Most often, the idea of boron is associated not with a simple substance, the properties of which are little known, but with compounds - boric acid or its salt, called borax. The element boron is widespread in the earth's crust; suffice it to say that more than a hundred rocks and minerals contain it in their composition. In our article, we will study the physical and chemical properties of an element and consider the areas of application of boron and its compounds in industry, medicine, and agriculture. Another interesting question is the effect of borates on the human body and their role in metabolism, which we will find out with specific examples.
Features of physical properties
For a person not related to chemistry, the basic characteristics of an element - the state of aggregation, density, boiling or melting points - are little known. Moreover, as a simple substance, the element boron does not occur in nature. Under ordinary conditions, it is an amorphous mass of dark color. The crystalline form has a different color: colorless, red or gray. The compound can form up to ten types of allotropic modifications that differ in the structure of the crystal lattice. She, in turn, depends on the temperature of the substance. Boron is brittle, but very hard, and in this characteristic is second only to diamond; it also conducts electric current well.
Position in the periodic system: characteristic features of the compound
The properties of the element boron are determined by the place that it occupies in the periodic system of chemical elements Mendeleev. Being a p-element, the substance studied by us exhibits both nonmetallic and metallic properties and in compounds has an oxidation state of +3. This means that for the formation of a chemical bond, a boron atom gives up its three electrons located at the last energy level. He has many common physical and chemical properties with silicon located diagonally in the periodic system. In the 13th group of the table, the properties of the chemical element boron have the most pronounced non-metallic character. With an increase in the charge of the atomic nucleus, all other representatives — aluminum, gallium, and indium — exhibit a smooth increase in the signs of metals. The atoms of the element are found in the form of two isotopes with mass numbers 10 and 11. The first of them has an interesting property, which made it possible to use the isotope in nuclear physics, the other is actively used in metallurgical production. Let's get acquainted with them in more detail.
The role of the element in modern industries
The 10 B isotope is capable of absorbing elementary particles, neutrons, that are fast moving in the reactors of nuclear plants. It is used as a factor that does not allow a nuclear reaction to go into an uncontrolled phase, ending in an explosion. When smelting ferrous and non-ferrous metals, a simple substance is used as an additive that reduces the grain size of the alloy, which significantly improves its physical properties. The ability to form a layer on metal surfaces - this characteristic of the chemical element boron, called boroning, improves the quality of products, protecting them from corrosion.
How to get a simple substance?
Free boron in the form of an amorphous powder can be obtained by reducing its oxide with metallic magnesium. The resulting compound contains impurities, not widely used. Therefore, the method of thermal decomposition of boranes - compounds with hydrogen, or the reduction of boron halides - has recently been used. In this case, the purity of boron is high. It has the appearance of a black and very hard crystal.
Spread in nature
More than a hundred minerals and ores contain an element in the form of borates and borosilicates. The most famous of them are datolite and crystalline hydrate Na 2 B 2 O 7 × 10 H 2 O, called borax. They are part of the rocks formed as a result of volcanic eruptions, as well as those of sedimentary origin. Here are some more representatives of boron-containing rocks. For example, the mineral named avogadrite, named after the Italian chemist A. Avogadro, who determined the molar volume of gases . This is a complex compound of potassium, fluorine and boron. Another, rather rare compound, ulexite, is a crystalline hydrate of calcium and sodium borates. Or peynite - a mineral containing a storehouse of valuable elements such as aluminum, zirconium, boron. The characteristic of an element will be incomplete if we do not recall its wide distribution in the composition of geothermal mineral waters, geysers, and sea water. A particularly high content of B 3+ ions is recorded in the balneological and drinking springs of the Caucasus and Crimea.
Features of reactions with chemicals
As we have already said, the properties of boron are largely reminiscent of silicon. At ordinary temperature and pressure, it is rather passive and interacts only with the most active non-metal - fluorine. When heated, reacts with chlorine, bromine and other halogens, as well as phosphorus, nitrogen and carbon. To obtain a compound of boron with hydrogen, a reaction is used between a strong inorganic acid and borates of alkali and alkaline earth metals. In redox reactions with oxides such as phosphorus or silicon, the boron element behaves like a reducing agent, but does not interact with alkalis at all. Tribasic acid - H 3 BO 3 , which is an important raw material for industry, can be obtained by acting on a simple substance with hot solutions of nitric or sulfuric acid or by dissolving boron in aqua regia: a mixture of nitric and hydrochloric acids. Boric acid has pronounced bactericidal properties and is used in medicine. However, in large doses, it is highly toxic, therefore, its use is currently limited.
Boric Acid Salts
If borates are mentioned in the chemical literature, then we are talking about salts of tetraboric acid H 2 B 4 O 7 or other, less hydrated compounds than ordinary boric acid. Sodium tetraborate is of the greatest importance for industry; in everyday life it is often called borax. In the manufacture of faience and porcelain products, the element boron is used as a component of glaze, and in the manufacture of enameled glassware, drill is a part of its coating. Sodium tetraborate has long been used in the glass industry to impart special properties to glass, for example, such as high transparency and the ability to transmit up to 75% of all ultraviolet rays perceived by living objects.
Boron as a trace element in organisms
The most important effect this component has on plants. It is part of the phytohormones that regulate the development of educational tissue - the meristem, located on the tops of young shoots and at the point of plant growth. If the soil is poor in B 3+ ions, then there is not only a lag in development, but also inhibition of reproductive functions, and the plant ceases to form flowers. The chemical element boron enters the soil along with mineral fertilizers that are applied in the fall.
There are indicator plants by which we can judge the content of the compound in the soil solution. For example, halophyte hodgepodge at a high concentration of BO 3 3– anions becomes gigantic in size, while salinos and wormwood steppe stop their growth. Boron is important for the human body. It affects the function of insulin, increasing its activity, regulates the production of sex hormones and the conduct of excitation along the nerve fiber.
In our article, we described the element boron and found out its significance for human life.