What Is Br In Chemistry

Few Facts About Bromine

• Elemental Bromine is poisonous, and it causes corrosion burns upon contact with the skin. Also, inhalation in low concentration lead to irritation and inhaling in higher concentration can cause death too.

• Bromine ranks 64th in the list of most abundant elements found in earths crust, having an abundance of 2.4 mg/kg.

• Elemental Bromine has a reddish-brown colour and a liquid state at room temperature. Mercury is the only other element that has a liquid state at room temperature.

Where Is Bromine Present In The Universe

The element bromine is not an abundant element in nature, and even so, it is never found as a free element. The Earths crust is estimated to be 0.00016% bromine due to natural weathering, bromine from rocks often transition straight to the hydrosphere. Bromine is more particularly concentrated as ions in saltwater, but not as much in freshwater. Likewise, bromine is heavy in some seawater and corals. The largest amounts of bromine can be harvested from the salt deposits, such as the Dead Sea, as well as oil brines, and deepwater reserves. Regarding minerals, bromine is actually found in the silver ores bromargyrite, embrolite, and iodobromite, as it bonds well with silver.

Bromine Chemical & Physical Properties

• Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
• B.A., Physics and Mathematics, Hastings College

Bromine is a halogen element with atomic number 35 and element symbol Br. At room temperature and pressure, it is one of the few liquid elements. Bromine is known for its brown color and characteristic acrid odor. Here is a collection of facts about the element:

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Most Notable Uses In Science

Bromine used to be commonly used in medicines. Bromine compounds have a sedative effect, and have been used to treat epilepsy. However, these compounds were toxic, so were eventually replaced with safer compounds. The food and drug administration no longer approves its use as a medicine. In the chemistry laboratory, bromine compounds are also used as pH indicators. Bromophenol blue for example, is yellow at pH 3.0 and blue at pH 4.6. Ethidium bromide is an organic compound use by scientists to visualize DNA. It gets stuck in the DNA molecule, so when DNA is exposed to ultraviolet light, it fluoresces .

Fig. 4

Electron Affinity And Electronegativity Of Bromine

Electron Affinity of Bromine is 324.6 kJ/mol.

Electronegativity of Bromine is 2.96.

Electron Affinity

In chemistry and atomic physics, the electron affinity of an atom or molecule is defined as:

the change in energy of a neutral atom or molecule when an electron is added to the atom to form a negative ion.

X + e X + energy Affinity = H

In other words, it can be expressed as the neutral atoms likelihood of gaining an electron. Note that ionization energies measure the tendency of a neutral atom to resist the loss of electrons. Electron affinities are more difficult to measure than ionization energies.

An atom of Bromine in the gas phase, for example, gives off energy when it gains an electron to form an ion of Bromine.

Br + e Br H = Affinity = 324.6 kJ/mol

To use electron affinities properly, it is essential to keep track of signs. When an electron is added to a neutral atom, energy is released. This affinity is known as the first electron affinity, and these energies are negative. By convention, the negative sign shows a release of energy. However, more energy is required to add an electron to a negative ion which overwhelms any release of energy from the electron attachment process. This affinity is known as the second electron affinity, and these energies are positive.

Affinities of Nonmetals vs. Affinities of Metals

Electronegativity

The electronegativity of Bromine is:

= 2.96

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Occurrence And Abundance Of Bromine

Of all of the elements on Earth, bromine is the 44th most abundant. It is less abundant than other halogens, such as fluorine and chlorine. It exists as ionic salts in Earths crust at about 2.5 parts per million. Thats a ratio of about 2 people in the city of Dallas, Texas. Because it exists as salts that are soluble in water, bromine tends to occur at high concentrations in salt lakes and mineral waters. For that reason, pure bromine is most easily extracted from those sources. The main sources of bromine are the United States and Israel.

How Does Bromine Compare To Other Halogens

Bromine is somewhat in the middle when its reactivity is compared to chlorine and iodine. This element can be considered as one of the most reactive elements. Bromine bond energies tend to be lower than chlorine bond energies but higher than iodine bond energies, and bromine is a weaker oxidizing agent than chlorine but a stronger oxidizing agent than iodine. This property of bromine can be observed from the halogens standard electrode potentials

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History And Discovery Of Bromine

Discovery of Bromine: Bromine was isolated independently by two scientists – the French chemist Antoine Jérôme Balard and the German chemist Carl Jacob Löwig .

• In 1825 Carl Jacob Löwig isolated bromine from a mineral water spring from his hometown Bad Kreuznach. He used a solution of the mineral salt saturated with chlorine and extracted the bromine with diethyl ether. After evaporation of the ether a brown liquid remained. Using this liquid as a sample for his work Löwig applied for a job in the laboratory of Leopold Gmelin in Heidelberg. Publication of Löwig’s work to isolate bromine in this way was delayed so Balard’s isolation of bromine was published results first.
• In 1826 Antoine Jérôme Balard found bromides in the ash of seaweed from the salt marshes of Montpellier. The seaweed was used to produce iodine, but also contained bromine. Balard distilled bromine from a solution of seaweed ash saturated with chlorine.

Early Use of Bromine: Bromine was not produced in large quantities until 1860. Apart from some minor early medical applications the first commercial use of bromine was for photographic processing. Potassium bromide and sodium bromide were used as anticonvulsants and sedatives in the late 19th and early 20th centuries, until superseded other drugs.

Atomic Number And Chemical Properties

Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. The chemical properties of the atom are determined by the number of protons, in fact, by number and arrangement of electrons. The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each elements electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.

It is the Pauli exclusion principle that requires the electrons in an atom to occupy different energy levels instead of them all condensing in the ground state. The ordering of the electrons in the ground state of multielectron atoms, starts with the lowest energy state and moves progressively from there up the energy scale until each of the atoms electrons has been assigned a unique set of quantum numbers. This fact has key implications for the building up of the periodic table of elements.

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What Safety Measures Are Usually Taken While Handling Bromine

Bromine is incompatible with almost all organic and inorganic compounds since it behaves as a very powerful oxidizing agent. Strict caution must be taken whilst transporting bromine. This element is usually transported with the help of steel tanks that are filled with lead and are protected by strong metal frameworks.

Summary Bromine Vs Bromide

Bromine is a chemical element in the periodic table and is denoted by Br. Meanwhile, bromide is the anion that forms when bromine abstracts an electron from another electropositive element. Further, the key difference between bromine and bromide is that bromide is the reduced form of bromine.

Image Courtesy:

1. Bromine 25ml By W. Oelen via Commons Wikimedia2. Br- By NEUROtiker Own work via Commons Wikimedia

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Immediate Signs And Symptoms Of Exposure To Bromine

• Breathing bromine gas could cause you to cough, have trouble breathing, get a headache, have irritation of your mucous membranes , be dizzy, or have watery eyes.
• Getting bromine liquid or gas on your skin could cause skin irritation and burns. Liquid bromine that touches your skin may first cause a cooling sensation that is closely followed by a burning feeling.
• Swallowing bromine-containing compounds would cause different effects depending on the compound. Swallowing a large amount of bromine in a short period of time would be likely to cause symptoms such as nausea and vomiting .
• Showing these signs and symptoms does not necessarily mean that a person has been exposed to bromine.

Bromination Of Organic Compounds

Bromination is the process of treating a substance with bromine to introduce it into organic compounds. This is the easiest way to begin many synthesis reactions in organic chemistry. UV light will split the diatomic bromine into two bromine radicalsone of the bromines will then go in a chain reaction to react with a hydrogen on the most-substituted carbon the other bromine will take its place in the molecule. See the example reaction below:

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Uses Of Uses Of Bromine

Bromine compounds are used as pesticides, dyestuffs, water purification compounds, and as a flame-retardants in plastics.

1,2-dibromoethane is used as an anti-knock agent to raise the octane number of gasoline and allow engines to run more smoothly. This application has declined as a result of environmental legislation.

Potassium bromide is used as a source of bromide ions for the manufacture of silver bromide for photographic film.

Most Notable Uses In General

Organic bromine compounds are commonly used as pesticides for agriculture. Certain organic bromine compounds also have flame retardant properties, and were once used commonly in fire extinguishers. However, it was later discovered that these compounds were contributing to depletion of the Earths ozone layer. Chemical solutions used to develop photographic film contain bromine. In the past, gasoline with lead added were used as a fuel in cars. So, to prevent lead accumulation in the engine, compounds with bromine were added to gasoline. Diesel gas is not used in most cars these days, so there is less need for bromine additives.

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Density Atomic Mass And Atomic Number Density

Since the density of a substance is the total mass of that substance divided by the total volume occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density ,

• Atomic Weight. The atomic mass is carried by the atomic nucleus, which occupies only about 10-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Therefore it is determined by the mass number .
• Atomic Number Density. The atomic number density , which is associated with atomic radii, is the number of atoms of a given type per unit volume of the material. The atomic number density of a pure material having atomic or molecular weight and the material density is easily computed from the following equation using Avogadros number :

Since nucleons make up most of the mass of ordinary atoms, the density of normal matter tends to be limited by how closely we can pack these nucleons and depends on the internal atomic structure of a substance. The densest material found on earth is the metal osmium, but its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars.

Atomic Number Of Bromine

Bromine is a chemical element with atomic number 35 which means there are 35 protons and 35 electrons in the atomic structure. The chemical symbol for Bromine is Br.

The atom consist of a small but massive nucleus surrounded by a cloud of rapidly moving electrons. The nucleus is composed of protons and neutrons. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The total electrical charge of the nucleus is therefore +Ze, where e equals to 1,602 x 10-19 coulombs. In a neutral atom there are as many electrons as protons moving about nucleus. It is the electrons that are responsible for the chemical bavavior of atoms, and which identify the various chemical elements.

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Bromine In The Environment

Bromine is a naturally occurring element that can be found in many inorganic substances. Humans however, have many years ago started the introduction of organic bromines in the environment. These are all compounds that are not natural and can cause serious harm to human health and the environment.

In diffuse crustal rock bromine naturally occurs as bromide salts. Bromine salts have accumulated in sea water , from which bromine is extracted. World production of bromine is more than 300.000 tonnes per year the three main producing countries are US, Istrael and the UK. In this last case it is extracted from sea water at a plant on the coast of Anglesey, Wales.

Chemical Properties Of Bromine

The element bromine has chemical properties in between chlorine and iodine, the halogens flanking bromine in group 17. Bromine is a very chemically reactive metal and thus is never pure in nature: due to its 7 valence electrons and high electron affinity, bromine reacts readily, and violently, with the alkali metals. It is a strong oxidizing agent, but it does not decompose easily under normal conditions. Bromine is slightly soluble water in a reversible production of hypobromite and is one of few elements with fire-resistant properties. Though bromine does not react with oxygen or nitrogen in the air, it forms a hazardous compound bromine oxide when reacting with ozone. Bromine additionally reacts with the other halogens.

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Does The Element Have Any Toxic Hazards

Accidental consumption of the liquid halogen or its compounds can lead to nausea and vomiting while inhalation of Br gas could cause respiratory distress, headache, and dizziness. Skin contact with its vapor or liquid is known to cause irritation and burns . In fact, its presence as potassium bromate in wheat flours used to make bread have been linked to serious health risks.

What Does Bromine Do To The Human Body

Bromine is corrosive to human tissue in a liquid state and its vapors irritate eyes and throat. Bromine vapors are very toxic with inhalation. Humans can absorb organic bromines through the skin, with food and during breathing. Organic bromines are widely used as sprays to kill insects and other unwanted pests.

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In Chemistry What Are London Forces

London forces, also known as London dispersion forces, are weak intermolecular forces that attract or repel atoms or molecules. They are named after Fritz London, a German physicist. These interactions come into play when instantaneous dipoles are formed, which happens when a separation of positive and negative charge across a molecule is created by the mass movement of electrons. London forces occur in both nonpolar and polar molecules and can affect a chemical compounds physical state.

A dipole exists when part of the molecule is has a net positive charge and another part has a net negative charge. Polar molecules, such as water, have permanent dipoles due to an inherent unevenness in electron distribution across their structures. Instantaneous or temporary dipoles may also form in nonpolar molecules. This type of dipole is created when electrons congregate, creating a net negative charge in the area of greater electron density and leaving the vacated area with a net positive charge.

Bromine Melting Point And Boiling Point

Melting point of Bromine is -7.3°C.

Boiling point of Bromine is 59°C.

Note that these points are associated with the standard atmospheric pressure.

Boiling Point Saturation

In thermodynamics, saturation defines a condition in which a mixture of vapor and liquid can exist together at a given temperature and pressure. The temperature at which vaporization starts to occur for a given pressure is called the saturation temperature or boiling point. The pressure at which vaporization starts to occur for a given temperature is called the saturation pressure. When considered as the temperature of the reverse change from vapor to liquid, it is referred to as the condensation point.

Melting Point Saturation

In thermodynamics, the melting point defines a condition in which the solid and liquid can exist in equilibrium. Adding heat will convert the solid into a liquid with no temperature change. The melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point.

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Physical And Chemical Properties

Free bromine is a reddish brown liquid with an appreciable vapour pressure at room temperature. Bromine vapour is amber in colour. Bromine has a pungent odour and is irritating to the skin, eyes, and respiratory system. Exposure to concentrated bromine vapour, even for a short time, may be fatal. Like the other halogens, bromine exists as diatomic molecules in all aggregation states.

About 3.41 grams of bromine dissolve in 100 millilitres of water at room temperature. The solution is known as bromine water. Like chlorine water, it is a good oxidizing agent, and it is more useful because it does not decompose so readily. It liberates free iodine from iodide-containing solutions and sulfur from hydrogen sulfide. Sulfurous acid is oxidized by bromine water to sulfuric acid. In sunlight bromine water , with release of oxygen, as in the following equation:

From bromine water a hydrate can be isolated that contains 172 water molecules and 20 cavities capable of accommodating the bromine molecules. Bromine dissolves in aqueous alkali hydroxide solutions, giving bromides, hypobromites, or bromates, depending on the temperature. Bromine is readily extracted from water by organic solvents such as carbon tetrachloride, chloroform, or carbon disulfide, in which it is very soluble. In the organic solvents it gives an orange solution.