Minimum and maximum degree of oxidation of bromine. Chemical properties of bromine

Among all the chemical elements, non-metals, there is a special series - halogens. These atoms get their name for the special properties that they exhibit in chemical interactions. These include:

• iodine;
• chlorine;
• bromine;
• fluorine.

Chlorine and fluorine are poisonous gases with a strong oxidizing ability. Iodine under normal conditions is a crystalline substance of dark purple color with a pronounced metallic luster. It shows the properties of the reducing agent. And what does the fourth halogen look like? What are the properties of bromine, its compounds and characteristics as an element, and as a simple substance? Let's try to understand.

Bromine: general characteristic of the element

As a particle of the periodic system, bromine occupies the cell under the order number 35. Accordingly, its core has 35 protons, and the electron shell contains the same number of electrons. The configuration of the outer layer: 4s ² p ⁵ .

Located in the VII group, the main subgroup, is part of the halogen - a special group of chemical elements. In total, about 28 different isotopic species of this atom are known. Mass numbers vary from 67 to 94. Two are known to be stable and stable, and also predominant in percentage terms in nature:

• Bromine ⁷⁹ - its 51%;
• Bromine ⁸¹ - its 49%.
  

The average atomic mass of an element is 79,904 units. The degree of oxidation of bromine varies from -1 to +7. It exhibits strong oxidizing properties, but is inferior to chlorine and fluorine in them, exceeding iodine.

History of the discovery

This element was opened later than its colleagues in the subgroup. By that time it was already known about chlorine and iodine. Who made this discovery? It is possible to name three names at once, since so many scientists practically simultaneously synthesized a new element, which later turned out to be an atom. These names are:

• Antoine Jerome Balar.
• Carl Leewig.
• Justus Liebig.

However, the official "father" is considered to be Balar, since he was the first not only to receive and describe, but also sent a new substance to the scientific conference of chemists, which is an unexplored element.

Antoine Balar studied the composition of sea salt. Carrying out numerous chemical experiments over it , he let chlorine pass through the solution one day and saw that some yellow compound was being formed. Taking this as the product of the interaction of chlorine and iodine in the solution, he began to further investigate the product obtained. Subject to the following treatments:

• Acted ether;
• Soaked in potassium hydroxide ;
• Treated with pyrolusite;
• Sustained in a sulfuric medium.

As a result, he received a volatile brownish-red liquid with an unpleasant odor. This was bromine. Then he conducted a thorough investigation of the physical and chemical characteristics of this substance. After sending a report on it, described the properties of bromine. The name that Balar gave to the element was murid, but it did not take root.

Today's generally accepted name for this atom is bromine, which in Latin means "smelly," "offensive." This is fully confirmed by the properties of its simple substance. The year of the discovery of the element is 1825.

Possible degrees of oxidation of bromine

There are several such. After all, thanks to its electronic configuration, bromine can exhibit both oxidative and reducing properties, with a clear predominance of the former. There are five possible options:

• -1 - the lowest degree of oxidation of bromine;
• +1;
• +2;
• +3;
• +5;
• +7.

In nature, only those compounds are found, in which the element is in a negative sense. +7 - maximum degree of oxidation of bromine. It manifests itself in the composition of bromic acid HBrO ₄ and its salts of bromates (NaBrO ₄ ). In general, this degree of oxidation of bromine is extremely rare, as well as +2. But the connection is -1; +3 and +5 are very common and are important not only in the chemical industry, but also in medicine, engineering and other branches of the economy.

Bromine as a simple substance

Under ordinary conditions, the element in question is a diatomic molecule, but it is not a gas, but a liquid. Very poisonous, fuming in the air and publishing an extremely unpleasant smell. Even couples in low concentrations can cause burns on the skin and irritation of the mucous membranes of the body. If you exceed the permissible rate, then choking and death are possible.

The chemical formula of this liquid is Br ₂ . It is obvious that the symbol is formed from the Greek name of the element - bromos. The bond between atoms is single, covalent nonpolar. The radius of the atom is relatively large, so bromine reacts fairly easily. This makes it possible to widely use it in chemical syntheses, often as a reagent for the qualitative determination of organic compounds.

In the form of a simple substance in nature is not found, as it easily evaporates in the form of reddish-brown smoke, which has a corrosive effect. Only in the form of various multicomponent systems. The degree of oxidation of bromine in compounds of various types depends on the element with which the reaction proceeds, that is, with what substance.

Physical properties

These characteristics can be expressed in several points.

1. Solubility in water is medium, but better than other halogens. A saturated solution is called bromine water, it has a reddish-brown color.
2. The boiling point of the liquid is +59.2 ^° C.
3. The melting point is -7.25 ^° C.
4. Smell - sharp, unpleasant, suffocating.
5. Color - reddish-brown.
6. The aggregate state of a simple substance is heavy (with high density), a thick liquid.
7. Electronegativity on the basis of the Polling scale is 2.8.

These characteristics affect the ways of obtaining this compound, and also impose obligations for observance of extreme caution when working with it.

Chemical properties of bromine

From the point of view of chemistry, bromine behaves in two ways. It shows both oxidizing and reducing properties. Like all other elements, it is capable of taking electrons from metals and less electronegative non-metals. It is a reducing agent with strong oxidizing agents, such as:

• oxygen;
• fluorine;
• chlorine;
• Some acids.

Naturally, the oxidation state of bromine varies from -1 to +7. With what exactly is the element under consideration capable of reacting?

1. With water - as a result, a mixture of acids (hydrobromic and bromate) is formed.
2. With various iodides, since bromine is able to displace iodine from its salts.
3. With all non-metals directly, except oxygen, carbon, nitrogen and noble gases.
4. Almost with all metals as a strong oxidizer. With many substances even with inflammation.
5. In the OBR reactions, bromine often promotes the oxidation of compounds. For example, sulfur and sulfites are converted to sulfate ions, iodides into iodine, as a simple substance.
6. With alkalis with the formation of bromides, bromates or hypobromates.

Of particular importance are the chemical properties of bromine, when it is part of the acids and salts they are formed. In this form, its properties are very strong, as an oxidizing agent. Much more vividly expressed than in a simple substance.

Receiving

The fact that the substance we are considering is important and significant from the point of view of chemistry, confirms the fact of its annual production of 550 thousand tons. Leading countries on these indicators:

• USA.
• China.
• Israel.

The industrial method of extraction of free bromine is based on the treatment of salt solutions of lakes, wells, seas. Of these, the salt of the desired element is released, which is converted to an acidified form. It is passed through a powerful stream of air or water vapor. Thus, gaseous bromine is formed. Then it is treated with calcined soda and a mixture of sodium salts - bromides and bromates is obtained. Their solutions are acidified and have a free liquid substance at the outlet.

Laboratory methods of synthesis are based on the displacement of bromine from its salts with chlorine, as a stronger halogen.

Being in nature

In pure form, the substance we are considering is not found in nature, since it is an air-freshening liquid that is fuming in the air. Basically, it is part of the compounds in which the minimum oxidation of bromine-1 is manifested. These are salts of hydrobromic acid - bromides. A lot of this element accompanies the natural chlorine salts - sylvics, carnallites and others.

Minerals of bromine were discovered later than he. The most common of these are three:

• Embolit - a mixture of chlorine and bromine with silver;
• Bromarginite;
• Bromsilvinite - a mixture of potassium, magnesium and bromine with bound water (crystalline hydrate).

This element is also included in the composition of living organisms. Its deficiency leads to the emergence of various diseases of the nervous system, disorders, sleep disturbance and memory impairment. In more inferior cases, it threatens infertility. Fish, marine life are able to accumulate bromine in significant quantities in the form of salts.

In the earth's crust, its mass content reaches 0.0021%. A lot of sea water and the whole hydrosphere of the Earth.

Bromine compounds with a lower oxidation state

What is the degree of oxidation of bromine in its compounds with metals and hydrogen? The lowest that is possible for a given element is minus one. It is these compounds that represent the greatest practical interest for a person.

1. HBr is hydrogen bromide (gas), or hydrobromic acid. In the gaseous aggregate state it does not have a color, but it smells very, very unpleasantly and smokes strongly. Has a corrosive effect on the mucous membranes of the body. It dissolves well in water, forming an acid. It, in turn, refers to strong electrolytes, is a good reducing agent. It easily passes into free bromine under the action of sulfuric, nitric acids and oxygen. Industrial importance has as a source of bromide ion for the formation of salts with metal cations.
2. Bromides are salts of the above-mentioned acid, in which the oxidation state of bromine is also equal to -1. Of practical interest are: LiBr and KBr.
3. Compounds of organic nature containing a bromide ion.

Compounds with a higher degree of oxidation

These include several basic substances. The degree of oxidation of the highest bromine is equal to +7, so in these compounds it is just it and should exhibit it.

1. Bromic acid is HBrO ₄ . The strongest of all known acids for this element, but at the same time the most resistant to attacks of strong reducing agents. This is due to the special geometric structure of the molecule, which in space has the form of a tetrahedron.
2. Perbromates are salts above the designated acid. For them, the maximum oxidation of bromine is also characteristic. They are strong oxidants, which is why they are used in the chemical industry. Examples: NaBrO ₄ , KBrO ₄ .

The use of bromine and its compounds

You can identify several areas in which bromine and its compounds are directly used.

1. Manufacture of dyes.
2. For the production of photographic materials.
3. As medicines in medicine (bromine salts).
4. In the automotive industry, namely as an additive to gasolines.
5. Used as impregnation to reduce the level of inflammability of some organic materials.
6. In the manufacture of drilling fluids.
7. In agriculture, in the manufacture of insect-proof sprayers.
8. As a disinfectant and disinfectant, including for water.

Biological action on the body

Both the excess and the lack of bromine in the body have very unpleasant consequences.

Pavlov was the first to determine the effect of this element on living things. Experiments on animals have proved that prolonged shortage of bromine ions leads to:

• Disruption of the nervous system;
• Disorder of sexual function;
• Miscarriages and infertility;
• Decrease in growth;
• Reduction of hemoglobin;
• Insomnia and so on.

Excessive accumulation in organs and tissues leads to suppression of the work of the brain and spinal cord, various external skin diseases.