Inert gases and hematopoiesis. inert gases

British International School

Abstract in chemistry

“Inert gases and their properties”

9th grade student

Sokolenko Alexey

Supervisor:

Chernysheva I.V.

IIntroduction………………………………………………………………………………2

1.1 Inert gases - elements of group VIIIA……………………………………...2

1.2 Argon on earth and in the universe…………………………………………………….5

IIstory of gas opening ………………………………………………… .................. 7

2.1 Argon…………………………………………………………………………………7

2.2 Helium…………………..…………………………………………………………..8

2.3 Krypton………………………………………………………..…………………..9

2.4 Neon……………………………………………………………..…………………9

2.5 Xenon……………………………………………………………….…………….9

2.6 Radon………………………………………………………………..…………….10

IIIProperties of inert gases and their compounds…………………………………….....10

3.1 Physical properties of inert gases………………………………………….10

3.2 Chemical properties of inert gases……………………………………….....11

3.3 Obtaining Argon…………………………………………………...…………..14

3.4 Physiological properties of inert gases……………………………………15

IV Application of inert gases……………………………………………………..…..16

List of used literature………………………………………………....18

IIntroduction.

Everywhere and everywhere we are surrounded by atmospheric air. What does it consist of? The answer is not difficult: out of 78.08 percent nitrogen, 20.9 percent oxygen, 0.03 percent carbon dioxide, 0.00005 percent hydrogen, about 0.94 percent are the so-called inert gases. The latter were discovered only at the end of the last century.

Radon is formed from the radioactive decay of radium and is found in trace amounts in uranium-containing materials, as well as in some natural waters. Helium, which is a product of the radioactive α-decay of elements, is sometimes found in significant amounts in natural gas and gas released from oil wells. This element is found in large quantities in the Sun and other stars. It is the second most abundant element in the universe (after hydrogen).

1.1 Inert gases - elements of group 8A.

Configuration of the outer electron layer of helium atoms 1 s 2 , other elements of subgroup VIII - ns 2 np 6 .

1.2 Argon on earth and in the universe.

There is much more argon on Earth than all the other elements of its group combined. Its average content in the earth's crust (clarke) is 14 times more than helium, and 57 times more than neon. There is argon in water, up to 0.3 cm 3 per liter of sea water and up to 0.55 cm 3 per liter of fresh water. It is curious that more argon is found in the air of the swim bladder of fish than in atmospheric air. This is because argon is more soluble in water than nitrogen... The main "storage" of terrestrial argon is the atmosphere. Its content (by weight) is 1.286%, and 99.6% of atmospheric argon is the heaviest isotope - argon-40. The proportion of this isotope in the argon of the earth's crust is even greater. Meanwhile, for the vast majority of light elements, the picture is reversed - light isotopes predominate. The reason for this anomaly was discovered in 1943. There is a powerful source of argon-40 in the earth's crust - a radioactive isotope of potassium 40 K. At first glance, there is not much of this isotope in the bowels - only 0.0119% of the total potassium content. However, the absolute amount of potassium-40 is large, since potassium is one of the most abundant elements on our planet. Each ton of igneous rocks contains 3.1 g of potassium-40. The radioactive decay of atomic nuclei of potassium-40 proceeds simultaneously in two ways. Approximately 88% of potassium-40 undergoes beta decay and turns into calcium-40. But in 12 cases out of 100 (on average), potassium-40 nuclei do not emit, but, on the contrary, capture one electron from the K-orbit closest to the nucleus (“K-capture”). The captured electron combines with a proton - a new neutron is formed in the nucleus and a neutrino is emitted. The atomic number of an element decreases by one, while the mass of the nucleus remains virtually unchanged. So potassium is converted to argon. The half-life of 40 K is quite large - 1.3 billion years. Therefore, the process of formation of 40 Ar in the bowels of the Earth will continue for a long time, a very long time. Therefore, although extremely slowly, the argon content in the earth's crust and atmosphere will steadily increase, where argon is "exhaled" by the lithosphere as a result of volcanic processes, weathering and recrystallization of rocks, as well as water sources. True, during the existence of the Earth, the stock of radioactive potassium has been thoroughly depleted - it has become 10 times smaller (if the age of the Earth is taken to be 4.5 billion years.). The ratio of isotopes 40 Ar: 40 K and 40 Ar: 36 Ar in rocks formed the basis of the argon method for determining the absolute age of minerals. Obviously, the greater this relationship, the older the breed. The argon method is considered the most reliable method for determining the age of igneous rocks and most potash minerals. For the development of this method, Professor E.K. Gerling was awarded the Lenin Prize in 1963. So, all or almost all argon-40 originated on Earth from potassium-40. Therefore, the heavy isotope dominates in terrestrial argon. By the way, this factor explains one of the anomalies of the periodic system. Contrary to the original principle of its construction - the principle of atomic weights - argon is placed ahead of potassium in the table. If light isotopes prevailed in argon, as in neighboring elements (as it apparently takes place in space), then the atomic weight of argon would be two or three units less ... Now about light isotopes. Where do 36 Ar and 38 Ar come from? It is possible that some part of these atoms is of relict origin, i.e. part of the light argon came into the earth's atmosphere from space during the formation of our planet and its atmosphere. But most of the light isotopes of argon were born on Earth as a result of nuclear processes. Probably, not all such processes have been discovered yet. Most likely, some of them stopped long ago, since the short-lived “parent” atoms were exhausted, but there are still ongoing nuclear processes in which argon-36 and argon-38 are born. This is the beta decay of chlorine-36, shelling alpha particles (in uranium minerals) of sulfur-33 and chlorine-35:

36 17 Cl β – → 36 18 Ar + 0 –1 e + ν.

33 16 S + 4 2 He → 36 18 Ar + 1 0 n .

35 17 Cl + 4 2 He → 38 18 Ar + 1 0 n + 0 +1 e .

In the matter of the universe, argon is even more abundant than on our planet. It is especially abundant in the matter of hot stars and planetary nebulae. It is estimated that there is more argon in space than chlorine, phosphorus, calcium, potassium - elements that are very common on Earth. The isotopes 36 Ar and 38 Ar dominate in cosmic argon, there is very little argon-40 in the Universe. This is indicated by the mass spectral analysis of argon from meteorites. Calculations of the prevalence of potassium convince of the same. It turns out that in space, potassium is about 50 thousand times less than argon, while on Earth their ratio is clearly in favor of potassium - 660: 1. And if there is little potassium, then where does argon-40 come from ?!

IIHistory of the discovery of inert gases.

By the end of the 18th century, many of the known gases had been discovered. These included: oxygen - a gas that supports combustion; carbon dioxide - it could be easily detected by a very remarkable property: it muddied lime water; and, finally, nitrogen, which does not support combustion and does not act on lime water. Such was the idea of the chemists of that time, the composition of the atmosphere, and no one, except for the famous English scientist Lord Cavendish, did not doubt it.

And he had reason to doubt.

In 1785 he made a rather simple experiment. First of all, he removed carbon dioxide from the air. He acted on the remaining mixture of nitrogen and oxygen with an electric spark. Nitrogen, reacting with oxygen, gave violent vapors of nitrogen oxides, which, dissolving in water, turned into nitric acid. This operation was repeated many times.

However, slightly less than one hundredth of the volume of air taken for the experiment remained unchanged. Unfortunately, this episode was not forgotten for many years.

In 1785, the English chemist and physicist G. Cavendish discovered some new gas in the air, which was unusually chemically stable. This gas accounted for about one hundred and twentieth of the volume of air. But what kind of gas, Cavendish failed to find out. This experience was remembered 107 years later, when John William Strutt (Lord Rayleigh) came across the same impurity, noticing that the nitrogen in the air was heavier than the nitrogen released from the compounds. Not finding a reliable explanation for the anomaly, Rayleigh, through the journal Nature, turned to his fellow naturalists with a proposal to think together and work on unraveling its causes ... Two years later, Rayleigh and W. Ramsay found that there is indeed an admixture of an unknown gas in the nitrogen of the air, heavier than nitrogen, and extremely inert chemically. When they made a public announcement of their discovery, it made a staggering impression. It seemed unbelievable to many that several generations of scientists who had performed thousands of air analyzes overlooked its component, and even such a noticeable one - almost a percentage! By the way, it was on this day and hour, August 13, 1894, that argon got its name, which means “inactive” in Greek. It was proposed by Dr. Medan, who presided over the meeting. Meanwhile, there is nothing surprising in the fact that argon has eluded scientists for so long. After all, in nature, he did not show himself decisively! A parallel with nuclear energy suggests itself: speaking about the difficulties of its detection, A. Einstein noted that it is not easy to recognize a rich man if he does not spend his money ... The skepticism of scientists was quickly dispelled by experimental verification and the establishment of physical constants of argon. But not without moral costs: frustrated by the attacks of colleagues (mainly chemists), Rayleigh left the study of argon and chemistry in general and concentrated his interests on physical problems. A great scientist, he also achieved outstanding results in physics, for which he was awarded the Nobel Prize in 1904. Then in Stockholm he met again with Ramsay, who on the same day received the Nobel Prize for the discovery and study of noble gases, including argon.

In February 1895, Razmai received a letter from the London meteorologist Myers, where he reported on the experiments of the American geologist Hillebrand, who boiled rare uranium minerals in sulfuric acid and observed the evolution of a gas resembling nitrogen in its properties. The more uranium contained in the minerals, the more gas was released. Hillebrand tentatively assumed that this gas was nitrogen. “Could it be argon?” asked the writer of the letter.

Soon Razmai sent his assistants to the London chemical shops for the uranium mineral cleveite. 30 grams of slanderite was bought, and on the same day Razmay and his assistant Matthews extracted several cubic centimeters of gas. Razmai subjected this gas to a spectroscopic study. He saw a bright yellow line, very similar to the sodium line and at the same time differing from it in its position in the spectrum. Razmai was so surprised that he dismantled the spectroscope and cleaned it, but with a new experiment he again discovered a bright yellow line that did not coincide with the sodium line. Razmai looked at the spectra of all the elements. Finally, he remembered the mysterious line in the spectrum of the solar corona.

In 1868, during a solar eclipse, the French researcher Jansen and the Englishman Lockyer discovered a bright yellow line in the spectrum of solar prominences, which was not found in the terrestrial spectrum of light sources. In 1871, Lockyer suggested that this line does not belong to the spectrum of a substance unknown on Earth.

He called this hypothetical element helium, that is, "solar". But it was not found on the ground. Physicists and chemists were not interested in him: on the Sun, they say, completely different conditions, and hydrogen will pass for helium there.

So is this very helium in his hands? Razmai is almost sure of this, but he wants to hear confirmation from the famous spectroscopist Crooks. Razmai sends him gas for research and writes that he has found some new gas, which he called krypton, which means “hidden” in Greek. A telegram from Crookes said: "Krypton is helium."

2.3 Krypton.

By 1895, two inert gases had been discovered. It was clear that between them there must be another gas, the properties of which Razmai described following the example of Mendeleev. Lecoq de Boisbaudran even predicted the weight of the undiscovered gas, 20.0945.

And it is not known whether the scientist would have discovered new inert gases if, during his search, Linde in Genmania and Hampson in England had not simultaneously taken out a patent for a machine that liquefied air.

This machine seems to have been specially created for the detection of inert gases. The principle of its operation is based on a well-known physical phenomenon, if you compress the air, then let it expand quickly, it cools. Cooled air cools a new portion of air entering the machine, etc., until the air turns into a liquid.

Having evaporated almost all the nitrogen and oxygen, Razmai placed the remaining liquid air into the gasometer. He thought to find helium in it, since he believed that this gas evaporates more slowly than oxygen and nitrogen. He cleaned the gas in the gasometer from oxygen and nitrogen impurities and took a spectrum in which he took two previously unknown lines.

Next, Razmai placed 15 liters of argon in a cylinder into liquid air. In order to find an inert gas, according to calculations, lighter than argon and krypton, Razmai collected the first portions of argon evaporation. The result is a new spectrum with bright red lines. Razmai named the emitted gas neon, which means “new” in Greek.

2.5 Xenon.

In 1888, Razmay's assistant Travers built a machine capable of producing a temperature of -253 0 C. With its help, solid argon was obtained. All gases were driven away, except for krypton. And already in the unpurified krypton, xenon (“foreign”) was found. In order to obtain 300 cubic centimeters of xenon, scientists had to process 77.5 million liters of atmospheric air within 2 years.

It has already been said that helium is present in uranium minerals. The more uranium in kleveite, the more helium. Razmai tried for a long time to find a relationship between the content of uranium and helium, but he did not succeed. The answer came from the other side; it was associated with the discovery of radioactivity.

Radium was found to give off a gaseous substance called emanation. 1 gram of radium per day emitted one cubic millimeter of emanation. In 1903, Razmai and the famous physicist Soddy began to study emanation. They had only 50 milligrams of radium bromide at their disposal; at the same time they had no more than 0.1 cubic millimeters of emanation.

To carry out the work, Razmai built an ultra-sensitive scale showing four billionths of a gram. Soon the researchers found out that emanation is the last representative of the family of inert gases.

For a long time they failed to consider the spectrum of emanation. Somehow, having left the tube with emanation for several days, they put it into the spectroscope and were surprised to see the known lines of helium in the spectroscope.

This fact confirmed the assumption of Rutherford and Soddy that radioactive transformation is connected with the transformation of atoms. Radium spontaneously decayed, turned into an emanation and released the nucleus of the helium atom. One element turned into another.

Scientists have understood why helium is found in uranium materials; it is one of the decay products of uranium. In 1923, by decision of the International Committee on Chemical Elements, the emanation was renamed radon.

IIIProperties of inert gases and their compounds.

3.1 Physical properties of inert gases.

Noble gases are colorless, odorless, monatomic gases.

Inert gases have a higher electrical conductivity than other gases and when a current passes through them, they glow brightly: helium with bright yellow light, because in its relatively simple spectrum the double yellow line prevails over all others; neon is fiery red, since its brightest lines lie in the red part of the spectrum.

The saturated nature of the atomic molecules of inert gases is also reflected in the fact that inert gases have lower liquefaction and freezing points than other gases of the same molecular weight. Of the subgroup of heavy inert gases, argon is the lightest. It is 1.38 times heavier than air. It becomes a liquid at -185.9°C, solidifies at -189.4°C (under normal pressure conditions).

Unlike helium and neon, it adsorbs rather well on the surfaces of solids and dissolves in water (3.29 cm3 per 100 g of water at 20°C). Argon dissolves even better in many organic liquids. But it is practically insoluble in metals and does not diffuse through them.

3.2 Chemical properties of inert gases.

For a long time, no conditions were found under which noble gases could enter into chemical interaction. They did not form true chemical compounds. In other words, their valency was zero. On this basis, it was decided to consider the new group of chemical elements as zero. The low chemical activity of noble gases is explained by the rigid eight-electron configuration of the outer electron layer. The polarizability of atoms increases with an increase in the number of electron layers. Therefore, it should increase on going from helium to radon. The reactivity of noble gases should also increase in the same direction.

Thus, already in 1924, the idea was expressed that some compounds of heavy inert gases (in particular, xenon fluorides and chlorides) are thermodynamically quite stable and can exist under normal conditions. Nine years later, this idea was supported and developed by well-known theorists - Pauling and Oddo. The study of the electronic structure of the shells of krypton and xenon from the standpoint of quantum mechanics led to the conclusion that these gases are able to form stable compounds with fluorine. There were also experimenters who decided to test the hypothesis, but time passed, experiments were made, but xenon fluoride did not work out. As a result, almost all work in this area was stopped, and the opinion about the absolute inertness of noble gases was finally established.

However, in 1961, Bartlett, an employee of one of the universities of Canada, studying the properties of platinum hexafluoride, a compound more active than fluorine itself, found that the ionization potential of xenon is lower than that of oxygen (12, 13 and 12, 20 eV, respectively). Meanwhile, oxygen formed a compound of the composition O 2 PtF 6 with platinum hexafluoride ... Bartlett sets up an experiment and at room temperature from gaseous platinum hexafluoride and gaseous xenon receives a solid orange-yellow substance - xenon hexafluoroplatinate XePtF 6 , whose behavior is no different from the behavior of conventional chemical compounds. When heated in a vacuum, XePtF 6 sublimates without decomposition, hydrolyzes in water, releasing xenon:

2XePtF 6 + 6H 2 O \u003d 2Xe + O 2 + 2PtO 2 + 12HF

Bartlett's subsequent work made it possible to establish that xenon, depending on the reaction conditions, forms two compounds with platinum hexafluoride: XePtF 6 and Xe (PtF 6) 2; when hydrolyzed, the same end products are obtained. Convinced that xenon had indeed reacted with platinum hexafluoride, Bartlett made a presentation and in 1962 published an article on his discovery in the Proceedings of the Chemical Society. The article aroused great interest, although many chemists reacted to it with undisguised distrust. But three weeks later, Bartlett's experiment was repeated by a group of American researchers led by Chernik at the Argonne National Laboratory. In addition, they were the first to synthesize analogous xenon compounds with ruthenium, rhodium, and plutonium hexafluorides. Thus, the first five xenon compounds were discovered: XePtF 6 , Xe (PtF 6) 2 , XeRuF 6 , XeRhF 6 , XePuF 6 - the myth of the absolute inertness of noble gases was dispelled and the beginning of xenon chemistry was laid. It is time to check the correctness of the hypothesis about the possibility of direct interaction of xenon with fluorine.

A mixture of gases (1 part of xenon and 5 parts of fluorine) was placed in a nickel (since nickel is the most resistant to fluorine) vessel and heated under relatively low pressure. An hour later, the vessel was quickly cooled, and the remaining gas was pumped out and analyzed. It was fluorine. All xenon reacted! The vessel was opened and colorless crystals of XeF 4 were found in it. Xenon tetrafluoride turned out to be a completely stable compound, its molecule has the shape of a square with fluorine ions at the corners and xenon in the center. Xenon tetrafluoride fluorinates mercury:

XeF 4 + 2Hg = Xe + 2HgF 2

Platinum is also fluorinated with this substance, but only dissolved in hydrogen fluoride.

It is interesting in the chemistry of xenon that, by changing the reaction conditions, it is possible to obtain not only XeF 4 , but also other fluorides-XeF 2 , XeF 6 .

Soviet chemists V. M. Khutoretsky and V. A. Shpansky showed that strict conditions are not at all necessary for the synthesis of xenon difluoride. According to the method proposed by them, a mixture of xenon and fluorine (in a molecular ratio of 1: 1) is fed into a vessel made of nickel or stainless steel, and when the pressure rises to 35 atm, a spontaneous reaction begins.

XeF 2 is the only xenon fluoride that can be obtained without using elemental fluorine. It is formed by the action of an electric discharge on a mixture of xenon and carbon tetrafluoride. Of course, direct synthesis is also possible. Very pure XeF 2 is obtained if a mixture of xenon and fluorine is irradiated with ultraviolet light. The solubility of difluoride in water is low, but its solution is the strongest oxidizing agent. Gradually, it self-decomposes into xenon, oxygen and hydrogen fluoride; decomposition is especially fast in an alkaline environment. Difluoride has a sharp specific smell. Of great theoretical interest is a method for the synthesis of xenon difluoride, based on exposure to a mixture of gases of ultraviolet radiation (wavelength of the order of 2500-3500 A). The radiation causes the splitting of fluorine molecules into free atoms. This is the reason for the formation of difluoride: atomic fluorine is unusually active. To obtain XeF 6, more stringent conditions are required: 700 ° C and 200 atm. Under such conditions, in a mixture of xenon and fluorine (ratio from 1:4 to 1:20), almost all xenon is converted into XeF 6 . Xenon hexafluoride is extremely reactive and explodes explosively. It readily reacts with alkali metal fluorides (except LiF):

XeF 6 + RbF = RbXeF 7 ,

but at 50°C this salt decomposes:

2RbXeF 7 = XeF 6 + Rb 2 XeF 8

The synthesis of higher fluoride XeF 8 was also reported, stable only at temperatures below minus 196 ° C.

The synthesis of the first xenon compounds raised the question of the place of inert gases in the periodic table before chemists. Formerly, the noble gases were separated into a separate zero group, which fully corresponded to the idea of their valency. But, when xenon entered into a chemical reaction, when its highest fluoride became known, in which the valence of xenon is eight (and this is in complete agreement with the structure of its electron shell), it was decided to transfer the inert gases to group VIII. The zero group ceased to exist.

It has not yet been possible to force xenon to react without the participation of fluorine (or some of its compounds). All currently known xenon compounds are derived from its fluorides. These substances are highly reactive. The interaction of xenon fluorides with water is best studied. Hydrolysis of XeF 4 in an acidic environment leads to the formation of xenon oxide XeO 3 - colorless crystals that spread in air. The XeO 3 molecule has the structure of a flattened triangular pyramid with a xenon atom at the top. This connection is extremely unstable; when it decomposes, the power of the explosion approaches the power of an explosion of TNT. A few hundred milligrams of XeO 3 are enough to blow the desiccator to pieces. It is possible that over time xenon trioxide will be used as a crushing explosive. Such an explosive would be very convenient, because all the products of an explosive reaction are gases. In the meantime, it is too expensive to use xenon trioxide for this purpose - after all, there is less xenon in the atmosphere than gold in sea water, and the process of its isolation is too laborious. Recall that in order to obtain 1 m 3 of xenon, 11 million m 3 of air must be processed. The corresponding trioxide unstable acid of hexavalent xenon H 6 XeO 6 is formed as a result of hydrolysis of XeF 6 at 0 ° C:

XeF 6 + 6H 2 O \u003d 6HF + H 6 XeO 6

If Ba (OH) 2 is quickly added to the products of this reaction, a white amorphous precipitate Ba 3 XeO 6 precipitates. At 125°C, it decomposes into barium oxide, xenon and oxygen. Similar sodium and potassium xenonate salts have been obtained. Under the action of ozone on a solution of XeO 3 in one molar sodium hydroxide, a salt of the higher xenon acid Na 4 XeO 6 is formed. Sodium perxenonate can be isolated as a colorless crystalline hydrate Na4XeO6 · 6H 2 O. Hydrolysis of XeF 6 in sodium and potassium hydroxides also leads to the formation of perxenonates. If the solid salt Na 4 XeO 6 is treated with a solution of lead, silver or uranyl nitrate, then the corresponding perxenonates are obtained: PbXeO 6 and (UO 2) 2XeO 6 yellow and Ag 4 XeO 6 - black. Similar salts give potassium, lithium, cesium, calcium.

The oxide corresponding to the highest acid of xenon is obtained by reacting Na 4 XeO 6 with anhydrous chilled sulfuric acid. This is xenon tetroxide XeO 4 . In it, as in octafluoride, the valency of xenon is eight. Solid tetroxide at temperatures above 0 ° C decomposes into xenon and oxygen, and gaseous (at room temperature) - into xenon trioxide, xenon and oxygen. The XeO 4 molecule has the shape of a tetrahedron with a xenon atom in the center. Depending on the conditions, the hydrolysis of xenon hexafluoride can proceed in two ways; in one case, tetraoxyfluoride XeOF 4 is obtained, in the other, dioxyfluoride XeO 2 F 2 . Direct synthesis from the elements leads to the formation of XeOF 2 oxyfluoride. All are colorless solids, stable under normal conditions.

Of great interest is the recently studied reaction of xenon difluoride with anhydrous HC1O 4 . As a result of this reaction, a new xenon compound XeClO 4 was obtained - an extremely powerful oxidizing agent, probably the strongest of all perchlorates.

Xenon compounds that do not contain oxygen have also been synthesized. These are mainly double salts, products of the interaction of xenon fluorides with fluorides of antimony, arsenic, boron, tantalum: XeF 2 · SbF 5 , XeF 6 · AsF 3 , XeF 6 · BF 3 and XeF 2 · 2ТаF 5 . Finally, materials of the XeSbF 6 type, which are stable at room temperature, and XeSiF 6, an unstable complex, have been obtained.

Chemists have very small amounts of radon at their disposal, however, it was possible to establish that it also interacts with fluorine, forming non-volatile fluorides. For krypton, difluoride KrF2 and tetrafluoride KrF 4 have been isolated and studied in terms of properties reminiscent of xenon compounds.

3.3 Obtaining Argon.

The earth's atmosphere contains 66 · 10 13 tons of argon. This source of argon is inexhaustible, especially since almost all argon returns to the atmosphere sooner or later, since it does not undergo any physical or chemical changes during use. The exception is very small amounts of argon isotopes, which are used to produce new elements and isotopes in nuclear reactions. Argon is produced as a byproduct of the separation of air into oxygen and nitrogen. Usually, air separation apparatuses of double rectification are used, consisting of a lower high pressure column (preliminary separation), an upper low pressure column and an intermediate evaporator condenser. Ultimately, nitrogen is removed from above, and oxygen is removed from the space above the condenser. The volatility of argon is greater than that of oxygen, but less than that of nitrogen. Therefore, the argon fraction is taken at a point located approximately at a third of the height of the upper column, and diverted to a special column. The composition of the argon fraction: 10...12% argon, up to 0.5% nitrogen, the rest is oxygen. In the "argon" column, attached to the main apparatus, argon is obtained with an admixture of 3 ... 10% oxygen and 3 ... 5% nitrogen. This is followed by the purification of "raw" argon from oxygen (chemically or by adsorption) and from nitrogen (rectification). On an industrial scale, argon is now produced up to 99.99% purity. Argon is also extracted from ammonia production waste - from nitrogen left after most of it has been bound with hydrogen. Argon is stored and transported in 40 l cylinders painted gray with a green stripe and a green inscription. The pressure in them is 150 atm. The transportation of liquefied argon is more economical, for which Dewar vessels and special tanks are used. Artificial radioisotopes of argon were obtained by irradiating certain stable and radioactive isotopes (37 Cl, 36 Ar, 40 Ar, 40 Ca) with protons and deuterons, as well as by irradiating products formed in nuclear reactors during the decay of uranium with neutrons. The isotopes 37 Ar and 41 Ar are used as radioactive tracers: the first is in medicine and pharmacology, the second is in the study of gas flows, the efficiency of ventilation, and in various scientific studies. But, of course, these applications of argon are not the most important.

3.4 Physiological action of inert gases.

It was natural to expect that such chemically inert substances as inert gases should not affect living organisms either. But it's not. Inhalation of higher inert gases (of course, mixed with oxygen) brings a person into a state similar to alcohol intoxication. The narcotic effect of inert gases is caused by dissolution in the nervous tissues. The higher the atomic weight of an inert gas, the greater its solubility and the stronger its narcotic effect.

Now about the effect of argon on a living organism. When inhaling a mixture of 69% Ar, 11% nitrogen and 20% oxygen at a pressure of 4 atm, anesthesia occurs, which are much more pronounced than when air is inhaled at the same pressure. Narcosis instantly disappears after the cessation of the argon supply. The reason is the non-polarity of argon molecules, while increased pressure increases the solubility of argon in nerve tissues. Biologists have found that argon favors plant growth. Even in an atmosphere of pure argon, rice, corn, cucumber, and rye seeds sprouted. Onions, carrots and lettuce germinate well in an atmosphere of 98% argon and only 2% oxygen.

IV Use of inert gases.

Helium is an important source of low temperatures. At the temperature of liquid helium, there is practically no thermal motion of atoms and free electrons in solids, which makes it possible to study many new phenomena, for example, superconductivity in the solid state.

Helium gas is used as a light gas for filling balloons. Since it is non-flammable, it is added to hydrogen to fill the airship envelope.

Since helium is less soluble in blood than nitrogen, large amounts of helium are used in respiratory mixtures for work under pressure, for example, in sea diving, when creating underwater tunnels and structures. When using helium, decompression (release of dissolved gas from the blood) is less painful for a diver, decompression sickness is less likely, and such a phenomenon as nitrogen anesthesia, a constant and dangerous companion of a diver's work, is excluded. He-O 2 mixtures are used, due to their low viscosity, to relieve asthma attacks and in various respiratory diseases.

Helium is used as an inert medium for arc welding, especially magnesium and its alloys, in the production of Si, Ge, Ti and Zr, for cooling nuclear reactors.

Other uses for helium are gas lubrication of bearings, neutron counters (helium-3), gas thermometers, x-ray spectroscopy, food storage, and high voltage switches. In a mixture with other noble gases, helium is used in outdoor neon advertising (in gas discharge tubes). Liquid helium is beneficial for cooling magnetic superconductors, particle accelerators, and other devices. An unusual application of helium as a coolant is the process of continuous mixing of 3 He and 4 He to create and maintain temperatures below 0.005 K

The applications of xenon are varied and sometimes unexpected. Man uses both its inertness and its miraculous ability to react with fluorine. In lighting technology, high-pressure xenon lamps have gained recognition. In such lamps, an arc discharge shines in xenon under pressure of several tens of atmospheres. Light in xenon lamps appears immediately after switching on, it is bright and has a continuous spectrum - from ultraviolet to near infrared. Physicians also use xenon - for fluoroscopic examinations of the brain. Like barite porridge, which is used for intestinal transillumination, xenon strongly absorbs X-rays and helps to find lesions. However, it is completely harmless. The active isotope of element No. 54, xenon - 133, is used in the study of the functional activity of the lungs and heart.

By blowing argon through liquid steel, gas inclusions are removed from it. This improves the properties of the metal.

Arc welding in an argon environment is increasingly being used. In an argon jet, thin-walled products and metals that were previously considered difficult to weld can be welded. It would not be an exaggeration to say that the electric arc in an argon atmosphere revolutionized metal cutting techniques. The process was greatly accelerated, it became possible to cut thick sheets of the most refractory metals. Argon blown along the arc column (mixed with hydrogen) protects the cut edges and the tungsten electrode from the formation of oxide, nitride and other films. At the same time, it compresses and concentrates the arc on a small surface, which is why the temperature in the cutting zone reaches 4000-6000 ° C. In addition, this gas jet blows out the cutting products. When welding in an argon jet, there is no need for fluxes and electrode coatings, and therefore, for cleaning the seam from slag and flux residues.

Neon and argon are used as fillers in neon lamps and daytime matchmaker lamps. Krypton is used to fill ordinary lamps in order to reduce evaporation and increase the brightness of the tungsten filament. Xenon is filled with high-pressure quartz lamps, which are the most powerful light sources. Helium and argon are used in gas lasers.

List of used literature

1. Petrov M.M., Mikhilev L.A., Kukushkin Yu.N. "Inorganic chemistry"

2. Guzey L.S. Lectures on General Chemistry”

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6. Khodakov Yu.V. “General and Inorganic Chemistry”

Even if you are not a chemist, or a person close to chemistry, you have probably heard of such a name as inert gases. Also, you probably heard about the existence of such a definition as noble gases.

Interestingly, this name is assigned to the same group of gases, and today we will understand why inert gases are called noble gases, and also briefly review information about them.

What are inert gases

Under the characteristic of gases of an inert type, a whole group of substances, or rather, chemical elements, immediately fits. All of them have similar properties. Inert gases are characterized by the absence of odor and odor under normal conditions. In addition, they also differ in very low rates of chemical reactivity.

The group of inert gases includes radon, helium, xenon, argon, krypton and neon.

Why are inert gases called noble gases?

Today, in chemistry, inert gases are increasingly called noble gases, however, even earlier this name was distributed no less than the official (“Inert”). And the history of the origin of this name is quite interesting.

The name takes its origin directly in the properties of gases, because they practically do not enter into any reactions with any other elements of the periodic table, even when it comes to gases. In turn, the rest of the elements are quite willing to make such a "connection", entering into reactions with each other. Proceeding from this, inert gases began to be called the very common name "Noble", which over time acquired an almost official status, used today by scientists.

It is also interesting to know that in addition to "noble", inert gases are also often called "rare". And this name is also easily explained - after all, among all the elements of the periodic table, only 6 such gases can be noted.

Use of inert gases

Due to their own characteristics, rare gases are quite capable of being used as a kind of refrigerants in cryogenic-type technology. This became available due to the fact that the boiling and melting points of the elements are at very low rates.

In addition, speaking directly about helium, it is used as one of the components for the production of breathing mixtures that are actively used in scuba diving.

Argon is also widely used, which is used in welding and cutting. And the properties of low thermal conductivity make argon also an ideal material for filling double-glazed windows.

Probably, even those people who are not so often faced with chemistry questions have repeatedly heard that some gases are called noble. However, few people wonder why the gases were called noble. And today in the framework of this article we will try to understand this issue in detail.

What are "noble" gases

The group of noble gases immediately includes a whole list of various chemical elements that can be ordered or combined according to their properties. Naturally, gases do not have a completely identical composition, and they are united by the fact that under the simplest conditions, which are called normal conditions in chemistry, these gases have no color, taste or smell. In addition, they are also united by the fact that they have an extremely low chemical reactivity.

List of "noble" gases

Only 6 names can be attributed to the list of noble gases known to mankind. Among them are the following chemical elements:

Radon;
Helium;
Xenon;
Argon;
Krypton;
Neon.

Why are gases called "noble"

As for the direct origin of the name that scientists assigned to the chemical elements described above, it was given to them because of the behavior of the atoms of the elements with other elements.

As you know, chemical elements can act on each other and exchange atoms with each other. This condition also applies to many gases. However, if we talk about the elements from the list presented above, then they do not react with any other elements present in the periodic table known to all of us. This led to the fact that scientists very quickly conditionally attributed gases to one group, naming it noble in honor of their “behavior”.

Other names for "noble" gases

It is important to note that noble gases also have other names that scientists call them and which can also be called official.

"Noble" gases are also called "Inert" or "Rare" gases.

As for the second option, its origin is quite obvious, because from the entire Mendeleev's table of elements, only 6 atoms can be noted that belong to the list of noble gases. If we talk about the origin of the name "Inert", then here you can use the synonyms of this word, among which there are such concepts as "inactive" or "inactive".

Thus, all three names used for such gases are relevant and rationally chosen.

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Helium

In terms of physical properties, helium is closest to molecular hydrogen. Due to the low polarizability of the helium atom, it has the lowest boiling and melting points compared to other elements of group VIIIA. However, it is less soluble than other inert gases in water.

Under normal conditions, helium is chemically inert, but in an excited state it is able to form unstable molecular ions He 2 + or ionized HeH + molecules.

Helium is the most common of the elements in space, after hydrogen, and consists of two isotopes - 4 He and 3 He. The presence of helium in the atmosphere of the Sun, stars and in meteorites has been proven.

Helium is obtained from some natural gases by deep cooling, while the helium remains in a gaseous state, while other gases condense.

Helium has found application in nuclear power engineering, in autogenous welding of metals, and in physical laboratories as a coolant. The helium isotope 3 He is the only substance suitable for measuring temperatures below 1K.

Neon. Argon

The main difference between neon and helium is the high polarizability of the atom, the tendency to form intermolecular bonds, a slightly higher solubility and the ability to be adsorbed.

Agron, like neon, has 8 electrons at the external energy level and, due to the high stability of the electronic structure of the neon atom, it is not capable of forming valence-type compounds. Argon forms molecular inclusion compounds - clathrates - with water, phenol, toluene and other substances. With compounds H 2 S, SO 2 , CO 2 , HCl, argon gives double hydrates, i.e. mixed clathrates.

Neon and argon are obtained from air by separating it with deep cooling. Argon, due to its relatively high content in the air, is obtained in significant quantities, neon - in smaller quantities.

Neon and argon are used as fillers for incandescent lamps, gas-light tubes (neon is characterized by a red glow, and blue-blue for argon). Argon, as the most accessible of the inert gases, is used in metallurgy, in particular in argon-arc welding of aluminum and aluminum-magnesium alloys.

Krypton subgroup

The ionization energy of the elements of the krypton subgroup (Kr, Xe, Rn) are characterized by lower ionization energies than the typical elements of group VIIIA, therefore they can form compounds of the usual type. So, xenon can show oxidation states "+2", "+4", "+6", "+8".

Krypton is used in electrovacuum technology, mixed with xenon, it is used as a filler for various types of lighting lamps and tubes. Radioactive radon is used in medicine.

Examples of problem solving

EXAMPLE 1

Exercise	During the interaction of manganese sulfate with xenon (II) fluoride in an aqueous solution, 4.8 liters of gas were released (at a temperature of 20 ° C and normal atmospheric pressure). What is the mass of the resulting permanganic acid?
Solution	Let's write the reaction equation: 5XeF 2 + 2MnSO 4 + 8H 2 O \u003d 5Xe + 2H 2 SO 4 + 10HF + 2HMnO 4

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