Bromine

=Bromine: Br=
 * Name:**Bromine


 * Symbol:** Br
 * Atomic Number:** 35
 * Atomic Mass:** 79.904 amu
 * Melting Point:** -7.2 °C (265.95 K, 19.04 °F)
 * Boiling Point:** 58.78 °C (331.93 K, 137.804 °F)
 * Number of Protons/Electrons:** 35
 * Number of Neutrons:** 45
 * Classification:** Halogen
 * Crystal Structure:** Orthorhombic
 * Density @ 293 K:** 3.119 g/cm 3
 * __Color__:** Red

Atomic Structure

 * ||  || **Number of Energy Levels:** 4
 * First Energy Level:** 2
 * Second Energy Level:**8
 * Third Energy Level:**18
 * Fourth Energy Level:**7 ||

Isotopes

 * ** Isotope ** || ** Half Life ** ||
 * Br-76 || 16.0 hours ||
 * Br-77 || 2.4 days ||
 * Br-79 || Stable ||
 * Br-80 || 17.7 minutes ||
 * Br-80m || 4.42 hours ||
 * Br-81 || Stable ||
 * Br-82 || 1.5 days ||
 * Br-83 || 2.4 hours ||
 * Br-84 || 31.8 minutes ||
 * Br-85 || 2.9 minutes ||

Facts

 * Date of Discovery:** 1826
 * Discoverer:** Antoine J. Balard
 * Name Origin:** From the Greek word //brômos// (stench)
 * Uses:** Poisonous
 * Obtained From:** Sea Water

Bromine was discovered by two chemists, Carol Jacob Lowig and Antoine Balard. Bromine exists as a diatomic molecule Br 2.

**History and Uses:** The only nonmetallic element that is a liquid at normal room temperatures, bromine was produced by Carl Löwig, a young chemistry student, the summer before starting his freshman year at Heidelberg. When he showed his professor, Leopold Gmelin, the red, smelly liquid he had produced, Gmelin realized that this was an unknown substance and encouraged Löwig to produce more of it so they could __study__ it in detail. Unfortunately, winter exams and the holidays delayed Löwig's work long enough for another chemist, Antoine-Jérôme Balard, to publish a paper in 1826 describing the new element. Balard was credited with the discovery and named it after the Greek word for stench, bromos. Today, bromine is primarily obtained by treating brine from wells in Michigan and Arkansas with [|chlorine]. Elemental bromine is a hazardous material. It causes severe burns when it comes in contact with the __skin__ and its vapor irritates the eyes, nose and throat. Most of the bromine produced in the United States was used in the manufacture of ethylene dibromide(C 2 H 4 Br 2 ), a chemical added to leaded gasoline that prevented the accumulation of [|lead] compounds within the engine. With the discontinuation of leaded gasoline in favor of unleaded gasoline, the demand for bromine has been greatly reduced. Silver bromide (AgBr), a chemical used in photography, now accounts for the largest use of bromine. Other bromine compounds are used in fumigants, in flameproofing agents and in some compounds used to __purify water__. Tyrian purple, an expensive purple dye known to ancient civilizations, was produced from an organic bromine compound secreted from a sea mussel known as the murex.

**Physical Characteristics of Bromine:** Elemental bromine exists as a diatomic molecule, Br 2. It is a dense, mobile, slightly transparent reddish-brown liquid, that evaporates very easily at standard temperature and pressures to give an orange vapor (its color resembles nitrogen dioxide) that has a strongly disagreeable odor resembling that of chlorine. It is one of only two elements on the periodic table that are liquids at room temperature (mercury is the other, although cesium, gallium, and rubidium melt just above room temperature).

At a pressure of 55 GPa bromine converts to a metal. At 75 GPa it converts to a face centered orthorhombic structure. At 100 GPa it converts to a body centered orthorhombic monoatomic form.

Being less reactive than chlorine but more reactive than iodine, bromine reacts vigorously with metals, especially in the presence of water, to give bromide salts. It is also reactive toward most organic compounds, especially upon illumination, conditions that favor the dissociation of the diatomic molecule into bromine radicals: Br 2 - 2 Br**·**
 * Chemical Characteristics:**



Elemental bromine is a fuming red-brown liquid at room temperature, corrosive and toxic, with properties between those of [|chlorine] and [|iodine]. Free bromine does not occur in nature, but occurs as colorless soluble crystalline mineral halide salts, analogous to [|table salt].

Bromine is rarer than about three-quarters of elements in the Earth's crust, however the high solubility of bromide ion has caused its accumulation in the oceans.

Bromine has no essential function in mammals, though it is preferentially used over chloride by one antiparasitic enzyme in the human immune system.

Being less reactive than chlorine but more reactive than iodine, bromine reacts vigorously with metals, especially in the presence of water, to give bromide salts.

The diatomic element Br 2 does not occur naturally. Instead, bromine exists exclusively as bromide salts in diffuse amounts in crustal rock.

It is often used as a flame retardant, a gasoline additive, and a pesticide. It is regulated as a pesticide because it depletes the ozone. It was also used medically as an anticonvulsant but was stopped by the FDA because of it's toxicity when used over a long time.

Bromine is used in some pharmaceuticals such as, medical sedatives.

The diatomic element Br 2 does not occur naturally. Instead, bromine exists exclusively as bromide salts in diffuse amounts in crustal rock. Owing to leaching, bromide salts have accumulated in sea water at 65 part per million (ppm), which is less than chloride. Bromine may be economically recovered from bromide-rich brine wells and from the Dead Sea waters (up to 50,000 ppm). It exists in the Earth's crust at an average concentration of 0.4 ppm, making it the 62nd most abundant element. The bromine concentration in soils varies normally between 5 and 40 ppm, but some volcanic soils can contain up to 500 ppm. The concentration of bromine in the atmosphere is extremely low, at only a few ppt. A large number of organobromine compounds are found in small amounts in nature. China's bromine reserves are located in the Shandong Province and Israel's bromine reserves are contained in the waters of the Dead Sea. The largest bromine reserve in the United States is located in Columbia County and Union County, Arkansas, U.S.
 * Natural Occurrences:**


 * __Other common uses of Bromine:__**
 * The largest use of bromine is in flame retardants. When the bromine substance burns it effectively starves the fire of oxygen causing it to go out.
 * Bromide compounds, in particular potassium bromide, are used in medical circles as anticonvulsants. They are also used in veterinary sciences. Most countries severely limit the use and availability of bromine salts for human use due to the fact that it caused neurological dysfunction.
 * Brominated substances are important ingredients of many over-the-counter and prescription drugs, including analgesics, sedatives, and antihistamines. In fact, bromine compounds are active ingredients in several drugs that treat pneumonia and cocaine addiction. Currently, several drugs containing bromine compounds are undergoing trials for treatment of Alzheimer’s disease and new generations of anti-cancer and AIDS drugs.
 * Bromides that come from calcium, sodium and zinc as used to create special salt solutions for drilling.
 * Bromine is used to create brominated vegetable oils that are used as emulsifies in some brands of soft drink.
 * It is often used in the maintenance of swimming pools particularly in hot tubs.
 * It is used in water purification in industrial circumstances, disinfectants and insecticides

__ The chemistry of atmospheric bromine: __
Steven C. Wofsy Center for Earth and Planetary Physics, Harvard University, Cambridge, Massachusetts Michael B. McElroy Center for Earth and Planetary Physics, Harvard University, Cambridge, Massachusetts Yuk Ling Yung Center for Earth and Planetary Physics, Harvard University, Cambridge, Massachusetts Bromine may act as a catalyst for recombination of ozone and could be more efficient than either nitric oxide or chlorine. The lower atmosphere contains small concentrations of gaseous bromine produced in part by marine activity, in part by volatilization of particulate material released during the combustion of leaded gasoline, with an additional contribution due to the use of methyl bromide as an agricultural fumigant. Observations by Lazrus et. al. (1975) indicate small concentrations of bromine, ∼ 10 −11 (v/v) in the contemporary stratosphere and appear to imply a reduction of approximately 0.3% in the global budget of O 3. Estimates are given for future reductions in O 3 which might occur if the use of CH 3 Br as an agricultural fumigant were to continue to grow at present rates.

Organic chemistry
Main article: Organobromine compound

//N//-Bromosuccinimide

Organic compounds are brominated by either addition or substitution reactions. Bromine undergoes electrophilic addition to the double-bonds of alkenes, via a cyclic bromonium intermediate. In non-aqueous solvents such as carbon disulfide, this yields the di-bromo product. For example, reaction with ethylene will produce 1,2-dibromoethane. Bromine also undergoes electrophilic addition to phenols and anilines. When used as bromine water, a small amount of the corresponding bromohydrin is formed as well as the dibromo compound. So reliable is the reactivity of bromine that bromine water is employed as a reagent to test for the presence of alkenes, phenols, and anilines. Like the other halogens, bromine participates in free radical reactions. For example, hydrocarbons are brominated upon treatment with bromine in the presence of light.