5000 purpm).

Approximately 500 million kilograms ($350 million USD) of bromine are produced per year (2001) worldwide with the United States and Israel being the primary producers.

Precautions

Elemental bromine is a strong irritant and, in concentrated form, will produce painful blisters on exposed skin and especially mucous membranes. Even low concentrations of bromine vapor (from 10 ppm) can affect breathing, and inhalation of significant amounts of bromine can seriously damage the respiratory system.

Accordingly, one should always wear safety goggles and ensure adequate ventilation when handling bromine.

Recycling

Because of its high cost, bromine is usually recycled rather than disposed of into the environment.

References

• Los Alamos National Laboratory – Bromine (http://periodic.lanl.gov/elements/35.html)

External link

• EnvironmentalChemistry.com – Bromine (http://environmentalchemistry.com/yogi/periodic/Br.html)