Where is beryllium used? Chemical properties of beryllium and its most important chemical compounds

Beryllium (lat. Beryllium), Be, chemical element Group II periodic system Mendeleev, atomic number 4, atomic mass 9.0122; light light gray metal. Has one stable isotope Ve.

Beryllium was discovered in 1798 in the form of BeO oxide isolated from the mineral beryl by L. Vauquelin. Metallic beryllium was first obtained in 1828 by F. Wehler and A. Bussy independently of each other. Since some salts of beryllium have a sweet taste, it was originally called "glucinium" (from the Greek glykys - sweet) or "glycium". The name Glicinium is used (along with Beryllium) only in France. The use of beryllium began in the 40s of the 20th century, although its valuable properties as a component of alloys were discovered even earlier, and remarkable nuclear ones - in the early 30s of the 20th century.

Distribution of beryllium in nature. Beryllium is a rare element. Beryllium is a typical lithophile element characteristic of felsic, subalkaline and alkaline magmas. About 40 Beryllium minerals are known. Of these, beryl is of the greatest practical importance; phenakite, gelvin, chrysoberyl, and bertrandite are promising and partially used.

Physical properties. The crystal lattice of Beryllium is hexagonal close-packed. Beryllium is lighter than aluminum, its density is 1847.7 kg/m3 (Al has about 2700 kg/m3), melting point is 1285oC, boiling point is 2470oC.

Initially, beryllium called glucinia. Translated from Greek as "sweet". The fact that metal crystals taste like candy was first noticed by Paul Lebeau.

The French chemist succeeded in synthesizing beryllium aggregates at the end of the 19th century. The electrolysis method helped. In a metallic form, the element was obtained back in 1828 by the German Friedrich Weller. Beryllium took the 4th place and was known as a substance with amazing properties. They are not limited to sweetness.

Chemical and physical properties beryllium

Beryllium formula differs by only 4 electrons. This is not surprising, given the place of the element in the periodic table. Surprisingly, they are all in s-orbits. There are no free positions for new electrons.

So, beryllium is an element unwilling to enter into chemical reactions. Metal makes exceptions for substances capable of taking away, replacing its own electrons. For example, halogen is capable of this.

Beryllium is a metal. However, he also has covalent bonds. This means that in beryllium atom overlap, some pairs of electron clouds are generalized, which is typical for non-metals. This duality affects the mechanical parameters of matter. The material is both brittle and hard.

Beryllium is distinguished by lightness. The density of the metal is only 1.848 grams per cubic centimeter. Only a few below the bar alkali metals. Converging with them in density, beryllium favorably stands out for its resistance to corrosion.

The element is saved from it by a film a fraction of a millimeter thick. This is beryllium oxide. It is formed in air in 1.5-2 hours. As a result, the access of oxygen to the metal is blocked, and it retains all its original characteristics.

Please and beryllium strength. A wire with a diameter of only 1 millimeter is able to hold a canopy of an adult man. For comparison, a similar thread breaks under a load of 12 kilograms.

Beryllium, properties which are discussed, almost does not lose strength when heated. If you bring the temperature to 400 degrees, the "strength" of the metal will only be halved. Duralumin, for example, becomes less durable by 5 times.

Limit temperature beryllium hardness- more than 1200 on the Celsius scale. This is unpredictable, because in the periodic table the 4th element is between and. The first melts at 180, and the second at 650 degrees.

In theory, the softening temperature of beryllium should be about 400 on the Celsius scale. But, the 4th element was included in the list of relatively refractory, yielding, for example, to iron only 300 degrees.

Limiting beryllium reaction to the boiling point. It occurs at 2450 degrees Celsius. Boiling, the metal turns into a single gray mass. In its usual form, the element, with a pronounced, slightly oily sheen.

The radiance is beautiful, but dangerous to health. Beryllium is poisonous. Once in the body, the metal replaces bone magnesium. beryllium begins. Its acute form is expressed by pulmonary edema, dry cough. There are fatal cases.

The effect on living tissues is one of the few disadvantages of beryllium. There are more advantages. They serve mankind, in particular in the field of heavy industry. So, it's time to study how the 4th element of the periodic table is applied.

Application of beryllium

beryllium hydroxide and uranium oxide make up nuclear fuel. The 4th metal is used in nuclear reactors and to slow down neutrons. Beryllium oxide is added not only to fuel, but also crucibles are made from it. These are high thermal conductivity, high temperature insulators.

In addition to nuclear technology beryllium compounds, on its basis come in handy in the aircraft industry and astronautics. Heat shields and guidance systems are made from the 4th metal. The element is also needed for rocket fuel, as well as ship plating. Their cases are made of beryllium bronzes.

Their properties are superior to alloyed steels. It is enough to add to only 1-3% of the 4th element to maximize the breaking strength. It doesn't get lost over time. Other alloys get tired over the years, their performance parameters are reduced.

Pure beryllium is poorly processed. Acting as an additive to, the metal becomes pliable. You can make a tape with a thickness of only 0.1 millimeters. Mass of beryllium lightens the alloy, eliminates its magneticness, sparking during impacts.

All this is useful in the production of springs, bearings, springs, shock absorbers, gears. Experts say that in a modern aircraft there are more than 1,000 parts made of beryllium bronze.

Steam is also used in metallurgy beryllium-magnesium. The last metal is lost during melting. The addition of 0.005% of the 4th element reduces the evaporation and oxidation of magnesium during melting and.

By analogy, they act in the same way with aluminum-based compositions. If you combine the 4th metal with or, you get beryllides. These are alloys of exceptional hardness, able to last 10 hours at a temperature of 1650 degrees Celsius.

beryllium chloride needed by physicians. They use the substance in the diagnosis of tuberculosis and in general in x-ray equipment. The 4th element is one of the few that do not interact with X-rays.

beryllium core, its atoms are almost weightless. This allows 17 times more soft rays to pass through than, for example, aluminum of the same thickness passes. Therefore, the windows of X-ray tubes are made of beryllium.

Beryllium mining

Metal is extracted from ores. Crushed beryllium is sintered with lime, sodium fluorosilicate and chalk. The resulting mixture is passed through several chemical reactions until the hydroxide of the 4th element is obtained. Involved in the process acid.

Beryllium cleaning is laborious. Hydroxide requires calcination to the state of oxide. It, in turn, is converted into chloride or fluoride. Of these, by electrolysis and mining beryllium metal. The magnesium recovery method is also used.

Obtaining beryllium is dozens of distillations and purifications. Get rid of, mainly, you need to metal oxide. The substance makes beryllium excessively brittle, unsuitable for industrial use.

The process of extracting the 4th element is complicated by its rarity. There is less than 4 grams of beryllium per ton of the earth's crust. Global reserves are estimated at only 80,000 tons. Every year, about 300 of them are extracted from the bowels. The volume of production is gradually increasing.

Most of the element is found in alkaline, silica-rich rocks. They are almost non-existent in the East. This is the only region that does not mine beryllium. Most metal in the US, in particular, the state of Utah. Rich in the 4th element and Central Africa, Brazil, Russia. They account for 50% of the world's beryllium reserves.

beryllium price

On the beryllium price due not only to its rarity, but also to the complexity of production. As a result, the cost of a kilogram reaches several hundred US dollars.

Pounds are traded on non-ferrous metal exchanges. The English measure of weight is approximately 450 grams. For this volume they ask for almost 230 conventional units. Accordingly, a kilogram is estimated at almost $ 500.

By 2017, the world beryllium market, according to experts, will reach 500 tons. This indicates the demand for the metal. This means that its value will probably continue to grow. No wonder beryllium is the basis of precious stones,,.

The price of raw materials is approaching the requests of jewelers for faceted crystals. By the way, they can be material for beryllium mining. But, of course, no one lets emeralds for remelting, while in nature there are deposits of ores containing the 4th element. As a rule, it accompanies aluminum. So, if it was possible to find the ores of the latter, for sure, it will be possible to detect beryllium in them.

BERYllIUM, Be (lat. Beryllium * a. berillium; n. Beryllium; f. beryllium; and. berilio), is a chemical element of group II of the Mendeleev periodic system, atomic number 4, atomic mass 9.0122. It has one stable isotope 9 Be. It was discovered in 1798 by the French chemist L. Vauquelin in the form of BeO oxide isolated from. Beryllium metal was independently obtained in 1828 by the German chemist F. Wöhler and the French chemist A. Bussy.

Beryllium properties

Beryllium is a light, light gray metal. The crystal structure of a-Be (269-1254°C) is hexagonal; R-Be (1254-1284 ° C) - body-centered, cubic. 1844 kg/m3, melting point 1287°C, boiling point 2507°C. It has the highest heat capacity of all metals, 1.80 kJ/kg. K, high thermal conductivity 178 W/m. K at 50°C, low specific electrical resistance(3.6-4.5). 10 ohm. m at 20°C; coefficient of thermal linear expansion 10.3-13.1 . 10 -6 deg -1 (25-100°С). Beryllium is a brittle metal; shock 10-50 kJ/m 2 . Beryllium has a small cross section capture of thermal neutrons.

Chemical properties of beryllium

Beryllium is a typical amphoteric element with high chemical activity; compact beryllium is stable in air due to the formation of a BeO film; the oxidation state of beryl is +2.

Beryllium compounds

When heated, it combines with halogens and other non-metals. It forms BeO oxide with oxygen, Be 3 N 2 nitride with nitrogen, Be 2 C carbide with c, BeS sulfide with c. Soluble in alkalis (with the formation of hydrooxoberyllates) and most acids. At high temperatures, beryllium reacts with most metals to form beryllides. Molten beryllium interacts with oxides, nitrides, sulfides, carbides. Of the compounds of beryllium, BeO, Be(OH) 2 , fluoroberyllates, such as Na 2 BeF 4 and others, are of the greatest industrial importance. Volatile beryllium compounds and dust containing beryllium and its compounds are toxic.

Beryllium is a rare (clarke 6.10 -4%), typically lithophile element, characteristic of acidic and alkaline rocks. Of the 55 native minerals, beryllium 50% belongs to silicates and beryllium silicates, 24% to phosphates, 10% to oxides, the rest to,. The proximity of the ionization potentials determines the affinity of beryllium and zinc in an alkaline environment, so that they are simultaneously in some, and are also part of the same mineral -. In neutral and acidic media, the migration paths of beryllium and zinc diverge sharply. Some scattering of beryllium in rocks determined by its chemical similarity with Al and Si. These elements are especially close in the form of tetrahedral groups of BeO 4 6- , AlO 4 5- and SiO 4 4- . In granites, a greater affinity of beryllium to, and in alkaline rocks - to. Since the replacement of Al 3+ IV with Be 2+ IV is energetically more favorable than Si 4+ IV with Be 2+ IV, the isomorphic dispersion of beryllium in alkaline rocks is, as a rule, higher than in acidic ones. The geochemical migration of beryllium is associated with , with which it forms very stable complexes BeF 4 2- , BeF 3 1- , BeF 2 0 , BeF 1+ . With an increase in temperature and alkalinity, these complexes are easily hydrolyzed to compounds Be(OH)F 0 , Be(OH) 2 F 1- , in the form of which beryllium migrates.

For the main genetic types of beryllium deposits and enrichment schemes, see Art. beryllium ores. In industry, metallic beryllium is obtained by thermal reduction of BeF 2 with magnesium, high-purity beryllium is obtained by remelting in vacuum and vacuum distillation.

Application of beryllium

Beryllium and its compounds are used in engineering (over 70% of the total metal consumption) as an alloying addition to alloys based on Cu, Ni, Zn, Al, Pb and other non-ferrous metals. In nuclear technology, Be and BeO are used as neutron reflectors and moderators, as well as as a neutron source. Low density, high strength and heat resistance, high modulus of elasticity and good thermal conductivity make it possible to use beryllium and its alloys as structural material in aircraft, rocket and space technology. Alloys of beryllium and beryllium oxide meet the requirements for strength and corrosion resistance as fuel cladding materials. Beryllium is used to make X-ray tube windows, to apply a solid diffusion layer on the steel surface (berylization), as an additive to rocket fuel. Consumers of Be and BeO are also electrical engineering and radio electronics; BeO is used as a material for housings, heat sinks and insulators. semiconductor devices. Due to its high refractoriness and inertness with respect to most molten metals and salts, beryllium oxide is used for the manufacture of crucibles and special ceramics.

Beryllium

BERYLLIUM-I; m. Chemical element (Be), light solid metal silver color.

◁ Beryllium, th, th. B. mineral. B-th alloys.

beryllium

(lat. Beryllium), a chemical element of group II of the periodic system. Named after the mineral beryl. Light gray metal, light and hard; density 1.816 g / cm 3, t pl 1287°C. Above 800°C it oxidizes to BeO. Beryllium and its alloys are used in electrical engineering, aircraft and rocket building, and for beryllization. AT nuclear reactors- neutron moderator and reflector. Mixed with Ra, Po, Ac - a source of neutrons. Beryllium compounds are poisonous.

BERYLLIUM

BERYLLIUM (lat. Beryllium), Be, a chemical element with atomic number 4 and atomic mass 9.01218. The chemical symbol for the element Be is "beryllium". Only one stable nuclide occurs in nature (cm. NUCLIDE) 9 Be. In the periodic system of elements of D. I. Mendeleev, beryllium is located in group IIA in the second period. Electronic configuration of the beryllium atom 1s 2 2s 2 . Atomic radius 0.113 nm, Be 2+ ion radius 0.034 nm. In compounds, it exhibits only the +2 oxidation state (valency II). The successive ionization energies of the Be atom are 9.3227 and 18.211 eV. Pauling's electronegativity value is 1.57. In its free form, it is a silver-gray light metal.
Discovery history
Beryllium was discovered in 1798 by L. Vauquelin (cm. VAUCLAIN Louis Nicola) in the form of beryl earth (BeO oxide), when this French chemist figured out common features chemical composition precious stones beryl (from the Greek beryllos - beryl) and emerald. Metallic beryllium was obtained in 1828 by F. Wehler (cm. Wehler Friedrich) in Germany and independently of him A. Bussy in France. However, due to impurities, it could not be fused. It was not until 1898 that the French chemist P. Lebo, by subjecting potassium and beryllium double fluoride to electrolysis, obtained sufficiently pure metal crystals of beryllium. Interestingly, because of the sweet taste of water-soluble compounds of beryllium, the element was originally called "glucinium" (from the Greek glykys - sweet).
Being in nature
Beryllium is a rare element, its content in earth's crust 2.6 10 -4% by weight. Sea water contains up to 6·10 -7 mg/l of beryllium. The main natural minerals containing beryllium: beryl (cm. BERYL) Be 3 Al 2 (SiO 3) 6, phenakite (cm. FENAKIT) Be 2 SiO 4 , bertrandite (cm. BERTRANDIT) Be 4 Si 2 O 8 H 2 O and gelvin (cm. GELVIN)(Mn,Fe,Zn) 4 3 S. Transparent varieties of beryl colored with impurities of cations of other metals - gems, for example, green emerald, blue aquamarine, helioder, sparrow. They learned to synthesize artificially.
Obtaining compounds of beryllium and metallic beryllium
The extraction of beryllium from its natural minerals (mainly beryl) includes several stages, and it is especially important to separate beryllium from aluminum similar in properties and accompanying beryllium in minerals. You can, for example, fuse beryl with sodium hexafluorosilicate Na 2 SiF 6:
Be 3 Al 2 (SiO 3) 6 + 12Na 2 SiF 6 = 6Na 2 SiO 3 + 2Na 3 AlF 6 + 3Na 2 + 12SiF 4 .
As a result of fusion, cryolite Na 3 AlF 6 is formed - a compound poorly soluble in water, as well as sodium fluoroberyllate Na 2 soluble in water. It is then leached out with water. For a deeper purification of beryllium from aluminum, the treatment of the resulting solution with ammonium carbonate (NH 4) 2 CO 3 is used. In this case, aluminum precipitates in the form of Al(OH) 3 hydroxide, while beryllium remains in solution in the form of a soluble complex (NH 4) 2 . This complex is then decomposed to beryllium oxide BeO upon calcination:
(NH 4) 2 \u003d BeO + 2CO 2 + 2NH 3 + H 2 O.
Another method for removing aluminum from beryllium is based on the fact that beryllium oxyacetate Be 4 O(CH 3 COO) 6 , unlike aluminum oxyacetate + CH 3 COO - , has a molecular structure and easily sublimates when heated. There is also known a method for processing beryl, in which the beryl is first treated with concentrated sulfuric acid at a temperature of 300°C, and then the sinter is leached with water. Aluminum and beryllium sulfates go into solution. After adding potassium sulfate K 2 SO 4 to the solution, it is possible to precipitate aluminum from the solution in the form of potassium alum KAl (SO 4) 2 12H 2 O. Further purification of beryllium from aluminum is carried out in the same way as in the previous method.
Finally, such a method of processing beryl is also known. The original mineral is first alloyed with potash K 2 CO 3 . In this case, beryllate K 2 BeO 2 and potassium aluminate KAlO 2 are formed:
Be 3 Al 2 (SiO 3) 6 + 10K 2 CO 3 = 3K 2 BeO 2 + 2KAlO 2 + 6K 2 SiO 3 + 10CO 2
After leaching with water, the resulting solution is acidified with sulfuric acid. As a result, silicic acid precipitates. Potassium alum is further precipitated from the filtrate, after which only Be 2+ ions remain in the solution from cations. From the beryllium oxide BeO obtained in one way or another, fluoride is then obtained, from which metallic beryllium is reduced by the magnesium thermal method:
BeF 2 + Mg = MgF 2 + Be.
Metallic beryllium can also be prepared by electrolysis of a melted mixture of BeCl 2 and NaCl at temperatures of about 300 °C. Previously, beryllium was obtained by electrolysis of a melt of barium fluoroberyllate Ba:
Ba = BaF 2 + Be + F 2 .
Physical and chemical properties
Metallic beryllium is characterized by high brittleness. Melting point 1278 ° C, boiling point about 2470 ° C, density 1.816 kg / m 3. Up to a temperature of 1277 ° C, alpha-Be is stable (magnesium-type hexagonal lattice, parameters a = 0.22855 nm, c = 0.35833 nm), at temperatures preceding the melting of the metal (1277-1288 ° C) - beta-Be with cubic lattice.
Chemical properties beryllium is in many ways similar to the properties of magnesium (cm. MAGNESIUM) and especially aluminum (cm. ALUMINUM). The closeness of the properties of beryllium and aluminum is explained by the almost identical ratio of the cation charge to its radius for the Be 2+ and Al 3+ ions. In air, beryllium, like aluminum, is covered with an oxide film, which gives the beryllium a dull color. The presence of an oxide film protects the metal from further destruction and causes its low chemical activity at room temperature. When heated, beryllium burns in air to form oxide BeO, reacts with sulfur and nitrogen. With halogens (cm. HALOGENS) beryllium reacts at ordinary temperature or with low heat, for example:
Be + Cl 2 \u003d BeCl 2
All these reactions are accompanied by the release a large number heat, since the strength of the crystal lattices of the resulting compounds (BeO, BeS, Be 3 N 2, BeCl 2) is quite large. Due to the formation of a strong oxide film on the surface, beryllium does not react with water, although it is in the series of standard potentials much to the left of hydrogen. Like aluminum, beryllium reacts with acids and alkali solutions:
Be + 2HCl \u003d BeCl 2 + H 2,
Be + 2NaOH + 2H 2 O \u003d Na 2 + H 2.
Beryllium hydroxide Be(OH) 2 is a polymer compound that is insoluble in water. It exhibits amphoteric (cm. AMPHOTERICITY) properties:
Be (OH) 2 + 2KOH \u003d K 2,
Be(OH) 2 + 2HCl = BeCl 2 + 2H 2 O.
In most compounds, beryllium exhibits a coordination number of 4. For example, in the structure of solid BeCl 2 there are chains with bridging chlorine atoms. Due to the formation of strong tetrahedral anions, many beryllium compounds react with salts of other metals:
BeF 2 + 2KF = K 2
Beryllium does not interact directly with hydrogen. Beryllium hydride BeH 2 is a polymer substance, it is obtained by the reaction
BeCl 2 + 2LiH = BeH 2 + 2LiCl,
carried out in ethereal solution. The action on beryllium hydroxide Be (OH) 2 solutions carboxylic acids or by evaporating solutions of their beryllium salts, beryllium oxysalts are obtained, for example, hydroxyacetate Be 4 O(CH 3 COO) 6 . These compounds contain the Be 4 O tetrahedral group; acetate groups are located along six edges of this tetrahedron. Such compounds play an important role in the purification of beryllium, since they do not dissolve in water, but are readily soluble in organic solvents and easily sublime in a vacuum.
Application
Beryllium is mainly used as an alloying addition to various alloys. The addition of beryllium significantly increases the hardness and strength of the alloys, the corrosion resistance of the surfaces of products made from these alloys. Beryllium weakly absorbs x-rays, therefore, windows of X-ray tubes are made from it (through which the radiation goes out). In nuclear reactors, beryllium is used to make neutron reflectors and is used as a neutron moderator. In mixtures with some a-radioactive nuclides, beryllium is used in ampoule neutron sources, since the interaction of beryllium-9 nuclei and a-particles produces neutrons: 9 Be (a, n) 12 C.
Physiological action
In living organisms, beryllium does not seem to have any biological function. Its content in the body of an average person (body weight 70 kg) is 0.036 mg, daily intake with food is about 0.01 mg. Volatile and soluble compounds of beryllium, as well as dust containing beryllium and its compounds, are very toxic. Beryllium replaces magnesium in enzymes and has a pronounced allergic and carcinogenic effect. His presence in atmospheric air leads to a severe respiratory disease - berylliosis. It should be noted that these diseases can occur 10-15 years after the termination of contact with beryllium. For air MPC in terms of beryllium is 0.001 mg/m 3 .

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Synonyms:

See what "beryllium" is in other dictionaries:

- (Greek). Metal serving as the main integral part beryl. Vocabulary foreign words included in the Russian language. Chudinov A.N., 1910. BERYLLIUM A special metal discovered for the first time by Wehler in 1828 and serving as the main component of beryl ... Dictionary of foreign words of the Russian language

Or glycium (chemical form. Be, atomic weight, according to Kruess, 9.05) a metal contained in the form of oxide compounds in many minerals: in beryllum, chrysoberyl, leukophane, emerald, aquamarine, euclase, phenakite, etc. In the metallic state beryllium for the first time ... ... Encyclopedia of Brockhaus and Efron

Modern Encyclopedia

Beryllium- (Beryllium), Be, a chemical element of group II of the periodic system, atomic number 4, atomic mass 9.01218; metal. Beryllium was discovered in 1798 by the French chemist L. Vauquelin and obtained in 1828 by the German chemists F. Wehler and A. Bussy. Beryllium is used ... ... Illustrated encyclopedic Dictionary

- (lat. Beryllium) Be, a chemical element of group II of the periodic system, atomic number 4, atomic mass 9.01218. Named after the mineral beryl. Light gray metal, light and hard; density 1.816 g/cm³, mp 1287.C. Above 800 .C oxidizes to ... ... Big Encyclopedic Dictionary

Be (lat. Beryllium * a. berillium; n. Beryllium; f. beryllium; and. berilio), chem. element II group periodic. Mendeleev systems, at. n. 4, at. weight 9.0122. It has one stable isotope 9Be. Opened in 1798 by the French. chemist L. Vauquelin in the form of ... Geological Encyclopedia

Beryllium- is a steel-gray metal, very light and hard, but extremely brittle. It can be rolled or pulled only under special conditions. Pure beryllium is used in the production of windows in X-ray tubes; as… … Official terminology

BERYLLIUM- chem. element, symbol Be (lat. Beryllium), at. n. 4, at. m. 9.012; pure beryllium light gray, light, hard and brittle metal, density 1848 kg/m3, tmelt = 1284 °C; chemically active, in compounds it exhibits an oxidation state of +2. Of the most… … Great Polytechnic Encyclopedia

- (symbol Be), a strong, light, silvery gray metal from the alkaline earth series, first obtained in its pure form in 1828. It is contained in many minerals, including aquamarine, emerald and morganite (all varieties of BERYL), as well as ... … Scientific and technical encyclopedic dictionary

DEFINITION

Beryllium is the fourth element in the Periodic Table. Designation - Be from the Latin "beryllium". Located in the second period, IIA group. Refers to metals. The nuclear charge is 4.

Beryllium is not widely distributed in the earth's crust. It is part of some minerals, of which beryl Be 3 Al 2 (SiO 3) 6 is the most common.

Beryllium is a steel-gray metal (Fig. 1) with a dense hexagonal crystal lattice quite hard and brittle. In air, it is covered with an oxide film, giving it a matte tint and causing a reduced chemical activity.

Rice. 1. Beryllium. Appearance.

Atomic and molecular weight of beryllium

Relative atomic mass A r is the molar mass of an atom of a substance, divided by 1/12 molar mass carbon atom-12 (12 C).

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.

Since in the free state beryllium exists in the form of monatomic Be molecules, the values ​​of its atomic and molecular masses coincide. They are equal to 9.0121.

Isotopes of beryllium

In nature, beryllium exists as a single isotope 9 Be. The mass number is 9. The nucleus of an atom contains four protons and five neutrons.

There are eleven artificial isotopes of beryllium with mass numbers from 5 to 16, of which the most stable are 10 Be with a half-life of 1.4 million years and 7 Be with a half-life of 53 days.

beryllium ions

On the outside energy level The beryllium atom has two electrons that are valence:

As a result of chemical interaction, beryllium loses its valence electrons, i.e. is their donor, and turns into a positively charged ion (Be 2+):

Be 0 -2e → Be 2+;

In compounds, beryllium exhibits an oxidation state of +2.

Molecule and atom of beryllium

In the free state, beryllium exists in the form of monatomic Be molecules. Here are some properties that characterize the lithium atom and molecule:

Beryllium alloys

The main field of application of beryllium are alloys in which this metal is introduced as an alloying additive. In addition to beryllium bronzes (sleep copper with 2.5% beryllium), nickel alloys with 2-4% beryllium are used, which are comparable in corrosion resistance, strength and elasticity to high-quality stainless steels, and in some respects surpass them. They are used to make springs and surgical instruments.

Small additions of beryllium to magnesium alloys increase their corrosion resistance. Such alloys, as well as alloys of aluminum with beryllium, are used in the aircraft industry.

Examples of problem solving

EXAMPLE 1

Exercise

Write the formulas of oxygen compounds (oxides) of the following elements: a) beryllium (II); b) silicon (IV); c) potassium (I); d) arsenic (V).

Answer

It is known that the valency of oxygen in compounds is always equal to II. In order to draw up the formula of a substance (oxide), you need to carry out the following sequence of actions. First we write chemical signs elements that make up complex substance and put a valence over the sign of each element with a Roman numeral: Find the smallest multiple of the number of valence units: a) (II × II) = 4; b) (IV × II) = 8; c) (I×II) = 2; d) (V × II) = 10. We divide the least common multiple by the number of units of valence of each element separately (the resulting private ones will be indices in the formula): a) 4/2 \u003d 2 and 4/2 \u003d 2, therefore, the formula of the oxide BeO; b) 8/4 \u003d 2 and 8/2 \u003d 4, therefore, the formula of the oxide is SiO 2; c) 2/1 \u003d 2 and 2/2 \u003d 1, therefore, the formula of the oxide is K 2 O; d) 10/5 \u003d 2 and 10/2 \u003d 5, therefore, the formula of the oxide is As 2 O 5.