Gaseous substances: examples and properties. Chemistry test on the topic “Gaseous, liquid, solid states of matter” (grade 11) Complex compounds of gaseous nature

AZ. In the series of halogens P - C1 - Br -1 from left to right electronegativity:

a) increases b) decreases c) does not change

d) first increases, then decreases

A4. In the series of elements C - N - O - P is electronegativeness:

a) the largest for fluorine b) the smallest for fluorine

c) does not change d) changes periodically

A5. Electronegativity in the series of elements with electronRonny configurations...2s1 - ...2 s2 2ps2 2р4-...2 s2 2р5: a) increases b) decreases c) does not change d) first increases, then decreases

A6. The electronegativity of elements increases asto the right in the row:

a) H, C, N, O b) C, Li, Be, B c) P, Si, A1, Mg d) F, C1, Br, I

A7. The electronegativity of elements first increases and then decreases in the series:

a) O, F, C b) H, Na, N c) C1, Br, I d) Na, Ca, A1

A8. An ionic bond is formed:

a) between elements with the same electronegativity due to the formation of shared electron pairs

b) if the electronegativity of the elements differs sharply

c) if the electronegativity of the elements differs slightly

d) electronegativity does not matter

A9. Chemical bond in a hydrogen chloride molecule:

a) ionic b) metallic c) covalent nonpolar

d) covalent polar

A10. What type of chemical bond occurs between alkali metals and halogens:

A)metallic b) ionic c) covalent polar d) covalent

AI. Specify the polar covalent bond:

a) N-Nb)C1-C1 c)Na-C1G)S-S1

A12. Indicate the symbol of an element whose atom can form ionic and metallic bonds:

A)K b) O c) C1 d)Si

A13. A chemical bond is formed by two shared electron pairs in a molecule:

a)H2b)02V)N2 d) C12

A14. Chemical bond in a nitrogen molecule:

a) tripleb) doublec) simple d) one and a half

A15. Ionic and covalent polar chemical bonds are present in the substance:

A) SiO2 b)CON c)NаС1d) C12

A16. The strongest chemical bond in a compound is: a)02b)H2V)N2 d) NVg

A17. In which case are the common electron pairs in a chemical bond shifted towards oxygen:

a) CO b)OF2 c)02 d)03

A18. Determine in which series in all substances all covalent bonds are polar:

a)02,K1,N2 b) HC1, CH4,NH3V)H2O, KOH, PH3 d) A1,NаС1, CaСО3

A19. Indicate which type of electron orbitals overlap during the formation of a hydrogen chloride molecule: a) 8 irb) rir c) 8 I 8 D) 8 I d

A20. Determine which molecule contains all o-type bonds:

a) K2b) H2Oc) C2H4d) C6H6

A21. Indicate a molecule with two i-bonds:

A)C2H5OH b) C2H2 c) CH4 d) C2H4

A22. Between atoms of elements with serial numbers11 and 17 a chemical bond is formed: a) metallic b) ionic c) covalent nonpolar

d) covalent polar

A23. Carbon monoxide molecule (IV) contains connections:

A) 1o> and 1l b) 2s and 2k V) 1a and 2p G) 2a and 1l

A24. Specify the compound in which the covalent bondbetween atoms is formed according to donor-acceptormechanism:

a) KS1 b) Ш4С1 c) СН3С1 d) М8С12

A25. Determine between the molecules of which substancepossible formation of hydrogen bonds:

a) CH3OH b) CH2O c) C2H4 d) H2

A26. The atomic type crystal lattice has:

a) rhombic sulfur b) white phosphorus c) oxygen d) silica

A27. Substances with chemical bonds have a molecular lattice:

a) covalent polar b) ionic c) metallic

d) with any type of connection

A28. Type of crystal lattice of a substance formedmetal and halogen:

a) atomic b) molecular c) ionic d) atomic-ionic (metallic)

A29. Iron has a crystal lattice:

a) metallic b) molecular c) ionic d) atomic

AZO. The highest boiling point is:

a) copper b) white phosphorus c) calcium carbonate d) hydrogen chloride

A31. The type of crystal lattice of a substance thatconducts electric current well, ductile, nottransparent:

a) atomic b) metal c) ionic d) molecular

A32. The substance has the highest melting pointin, the formula of which is:

a) Pb b) CH4 c) 5O2 d) KR

AZZ. Indicate the row in which increasing from left to rightmelting point of substances:

a) HC1-H2O-MaC1 b) H2O - Fe - K2 c) KR-A1-Br2 d) H2-SH-CH4

A34. Determine which substance, under normal conditions, has ions as its structural units:

A)water b) oxygen c) iron d) table salt

A35. Indicate the row in which the ionic bond strength increases from left to right:

b)MaC1-CaC12-A1C13c) CaCO3 - KS1 - CaC12d)1LS1-KaS1-KS1

81. What chemical bond exists between the atoms in the compound 1ChH3? (Write the name of the type of connection in the nominative case.)

82. To which atoms of the element are the common electron pairs shifted in the compound OP2? (In your answer, indicate the name of the element in the nominative case.)

83. Due to the electrons of what energy level, the bond in compound N2 is carried out? (Indicate the level number in Arabic numerals.)

84. Indicate the number of a-bonds existing in the toluene molecule. (Write your answer in Arabic numerals).

85. Write down the formula of a substance in whose molecules the most polar chemical bonds are: chlorine, potassium chloride, hydrogen chloride.

86. What orbitals are involved in the formation of a chemical bond in a hydrogen fluoride molecule? (In your answer, write down the letter designations of the orbitals in the order they appear at the energy level and without spaces.)

87. Atoms of which elements of the second period can form a hydrogen bond? (In your answer, write down the chemical signs of the elements in increasing order of their atomic numbers without spaces.)

88. Under ordinary conditions, a certain substance is a gas that forms diatomic molecules. The transition of this substance into a solid state occurs at temperatures below -210 ° C. What type of crystal lattice does this substance form in
solid state? (Write the name of the grid type in the nominative case.)

89. What type of crystal lattice does a substance have if it is highly soluble in water and has a high melting and boiling point? (Write the name of the grid type in the nominative case.)

Nonmetals are chemical elements that form simple substances in free form that do not have the physical properties of metals. Of the 114 chemical elements, 92 are metals, 22 are non-metals. Nonmetals are simple substances; under normal conditions they can be gases, liquids and solids (Fig. 46).

Rice. 46.
Simple substances - non-metals

Laboratory experiment No. 6
Familiarization with the collection of non-metals

Check out the collection of non-metals. Write down the chemical formulas of the nonmetals given to you, arrange them in ascending order:

1. density;
2. hardness;
3. shine;
4. intensity of color change.

To complete the task, use Appendices 1 and 2, additional sources of information.

The gases are helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn. They are called inert gases. Inert gas molecules consist of one atom. Atoms of noble gases (with the exception of helium) have eight electrons in their outer electron layer. Helium has two. In their chemical stability, inert gases resemble noble metals - gold and platinum, and they have a second name - noble gases. This name is more suitable for inert gases, which sometimes nevertheless enter into chemical reactions and form compounds. In 1962, a message appeared that a compound of xenon and fluorine had been obtained. More than 150 compounds of xenon, krypton, radon with fluorine, oxygen, chlorine and nitrogen are now known.

The idea of ​​the chemical exclusivity of the noble gases turned out to be not very consistent, and therefore, instead of the supposed zero group, the noble gases were placed in Group VIII (Group VIIIA) of D.I. Mendeleev’s table.

Helium, which is second only to hydrogen in lightness, but, unlike the latter, is non-flammable, i.e., does not pose a fire hazard, is used to fill balloons and airships (Fig. 47).

Rice. 47.
Balloons and airships are filled with helium

Neon is used to make illuminated advertising (Fig. 48). Remember the figurative expression “the city streets were flooded with neon.”

Gases hydrogen, oxygen, nitrogen, chlorine, fluorine form diatomic molecules, respectively - H 2, O 2, N 2, Cl 2, F 2.

The composition of a substance is depicted in writing using chemical symbols and numbers - indices, using a chemical formula. Using a chemical formula, as you already know, the relative molecular mass of a substance (Mr) is calculated. The relative molecular mass of a simple substance is equal to the product of the relative atomic mass and the number of atoms in the molecule, for example oxygen O 2:

Мr(02) = Аr(0) × 2 = 16 × 2 = 32.

However, the element oxygen forms another gaseous simple substance - ozone, the molecules of which already contain three oxygen atoms. The chemical formula of ozone is 0 3, and its relative molecular weight: Mr(03) = 16 × 3 = 48.

The properties of allotropic modifications of the chemical element oxygen - the simple substances oxygen O 2 and ozone O 3 - are different. Oxygen is odorless, but ozone smells (hence its name - ozone means “smelling” in Greek). This smell, the aroma of freshness, can be felt during a thunderstorm, as ozone is formed in small quantities in the air as a result of electrical discharges.

Oxygen is a colorless gas, while ozone is a pale violet color. Ozone is more bactericidal (lat. tsidao - to kill) than oxygen. Therefore, ozone is used to disinfect drinking water. Ozone is capable of retaining ultraviolet rays from the solar spectrum, which are destructive to all life on Earth, and therefore the ozone layer, located in the atmosphere at an altitude of 20-35 km, protects life on our planet (in Figure 49 you see a photograph taken from space using an artificial satellite Earths where areas of low ozone content in the atmosphere (“ozone holes”) are indicated in white).

Rice. 49.
"Ozone holes" in the Earth's atmosphere

Of the simple substances - non-metals, under normal conditions only bromine is a liquid, the molecules of which are diatomic. Bromine formula Br 2. It is a heavy brown liquid with an unpleasant odor (hence the name, since bromos is translated from ancient Greek as “fetid”).

Some solid substances - non-metals - have been known since ancient times - sulfur and carbon (in the form of charcoal, diamond and graphite).

In solid substances - non-metals, the phenomenon of allotropy is also observed. Thus, the element carbon forms simple substances that differ in appearance, such as diamond and graphite (Fig. 50). The reason for the difference in the properties of diamond and graphite is the structure of the crystal lattices of these substances, which you will consider a little later.

Rice. 50.
Allotropic modifications of carbon and their areas of application

The element phosphorus has two allotropic modifications: red phosphorus (they cover the side of a matchbox with it) and white phosphorus. The latter has a tetraatomic molecule, its composition is reflected by the formula P 4.

A solid non-metal is crystalline iodine with a diatomic molecule I 2. Do not confuse it with an alcohol solution of iodine - an iodine tincture that is found in every home medicine cabinet.

Crystalline iodine and graphite are not like other simple substances - non-metals, they have a metallic luster.

To show the relativity of dividing simple substances into metals and non-metals based on their physical properties, let us consider the allotropy of the chemical element tin Sn. At room temperature, beta tin (β-Sn) usually exists. This is the well-known white tin - the metal from which tin soldiers were previously cast (Fig. 51, a) (remember the fairy tale by H. C. Andersen “The Steadfast Tin Soldier”). The inside of cans is coated with tin (Fig. 51, b). It is part of such a well-known alloy as bronze, as well as solder (Fig. 51, c).

Rice. 51.
Application areas of tin:
a - toys; b - production of cans; c - solder

At temperatures below +13.2 °C, alpha tin (α-Sn) is more stable - a gray fine-crystalline powder that has rather the properties of a non-metal. The process of turning white tin into gray occurs most quickly at a temperature of -33 ° C. This transformation received the figurative name “tin plague.”

Let us now compare simple substances - metals and non-metals using Table 3.

Table 3
Simple substances

Key words and phrases

1. Noble gases.
2. Allotropy and allotropic modifications, or modifications.
3. Oxygen and ozone.
4. Diamond and graphite.
5. Phosphorus red and white.
6. White and gray tin.
7. The relativity of the division of simple substances into metals and non-metals.

Work with computer

1. Refer to the electronic application. Study the lesson material and complete the assigned tasks.
2. Find email addresses on the Internet that can serve as additional sources that reveal the content of keywords and phrases in the paragraph. Offer your help to the teacher in preparing a new lesson - make a report on the key words and phrases of the next paragraph.

Questions and tasks

1. Consider the etymology of the names of individual noble gases.
2. Why is the poetic expression “There was a thunderstorm in the air” chemically incorrect?
3. Write down the formation schemes for molecules: Na 2, Br 2, O 2, N 2. What type of chemical bond is in these molecules?
4. What type of chemical bond must exist in metallic hydrogen?
5. The expedition of polar explorer R. Scott to the South Pole in 1912 died due to the fact that it lost its entire fuel supply: it was in tanks sealed with tin. What chemical process was behind this?

Non-metals are chemical elements that form simple substances in free form; they do not have the physical properties of metals. Of the 109 chemical elements, 87 can be classified as metals, 22 are non-metals.

Under normal conditions, nonmetals can be found in gaseous, liquid, and solid state.

Gases are helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn. This is all inert gases. Each molecule of an inert gas consists of one atom. At the outer electronic level, atoms of noble gases (except helium) have eight electrons. Helium only has two. Due to their chemical stability, noble gases can be compared to noble precious metals - gold and platinum, they also have another name - noble gases. This name is better suited to inert gases, since they can enter into chemical reactions and form chemical compounds. In 1962, it became known that xenon and fluorine could form compounds. Since that time, more than 150 chemical compounds of xenon, krypton, radon with fluorine, oxygen, chlorine and nitrogen have been known.

The idea of ​​the chemical exclusivity of noble or inert gases turned out to be not entirely correct, therefore, instead of the expected zero group, inert gases were assigned to the eighth group of the Periodic System.

Gases such as hydrogen, oxygen, nitrogen, chlorine and fluorine form diatomic molecules, already familiar to us H 2, O 2, N 2, CL 2, F 2.

The composition of a substance can be expressed using chemical and mathematical symbols - a chemical formula. As we already know, using a chemical formula you can calculate the relative molecular mass of a substance (Mr). The relative molecular mass of a simple substance is equal to the product of the relative atomic mass and the number of atoms in the molecule, for example, oxygen: O 2

Mr (O 2) = Ar (O) 2 = 16 · 2 = 32

However, oxygen can form another gaseous simplest substance - ozone; the ozone molecule already contains three oxygen atoms. Chemical formula O3.

The ability of atoms of one chemical element to create several simple substances is called allotropy, and these simple substances - allotropic changes, they are also called modifications.

The properties of allotropic modifications of the chemical element oxygen: simple substances O 2 and ozone O 3 differ significantly.

Oxygen does not have a characteristic odor, unlike ozone (this is where the name ozone comes from - translated from Greek, ozone means “smelling”). A similar aroma can be felt during a thunderstorm; the gas is formed in the air due to electrical discharges.

Oxygen has no color, unlike ozone, which can be distinguished by its pale purple hue. Ozone has bactericidal properties. It is also used to disinfect drinking water. Ozone can block the passage of ultraviolet rays from the solar spectrum, which are harmful to all living organisms on Earth. The ozone screen (layer), which is located at an altitude of 20-35 km, protects all living things from the harmful rays of the sun.

Of 22 simple non-metal substances under normal conditions in liquid-like state, only bromine exists, its molecules are diatomic. Bromine formula: Br 2.

Bromine is a heavy brown liquid with an unpleasant odor (bromos is translated from ancient Greek as “fetid”).

Non-metal solids such as sulfur and carbon have been known since ancient times (charcoal).

Solid Non-metallic substances are also prone to the phenomenon of allotropy. Carbon can form simple substances such as diamond, graphite, etc. The difference in the structure of diamond and graphite lies in the structure of the crystal lattices.

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A substance in which its constituent atoms and molecules move almost freely and chaotically in the intervals between collisions, during which a sharp change in the nature of their movement occurs. The French word gaz is derived from the Greek "chaos". The gaseous state of matter is the most common state of matter in the Universe. The sun, stars, clouds of interstellar matter, nebulae, and planetary atmospheres consist of gases, either neutral or ionized (plasma). Gases are widespread in nature: they form the Earth’s atmosphere, are found in significant quantities in solid earth rocks, and are dissolved in the water of oceans, seas and rivers. Naturally occurring gases are usually mixtures of chemically individual gases.

Gases uniformly fill the space available to them, and unlike liquids and solids, they do not form a free surface. They exert pressure on the shell that limits the space they fill. The density of gases at normal pressure is several orders of magnitude less than the density of liquids. Unlike solids and liquids, the volume of gases depends significantly on pressure and temperature.

The properties of most gases - transparency, colorlessness and lightness - made them difficult to study, so the physics and chemistry of gases developed slowly. Only in the 17th century. it was proven that air has weight (E. Torricelli and B. Pascal). At the same time, J. van Helmont introduced the term gases to designate air-like substances. And only by the middle of the 19th century. the basic laws that gases obey were established. These include Boyle-Mariotte's law, Charles's law, Gay-Lussac's law, Avogadro's law.

The properties of fairly rarefied gases, in which the distances between molecules under normal conditions are on the order of 10 nm, have been most fully studied, which is significantly greater than the radius of action of intermolecular interaction forces. Such a gas, whose molecules are considered as non-interacting material points, is called an ideal gas. Ideal gases strictly obey the laws of Boyle - Mariotte and Gay-Lussac. Almost all gases behave as ideal gases at not too high pressures and not too low temperatures.

The molecular kinetic theory of gases considers gases as a collection of weakly interacting particles (molecules or atoms) in continuous chaotic (thermal) motion. Based on these simple concepts of kinetic theory, it is possible to explain the basic physical properties of gases, especially the properties of rarefied gases. For sufficiently rarefied gases, the average distances between molecules are significantly larger than the radius of action of intermolecular forces. So, for example, under normal conditions there are ~ 10 19 molecules in 1 cm 3 of gas and the average distance between them is ~ 10 -6 cm. From the point of view of molecular kinetic theory, gas pressure is the result of numerous impacts of gas molecules on the walls of the vessel, averaged over time and along the walls of the vessel. Under normal conditions and the macroscopic dimensions of the vessel, the number of impacts on 1 cm 2 of surface is approximately 10 24 per second.

The internal energy of an ideal gas (the average value of the total energy of all its particles) depends only on its temperature. The internal energy of a monatomic gas having 3 translational degrees of freedom and consisting of N atoms is equal to:

As the density of a gas increases, its properties cease to be ideal, collision processes begin to play an increasingly important role, and the sizes of molecules and their interactions can no longer be neglected. Such a gas is called real gas. The behavior of real gases, depending on their temperature, pressure, and physical nature, differs to a greater or lesser extent from the laws of ideal gases. One of the main equations describing the properties of a real gas is the van der Waals equation, in the derivation of which two corrections were taken into account: the forces of attraction between molecules and their size.

Any substance can be converted into a gaseous state by appropriate selection of pressure and temperature. Therefore, the possible region of existence of the gaseous state is graphically depicted in variables: pressure R- temperature T(on p-T-diagram). There is a critical temperature Tk, below which this region is limited by the sublimation (sublimation) and vaporization curves, i.e. at any pressure below the critical pk there is a temperature T, defined by the sublimation or vaporization curve above which a substance becomes gaseous. At temperatures below Tc, the gas can be condensed - converted into another state of aggregation (solid or liquid). In this case, the phase transformation of a gas into a liquid or solid occurs abruptly: a slight change in pressure leads to a change in a number of properties of the substance (for example, density, enthalpy, heat capacity, etc.). Gas condensation processes, especially gas liquefaction, are of great technical importance.

The region of the gas state of a substance is very vast, and the properties of gases with changes in temperature and pressure can vary within wide limits. Thus, under normal conditions (at 0°C and atmospheric pressure), the density of a gas is approximately 1000 times less than the density of the same substance in a solid or liquid state. On the other hand, at high pressures, matter, which at supercritical temperatures can be considered a gas, has an enormous density (for example, in the center of some stars ~ 10 9 g/cm 3).

The internal structure of gas molecules has little effect on pressure, temperature, density and the connection between them, but significantly affects its electrical and magnetic properties. The caloric properties of gases, such as heat capacity, entropy, etc., also depend on the internal structure of the molecules.

The electrical properties of gases are determined by the possibility of ionization of molecules or atoms, i.e., the appearance of electrically charged particles (ions and electrons) in the gas. In the absence of charged particles, gases are good dielectrics. With increasing charge concentration, the electrical conductivity of gases increases. At temperatures above several thousand K, the gas is partially ionized and turns into plasma.

According to their magnetic properties, gases are divided into diamagnetic (inert gases, CO 2, H 2 O) and paramagnetic (O 2). Molecules of diamagnetic gases do not have a permanent magnetic moment and acquire it only under the influence of a magnetic field. Those gases whose molecules have a permanent magnetic moment behave like paramagnets.

In modern physics, gases are not only one of the aggregate states of matter. Gases with special properties include, for example, a set of free electrons in a metal (electron gas), phonons in a crystal (phonon gas). The properties of such gas particles are described by

The main component of the Earth's atmosphere. The word "Nitrogen", proposed by the French chemist A. Lavoisier at the end of the 18th century, is of Greek origin. "Nitrogen" means "Lifeless". This is exactly what Lavoisier, as well as his contemporaries, believed. The element nitrogen forms a simple substance, which under normal conditions is a gas, colorless, odorless and tasteless. This gas was isolated from the air in 1772 by Rutherford and Scheele. This gas did not support respiration or combustion, which is why it was named so. However, a person cannot breathe pure oxygen all the time. Even patients are given pure oxygen only for a short time. Calling it lifeless is not entirely correct. All plants are fed with nitrogen, potassium, phosphorus, and mineral fertilizers. Nitrogen is part of the most important organic compounds, including such important ones as proteins and amino acids. The relative inertness of this gas is extremely useful for humans. If it were more prone to chemical reactions, the Earth's atmosphere could not exist in the form in which it exists. A strong oxidizing agent, oxygen, would react with nitrogen to form toxic nitrogen oxides. But if nitrogen could not be fixed under any conditions, there would be no life on Earth. Nitrogen accounts for about 3% of the mass of the human body. Unfixed nitrogen is widely used. This is the cheapest of gases, chemically inert under normal conditions, therefore, in those processes of metallurgy and big chemistry where it is necessary to protect an active compound or molten metal from interaction with atmospheric oxygen, purely nitrogen protective atmospheres are created. Easily oxidizing substances are stored in laboratories under the protection of nitrogen. In metallurgy, the surfaces of some metals and alloys are saturated with nitrogen to give them greater hardness and wear resistance. For example, nitriding of steel and titanium alloys is widely known.

Liquid nitrogen (nitrogen melting and boiling points: -210*C and -196*C) is used in refrigeration units.

The low chemical activity of nitrogen is explained, first of all, by the structure of its molecule. In the molecule there is a triple bond between the nitrogen atoms. To destroy a nitrogen molecule, it is necessary to expend very high energy - 954.6 kJ/mol. Without the destruction of the molecule, nitrogen will not enter into a chemical bond. Under normal conditions, only lithium can react with it, forming nitride.

Atomic nitrogen is much more active, but even at 3000*C there is no noticeable decomposition of nitrogen molecules into atoms.

Nitrogen compounds are of great importance for science and for many industries. To obtain fixed nitrogen, humanity goes to enormous energy costs. The main method of nitrogen fixation in industrial conditions remains the synthesis of ammonia. Ammonia itself is used to a limited extent and usually in the form of aqueous solutions. But ammonia, unlike atmospheric nitrogen, quite easily enters into addition and substitution reactions. And it oxidizes more easily than nitrogen. Therefore, ammonia became the starting product for the production of most nitrogen-containing substances. There are five known nitrogen oxides. Nitric acid is widely used in industry. Its salts, nitrates, are used as fertilizers.

Nitrogen forms another acid – nitrous acid. Some microorganisms can bind nitrogen from the air. These are soil nitrogen-fixing bacteria.

The Latin name for nitrogen “nitrogenium” was introduced in 1790 by J. Chaptal, meaning

"giving birth to saltpeter."

V O D O R O D No. 1 N 1

In 1766, the English chemist G. Cavendish collected “combustible air” displaced by metals from acids and studied its properties. But only in 1787 A. Lavoisier proved that this “air” is part of water, and gave it the name “hydrogenium”, that is, giving birth to water, hydrogen.

Hydrogen on Earth, including water and air, accounts for about 1% by mass. This is a common and vital element. It is part of all plants and animals, as well as the most common substance on Earth - water.

Hydrogen is the most abundant element in the Universe. It stands at the beginning of a long and complex process of synthesis of elements in stars.

Solar energy is the main source of life on Earth. And the fundamental basis of this energy is the thermonuclear reaction, which occurs on the Sun in several stages. This releases a huge amount of energy. Man managed to reproduce on Earth a not very accurate semblance of the main solar reaction. Under terrestrial conditions, we can force only heavy isotopes of hydrogen - deuterium and tritium - to enter into such a reaction. Ordinary hydrogen - protium - with a mass of 1 is not subject to our control here.

Hydrogen occupies a special place in the periodic table of elements. This is the element from which the periodic table begins. It usually stands in group 1 above lithium. Because the hydrogen atom has one valence electron. But in modern editions of the table, hydrogen is placed in group 7 above fluorine, since hydrogen has something in common with halogens. In addition, hydrogen is capable of forming a compound with metals – a metal hydride. In practice, the most important of these is the compound of lithium with heavy hydrogen, deuterium. Hydrogen isotopes have very different physical and chemical properties, so they can be easily separated. The element hydrogen forms a simple substance, which is also called hydrogen. It is a gas, colorless, tasteless and odorless. It is the lightest of gases, 14.4 times lighter than air. Hydrogen becomes liquid at -252.6*C and solid at -259.1*C. Under normal conditions, the chemical activity of hydrogen is low; it reacts with fluorine and chlorine. But at elevated temperatures, hydrogen reacts with bromine, iodine, sulfur, selenium, tellurium, and in the presence of catalysts, with nitrogen, forming ammonia. A mixture of 2 volumes of hydrogen and 1 volume of oxygen is called detonating gas. It explodes violently when ignited. When hydrogen burns, it forms water. At high temperatures, hydrogen can “remove” oxygen from many molecules, including most metal oxides. Hydrogen is an excellent reducing agent. But since this reducing agent is expensive and not easy to work with, it is used to a limited extent for the reduction of metals. Hydrogen is widely used in the process of hydrogenation - converting liquid fats into solid ones. The largest consumers of hydrogen remain the production of ammonia and methyl alcohol. There is increasing interest these days in hydrogen as a source of thermal energy. This is due to the fact that the combustion of pure hydrogen releases more heat than the combustion of the same amount of any fuel. In addition, when burning hydrogen, no harmful impurities are released that pollute the atmosphere.

B E R I L I Y No. 4 Be 2 2

Beryllium was discovered in 1798 by the famous French chemist L. Vauquelin in the semi-precious stone beryl. Hence the name of the element. However, Vauquelin isolated only a new “earth” - an oxide of an unknown metal. Relatively pure beryllium was obtained in powder form only 30 years later, independently by F. Wöhler in Germany and E. Bussy in France.

For a long time, many chemists believed that beryllium was a trivalent metal with an atomic mass of 13.8. There was no place for such a metal in the periodic table, and then, despite the obvious similarity of beryllium with aluminum, D.I. Mendeleev placed this element in the second group, changing its atomic mass to 9. Soon the Swedish scientists L. Nilsson and O. Peterson found that the atomic mass of beryllium was 9.1, which corresponded to the assumptions of D.I. Mendeleev.

Beryllium is a rare element. The most common beryllium compound is beryl.

Be3Al2(SiO3)6. Beryllium is also found in other natural compounds. Among them are precious stones: emerald, aquamarine, heliodor, which were used for jewelry in ancient times.

Pure beryllium is a light gray, light and brittle metal. Beryllium is chemically active. Its atom easily gives up its 2 electrons from the outer shell (oxidation state +2). In air, beryllium is covered with an oxide film, BeO, which protects it from corrosion and is very refractory, and in water - with a film of Be(OH)2, which also protects the metal. Beryllium reacts with sulfuric, hydrochloric and other acids. It reacts with nitrogen only when heated. Easily combines with halogens, sulfur, and carbon.

In the second half of the 20th century, beryllium became necessary in many branches of technology. This metal and its alloys are distinguished by a unique combination of various properties. Beryllium-based structural materials are both lightweight and durable. They are also resistant to high temperatures. Being 1.5 times lighter than aluminum, these alloys are at the same time stronger than many special steels. Beryllium itself and many of its alloys do not lose these qualities at temperatures of 700–800 *C, which is why they are used in space and aviation technology.

Beryllium is also necessary in nuclear technology: it is resistant to radiation and acts as a neutron reflector.

The disadvantages of beryllium are its fragility and toxicity. All beryllium compounds are poisonous. A specific disease is known - berylliosis, which affects many systems of a living organism and even the skeleton.
L I T I Y No. 3 Li 2 1

Lithium was discovered in 1817 by the Swedish chemist A. Arfvedson while analyzing the mineral

petalite LiAl(Si4O10). This mineral looks like an ordinary stone, and therefore the metal was called lithium, from the Greek “lithos” - stone. The earth's crust contains three thousandths of a percent of its total mass. About 30 lithium minerals are known, 5 of them are of industrial importance.

Lithium is the lightest of the metals, almost twice as light as water. It is silvery-white in color, with a bright metallic sheen. Lithium is soft and can be easily cut with a knife. In air it quickly fades, combining with oxygen in the air. Lithium is significantly weaker than potassium or sodium. Reacting with water, it forms the alkali LiOH. However, it does not ignite, as happens in the reaction of potassium with water. But lithium reacts with nitrogen, carbon, and hydrogen more easily than other alkali metals. It is one of the few elements that combine directly with nitrogen.

Some lithium salts (carbonate, fluoride), unlike similar salts of its group neighbors, are poorly soluble in water. For a long time, both lithium and its compounds found almost no practical use. Only in the 20th century did they begin to be used in the production of batteries, in the chemical industry as catalysts, and in metallurgy. Lithium alloys are light, strong, and ductile. But the main area of ​​application of lithium today is nuclear technology.

One of the two natural isotopes of lithium with a mass of 6 turned out to be the most accessible source of industrial production of the heavy isotope of hydrogen - tritium, which participates in the thermonuclear reaction. Another lithium isotope with mass 7 is used as a coolant for nuclear reactors. Lithium deficiency in the human body leads to mental disorders. Excess metal in the body causes general lethargy, impaired breathing and heart rhythm, weakness, drowsiness, loss of appetite, thirst, visual disturbances, as well as dermatitis of the face and hands.

B O R No. 5 B 2 3

The name "bor" comes from the Arabic "burak" - "borax". This element was first isolated from boric acid in 1808 by the famous French chemists J. Gay-Lussac and L. Thénard. True, the boron substance they obtained contained no more than 70%. Boron of 99% purity was first obtained by the American chemist E. Weintraub only 101 years later.

In nature, boron occurs mainly in the form of borax NaB4O7 on 10H2O,

Kernite Na2B4O7 on 4H2O and sassolin (natural boric acid) H3BO3.

Very pure boron is colorless, but few have seen colorless boron. Due to impurities, fine-crystalline boron is usually dark gray, black or brown in color.

At ordinary temperatures, boron interacts only with fluorine; when heated, it interacts with other halogens, oxygen, sulfur, carbon, nitrogen, phosphorus, and metals, and among acids, with nitric and sulfuric acids. In compounds it exhibits an oxidation state of +3.

The most famous boron compound, boric acid, is quite widely used in medicine as a disinfectant. Borax, a salt of boric acid, has long been used in the production of special types of glass. But this is not why boron has become a very important element for industry these days.

Natural boron consists of only two isotopes with masses 10 and 11. In terms of chemical properties, they, like any isotopes of the same element, are practically indistinguishable, but for nuclear physics these isotopes are antipodes. Physicists are primarily interested in such characteristics of light isotopes as the ability of their nuclei to capture (or, conversely, not capture) neutrons formed during a nuclear chain reaction and necessary to maintain it. It turned out that the light boron isotope with mass 10 is one of the most aggressive “invaders” of thermal neutrons, while the heavy boron isotope with mass 11 is indifferent to them. Each of these isotopes can be useful in the construction of nuclear reactors to a greater extent than the natural mixture of isotopes of that element.

They have learned to separate boron isotopes in complex physical and chemical processes and obtain monoisotopic compounds and alloys. A boron isotope with a mass of 11 is used as an alloying additive in reactor core materials, and control rods are made from boron isotopes with a mass of 10, with the help of which they trap excess neutrons and thus regulate the course of the nuclear chain reaction.

Sodium and its compounds are widely used in industry. Liquid sodium serves as a coolant in some nuclear reactor designs. Metallic sodium is used to restore valuable metals such as zirconium, tantalum, and titanium from compounds. The world's first industrial method for producing rubber, developed by S.V. Lebedev, involved the use of a sodium catalyst. Sodium also participates in organic synthesis processes.

Many sodium compounds are important products of the chemical industry. This is caustic soda, or caustic soda, or caustic soda - NaOH. Soda ash or sodium carbonate. Sodium carbonate forms a decahydrate crystalline hydrate, known as crystalline soda. Potassium carbonate, known as potash, is widely used. The element is named sodium from the Arabic “natrun” - soda.