BOR (Latin Borum), B, a chemical element of the III group of the short form (the 13th group of the long form) of the periodic system, atomic number 5, atomic mass 10.811; non-metal. There are two stable isotopes in nature: 10 V (19.9%) and 11 V (80.1%); artificially obtained isotopes with mass numbers 7-19.
Historical reference. Natural boron compounds, mainly borax, have been known since the early Middle Ages. Borax, or tinkal, was imported to Europe from Tibet, it was used in the forging of metals, mainly gold and silver. From the Arabic name buraq (burak) and the Late Latin borax (borax), the name of the element came from. Boron was discovered in 1808: J. Gay-Lussac and L. Tenard isolated the element from oxide B 2 O 3 by heating with metallic potassium, G. Davy - by electrolysis of molten B 2 O 3.
Distribution in nature. The content of boron in the earth's crust is 5·10 -3% by weight. It does not occur in free form. The most important minerals: borax Na 2 B 4 O 7 10H 2 O, kernite Na 2 B 4 O 7 -4H 2 O, colemanite Ca 2 B 6 O 11 5H 2 O, etc. Boron is concentrated in the form of potassium borates and alkaline earth elements in sedimentary rocks (see natural borates, boron ores).
Properties. The configuration of the outer electron shell of the boron atom is 2s 2 2p 1 ; oxidation state +3, rarely +2; Pauling electronegativity 2.04; atomic radius 97 pm, ionic radius B 3+ 24 pm (coordination number 4), covalent radius 88 pm. Ionization energy B 0 → B + → B 2+ → B 3+ 801, 2427 and 3660 kJ/mol. The standard electrode potential of the B (OH) 3 / B 0 pair is -0.890 V.
Boron exists in several allotropic modifications. At temperatures below 800 °C, amorphous boron is formed (dark powder, density 2350 kg/m with a reddish tinge, the most stable), 1200-1500 ° C - tetragonal modifications. At temperatures above 1500 °C, the β-rhombohedral modification is stable. Crystal lattices of all types consist of B 12 icosahedrons packed differently in a crystal. For the β-rhombohedral modification: t PL 2074 °C, t KIP 3658 °C, density 2340 kg / m 3 (293 K), thermal conductivity 27.0 W / (m K) (300 K).
Boron is diamagnetic, specific magnetic susceptibility is -0.78·10 m 3 /kg. It is a p-type semiconductor with a band gap of 1.56 eV. The hardness of boron on the Mohs scale is 9.3. It is characterized by a high ability to absorb neutrons (for the 10 V isotope, the thermal neutron capture cross section is 3.8 10 -25 m 2).
Boron is chemically inert. It reacts with oxygen at temperatures above 700 ° C, forming a glassy oxide B 2 O 3. At temperatures above 1200 ° C, boron interacts with N 2 and NH 3, giving boron nitride BN. Forms with P and As at temperatures above 700 ° C phosphides and arsenides, which are high-temperature semiconductors. At temperatures above 2000 °C, boron reacts with carbon to form boron carbides. With halogens at elevated temperatures, it forms volatile trihalides, which are easily hydrolyzed and tend to form H-type complexes; boron does not interact with hydrogen, water, acids, and alkali solutions. Concentrated HNO 3 and aqua regia oxidize boron to orthoboric acid H 3 BO 3 . Fusion of boron with alkalis in the presence of an oxidizing agent results in the formation of borates. Forms borides with metals at high temperatures. By the action of acids on borides, borohydrides can be obtained, which are characterized by addition reactions with the formation of metal borohydrides. For organoelement compounds of boron, see the article Organoboron compounds.
Boron belongs to microelements, its content in plant and animal tissues is 10-10-4%. Boron is involved in carbohydrate-phosphate metabolism. Human consumption of foods high in boron causes a violation of the metabolism of carbohydrates and proteins, which leads to gastrointestinal diseases. Boron is a biogenic element necessary for plant life. With a deficiency or excess of boron in plant tissues, usually associated with a deficiency or excess of an element in the soil, morphological changes and plant diseases occur (gigantism, dwarfism, impaired growth points, etc.). Small amounts of boron dramatically increase the yield of many crops (see Microfertilizers).
Receipt. In industry, boron is obtained from natural borates: colemanite and inioite are processed by the alkaline method with the release of boron in the form of borax, boracite is processed by the acid method with the formation of orthoboric acid, which is converted to B 2 O 3 at a temperature of about 235 ° C. Amorphous boron is obtained by reduction of borax or B 2 O 3 with active metals - Mg, Na, Ca, etc., as well as by electrolysis of a Na or K melt, Crystalline boron - by reduction of BCl 3 or BF 3 halides with hydrogen, decomposition of boron halides and hydrides (mainly B 2 H 6) at a temperature of 1000-1500 ° C or crystallization of amorphous boron.
Application. Boron is used as a component of corrosion-resistant and heat-resistant alloys, such as ferroboron - an alloy of Fe with 10-20% B, composite materials (boroplastics). A small addition of boron (fractions of a percent) significantly increases the mechanical properties of steel, non-ferrous metal alloys. The surface of steel products is saturated with boron (boriding) in order to improve mechanical and corrosion properties. Boron is used as a semiconductor for the manufacture of thermistors. About 50% of the obtained artificial and natural boron compounds are used in the production of glass, up to 30% - in the production of detergents. Many borides are used as cutting and abrasive materials. The Nd 2 Fe 14 V ferromagnet is used for the manufacture of powerful permanent magnets, the Co-Pt-Cr-B ferromagnetic alloy is used as a medium for recording in modern information media. Boron and its alloys are neutron absorbers in the production of control rods for nuclear reactors.
Lit.: Boron, its compounds and alloys. K., 1960; Golikova O., Samatov S. Bor and its semiconductor compounds. Tash., 1982; Boron chemistry at the millennium / Ed. R. V. King. Amst.; Oxf., 1999.
A. A. Eliseev, Yu. D. Tretyakov.
DEFINITION
Bor- the fifth element of the Periodic table. Designation - B from the Latin "borum". Located in the second period, IIIA group. Refers to non-metals. The nuclear charge is 5.
Boron is relatively uncommon in nature; the total content in the earth's crust is about 10 -3% (wt.).
The main natural boron compounds include boric acid H 3 BO 3 and salts of boric acids, of which borax Na 2 B 4 O 7 × 10H 2 O is best known.
Under normal conditions, boron is a substance of a crystalline structure (rhombohedral syngony) of a dark gray color (Fig. 1). Refractory (melting point 2075 o C, boiling point 3700 o C), diamagnetic, has semiconductor properties.
Rice. 1. Bor. Appearance.
Atomic and molecular weight of boron
Relative molecular weight M r is the molar mass of the molecule, referred to 1/12 of the molar mass of the carbon-12 atom (12 C). This is a dimensionless quantity.
Relative atomic mass A r is the molar mass of an atom of a substance, referred to 1/12 of the molar mass of a carbon-12 atom (12 C).
Since boron exists in the free state in the form of monatomic molecules B, the values of its atomic and molecular masses are the same. They are equal to 10.806.
Allotropy and allotropic modifications of boron
Boron is characterized by the manifestation of allotropy, i.e. existence in the form of several simple substances, called allotropic (allotropic) modifications. First, boron exists in two states of aggregation - crystalline (colored gray) and amorphous (colored white). Secondly, in the crystalline form, boron has more than 10 allotropic modifications. For example, boron atoms can be combined into groups B 12 that have the shape of an icosahedron - twenty-sided (Fig. 2).
Rice. 2. Icosahedral grouping of boron atoms B 12 .
These B 12 icosahedrons, in turn, can be located relative to each other in the crystal in different ways:
Boron isotopes
In nature, boron exists as two stable isotopes 10 B (19.8%) and 11 B (80.2%). Their mass numbers are 10 and 11, respectively. The 10 B boron isotope has five protons and five neutrons, while the 11 B isotope has the same number of protons and four neutrons.
There are twelve artificial (radioactive) isotopes of boron with mass numbers from 5 to 17, of which 8 B is the most stable, with a half-life of 0.77 s.
Boron ions
On the outer energy level of the boron atom, there are three electrons that are valence:
1s 2 2s 2 2p 1 .
As a result of chemical interaction, boron can lose its valence electrons, i.e. be their donor, and turn into a positively charged ion (B 3+) or accept electrons from another atom, i.e. be their acceptor, and turn into a negatively charged ion (B 3-):
B 0 -3e → B 3+;
B 0 +3e → B 3- .
Molecule and atom of boron
In the free state, boron exists in the form of monatomic molecules B. Here are some properties that characterize the atom and molecule of boron:
Boron alloys
In metallurgy, boron is used as an additive to steel and some non-ferrous alloys. The addition of very small amounts of boron reduces the grain size, which leads to an improvement in the mechanical properties of the alloys. Surface saturation of steel products with boron is also used - borating, which increases hardness and resistance to corrosion.
Examples of problem solving
EXAMPLE 1
EXAMPLE 2
| Exercise | Find the formula for the compound of boron with hydrogen (borane), which has a composition in mass fractions of a percent: boron - 78.2; hydrogen - 21.8. If the mass of 1 cm 3 of this gas is equal to the mass of 1 cm 3 of nitrogen. |
| Solution | The mass fraction of the element X in the molecule of the HX composition is calculated by the following formula: ω (X) = n × Ar (X) / M (HX) × 100%. Let us denote the number of moles of elements that make up the compound as "x" (boron), "y" (hydrogen). Then, the molar ratio will look like this (the values of relative atomic masses taken from the Periodic Table of D.I. Mendeleev will be rounded to integers): x:y = ω(B)/Ar(B) : ω(H)/Ar(H); x:y= 78.2/11: 21.8/1; x:y= 7.12: 21.8= 1: 3. This means that the simplest formula for the compound of boron with hydrogen (borane) will have the form BH 3 and a molar mass of 14 g / mol. According to the condition of the problem: m (N 2) \u003d M (N 2) × V (N 2) / V m \u003d 28 × 1 / 22.4 \u003d 1.25 g. m(B x H y) = M(B x H y) × V(B x H y) / V m = M(B x H y) × 1 / 22.4. m(N 2) \u003d m (B x H y) \u003d M (B x H y) × 1 / 22.4; M (B x H y) \u003d m (N 2) × 22.4 \u003d 1.25 × 22.4 \u003d 28 g / mol. To find the true formula of a substance, we find the ratio of the obtained molar masses: M(B x H y) / M(BH 3) = 28 / 12 = 2. This means that the indices of boron and hydrogen atoms should be 2 times higher, i.e. the borane formula will look like B 2 H 6 . |
| Answer | B2H6 |
chemical element, B
Alternative descriptions. (mascaret) the propagation of a tidal wave upstream a river through an estuary
Niels (1885-1962) Danish physicist, one of the founders of modern physics, Nobel Prize 1922
Aage (born 1922) Danish physicist, Nobel Prize (1975, jointly with B. Mottelson and J. Rainwater)
Harald (1887-1951) date. mathematician
In Norse mythology, Odin's father (mythical)
City (since 1938) in Russia, Nizhny Novgorod region, on the Volga River
City in Yugoslavia, Serbia
dental drill
A tidal wave moving at high speed against the current of a river in the form of a wave of water with an overturning crest
Pine forest on sandy and rocky soils
Among the paintings by Ivan Shishkin there is "Pine ..."
Steel drill used in dental practice
Herbaceous plant, grass family
Coniferous tree, a kind of pine, var. borika
Chemical element
Scandinavian Thunderer
According to Dahl, this word means “bargaining, bazaar, market”, but for many people it is associated with a famous Dane, and at the same time with “fifth number”
The chemical element most resistant to tearing
Forest with cones
Which physicist created the model of the atom?
Danish physicist, Nobel laureate (1975)
Danish physicist, Nobel Prize winner (1922), founder of modern physics
The forest that burns with cheese
The novel of the Russian writer S. Krutilin "Apraskin ..."
The Fifth Element, but not a Luc Besson film
. "forest" chemical element
coniferous forest
plant of the grass family
Tidal wave
Father of god Odin
Dense spruce forest
Physicist Niels...
Forest with lots of cones
The forest where the pines rustle
Pine forest
Forest with pines
Who created the model of the atom?
Crowd of pines
Tree sticks
Dentist drill
A bunch of pines
Pine...
The cheese is on fire...
Both scientist and pine
Element #5
Danish physicist
Father of Odin
The Fifth Element, but not a movie
. "drill" dentist
Forest burning with cheese
Fifth Element
Forest of increased thorniness
Niels from physicists
In the periodic table, he is number 5
Between carbon and beryllium
Fifth chemical element
. (Svyatobor) in glory. myth. god of forests, patron of hunting
Fifth column of chemical elements
Forest where pines grow
Wood suitable for butterflies
Forest with the smell of pine needles
coniferous forest
Danish physicist, creator of the planetary model of the atom
Chemical element, crystalline substance
In Scandinavian mythology, god, father of Odin
Danish physicists, father (1885-1962, Nobel Prize 1922) and son (Nobel Prize 1975)
Danish mathematician (1887-1951)
City in Nizhny Novgorod Oblast
City in Serbia
Pine forest
Name of a chemical element
. "Drill" of the dentist
. "Forest" chemical element
Which physicist created the model of the atom
Who created the model of the atom
M. (to take) scolding, taking, leaving and receiving; there is no boron, merchants say, to analysis, demand for goods. Campfire bargain. bazaar, market, torzhok; novelty forest, canvas market. Star. collection, requisition, levy, pecuniary duty. With a boron, take with a bork, with your hands, tear. Boron berries, collection. Boron fish, biting. Take goods to the forest, to the forest, on credit, not for cash. Red or coniferous forest; drill pine or spruce forest on dry soil, on a hill; fresh soil, pure pine forest, on sandy loam; ephedra with berry bushes and mushrooms. From the spark, the cheese boron caught fire. The woman walked around the forest, wore out three bast shoes, for a long time. Alien soul dense forest. Bazheny not from a bork, but from an axe. Every pine makes noise to its forest (it gives a message to its forest). Cheese-boron caught fire, trouble, noise from the empty. Sev. dry land, dry land, opposite sex. tundra, swamp, floodplains. Arch. novg. burial ground, cemetery, God's cornfield, because dry land or uplands are chosen for cemeteries there. On the bork, Novg.-Wald. at the cemetery. Lower boron, a fold in clothes, a wrinkle in the face. Plant Panicum miliaceum, Milium effusum, black, bird millet, millet, prosovka, millet genus in black cones (symb. Sam.) Divy boron, plant Alopecurus pratensis, glasnik, meadow wheatgrass, fox tail, homogeneous with arzhants. Borovoy, related to boron, forest. Borovoe place, gristly, dry, under coniferous forest, juniper and heather. Borovoy kulik, birch, mating, woodcock. Borovaya porridge, from boron cereals, from boron millet. Upland outcast, mohnatik, hairy, plant Adonis vernalis. Borovnoy forest, sowing. pine, drill and mast, along dry land. Borystoe place, upland, abundant pine forests. Bory caftan, with burs (see boron). Borovina upland, coniferous, non-grain soil. Borovinka will diminish. breed of small but good apples. Boletus m. edible mushroom Boletus bovinus (mutabilis?) Arch.-mez. a broom, a golik, a broom, because brooms are knitted in a birch forest, in a forest, along dry land, not along the tundra. card game, the selection of the red suit, boletus, and black, the raven's wing. Black grouse, especially kosach, but much taller than a simple (field), probably a mixture of black grouse and capercaillie. Kaluga squash valley. Boroviki pl. wild, upland bees; plant Chimaphila umbellata, stanovnik, upland exile, ramen exile. Borovik ryaz. bush and berry of brusena, lingonberry. Borovnik m. plant Digitaria, mohar. Blitum plant, boletus, zhminda, zhmonda, waste grass; Blitum virgatum, magpie berries. Borovaya nyasha, Borovnitsa? sowing medicinal plant among the people, along the shores of pine forest lakes and hollows. Fight psk. about deposits: grow with conifer, thickets
M. chemical. a combustible substance extracted from borax and serving as a base for boric acid
According to Dahl, this word means "bargaining, bazaar, market", but for many people it is associated with a famous Dane, and at the same time with "fifth number"
The novel of the Russian writer S. Krutilin "Apraskin ..."
Among the paintings by Ivan Shishkin there is "Pine..."
What is the chemical element B
element number five
From chicken to human. Usually, they say: - "From the monkey." But, this is not about evolution, but about proving the importance boron for the body.
Until 1981, the element was considered insignificant, not requiring inclusion in the diet. The scientists' beliefs shook the chickens.
Their cultivation was more successful if the food included boron. Its necessity for chickens was proved in 1985, and by the 1990s it came to humans.
It turned out that boron is an element supporting bone density.
In addition, the substance keeps the normal production of both male and female hormones, that is, estrogen and progesterone.
Experiments have shown that taking boron preparations, people lose 40% less and 33% with .
Boron properties
Boron is a chemical element standing in under the 5th number. The structure of matter is atomic.
This is typical for metals, however, boron does not apply to them. The element is an exception among its group of non-metals.
They, in fact, in the periodic system are on and above the line drawn from boron to.
Non-metals are characterized by a molecular structure, but, and the 5th substance is outside the rules.
The atomic lattice provides the hero with a record tensile strength of 5.7 hectopascals.
No wonder fibrous boron - chem. element added to composite materials.
They are created artificially by combining components with different properties. As a result, lightweight, but rigid, durable and wear-resistant structures are obtained.
Boron atoms consist of 5 protons and the same number, or 6, neutrons. Accordingly, there are two natural isotopes: - 10th and 11th.
5 particles rotate on the electron shells of an atom of an element. Two electrons are located in the orbit closest to the nucleus, and three are in the far one.
Therefore, the standard boron valence equals +3. Valency refers to the ability of an atom to form a certain number of chemical bonds with other elements.
Three electrons, ready to interact, provide the 5th element with high chemical activity.
Typical, for example, is the sintering reaction with metal powders. Borides are formed. The 5th substance “strives” and to. True, the formed borohydride is unstable.
And here boron oxides resistant. The latter are obtained, as a rule, at high temperatures from oxides of other elements. So, boron is able to replace carbon in carbon monoxide, silicon in.
Boron compounds are the only representatives of it in nature. In a free form, the 5th element is obtained only in laboratories.
For the first time, the experiment was successful by Henri Moissan. The French chemist developed a magnesium-thermal method for obtaining pure boron. Element of the periodic table extracted during the reaction: B 2 O 3 + 3Mg -à3MgO + 2B.
At the same time, the final boron was contaminated with impurities by no more than 10%. It was possible to consider the appearance of the element.
It is hard, gray matter. It can only be melted at 4000 degrees Celsius.
The two natural isotopes of boron differ significantly in their characteristics, in particular, in the thermal neutron capture cross section.
The latter provoke atomic reactions. The capture cross section is the ability of the boron nucleus to capture slow neutrons. If the indicator is large, you can regulate the course of the reaction, stop it.
This means that substances with a large capture cross section are suitable for rods of nuclear reactors. Of the isotopes of boron, only one is suitable. Which one, we will tell in the next chapter.
Boron application
Lightweight is suitable for reactor rods boron isotope, that is, B10. It has not just a large capture cross section, but the first among all the elements of the periodic table.
The 11th bur, on the contrary, has the smallest indicator. Accordingly, a heavy version of the 5th substance can be used in the hot zone of the reactors. That is, B11 is an excellent structural material for nuclear power plants.
The nuclear power industry values not only pure boron, but also its connection with .
This is the gas needed in thermal neutron counters. They are also called boron. The apparatus serves as a radiation receiver.
In nuclear reactors, and not only, by the way, the refractoriness and heat resistance of boron come in handy.
Therefore, the element becomes an addition to many . Most often, they saturate their surface.
This process is called boriding. Subjected to it, as a rule. Their surface becomes more durable and resistant to corrosion.
As a result, borated steel can serve in aggressive environments and withstand increased shock loads.
Boron carbides, that is, compounds with carbon, have long been used by dental technicians. Wondering why they're called that?
Because the drills in the devices are made of an alloy with the carbide of the 5th element. Such drilling of teeth is most quickly and efficiently.
Boron Formula c: — B 4 C. There is also a rarer compound B 13 C 2 . Both are excellent abrasives because, like .
The nitrides of the 5th substance, that is, its compounds with, are excellent semiconductors.
Their specific conductivity is greater than that of dielectrics, but less than that of metals.
Semiconductors are needed in integrated circuits, transistors, optoelectronics.
The secret of materials is that as the temperature rises, they begin to conduct current better. Ordinary conductors in heat, on the contrary, lose their properties.
Boron mining
In compounds, boron is extracted from the earth's interior. On average, there are 4 grams of the 5th element per ton of rock.
Most of all, about 100 micrograms per kilogram of rock, in boron. It is also searched for where there are alkaline soils.
They are the most saturated with the element. Interestingly, it can even be extracted from marine plants. In them, the 5th substance is 120 micrograms per kilo.
Of the minerals, ulexite is the richest in boron. Its deposits, for example, are being developed in Chile. The total reserves are estimated at 30,000,000 tons.
All deposits are located in the Atacama Desert. The first deliveries from here began in the middle of the 19th century, immediately after the construction of the railway in the country.
How much boron cost in those years is not said. However, we can find out the current price tag.
Boron price
The cost of production depends on the type and volume. So, in metallurgy you need a clean, amorphous boron.
Amorphous is a substance that does not have a crystal lattice.
If industrialists acquire a crystalline element, then it is as crushed as possible.
So, amorphous boron powder in a package of 15 kilograms costs about 9,000 rubles.
However, there are proposals where a kilo is estimated at only 50 rubles. Here you already need to collect a dossier on the supplier.
The reason for the low cost may be the contamination of boron, a large percentage of impurities. Although, there are also honest offers, especially with wholesale deliveries.
As for the compounds of the 5th element, for carbides they give from 100 to 700 rubles. This is the price tag for 1000 grams.
The spread in cost is justified by different formulas and properties of carbides. For a kilo of boric anhydrite, you have to pay around 250, and for nitride - several thousand rubles.
Meets and organobor. This is a complex fertilizer, because if the 5th element was not needed by plants, like the human body, it would not be extracted from algae. Typical packaging of organobor is liter. Its cost is 350-400 rubles.
Most often, ideas about boron are 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 widely distributed 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 the element and consider the areas of application of boron and its compounds in industry, medicine and agriculture. The question of the influence of borates on the human body and their role in metabolism, which we will find out with specific examples, is also interesting.
Features of physical properties
For a person who is not associated with chemistry, the main characteristics of an element - state of aggregation, density, boiling point or melting point - are little known. Moreover, as a simple substance, the element boron does not occur in nature. Under normal 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, differing from each other in the structure of the crystal lattice. It, in turn, depends on the temperature of obtaining the substance. Boron is brittle, but very hard, and second only to diamond in this characteristic, it is also a good conductor of electricity.
Position in the periodic system: characteristic features of the compound
The properties of the element boron are determined by the place it occupies in the chemical elements of D.I. Mendeleev. Being a p-element, the substance we are studying exhibits both non-metallic and metallic properties and in compounds has an oxidation state of +3. This means that in order to form a chemical bond, the boron atom gives up three of its electrons located at the last energy level. It has many physical and chemical properties in common with silicon, located diagonally in the periodic table. 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, in all other representatives - aluminum, gallium, indium - a gradual increase in the signs of metals is observed. The atoms of an element occur 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, which move rapidly in the reactors of nuclear power plants. It is used as a factor that does not allow a nuclear reaction to go into an uncontrolled phase, ending in an explosion. In the smelting of 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 boron, improves the quality of products, protecting them from corrosion.
How is a simple substance obtained?
Free boron in the form of an amorphous powder can be obtained by reduction of its oxide with metallic magnesium. The resulting compound contains impurities and is not widely used. Therefore, recently the method of thermal decomposition of boranes - compounds with hydrogen, or the reduction of boron halides has been used. In this case, the purity of boron is high. It has the appearance of a black and very hard crystal.
Distribution in nature
More than a hundred minerals and ores contain the element in the form of borates and borosilicates. The most famous of them are datolite and Na 2 B 2 O 7 × 10 H 2 O crystalline hydrate, called borax. They are part of the rocks formed as a result of volcanic eruptions, as well as those that are of sedimentary origin. Here are some more representatives of boron-containing rocks. For example, named after the Italian chemist A. Avogadro, who identified the mineral avogadrite. It is a complex compound of potassium, fluorine and boron. Another, rather rare compound, ulexite, is a crystalline hydrate of calcium and sodium borates. Or painite - a mineral containing a storehouse of valuable elements such as aluminum, zirconium, boron. The characterization of the element will be incomplete if we do not remember 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 in many ways similar to silicon. At ordinary temperature and pressure, it is quite passive and interacts only with the most active non-metal - fluorine. When heated, it reacts with chlorine, bromine and other halogens, as well as with phosphorus, nitrogen and carbon. To obtain a compound of boron with hydrogen, a reaction is used between a strong inorganic acid and alkali and alkaline earth metal borates. In redox reactions with oxides, such as phosphorus or silicon, the element boron 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 acids 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, it is highly toxic in high doses, so 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 the glaze, and in the production of enamelware, borax is part of its coating. Sodium tetraborate has long been used in the glass industry to impart special properties to glass, 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
This component has the most important effect 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 not only developmental delay is observed, but also reproductive functions are suppressed, and the plant ceases to form flowers. The chemical element boron enters the soil along with mineral fertilizers, which are applied in the fall.
There are indicator plants by which one can judge the content of the compound in the soil solution. For example, saltwort halophyte at a high concentration of BO 3 3- anions becomes gigantic in size, while saltwort and steppe wormwood stop growing. Boron is also important for the human body. It affects the function of insulin, increasing its activity, regulates the production of sex hormones and the conduction of excitation along the nerve fiber.
In our article, we gave a description of the element boron and found out its significance for human life.
