How is nitrogen designated in the periodic table? What kind of substance is nitrogen? Types and properties of nitrogen. Obtaining and using nitrogen

Properties of elements of the V-A subgroup

Element	Nitrogen N	Phosphorus R	Arsenic As	Antimony Sb	Bismuth Bi
Property
Element serial number	7	15	33	51	83
Relative atomic mass	14,007	30,974	74,922	121,75	208,980
Melting point, C 0	-210	44,1 (white)	817 (4MPa)	631	271
Boiling point, C 0	-196	280 (white)	613	1380	1560
Density g/cm 3	0,96 (solid)	1,82 (white)	5,72	6,68	9,80
Oxidation states	+5, +3,-3	+5, +3,-3	+5, +3,-3	+5, +3,-3	+5, +3,-3

1. Structure of atoms of chemical elements

Name chemical element	Atomic structure diagram	Electronic structure of the last energy level	Formula of higher oxide R 2 O 5	Volatile hydrogen compound formula RH 3
1. Nitrogen	N+7) 2) 5	…2s 2 2p 3	N2O5	NH 3
2. Phosphorus	P+15) 2) 8) 5	…3s 2 3p 3	P2O5	PH 3
3. Arsenic	As+33) 2) 8) 18) 5	…4s 2 4p 3	As2O5	AsH 3
4. Antimony	Sb+51) 2) 8) 18) 18) 5	…5s 2 5p 3	Sb2O5	SbH 3
5. Bismuth	Bi+83) 2) 8) 18) 32) 18) 5	…6s 2 6p 3	Bi2O5	BiH 3

The presence of three unpaired electrons at the outer energy level explains that in a normal, unexcited state, the valence of elements of the nitrogen subgroup is three.

Atoms of elements of the nitrogen subgroup (except for nitrogen - the outer level of nitrogen consists of only two sublevels - 2s and 2p) have vacant cells of the d-sublevel at the outer energy levels, so they can vaporize one electron from the s-sublevel and transfer it to the d-sublevel . Thus, the valency of phosphorus, arsenic, antimony and bismuth is 5.

Elements of the nitrogen group form compounds of the composition RH 3 with hydrogen, and oxides of the type R 2 O 3 and R 2 O 5 with oxygen. Oxides correspond to acids HRO 2 and HRO 3 (and ortho acids H 3 PO 4, except nitrogen).

The highest oxidation state of these elements is +5, and the lowest is -3.

Since the charge of the nucleus of atoms increases, the number of electrons at the outer level is constant, the number of energy levels in atoms increases and the radius of the atom increases from nitrogen to bismuth, the attraction of negative electrons to the positive nucleus weakens and the ability to lose electrons increases, and, therefore, in the nitrogen subgroup with As the serial number increases, non-metallic properties decrease, and metallic properties increase.

Nitrogen is a non-metal, bismuth is a metal. From nitrogen to bismuth, the strength of RH 3 compounds decreases, and the strength of oxygen compounds increases.

The most important among the elements of the nitrogen subgroup are nitrogen and phosphorus .

Nitrogen, physical and chemical properties, preparation and application

1. Nitrogen is a chemical element

N +7) 2) 5

1 s 2 2 s 2 2 p 3 unfinished external level, p -element, non-metal

Ar(N)=14

2. Possible oxidation states

Due to the presence of three unpaired electrons, nitrogen is very active and is found only in the form of compounds. Nitrogen exhibits oxidation states in compounds from “-3” to “+5”

3. Nitrogen - a simple substance, molecular structure, physical properties

Nitrogen (from Greek ἀ ζωτος - lifeless, lat. Nitrogenium), instead of the previous names (“phlogisticated”, “mephitic” and “spoiled” air) proposed in 1787 Antoine Lavoisier . As shown above, it was already known at that time that nitrogen supports neither combustion nor respiration. This property was considered the most important. Although it later turned out that nitrogen, on the contrary, is essential for all living beings, the name was preserved in French and Russian.

N 2 – covalent nonpolar bond, triple (σ, 2π), molecular crystal lattice

Conclusion:

1. Low reactivity at normal temperature

2. Gas, colorless, odorless, lighter than air

Mr ( B air)/ Mr ( N 2 ) = 29/28

4. Chemical properties of nitrogen

N – oxidizing agent (0 → -3)	N – reducing agent (0 → +5)
1. With metals nitrides are formed Mx Ny - when heated with Mg and alkaline earth and alkaline: 3С a + N 2= Ca 3 N 2 (at t) - c Li at k t room Nitrides are decomposed by water Ca 3 N 2 + 6H 2 O = 3Ca(OH) 2 + 2NH 3 2. With hydrogen 3 H 2 + N 2 ↔ 2 NH 3 (conditions - T, p, kat)	N 2 + O 2 ↔ 2 NO – Q (at t= 2000 C) Nitrogen does not react with sulfur, carbon, phosphorus, silicon and some other non-metals.

5. Receipt:

In industry nitrogen is obtained from the air. To do this, the air is first cooled, liquefied, and the liquid air is subjected to distillation. Nitrogen has a slightly lower boiling point (–195.8°C) than the other component of air, oxygen (–182.9°C), so when liquid air is gently heated, nitrogen evaporates first. Nitrogen gas is supplied to consumers in compressed form (150 atm. or 15 MPa) in black cylinders with a yellow “nitrogen” inscription. Store liquid nitrogen in Dewar flasks.

In the laboratorypure (“chemical”) nitrogen is obtained by adding a saturated solution of ammonium chloride NH 4 Cl to solid sodium nitrite NaNO 2 when heated:

NaNO 2 + NH 4 Cl = NaCl + N 2 + 2H 2 O.

You can also heat solid ammonium nitrite:

NH 4 NO 2 = N 2 + 2H 2 O. EXPERIMENT

6. Application:

In industry, nitrogen gas is used mainly to produce ammonia. As a chemically inert gas, nitrogen is used to provide an inert environment in various chemical and metallurgical processes, when pumping flammable liquids. Liquid nitrogen is widely used as a refrigerant; it is used in medicine, especially in cosmetology. Nitrogen mineral fertilizers are important in maintaining soil fertility.

7. Biological role

Nitrogen is an element necessary for the existence of animals and plants; it is part ofproteins (16-18% by weight), amino acids, nucleic acids, nucleoproteins, chlorophyll, hemoglobin etc. In the composition of living cells, the number of nitrogen atoms is about 2%, and the mass fraction is about 2.5% (fourth place after hydrogen, carbon and oxygen). In this regard, a significant amount of fixed nitrogen is contained in living organisms, “dead organic matter” and dispersed matter of the seas and oceans. This amount is estimated at approximately 1.9 10 11 tons. As a result of the processes of rotting and decomposition of nitrogen-containing organic matter, subject to favorable environmental factors, natural mineral deposits containing nitrogen can form, for example, “Chilean saltpeterN 2 → Li 3 N → NH 3

No. 2. Write down equations for the reaction of nitrogen with oxygen, magnesium and hydrogen. For each reaction, create an electronic balance, indicate the oxidizing agent and the reducing agent.

No. 3. One cylinder contains nitrogen gas, another contains oxygen, and the third contains carbon dioxide. How to distinguish these gases?

No. 4. Some flammable gases contain free nitrogen as an impurity. Can nitrogen oxide (II) be formed during the combustion of such gases in ordinary gas stoves? Why?

Nitrogen is a chemical element of group V of the periodic system of Mendeleev, having atomic number 7 and atomic mass 14.00674. What properties does this element have?

Physical properties of nitrogen

Nitrogen is a diatomic gas, odorless, colorless and tasteless. The boiling point of nitrogen at atmospheric pressure is -195.8 degrees, the melting point is -209.9 degrees. Solubility in water at 20 degrees is very low - 15.4 ml/l.

Rice. 1. Nitrogen atom.

Atmospheric nitrogen consists of two isotopes: 14N (99.64%) and 15N (0.36%). Radioactive isotopes of nitrogen 13N and 16N are also known.

The translation of the name of the element “nitrogen” is lifeless. This name is true for nitrogen as a simple substance, but in a bound state it is one of the main elements of life, and is also part of proteins, nucleic acids, vitamins, etc.

Chemical properties of nitrogen

In the nitrogen molecule, the chemical bond is carried out due to three common pairs of p-electrons, the orbitals of which are directed along the x, y, z axes.

A covalent bond that is formed by overlapping orbitals along a line connecting the centers of the joining atoms is called a q-bond.

A covalent bond that occurs when the orbitals on either side of the line connecting the centers of the joining atoms overlap is called a n-bond. The nitrogen molecule has one q-bond and two p-bonds.

Rice. 2. Bonds in a nitrogen molecule.

Molecular nitrogen is a chemically inactive substance, this is explained by the triple bond between the nitrogen atoms and its short length

Under normal conditions, nitrogen can only react with lithium:

6Li+N 2 =2Li 3 N (lithium nitrite)

At high temperatures, the bonds between atoms weaken and nitrogen becomes more reactive. When heated, it can react with other metals, for example with magnesium, calcium, aluminum to form nitrides:

3Mg+N 2 =Mg 3 N 2

3Ca+N2 =Ca3N2

By passing nitrogen through hot coke, a compound of nitrogen and carbon is obtained - cyanogen.

Rice. 3. Dicyan formula.

With aluminum oxide and carbon, nitrogen also forms aluminum nitride at high temperatures:

Al 2 O 3 +3C+N 2 =2AlN+3CO,

and with soda and coal - sodium cyanide:

Na 2 CO 3 +4C+N 2 =2NaCN+3CO

When in contact with water, many nitrides completely hydrolyze to form ammonia and metal hydroxide:

Mg 3 N 2 +6H 2 O=3Mg(OH) 2 +2NH 3

At the temperature of the electric arc (3000-4000 degrees), nitrogen reacts with oxygen:. Total ratings received: 224.

Electronic configuration 2s 2 2p 3 Chemical properties Covalent radius 75 pm Ion radius 13 (+5e) 171 (-3e) pm Electronegativity
(according to Pauling) 3,04 Electrode potential — Oxidation states 5, 4, 3, 2, 1, 0, -1, -3 Thermodynamic properties of a simple substance Density 0.808 (−195.8 °C)/cm³ Molar heat capacity 29.125 (gas N 2) J /( mol) Thermal conductivity 0.026 W/( ·) Melting temperature 63,29 Heat of Melting (N 2) 0.720 kJ/mol Boiling temperature 77,4 Heat of vaporization (N 2) 5.57 kJ/mol Molar volume 17.3 cm³/mol Crystal lattice of a simple substance Lattice structure cubic Lattice parameters 5,661 c/a ratio — Debye temperature n/a

N	7
14,00674
2s 2 2p 3
Nitrogen

Nitrogen, in the form of diatomic N2 molecules, makes up most of the atmosphere, where its content is 75.6% (by mass) or 78.084% (by volume), that is, about 3.87 10 15 tons.

The mass of nitrogen dissolved in the hydrosphere, taking into account that the processes of dissolution of atmospheric nitrogen in water and its release into the atmosphere simultaneously occur, is about 2 10 13 tons, in addition, approximately 7 10 11 tons of nitrogen are contained in the hydrosphere in the form of compounds.

Biological role

Nitrogen is an element necessary for the existence of animals and plants; it is part of proteins (16-18% by weight), amino acids, nucleic acids, nucleoproteins, chlorophyll, hemoglobin, etc. In the composition of living cells, the number of nitrogen atoms is about 2%, by mass fraction - about 2.5% (fourth place after hydrogen, carbon and oxygen). In this regard, a significant amount of fixed nitrogen is contained in living organisms, “dead organic matter” and dispersed matter of the seas and oceans. This amount is estimated at approximately 1.9 10 11 tons. As a result of the processes of rotting and decomposition of nitrogen-containing organic matter, subject to favorable environmental factors, natural deposits of minerals containing nitrogen can form, for example, “Chilean saltpeter” (sodium nitrate with impurities other compounds), Norwegian, Indian saltpeter.

Nitrogen cycle in nature

Nitrogen cycle in nature

Fixation of atmospheric nitrogen in nature occurs in two main directions - abiogenic and biogenic. The first pathway involves mainly reactions of nitrogen with oxygen. Since nitrogen is chemically very inert, large amounts of energy (high temperatures) are required for oxidation. These conditions are achieved during lightning strikes when the temperature reaches 25,000 °C or more. In this case, the formation of various nitrogen oxides occurs. There is also the possibility that abiotic fixation occurs as a result of photocatalytic reactions on the surface of semiconductors or broadband dielectrics (desert sand).

However, the main part of molecular nitrogen (about 1.4·10 8 t/year) is fixed biotically. For a long time it was believed that only a small number of species of microorganisms (albeit widespread on the Earth’s surface) could bind molecular nitrogen: bacteria Azotobacter And Clostridium, nodule bacteria of leguminous plants Rhizobium, cyanobacteria Anabaena, Nostoc etc. It is now known that many other organisms in water and soil have this ability, for example, actinomycetes in the tubers of alder and other trees (160 species in total). All of them convert molecular nitrogen into ammonium compounds (NH 4 +). This process requires significant energy expenditure (to fix 1 g of atmospheric nitrogen, bacteria in legume nodules consume about 167.5 kJ, that is, they oxidize approximately 10 g of glucose). Thus, the mutual benefit from the symbiosis of plants and nitrogen-fixing bacteria is visible - the former provide the latter with a “place to live” and supply the “fuel” obtained as a result of photosynthesis - glucose, the latter provide the nitrogen necessary for plants in a form that they can absorb.

Nitrogen in the form of ammonia and ammonium compounds, resulting from biogenic nitrogen fixation processes, is quickly oxidized to nitrates and nitrites (this process is called nitrification). The latter, not connected by plant tissues (and further along the food chain by herbivores and predators), do not remain in the soil for long. Most nitrates and nitrites are highly soluble, so they are washed away by water and eventually end up in the world's oceans (this flow is estimated at 2.5-8·10 7 t/year).

Nitrogen included in the tissues of plants and animals, after their death, undergoes ammonification (decomposition of nitrogen-containing complex compounds with the release of ammonia and ammonium ions) and denitrification, that is, the release of atomic nitrogen, as well as its oxides. These processes occur entirely due to the activity of microorganisms under aerobic and anaerobic conditions.

In the absence of human activity, the processes of nitrogen fixation and nitrification are almost completely balanced by the opposite reactions of denitrification. Part of the nitrogen enters the atmosphere from the mantle with volcanic eruptions, part is firmly fixed in soils and clay minerals, in addition, nitrogen is constantly leaking from the upper layers of the atmosphere into interplanetary space.

Toxicology of nitrogen and its compounds

Atmospheric nitrogen itself is inert enough to have a direct effect on the human body and mammals. However, with high blood pressure, it causes narcosis, intoxication or suffocation (due to lack of oxygen); When pressure decreases rapidly, nitrogen causes decompression sickness.

Many nitrogen compounds are very active and often toxic.

Receipt

In laboratories it can be obtained by the decomposition reaction of ammonium nitrite:

NH 4 NO 2 → N 2 + 2H 2 O

The reaction is exothermic, releasing 80 kcal (335 kJ), so the vessel must be cooled while it occurs (although ammonium nitrite must be heated to start the reaction).

In practice, this reaction is performed by adding dropwise a saturated solution of sodium nitrite to a heated saturated solution of ammonium sulfate, and the ammonium nitrite formed as a result of the exchange reaction instantly decomposes.

The gas released in this case is contaminated with ammonia, nitrogen oxide (I) and oxygen, from which it is purified by successively passing through solutions of sulfuric acid, iron (II) sulfate and over hot copper. The nitrogen is then dried.

Another laboratory method for producing nitrogen is heating a mixture of potassium dichromate and ammonium sulfate (in a ratio of 2:1 by weight). The reaction proceeds according to the equations:

K 2 Cr 2 O 7 + (NH 4) 2 SO 4 = (NH 4) 2 Cr 2 O 7 + K 2 SO 4

(NH 4) 2 Cr 2 O 7 →(t) Cr 2 O 3 + N 2 + 4H 2 O

The purest nitrogen can be obtained by decomposition of metal azides:

2NaN 3 →(t) 2Na + 3N 2

The so-called “air” or “atmospheric” nitrogen, that is, a mixture of nitrogen with noble gases, is obtained by reacting air with hot coke:

O 2 + 4N 2 + 2C → 2CO + 4N 2

This produces so-called “generator” or “air” gas - raw materials for chemical synthesis and fuel. If necessary, nitrogen can be separated from it by absorbing carbon monoxide.

Molecular nitrogen is produced industrially by fractional distillation of liquid air. This method can also be used to obtain “atmospheric nitrogen”. Nitrogen plants that use adsorption and membrane gas separation methods are also widely used.

One of the laboratory methods is passing ammonia over copper (II) oxide at a temperature of ~700°C:

2NH 3 + 3CuO → N 2 + 3H 2 O + 3Cu

Ammonia is taken from its saturated solution by heating. The amount of CuO is 2 times greater than calculated. Immediately before use, nitrogen is purified from oxygen and ammonia by passing over copper and its oxide (II) (also ~700°C), then dried with concentrated sulfuric acid and dry alkali. The process is quite slow, but it is worth it: the gas obtained is very clean.

Properties

Physical properties

Optical line emission spectrum of nitrogen

Under normal conditions, nitrogen is a colorless gas, odorless, and slightly soluble in water (2.3 ml/100g at 0 °C, 0.8 ml/100g at 80 °C).

In the liquid state (boiling point -195.8 °C) it is a colorless, mobile liquid like water. When in contact with air, it absorbs oxygen from it.

At -209.86 °C, nitrogen turns into a solid state in the form of a snow-like mass or large snow-white crystals. Upon contact with air, it absorbs oxygen from it and melts, forming a solution of oxygen in nitrogen.

Three crystalline modifications of solid nitrogen are known. In the range 36.61 - 63.29 K there is a β-N 2 phase with hexagonal close packing, space group P6 3/mmc, lattice parameters a=3.93 Å and c=6.50 Å. At temperatures below 36.61 K, the α-N 2 phase with a cubic lattice is stable, having space group Pa3 or P2 1 3 and period a = 5.660 Å. Under a pressure of more than 3500 atmospheres and a temperature below 83 K, the hexagonal γ-N 2 phase is formed.

Chemical properties, molecular structure

Nitrogen in the free state exists in the form of diatomic N 2 molecules, the electronic configuration of which is described by the formula σ s ²σ s *2 π x, y 4 σ z ², which corresponds to the triple bond between nitrogen molecules N≡N (bond length d N≡N = 0.1095 nm). As a result, the nitrogen molecule is extremely strong for the dissociation reaction N 2 ↔ 2N specific enthalpy of formation ΔH° 298 =945 kJ, reaction rate constant K 298 =10 -120, that is, dissociation of nitrogen molecules practically does not occur under normal conditions (equilibrium is almost completely shifted to the left). The nitrogen molecule is nonpolar and weakly polarized, the interaction forces between molecules are very weak, therefore, under normal conditions, nitrogen is gaseous.

Even at 3000 °C, the degree of thermal dissociation of N 2 is only 0.1%, and only at a temperature of about 5000 °C reaches several percent (at normal pressure). In high layers of the atmosphere, photochemical dissociation of N 2 molecules occurs. In laboratory conditions, it is possible to obtain atomic nitrogen by passing gaseous N 2 under strong discharge through the field of a high-frequency electric discharge. Atomic nitrogen is much more active than molecular nitrogen: in particular, at ordinary temperatures it reacts with sulfur, phosphorus, arsenic and a number of metals, for example, co.

Due to the great strength of the nitrogen molecule, many of its compounds are endothermic, the enthalpy of their formation is negative, and nitrogen compounds are thermally unstable and quite easily decompose when heated. That is why nitrogen on Earth is mostly in a free state.

Due to its significant inertness, nitrogen reacts only with lithium under normal conditions:

6Li + N 2 → 2Li 3 N,

when heated, it reacts with some other metals and non-metals, also forming nitrides:

3Mg + N 2 → Mg 3 N 2,

Hydrogen nitride (ammonia) is of greatest practical importance:

Industrial fixation of atmospheric nitrogen

Nitrogen compounds are extremely widely used in chemistry; it is impossible even to list all the areas where substances containing nitrogen are used: this is the industry of fertilizers, explosives, dyes, medicines, etc. Although colossal quantities of nitrogen are available literally “from the air,” due to the strength of the nitrogen molecule N 2 described above, the problem of obtaining nitrogen-containing compounds from the air has long remained unsolved; Most of the nitrogen compounds were extracted from its minerals, such as Chilean saltpeter. However, the reduction in reserves of these minerals, as well as the growing need for nitrogen compounds, forced work on the industrial fixation of atmospheric nitrogen to be accelerated.

The most common ammonia method of fixing atmospheric nitrogen. Reversible reaction of ammonia synthesis:

3H 2 + N 2 ↔ 2NH 3

exothermic (thermal effect 92 kJ) and comes with a decrease in volume, therefore, to shift the equilibrium to the right in accordance with the Le Chatelier-Brown principle, cooling of the mixture and high pressures are necessary. However, from a kinetic point of view, lowering the temperature is unfavorable, since this greatly reduces the reaction rate - already at 700 °C the reaction rate is too low for practical use.

In such cases, catalysis is used because a suitable catalyst allows the reaction rate to be increased without shifting the equilibrium. In the process of searching for a suitable catalyst, about twenty thousand different compounds were tried. Based on the combination of properties (catalytic activity, resistance to poisoning, low cost), the most widely used catalyst is one based on metallic iron with admixtures of aluminum and potassium oxides. The process is carried out at temperatures of 400–600°C and pressures of 10–1000 atmospheres.

It should be noted that at pressures above 2000 atmospheres, the synthesis of ammonia from a mixture of hydrogen and nitrogen occurs at high speed and without a catalyst. For example, at 850 °C and 4500 atmospheres, the product yield is 97%.

There is another, less common method for the industrial binding of atmospheric nitrogen - the cyanamide method, based on the reaction of calcium carbide with nitrogen at 1000 °C. The reaction occurs according to the equation:

CaC 2 + N 2 → CaCN 2 + C.

The reaction is exothermic, its thermal effect is 293 kJ.

Every year, approximately 1·10 6 tons of nitrogen are removed from the Earth's atmosphere industrially. The process of obtaining nitrogen is described in detail here GRASYS

Nitrogen compounds

The oxidation states of nitrogen in compounds are −3, −2, −1, +1, +2, +3, +4, +5.

Nitrogen compounds in the −3 oxidation state are represented by nitrides, of which ammonia is practically the most important;
Nitrogen compounds in the −2 oxidation state are less typical and are represented by pernitrides, of which the most important is hydrogen pernitride N2H4 or hydrazine (there is also an extremely unstable hydrogen pernitride N2H2, diimide);
Nitrogen compounds in the oxidation state −1 NH2OH (hydroxylamine) is an unstable base used, along with hydroxylammonium salts, in organic synthesis;
Nitrogen compounds in oxidation state +1 nitric oxide (I) N2O (nitrous oxide, laughing gas);
Nitrogen compounds in oxidation state +2 nitric oxide (II) NO (nitrogen monoxide);
Nitrogen compounds in the oxidation state +3 nitrogen oxide (III) N2O3, nitrous acid, derivatives of the anion NO2-, nitrogen trifluoride NF3;
Nitrogen compounds in oxidation state +4 nitrogen oxide (IV) NO2 (nitrogen dioxide, brown gas);
Nitrogen compounds in the oxidation state +5 - nitric oxide (V) N2O5, nitric acid and its salts - nitrates, etc.

Use and application

Low-boiling liquid nitrogen in a metal beaker.

Liquid nitrogen is used as a refrigerant and for cryotherapy.

Industrial applications of nitrogen gas are due to its inert properties. Gaseous nitrogen is fire and explosion-proof, prevents oxidation and rotting. In petrochemistry, nitrogen is used to purge tanks and pipelines, check the operation of pipelines under pressure, and increase the production of fields. In mining, nitrogen can be used to create an explosion-proof environment in mines and to expand rock layers. In electronics manufacturing, nitrogen is used to purge areas that do not allow the presence of oxidizing oxygen. In a process traditionally carried out using air, if oxidation or decay are negative factors, nitrogen can successfully replace air.

An important area of ​​application of nitrogen is its use for the further synthesis of a wide variety of compounds containing nitrogen, such as ammonia, nitrogen fertilizers, explosives, dyes, etc. Large quantities of nitrogen are used in coke production (“dry quenching of coke”) during unloading coke from coke oven batteries, as well as for “pressing” fuel in rockets from tanks to pumps or engines.

In the food industry, nitrogen is registered as a food additive E941, as a gaseous medium for packaging and storage, a refrigerant, and liquid nitrogen is used when bottling oils and non-carbonated drinks to create excess pressure and an inert environment in soft containers.

Liquid nitrogen is often shown in movies as a substance that can instantly freeze fairly large objects. This is a common mistake. Even freezing a flower requires quite a long time. This is partly due to the very low heat capacity of nitrogen. For the same reason, it is very difficult to cool, say, locks to −196 °C and split them with one blow.

A liter of liquid nitrogen, evaporating and heating to 20 °C, forms approximately 700 liters of gas. For this reason, liquid nitrogen is stored in special open-type vacuum-insulated Dewar vessels or cryogenic pressure tanks. The principle of extinguishing fires with liquid nitrogen is based on the same fact. By evaporating, nitrogen displaces the oxygen necessary for combustion, and the fire stops. Since nitrogen, unlike water, foam or powder, simply evaporates and disappears, nitrogen fire extinguishing is the most effective fire extinguishing mechanism in terms of preservation of valuables.

Freezing living beings with liquid nitrogen with the possibility of their subsequent defrosting is problematic. The problem is the inability to freeze (and unfreeze) a creature quickly enough so that the inhomogeneity of freezing does not affect its vital functions. Stanislaw Lem, fantasizing about this topic in his book “Fiasco,” came up with an emergency nitrogen freezing system in which a nitrogen hose, knocking out teeth, was thrust into the astronaut’s mouth and a copious stream of nitrogen was supplied inside.

Cylinder marking

Nitrogen cylinders are painted black, must have a yellow inscription and a brown stripe (standards

Nitrogen is a chemical element with atomic number 7. It is an odorless, tasteless and colorless gas.


Thus, a person does not feel the presence of nitrogen in the earth’s atmosphere, while it consists of 78 percent of this substance. Nitrogen is one of the most common substances on our planet. You can often hear that without nitrogen there would be no food, and this is true. After all, the protein compounds that make up all living things necessarily contain nitrogen.

Nitrogen in nature

Nitrogen is found in the atmosphere in the form of molecules consisting of two atoms. In addition to the atmosphere, nitrogen is found in the Earth's mantle and in the humus layer of the soil. The main source of nitrogen for industrial production is minerals.

However, in recent decades, when mineral reserves began to deplete, an urgent need arose to separate nitrogen from the air on an industrial scale. This problem has now been solved, and huge volumes of nitrogen for industrial needs are extracted from the atmosphere.

The role of nitrogen in biology, the nitrogen cycle

On Earth, nitrogen undergoes a number of transformations in which both biotic (life-related) and abiotic factors are involved. Nitrogen enters plants from the atmosphere and soil, not directly, but through microorganisms. Nitrogen-fixing bacteria retain and process nitrogen, converting it into a form that can be easily absorbed by plants. In the plant body, nitrogen is converted into complex compounds, in particular proteins.

Through the food chain, these substances enter the bodies of herbivores and then predators. After the death of all living things, nitrogen returns to the soil, where it undergoes decomposition (ammonification and denitrification). Nitrogen is fixed in the soil, minerals, water, enters the atmosphere, and the circle repeats.

Application of nitrogen

After the discovery of nitrogen (this happened in the 18th century), the properties of the substance itself, its compounds, and the possibility of using it on the farm were well studied. Since the reserves of nitrogen on our planet are huge, this element has become extremely actively used.


Pure nitrogen is used in liquid or gaseous form. Liquid nitrogen has a temperature of minus 196 degrees Celsius and is used in the following areas:

— in medicine. Liquid nitrogen is a refrigerant in cryotherapy procedures, that is, cold treatment. Flash freezing is used to remove various tumors. Tissue samples and living cells (in particular, sperm and eggs) are stored in liquid nitrogen. Low temperature allows the biomaterial to be preserved for a long time, and then thawed and used.

The possibility of storing entire living organisms in liquid nitrogen, and, if necessary, defrosting them without any harm, was expressed by science fiction writers. However, in reality it has not yet been possible to master this technology;

— in the food industry Liquid nitrogen is used when bottling liquids to create an inert environment in the container.

In general, nitrogen is used in areas where a gaseous environment without oxygen is required, e.g.

— in fire fighting. Nitrogen displaces oxygen, without which combustion processes are not supported and the fire goes out.

Nitrogen gas has found application in the following industries:

— food production. Nitrogen is used as an inert gas medium to maintain the freshness of packaged products;

— in the oil industry and mining. Pipelines and tanks are purged with nitrogen, it is injected into mines to form an explosion-proof gas environment;

— in aircraft manufacturing The chassis tires are inflated with nitrogen.

All of the above applies to the use of pure nitrogen, but do not forget that this element is the starting material for the production of a mass of various compounds:

- ammonia. An extremely sought-after substance containing nitrogen. Ammonia is used in the production of fertilizers, polymers, soda, and nitric acid. It is itself used in medicine, in the manufacture of refrigeration equipment;

— nitrogen fertilizers;

- explosives;

- dyes, etc.


Nitrogen is not only one of the most common chemical elements, but also a very necessary component used in many branches of human activity.

Nitrogen is a well-known chemical element, which is denoted by the letter N. This element is perhaps the basis of inorganic chemistry; it begins to be studied in detail in the 8th grade. In this article we will look at this chemical element, as well as its properties and types.

History of the discovery of a chemical element

Nitrogen is an element that was first introduced by the famous French chemist Antoine Lavoisier. But many scientists are fighting for the title of discoverer of nitrogen, including Henry Cavendish, Karl Scheele, and Daniel Rutherford.

As a result of the experiment, he was the first to isolate a chemical element, but never realized that he had obtained a simple substance. He reported on his experience and also did a number of studies. Priestley probably also managed to isolate this element, but the scientist could not understand what exactly he got, so he did not deserve the title of discoverer. Karl Scheele carried out the same research at the same time as them, but did not come to the desired conclusion.

In the same year, Daniel Rutherford managed not only to obtain nitrogen, but also to describe it, publish a dissertation and indicate the basic chemical properties of the element. But even Rutherford never fully understood what he got. However, it is he who is considered the discoverer, because he was closest to the solution.

Origin of the name nitrogen

From Greek "nitrogen" is translated as "lifeless". It was Lavoisier who worked on the rules of nomenclature and decided to name the element that way. In the 18th century, all that was known about this element was that it did not support breathing. Therefore, this name was adopted.

In Latin, nitrogen is called “nitrogenium”, which means “giving birth to saltpeter”. The designation for nitrogen came from the Latin language - the letter N. But the name itself did not take root in many countries.

Element prevalence

Nitrogen is perhaps one of the most abundant elements on our planet, ranking fourth in abundance. The element is also found in the solar atmosphere, on the planets Uranus and Neptune. The atmospheres of Titan, Pluto and Triton are made of nitrogen. In addition, the Earth's atmosphere consists of 78-79 percent of this chemical element.

Nitrogen plays an important biological role, because it is necessary for the existence of plants and animals. Even the human body contains 2 to 3 percent of this chemical element. Part of chlorophyll, amino acids, proteins, nucleic acids.

A liquid nitrogen

Liquid nitrogen is a colorless transparent liquid, one of the aggregate states of the chemical nitrogen, widely used in industry, construction and medicine. It is used for freezing organic materials, cooling equipment, and in medicine for removing warts (aesthetic medicine).

Liquid nitrogen is non-toxic and non-explosive.

Molecular nitrogen

Molecular nitrogen is an element that is found in the atmosphere of our planet and forms most of it. The formula of molecular nitrogen is N 2. Such nitrogen reacts with other chemical elements or substances only at very high temperatures.

Physical properties

Under normal conditions, the chemical element nitrogen is odorless, colorless, and practically insoluble in water. Liquid nitrogen has a consistency similar to water, and is equally transparent and colorless. Nitrogen has another state of aggregation; at temperatures below -210 degrees, it turns into a solid and forms many large snow-white crystals. Absorbs oxygen from the air.

Chemical properties

Nitrogen belongs to the group of non-metals and takes on properties from other chemical elements from this group. In general, nonmetals are not good conductors of electricity. Nitrogen forms various oxides, such as NO (monoxide). NO or nitric oxide is a muscle relaxant (a substance that significantly relaxes muscles without causing any harm or other effects on the human body). Oxides containing more nitrogen atoms, for example N 2 O, is a laughing gas with a slightly sweet taste, which is used in medicine as an anesthetic. However, NO 2 oxide has nothing to do with the first two, because it is a rather harmful exhaust gas, which is contained in car exhaust and seriously pollutes the atmosphere.

Nitric acid, which is formed by hydrogen atoms, nitrogen atoms and three oxygen atoms, is a strong acid. It is widely used in the production of fertilizers, jewelry, organic synthesis, the military industry (production of explosives and the synthesis of toxic substances), production of dyes, medicines, etc. Nitric acid is very harmful to the human body; it leaves ulcers and chemical burns on the skin.

People mistakenly believe that carbon dioxide is nitrogen. In fact, due to its chemical properties, the element reacts with only a small number of elements under normal conditions. And carbon dioxide is carbon monoxide.

Application of a chemical element

Liquid nitrogen is used in medicine for cold treatment (cryotherapy), and also in cooking as a refrigerant.

This element has also found wide application in industry. Nitrogen is a gas that is explosion- and fireproof. In addition, it prevents rotting and oxidation. Now nitrogen is used in mines to create an explosion-proof environment. Nitrogen gas is used in petrochemicals.

In the chemical industry it is very difficult to do without nitrogen. It is used for the synthesis of various substances and compounds, for example, some fertilizers, ammonia, explosives, and dyes. Nowadays large amounts of nitrogen are used for the synthesis of ammonia.

In the food industry, this substance is registered as a food additive.

Mixture or pure substance?

Even scientists in the first half of the 18th century who managed to isolate the chemical element thought that nitrogen was a mixture. But there is a big difference between these concepts.

It has a whole range of permanent properties, such as composition, physical and chemical properties. A mixture is a compound that contains two or more chemical elements.

We now know that nitrogen is a pure substance because it is a chemical element.

When studying chemistry, it is very important to understand that nitrogen is the basis of all chemistry. It forms various compounds that we all encounter, including laughing gas, brown gas, ammonia, and nitric acid. It is not for nothing that chemistry at school begins with the study of such a chemical element as nitrogen.