Why and what gases are called “noble”? What is an inert gas? Chemical properties of noble gases

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

It is interesting that this name is assigned to the same group of gases, and today we will understand why noble gases are called noble gases, and also briefly consider information about them.

What are inert gases

A whole group of substances, or rather chemical elements, immediately fits the characteristics of inert gases. They all have similar properties. Inert gases are characterized by being odorless and odorless under normal conditions. In addition, they are also distinguished by very low levels of chemical reactivity.

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

Why did inert gases come to be called noble gases?

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

The name takes its origin directly from the properties of gases, because they practically do not enter into any reactions with any other elements of the periodic table, even if we are talking about gases. In turn, the remaining elements quite willingly make such a “connection”, entering into reactions with each other. Based on this, inert gases began to be called by the very common name “Noble”, which over time acquired almost official status, used today by scientists.

It is also interesting to know that in addition to “noble” gases, 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 in the form of unique refrigerants in cryogenic technology. This became possible because the boiling and melting points of the elements are very low.

In addition, if we talk directly about helium, it is used as one of the components for the production of breathing mixtures that are actively used during 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.

The main subgroup of the eighth group of the periodic table consists of noble gases - helium, neon, argon, krypton, xenon and radon. These elements are characterized by very low chemical activity, which gives rise to calling them noble, or inert, gases. They only form compounds with other elements or substances with difficulty; chemical compounds of helium, neon and argon have not been obtained. Atoms of noble gases are not combined into molecules, in other words, their molecules are monatomic.

The noble gases end each period of the system of elements. Except for helium, they all have eight electrons in the outer electron layer of the atom, forming a very stable system. The electron shell of helium, consisting of two electrons, is also stable. Therefore, noble gas atoms are characterized by high ionization energies and, as a rule, negative electron affinity energies.

In table 38 shows some properties of noble gases, as well as their content in the air. It can be seen that the temperatures of liquefaction and solidification of noble gases are lower, the lower their atomic masses or serial numbers: the lowest liquefaction temperature is for helium, the highest for radon.

Table 38. Some properties of noble gases and their content in the air

Until the end of the 19th century, it was believed that air consisted only of oxygen and nitrogen. But in 1894, the English physicist J. Rayleigh established that the density of nitrogen obtained from air (1.2572) is slightly greater than the density of nitrogen obtained from its compounds (1.2505). Chemistry professor W. Ramsay suggested that the difference in density is caused by the presence of some heavier gas in atmospheric nitrogen. By combining nitrogen with hot magnesium (Ramsay) or causing its combination with oxygen by the action of an electric discharge (Rayleigh), both scientists isolated small quantities of a chemically inert gas from atmospheric nitrogen. Thus, a hitherto unknown element called argon was discovered. Following argon, helium, neon, krypton and xenon, contained in the air in negligible quantities, were isolated. The last element of the subgroup - radon - was discovered during the study of radioactive transformations.

It should be noted that the existence of noble gases was predicted back in 1883, i.e. 11 years before the discovery of argon, by the Russian scientist II A. Morozov (1854-1946), who was imprisoned in 1882 for participating in the revolutionary movement by the tsarist government to the Shlisselburg fortress. N.A. Morozov correctly determined the place of noble gases in the periodic table, put forward ideas about the complex structure of the atom, the possibility of synthesizing elements and using intra-atomic energy. N.A. Morozov was released from prison in 1905, and his remarkable foresights became known only in 1907 after the publication of his book “Periodic Systems of the Structure of Matter,” written in solitary confinement.

In 1926, N. A. Morozov was elected an honorary member of the USSR Academy of Sciences.

For a long time it was believed that noble gas atoms are generally incapable of forming chemical bonds with atoms of other elements. Only relatively unstable molecular compounds of noble gases were known - for example, hydrates formed by the action of compressed noble gases on crystallizing supercooled water. These hydrates belong to the clathrate type (see § 72); valence bonds do not arise during the formation of such compounds.

The formation of clathrates with water is favored by the presence of numerous cavities in the crystalline structure of ice (see § 70).

However, over the past decades it has been found that krypton, xenon and radon are capable of combining with other elements and, above all, with fluorine. Thus, by direct interaction of noble gases with fluorine (by heating or in an electric discharge), fluorides and were obtained. All of them are crystals that are stable under ordinary conditions. Xenon derivatives have also been obtained in the oxidation state - hexafluoride, trioxide, hydroxide. The last two compounds exhibit acidic properties; so, reacting with alkalis, they form salts of xenonic acid, for example: .

- (inert gas), a group of colorless and odorless gases that make up group 0 in the periodic table. These include (in increasing order of atomic number) HELIUM, NEON, ARGON, KRYPTON, XENON and RADON. Low chemical activity... ... Scientific and technical encyclopedic dictionary

NOBLE GASES- NOBLE GASES, chem. elements: helium, neon, argon, krypton, xenon and emanation. They got their name from their inability to react with other elements. In 1894 English. Scientists Rayleigh and Ramsay found that N obtained from air... ... Great Medical Encyclopedia

- (inert gases), chemical elements of group VIII of the periodic system: helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn. Chemically inert; all elements except He form inclusion compounds, for example Ar?5.75H2O, Xe oxides,... ... Modern encyclopedia

Noble gases- (inert gases), chemical elements of group VIII of the periodic system: helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn. Chemically inert; all elements except He form inclusion compounds, for example Ar´5.75H2O, Xe oxides,... ... Illustrated Encyclopedic Dictionary

- (inert gases) chemical elements: helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn; belong to group VIII of the periodic table. Monatomic gases are colorless and odorless. Present in small quantities in the air, found in... ... Big Encyclopedic Dictionary

Noble gases- (inert gases) elements of group VIII of the periodic table of D.I. Mendeleev: helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn. Present in small quantities in the atmosphere, found in some minerals, natural gases,... ... Russian encyclopedia of labor protection

NOBLE GASES- (see) simple substances formed by atoms of elements of the main subgroup of group VIII (see): helium, neon, argon, krypton, xenon and radon. In nature, they are formed during various nuclear processes. In most cases, they are obtained fractionally... ... Big Polytechnic Encyclopedia

- (inert gases), chemical elements: helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn; belong to group VIII of the periodic table. Monatomic gases are colorless and odorless. Present in small quantities in the air, found in... ... encyclopedic Dictionary

- (inert gases, rare gases), chemical. elements VIII gr. periodic systems: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn). In nature they are formed as a result of decomposition. nuclear processes. Air contains 5.24 * 10 4% by volume He, ... ... Chemical encyclopedia

- (inert gases), chemical elements: helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn; belong to the VIII periodic group. systems. Monatomic gases are colorless and odorless. They are present in small quantities in the air, contained in certain... ... Natural science. encyclopedic Dictionary

Books

• , D. N. Putintsev, N. M. Putintsev. The book examines the structural, thermodynamic and dielectric properties of noble gases, their relationship with each other and with intermolecular interaction. Part of the text of the manual serves...
• Structure and properties of simple substances. Noble gases. Tutorial. Grif MO RF, Putintsev D.N. The book examines the structural, thermodynamic and dielectric properties of noble gases, their relationship with each other and with intermolecular interaction. Part of the text of the manual serves...

British International School

Abstract on chemistry

“Inert gases and their properties”

9th grade student

Sokolenko Alexey

Supervisor:

Chernysheva I.V.

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

1.1 Inert gases – elements of group VIIIА……………………………………...2

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

IIHistory of the discovery of gases……………………………………………………………......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

IVUse of inert gases…………………………………………………..…..16

List of references………………………………………………………………....18

IIntroduction.

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

Radon is formed during the radioactive decay of radium and is found in negligible quantities in uranium-containing materials, as well as in some natural waters. Helium, a product of radioactive α-decay of elements, is sometimes found in appreciable quantities in natural gas and gas released from oil wells. This element is found in huge quantities on 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, the remaining elements of subgroup VIII – ns 2 n.p. 6 .

1.2 Argon on earth and in the universe.

There is much more argon on Earth than all other elements of its group combined. Its average content in the earth's crust (clarke) is 14 times higher than helium and 57 times higher 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. It contains (by weight) 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 the opposite - light isotopes predominate. The reason for this anomaly was discovered in 1943. In the earth's crust there is a powerful source of argon-40 - a radioactive isotope of potassium 40 K. At first glance, there is not much of this isotope in the depths - 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 rock contains 3.1 g of potassium-40. The radioactive decay of potassium-40 atomic nuclei occurs simultaneously in two ways. Approximately 88% of potassium-40 undergoes beta decay and is converted to 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 the element decreases by one, but the mass of the nucleus remains virtually unchanged. This is how potassium turns into argon. The half-life of 40 K is quite long - 1.3 billion years. Therefore, the process of formation of 40 Ar in the bowels of the Earth will continue for a long, 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 by water sources. True, during the existence of the Earth, the supply of radioactive potassium was thoroughly depleted - it became 10 times less (if the age of the Earth is considered equal to 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 the relationship, the older the breed. The argon method is considered the most reliable 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 on Earth originated from potassium-40. Therefore, the heavy isotope dominates in terrestrial argon. This factor explains, by the way, one of the anomalies of the periodic table. Contrary to the original principle of its construction - the principle of atomic weights - argon is placed in the table ahead of potassium. If light isotopes predominated in argon, as in neighboring elements (as is apparently the case in space), then the atomic weight of argon would be two to 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. Some 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. It is likely that 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, the bombardment of 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 .

Argon is present in the matter of the Universe even more abundantly 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, and 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 mass spectral analysis of argon from meteorites. Calculations of the prevalence of potassium convince us of the same. It turns out that in space there is approximately 50 thousand times less potassium than argon, while on Earth their ratio is clearly in favor of potassium - 660: 1. And since 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 clouded lime water; and, finally, nitrogen, which does not support combustion and has no effect on lime water. This was the composition of the atmosphere in the minds of chemists of that time, and no one except the famous English scientist Lord Cavendish doubted it.

And he had reason to doubt.

In 1785 he performed 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, produced 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 forgotten for many years.

In 1785, the English chemist and physicist G. Cavendish discovered some new gas in the air, unusually chemically stable. This gas accounted for approximately one hundred and twentieth of the volume of air. But Cavendish was unable to find out what kind of gas it was. This experiment was remembered 107 years later, when John William Strutt (Lord Rayleigh) came across the same impurity, noting that the nitrogen in the air was heavier than the nitrogen isolated from the compounds. Having not found a reliable explanation for the anomaly, Rayleigh, through the journal Nature, turned to his fellow natural scientists with a proposal to think together and work on unraveling its causes... Two years later, Rayleigh and W. Ramsay established 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 went public with their discovery, it was stunning. It seemed incredible to many that several generations of scientists, who performed thousands of air tests, 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 received its name, which translated from Greek means “inactive.” It was proposed by Dr. Medan, who chaired the meeting. Meanwhile, it is not surprising that argon eluded scientists for so long. After all, in nature he showed absolutely nothing of himself! 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 person if he does not spend his money... The skepticism of scientists was quickly dispelled by experimental testing and the establishment of physical constants of argon. But it was not without moral costs: upset by the attacks of his colleagues (mainly chemists), Rayleigh abandoned the study of argon and chemistry in general and focused his interests on physical problems. A great scientist, he achieved outstanding results in physics, for which he was awarded the Nobel Prize in 1904. Then in Stockholm he again met with Ramsay, who on the same day received the Nobel Prize for the discovery and study of noble gases, including argon.

In February 1895, Razmay 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 release of a gas whose properties resembled nitrogen. 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 author of the letter.

Soon Razmay sent his assistants to London chemical stores for the uranium mineral kleveite. 30 grams of kleveite were purchased, and on the same day Razmay and his assistant Matthews extracted several cubic centimeters of gas. Razmay subjected this gas to spectroscopic examination. He saw a bright yellow line, very similar to the sodium line and at the same time different from it in its position in the spectrum. Razmay was so surprised that he disassembled the spectroscope, cleaned it, but with a new experiment he again discovered a bright yellow line that did not coincide with the sodium line. Razmay looked through the spectra of all the elements. Finally he remembered a 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 in the terrestrial spectrum of light sources. In 1871, Lockyer suggested whether this line might belong to the spectrum of a substance unknown on Earth.

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

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

2.3 Krypton.

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

And it is unknown 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 seemed to be specially created for detecting inert gases. The principle of its operation is based on a well-known physical phenomenon: if you compress air, then let it expand quickly, it cools. The cooled air is used to cool a new portion of air entering the machine, etc., until the air turns into 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 purified the gas in a gasometer from oxygen and nitrogen impurities and recorded a spectrum in which he recorded two previously unknown lines.

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

Next, Razmay placed 15 liters of argon in a cylinder in liquid air. In order to find an inert gas, calculated to be lighter than argon and krypton, Razmay collected the first portions of argon evaporation. The result was a new spectrum with bright red lines. Razmai named the new 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 distilled off except krypton. And already in the unrefined krypton, xenon (“alien”) was found. In order to obtain 300 cubic centimeters of xenon, scientists had to process 77.5 million liters of atmospheric air over the course of 2 years.

It has already been said that helium is present in uranium minerals. The more uranium in kleveite, the more helium. Razmay tried for a long time to find a relationship between the content of uranium and helium, but he failed. The solution came from the other side; it was associated with the discovery of radioactivity.

It was discovered that radium gave off a gaseous substance called emanation. 1 gram of radium per day released one cubic millimeter of emanation. In 1903, Razmay and the famous physicist Soddy began studying emanation. They had only 50 milligrams of radium bromide at their disposal; at the same time they had no more than 0.1 cubic millimeter of emanation.

To carry out the work, Razmay built ultra-sensitive scales that showed four billionths of a gram. Researchers soon discovered that emanation is the latest member of the noble gas family.

For a long time they were unable to examine the spectrum of emanation. Once, after leaving the tube with the emanation for several days, they placed it in a spectroscope and were surprised to see the well-known lines of helium in the spectroscope.

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

Scientists now understand 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.

III Properties of inert gases and their compounds.

3.1 Physical properties of inert gases.

Noble gases are colorless, monatomic gases without color or odor.

Noble gases have higher electrical conductivity than other gases and glow brightly when current passes through them: helium with a bright yellow light, because in its relatively simple spectrum the double yellow line predominates over all others; neon has a fiery red light, 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 with 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 liquid at – 185.9°C, solidifies at – 189.4°C (under normal pressure conditions).

Unlike helium and neon, it is quite well adsorbed on the surfaces of solids and dissolves in water (3.29 cm 3 in 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, conditions were not found under which noble gases could enter into chemical interactions. 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 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 increasing number of electronic layers. Therefore, it should increase when 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 famous 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 carried out, and xenon fluoride was not obtained. 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 in 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 with the composition O 2 PtF 6 with platinum hexafluoride ... Bartlett carried out an experiment and at room temperature from gaseous platinum hexafluoride and gaseous xenon he obtained a solid orange-yellow substance - xenon hexafluoroplatinate XePtF 6, the behavior of which is no different from the behavior of ordinary chemical compounds. When heated in a vacuum, XePtF 6 sublimes without decomposition; in water it hydrolyzes, releasing xenon:

2XePtF 6 + 6H 2 O = 2Xe + O 2 + 2PtO 2 + 12HF

Subsequent work by Bartlett 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 they are hydrolyzed, the same end products are obtained. Having convinced himself that xenon had indeed reacted with platinum hexafluoride, Bartlett made a report and in 1962 published an article in the journal Proceedings of the Chemical Society on his discovery. The article aroused great interest, although many chemists treated 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 similar xenon compounds with ruthenium, rhodium and plutonium hexafluorides. This is how the first five xenon compounds were discovered: XePtF 6, Xe (PtF 6) 2, XeRuF 6, XeRhF 6, XePuF 6 - the myth about the absolute inertness of noble gases was dispelled and the beginning of xenon chemistry was laid. The time has come to test the correctness of the hypothesis about the possibility of direct interaction of xenon with fluorine.

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

XeF 4 + 2Hg = Xe + 2HgF 2

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

An interesting thing about xenon chemistry is 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 harsh conditions are not at all necessary for the synthesis of xenon difluoride. According to the method they proposed, 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 increases to 35 atm, a spontaneous reaction begins.

XeF 2 is the only xenon fluoride that can be produced 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 a strong oxidizing agent. Gradually it self-decomposes into xenon, oxygen and hydrogen fluoride; Decomposition occurs especially quickly in an alkaline environment. Difluoride has a sharp, specific odor. Of great theoretical interest is the method for the synthesis of xenon difluoride, based on exposure of a mixture of gases to ultraviolet radiation (wavelength of the order of 2500-3500 A). Radiation causes fluorine molecules to split 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 active and decomposes explosively. It reacts easily 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, which is stable only at temperatures below minus 196° C, has also been reported.

The synthesis of the first xenon compounds raised the question for chemists about the place of inert gases in the periodic table. Previously, the noble gases were allocated to a separate zero group, which fully corresponded to the idea of ​​their valence. But when xenon entered into a chemical reaction, when its higher fluoride became known, in which the valency of xenon is eight (and this is quite consistent with the structure of its electron shell), they 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 obtained from its fluorides. These substances have increased reactivity. The interaction of xenon fluorides with water has been best studied. Hydrolysis of XeF 4 in an acidic environment leads to the formation of xenon oxide XeO 3 - colorless crystals that diffuse 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 a TNT explosion. A few hundred milligrams of XeO 3 are enough for the desiccator to be blown into pieces. It is possible that over time xenon trioxide will be used as a crushing explosive. Such explosives would be very convenient, because all the products of an explosive reaction are gases. In the meantime, using xenon trioxide for this purpose is too expensive - after all, there is less xenon in the atmosphere than gold in sea water, and the process of isolating it is too labor-intensive. Let us recall that to obtain 1 m 3 of xenon, 11 million m 3 of air must be processed. The unstable acid of hexavalent xenon H 6 XeO 6 corresponding to the trioxide is formed as a result of the hydrolysis of XeF 6 at 0 ° C:

XeF 6 + 6H 2 O = 6HF + H 6 XeO 6

If Ba (OH) 2 is quickly added to the products of this reaction, a white amorphous precipitate of Ba 3 XeO 6 precipitates. At 125°C it decomposes into barium oxide, xenon and oxygen. Similar sodium and potassium xenonate salts were obtained. When ozone acts on a solution of XeO 3 in one-molar sodium hydroxide, a salt of the higher acid xenon Na 4 XeO 6 is formed. Sodium perxenonate can be isolated in the form of a colorless crystalline hydrate Na4XeO6 · 6H 2 O. The 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, the corresponding perxenonates are obtained: PbXeO 6 and (UO 2) 2XeO 6 are yellow and Ag 4 XeO 6 is black. Similar salts are produced by potassium, lithium, cesium, and calcium.

The oxide corresponding to the higher acid of xenon is obtained by reacting Na 4 XeO 6 with anhydrous cooled 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 elements leads to the formation of oxyfluoride XeOF 2. All are colorless solids, stable under normal conditions.

The recently studied reaction of xenon difluoride with anhydrous HC1O 4 is very interesting. As a result of this reaction, a new xenon compound, XeClO 4, was obtained - an extremely powerful oxidizing agent, probably the most powerful 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 2TaF 5. Finally, substances of the XeSbF 6 type, stable at room temperature, and XeSiF 6, an unstable complex, were obtained.

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

3.3 Preparation of Argon.

The Earth's atmosphere contains 66 · 10 13 tons of argon. This source of argon is inexhaustible, especially since almost all argon sooner or later returns to the atmosphere, since it does not undergo any physical or chemical changes when used. The exception is very small amounts of argon isotopes, which are spent to produce new elements and isotopes in nuclear reactions. Argon is produced as a by-product when air is separated into oxygen and nitrogen. Typically, double rectification air separation devices are used, consisting of a lower high-pressure column (pre-separation), an upper low-pressure column and an intermediate condenser-evaporator. Ultimately, nitrogen is removed from above, and oxygen 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 selected at a point located approximately at a third of the height of the upper column and taken to a special column. Composition of the argon fraction: 10...12% argon, up to 0.5% nitrogen, the rest is oxygen. In an “argon” column connected to the main apparatus, argon is produced with an admixture of 3...10% oxygen and 3...5% nitrogen. Next comes the purification of “raw” argon from oxygen (chemically or by adsorption) and from nitrogen (by rectification). Argon up to 99.99% purity is now produced on an industrial scale. Argon is also extracted from ammonia production waste - from the nitrogen remaining after most of it has been bound with hydrogen. Argon is stored and transported in cylinders with a capacity of 40 liters, painted gray with a green stripe and green inscription. The pressure in them is 150 atm. It is more economical to transport liquefied argon, for which Dewar flasks and special tanks are used. Artificial radioisotopes of argon were obtained by irradiation of some stable and radioactive isotopes (37 Cl, 36 Ar, ​​40 Ar, 40 Ca) with protons and deuterons, as well as by irradiation of 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 - in medicine and pharmacology, the second - in the study of gas flows, the effectiveness of ventilation and in various scientific research. But, of course, these are not the most important uses of argon.

3.4 Physiological effect of inert gases.

It was natural to expect that such chemically inert substances as inert gases should not affect living organisms. But that's not true. Inhalation of higher inert gases (of course, mixed with oxygen) leads a person to a state similar to intoxication with alcohol. The narcotic effect of inert gases is caused by dissolution in nerve 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 under a pressure of 4 atm, narcosis phenomena occur, which are much more pronounced than when inhaling air under the same pressure. The anesthesia disappears instantly after stopping 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 promotes plant growth. Even in an atmosphere of pure argon, the seeds of rice, corn, cucumbers and rye sprouted. Onions, carrots and lettuce grow well in an atmosphere consisting of 98% argon and only 2% oxygen.

IV Application of inert gases.

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

Helium gas is used as a light gas to fill balloons. Because it is non-flammable, it is added to hydrogen to fill the airship's shell.

Since helium is less soluble in the blood than nitrogen, large quantities of helium are used in breathing mixtures for work under pressure, for example during 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 the phenomenon of nitrogen narcosis, a constant and dangerous companion to a diver’s work, is eliminated. He–O 2 mixtures are used, due to their low viscosity, to relieve asthma attacks and for 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 of helium are for gas lubrication of bearings, in neutron counters (helium-3), gas thermometers, X-ray spectroscopy, food storage, and high voltage switches. Mixed 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 refrigerant is the process of continuously mixing 3 He and 4 He to create and maintain temperatures below 0.005 K

The areas of application of xenon are varied and sometimes unexpected. Man takes advantage of both its inertness and its wonderful ability to react with fluorine. In lighting technology, high-pressure xenon lamps have gained recognition. In such lamps, an arc discharge shines in xenon, which is under a pressure of several tens of atmospheres. The light in xenon lamps appears immediately after switching on, it is bright and has a continuous spectrum - from ultraviolet to near-infrared. Xenon is also used by doctors for fluoroscopic examinations of the brain. Like barite porridge, which is used for intestinal candling, 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 studying 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.

Electric arc welding in an argon environment is increasingly being used. In an argon jet it is possible to weld thin-walled products and metals that were previously considered difficult to weld. It would not be an exaggeration to say that the electric arc in an argon atmosphere revolutionized the technology of cutting metals. The process was much faster, and 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, causing the temperature in the cutting zone to reach 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, there is no need to clean the seam from slag and flux residues.

Neon and argon are used as fillers in neon lamps and daylight lamps. Krypton is used to fill ordinary lamps in order to reduce evaporation and increase the brightness of the tungsten filament. High-pressure quartz lamps, which are the most powerful light sources, are filled with xenon. 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”

3. Akhmetov N.S. “General and inorganic chemistry”

4. Nekrasov B.V. “Textbook of General Chemistry”

5. Glinka N.L. "General chemistry

6. Khodakov Yu.V. “General and inorganic chemistry”

Opening:

In 1893, attention was drawn to the discrepancy between the densities of nitrogen from the air and nitrogen obtained from the decomposition of nitrogen compounds: a liter of nitrogen from the air weighed 1.257 g, and that obtained chemically weighed 1.251 g. A very accurate study of the composition of the air carried out to clarify this mysterious circumstance showed that after all the oxygen and nitrogen were removed, there was a small residue (about 1%) that did not react chemically with anything.

The discovery of a new element, called argon (Greek for inactive), thus represented the “triumph of the third decimal place.” The molecular weight of argon turned out to be 39.9 g/mol.

The next inert gas to be discovered, helium (“solar”), was discovered on the Sun earlier than on Earth. This turned out to be possible thanks to the spectral analysis method developed in the 50s of the last century.

A few years after the discovery of argon and helium (in 1898), three more noble gases were isolated from the air: neon (“new”), krypton (“hidden”) and xenon (“alien”). How difficult it was to detect them can be seen from the fact that 1 m 3 of air, along with 9.3 liters of argon, contains only 18 ml of neon, 5 ml of helium, 1 ml of krypton and 0.09 ml of xenon.

The last inert gas, radon, was discovered in 1900 while studying certain minerals. Its content in the atmosphere is only 6-10 -18% by volume (which corresponds to 1-2 atoms per cubic centimeter). It has been estimated that the entire earth's atmosphere contains only 374 liters of radon.

Physical properties:

All noble gases are colorless and consist of monatomic molecules. The separation of inert gases is based on the difference in their physical properties.

Inert gases are colorless and odorless. They are present in small quantities in the air. Inert gases are not poisonous. However, an atmosphere with an increased concentration of inert gases and a corresponding decrease in oxygen concentration can have a suffocating effect on a person, including loss of consciousness and death. There are known cases of death due to argon leaks.

Melting point, °C
Boiling point, °C

The amount of heat required to transfer a substance from a solid to a liquid state is called the heat of fusion, and to transfer from a liquid to a vapor state is called the heat of evaporation. Both quantities are usually referred to as transitions occurring under normal pressure. For inert gases they have the following values ​​(kcal/g-atom):

Heat of Melting
Heat of vaporization

Below are compared critical temperatures inert gases and those pressures that are necessary and sufficient for their transfer at these temperatures from a gaseous state to a liquid state, - critical pressures:

Critical temperature, °C
Critical pressure, atm

This is interesting :

The question of the atomicity of the argon molecule was resolved using kinetic theory. According to it, the amount of heat that needs to be expended to heat a gram-molecule of a gas by one degree depends on the number of atoms in its molecule. At constant volume, a gram-molecule of a monatomic gas requires 3 feces, diatomic - 5 cal. For argon the experiment gave 3 feces, which indicated the monoatomic nature of its molecule. The same applies to other inert gases.

Helium was the last gas to be converted into a liquid and solid state. In relation to it, there were special difficulties due to the fact that as a result of expansion at ordinary temperatures, helium does not cool, but heats up. Only below -250 °C does it begin to behave “normally”. It follows that the usual liquefaction process could be applied to helium only after it had been very strongly cooled beforehand. On the other hand, the critical temperature of helium is extremely low. Due to these circumstances, favorable results when working with helium were obtained only after mastering the technique of operating with liquid hydrogen, using the evaporation of which only it was possible to cool helium to the required temperatures. It was possible to obtain liquid helium for the first time in 1908, solid helium-V1926

Chemical properties:

Inert gases are characterized by a complete (He, Ne, Ar) or almost complete (Kr, Xe, Rn) lack of chemical activity. In the periodic table they form a special group (VIII). Soon after the discovery of inert gases, the new group they formed in the periodic table was called zero, in order to emphasize the zero valency of these elements, i.e., their lack of chemical activity. This name is often used at the present time, however, in essence of the periodic law, it is more correct to consider the group of inert gases as the eighth group, since the corresponding periods do not begin with these elements, but end.

The absence of complete chemical inertness in heavy inert gases was discovered only in 1962. It turned out that they are capable of combining with the most active metalloid - fluorine (and only with it). Xenon (and radon) react quite easily, krypton much more difficult. XeF 2 , XeF 4 , XeF 6 and low-stable KrF 2 were obtained. All of them are colorless volatile crystalline substances.

Xenon difluoride(XeF 2) - is slowly formed under the influence of daylight on a mixture of Xe and F 2 at zero conditions. It has a characteristic nauseating odor. The formation of a molecule requires excitation of the xenon atom from 5s 2 5p 6 to the nearest divalent state 5s 2 5p 5 s 1 - 803 kJ/mol, to 5s 2 5p 5 6p 1 -924 kJ/mol, 25s 2 5p 1 6d 1 - 953 kJ/ mole.

Xe+F 2 →XeF 2

0.15 mol/l dissolves in water. The solution is a very strong oxidizing agent. The solution decomposes according to the following scheme:

XeF 2 +H 2 O →HF+Xe+O 2 (the process occurs faster in an alkaline environment, slower in an acidic environment).

Xenontetrafluoride- formed from simple substances, the reaction is highly exothermic, and is the most stable of all fluorides.

XeF 4 +2Hg=2HgF 2 +Xe

XeF 4 +Pt=PtF 4 +Xe

Qualitative reaction to xenon tetrafluoride :

XeF 4 +4KI=4KF+2I 2 ↓+Xe

Xenon tetrafluoride decomposes according to the following schemes:

3Xe 4+ →Xe 6+ +2Xe 0 (in acidic medium).

Xe 4+ →Xe 0 +Xe 8+ (in an alkaline medium).

Xenon hexafluoride is colorless, known in 3 crystalline modifications. At 49 ℃, turning into a yellow liquid, when hardening it becomes discolored again. The vapors are pale yellow in color. Explosively decomposes. Under the influence of moist air hydrolyze:

XeF 6 +H 2 O→2HF+OXeF 4

OXeF 4 is a colorless liquid, less reactive than XeF 6. Forms crystalline hydrates with alkali metal fluorides, for example: KF∙OXeF 4

Further hydrolysis can produce xenon trioxide:

XeF 6 +3H 2 O→XeO 3 +6HF

XeO 3 is a colorless explosive substance that diffuses in air. It disintegrates explosively, but when gently heated at 40 degrees Celsius, the reaction occurs:

2XeO 3 →2Xe+3O 2

There is an acid that formally corresponds to this oxide - H 2 XeO 4. There are salts corresponding to this acid: MHXeO 4 or MH 5 XeO 6, an acid (M - from sodium to cesium) corresponding to the last salt was obtained:

3XeF 4 +6Ca(OH) 2 →6CaF 2 ↓+Xe+2H 2 XeO 6

In a strongly alkaline environment, Xe 6+ dismutates:

4Xe 6+ →Xe 0 +3Xe 8+

Krypton difluoride- volatile, colorless crystals , a chemically active substance. At elevated temperatures it decomposes into fluorine krypton . It was first obtained by the action of an electric discharge on a mixture of substances, at -188℃:

F 2 +Kr→KrF 2

Decomposes with water according to the following scheme:

2KrF 2 +2H 2 O→O 2 +4HF+2Kr

Application of inert gases:

Inert gases find quite a variety of practical applications. In particular, the role of helium in obtaining low temperatures is extremely important, since liquid helium is the coldest of all liquids. Artificial air, in which nitrogen is replaced by helium, was first used to ensure the breathing of divers. The solubility of gases increases greatly with increasing pressure, therefore, when a diver descends into water and is supplied with ordinary air, the blood dissolves more nitrogen than under normal conditions. During ascent, when the pressure drops, dissolved nitrogen begins to be released and its bubbles partially clog small blood vessels, thereby disrupting normal blood circulation and causing attacks of “caisson sickness.” Thanks to the replacement of nitrogen with helium, painful effects are sharply weakened due to the much lower solubility of helium in the blood, which is especially noticeable at high pressures. Working in an atmosphere of “helium” air allows divers to descend to great depths (over 100 m) and significantly extend their stay under water.

Since the density of such air is approximately three times less than that of normal air, it is much easier to breathe. This explains the great medical importance of helium air in the treatment of asthma, suffocation, etc., when even short-term relief of a patient’s breathing can save his life. Similar to helium, “xenon” air (80% xenon, 20% oxygen) has a strong narcotic effect when inhaled, which can be used medically.

Neon and argon are widely used in the electrical industry. When an electric current passes through glass tubes filled with these gases, the gas begins to glow, which is used to design illuminated inscriptions.

High-power neon tubes of this type are especially suitable for lighthouses and other signaling devices, since their red light is little blocked by fog. The color of the helium glow changes from pink through yellow to green as its pressure in the tube decreases. Ar, Kr and Xe are characterized by different shades of blue.

Argon (usually mixed with 14% nitrogen) is also used to fill electric lamps. Due to their significantly lower thermal conductivity, krypton and xenon are even better suited for this purpose: electric lamps filled with them provide more light with the same energy consumption, withstand overload better and are more durable than conventional ones.

Editor: Galina Nikolaevna Kharlamova