Gas is one of the states of aggregation substances. Gases are present not only in the air on Earth, but also in space. They are associated with lightness, weightlessness, and volatility. The lightest is hydrogen. Which gas is the heaviest? Let's find out.
The heaviest gases
The word "gas" comes from ancient Greek word"chaos". Its particles are mobile and weakly connected to each other. They move chaotically, filling all the space available to them. A gas can be a simple element and consist of atoms of one substance, or it can be a combination of several.
The simplest heavy gas (at room temperature) is radon, its molar mass 222 g/mol. It is radioactive and completely colorless. After it, xenon is considered the heaviest, atomic mass which is 131 g/mol. The remaining heavy gases are compounds.
Among inorganic compounds the heaviest gas at a temperature of +20 o C is tungsten (VI) fluoride. Its molar mass is 297.84 g/mol and its density is 12.9 g/L. IN normal conditions It is a colorless gas; in humid air it smokes and turns blue. Tungsten hexafluoride is very active and easily turns into a liquid when cooled.
Radon
The discovery of the gas occurred during a period of research into radioactivity. During the decay of certain elements, scientists have repeatedly noted some substance emitted along with other particles. E. Rutherford called it emanation.
This is how the emanation of thorium - thoron, radium - radon, actinium - actinon was discovered. Later it was found that all these emanations are isotopes of the same element - an inert gas. Robert Gray and William Ramsay were the first to isolate it in its pure form and measure its properties.
IN periodic table Mendeleev's radon is an element of group 18 with atomic number 86. It is located between astatine and francium. Under normal conditions, the substance is a gas and has no taste, smell or color.
The gas is 7.5 times denser than air. It dissolves in water better than other noble gases. In solvents this figure increases even more. Of all inert gases it is the most active, easily interacting with fluorine and oxygen.
Radioactive gas radon
One of the properties of the element is radioactivity. The element has about thirty isotopes: four are natural, the rest are artificial. All of them are unstable and subject to radioactive decay. radon, or more precisely, its most stable isotope, is 3.8 days.
Due to its high radioactivity, the gas exhibits fluorescence. In gaseous and liquid state the substance is highlighted in blue. Solid radon changes its palette from yellow to red when cooled to nitrogen temperature - about -160 o C.
Radon can be very toxic to humans. As a result of its decay, heavy non-volatile products are formed, for example, polonium, lead, bismuth. They are extremely difficult to remove from the body. As they settle and accumulate, these substances poison the body. After smoking, radon is the second most common cause of lung cancer.
Location and uses of radon
The heaviest gas is one of the rarest elements in the earth's crust. In nature, radon is part of ores containing uranium-238, thorium-232, uranium-235. When they decay, it is released, entering the hydrosphere and atmosphere of the Earth.
Radon accumulates in river and sea waters, in plants and soil, and in building materials. In the atmosphere, its content increases during the activity of volcanoes and earthquakes, during the mining of phosphates and the operation of geothermal power plants.
This gas is used to find tectonic faults and deposits of thorium and uranium. It is used in agriculture to activate pet food. Radon is used in metallurgy, in the study of groundwater in hydrology, and radon baths are popular in medicine.
Often our knowledge and ideas about any potentially dangerous phenomenon are limited enough to take it seriously. On the one hand, the absence of worries about this greatly makes our life easier, but on the other hand, at a critical moment in the face of danger, we find ourselves completely unprepared to defend ourselves. own health. This is approximately the situation with radon, which many have heard about, but not many know what kind of animal it is.
A considerable proportion of the population perceives radon only in connection with therapeutic radon baths, and therefore some people experience extreme bewilderment when they are told that under normal conditions constant contact with radon does not so much cure as cripple.
Let's figure out under what circumstances radon is useful and when it becomes harmful.
What is radon?
Radon is an inert gas that is colorless and odorless. The trouble is that this gas is radioactive, that is, when it decays, it becomes a source of ionizing radiation. There are four isotopes of radon in nature, but the two most well known are radon (Rn 222) and thoron (Rn 220). The other two isotopes (Rn 219 and Rn 218) are very unstable and “live” so short after their occurrence that we have practically no chance of coming across them face to face.
Radon (Rn 222) is the longest-living of this family, which is why we can meet it in our everyday life.
Where does radon come from?
Like most radioactive elements Radon is obtained from other radioactive elements, for example Rn 222 is a product of the fission of radium nuclei, which in turn appear after the decay of uranium. Thus, the source of radon is soil, the rocks of which contain varying amounts of uranium.
Granites contain the most uranium, so areas located above such soils are classified as radon-hazardous areas.
Due to its inertness, this gas is quite easily released from the crystalline lattices of minerals and spreads through cracks over fairly long distances. Damage to the soil with an increase in the number of cracks, for example during construction, increases the release of radon into the atmosphere.
Radon is highly soluble in water, which means that if a layer of underground interstratal water comes into contact with rocks containing radon, then artesian wells will produce water rich in this gas.
Why is radon dangerous?
As you probably already guessed, the danger of radon lies in its radioactivity. Radon released into the atmosphere is inhaled along with the air and already in the bronchi begins to irradiate the mucous membrane. Radon decay products are also radioactive. Once in the blood, they spread throughout the body, continuing to irradiate it.
It is currently believed that radon and its decay products account for about eighty percent of the annual radiation dose to the planet's population from .
Ionizing radiation in relatively small doses that do not lead to radiation sickness is dangerous due to its long-term probabilistic effects, or they are also called stochastic effects.
The likelihood and timing of such effects are difficult to predict, but the risk of their occurrence in people exposed to radiation is significantly higher than in people who have not been exposed to radiation. The scale of the consequences is also difficult to assess, since the severity of stochastic effects does not depend on the radiation dose.
The most dangerous stochastic effects of exposure to ionizing radiation are cancer. Exposed people develop cancer more often, and exposure to radon is no exception.
More than a tenth of lung cancer cases recorded each year are caused by radon radiation, second only to smoking. By the way, in conjunction with smoking, the oncogenic effect of radon increases.
There is statistical evidence that radon exposure increases the risk of cancer of the bladder, skin, stomach, and rectum. In addition, there is information about the harmful effects of radon on the bone marrow, thyroid gland, liver, cardiovascular system and reproductive organs.
Where is radon dangerous?
Speaking on a national scale, high-risk areas are regions where granite, grace, phosphorite, etc. lie close to the surface of the earth. Relatively high doses are received by the population of territories where industrial enterprises for the extraction and processing of mineral raw materials, as well as metallurgical enterprises and thermal power plants are located.
As already mentioned, radon penetrates into the atmosphere from the soil, and if a building is built on such a site, then nothing prevents radon from accumulating indoors. With absent or poorly functioning ventilation, the concentration of radon in the air of enclosed spaces can be tens of times higher than the concentration in the outdoor air.
Radon is more than seven times heavier than air, so it accumulates most in basements and on the first floors.
The second possible way for radon to penetrate into housing is through building materials. If raw materials containing radon were used in their production, then it will inevitably enter the premises, and then the number of floors does not matter.
In the case where water is supplied to the building from underground sources and without additional water treatment, radon can enter the home with water. Then the highest concentration of radon will be in the rooms in which water is distributed, for example, in Finland, where there is a lot of radon in the soil, a radon concentration 50 times higher than the norm was found in the bathrooms of houses. By the way, only about 5 million people live in this country; Finland ranks first in the world in terms of the incidence of lung cancer, and the mortality rate from this tumor is 200–600 people per year.
Quite often, radon can be found in apartments equipped with gas stoves. In this case, radon comes with natural gas and creates high concentrations in kitchens.
What is the standard for radon content?
In our country, the normalization of radon content in indoor air is carried out according to the average annual equivalent equilibrium volumetric activity (ERVA) of radon isotopes, which is measured in Bq/m³.
In residential and public buildings that are handed over after construction, major repairs or reconstruction, the radon energy content should not exceed 100 Bq/m³, and in operated buildings - 200 Bq/m³.
- SanPiN 2.6.1.2523-09 “Standards radiation safety(NRB-99/2009)", clause 5.3.2, clause 5.3.3;
- SP 2.6.1.2612-10 “Basic sanitary rules for ensuring radiation safety (OSPORB - 99/2010)”, clause 5.1.3.
- SanPiN 2.6.1.2800-10 “Radiation safety requirements for public exposure natural sources ionizing radiation", clause 4.2.6, clause 4.2.7.
What to do if radon is higher than normal?
If the standards for radon in residential and public buildings are higher than normal, then additional anti-radon protection measures must be taken.
There are passive and active protection systems.
Passive protection involves insulating the building envelope to prevent the diffusion of radon from the basement into living spaces (sealing, membranes, barriers, impregnations, coatings). Such events do not require energy or maintenance, which is their advantage.
Active protection is based on the forced removal of radon from the source into the atmosphere (forced ventilation of the basement, basement collector, basement soil). This requires special installations, energy sources and personnel for maintenance, but the effectiveness of active measures is noticeably superior to passive ones.
If for some reason, including economic reasons, it is impossible to carry out additional measures, then the issue of relocating residents, repurposing buildings and premises, or demolishing an existing building should be considered (clause 5.1.4 OSPORB - 99/2010, p. .4.2.6, clause 4.2.7 SanPiN 2.6.1.2800-10).
About the benefits of radon
Since we are talking about radon, we cannot omit the question of the healing properties of radon baths. The use of this treatment method is based on the opinion of scientists that small doses of radiation, acting as a mild stress factor, stimulate cellular defense and immunity of the body as a whole.
Treatment with radon baths is used for arthrosis, arthritis, hypertension, etc.
It should be noted that the concentration of radon in such baths is negligible, and the course of treatment is usually short-lived.
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Discussion: 13 comments
hello, for several years I had contact with Adrianov compasses that were in my storage (more than 800 pieces) and all of them, as I later found out, were phonic and since they were lying in the same rack in wooden boxes at a distance of 2-3 meters, the Geiger counter showed LARGE dose. periodically they had to be taken out, counted, etc. Question: Could I get the dose and how should it manifest itself?
Answer
Without measuring the levels of ionizing radiation, it is impossible to say anything definitely, but I found information on the Internet that Hadrian’s radium (up to 0.03%) included in compasses creates a total equivalent dose of 0.95 μSv/h, as far as I understand it was measured directly at the surface of the compass. That is, if you wear a compass on your hand or in your body pocket every day without taking it off even at night, then the dose per year will be about 7.8 - 8.6 mSv/year (the effective dose rate according to NRB-99/2009 for the population is 1 mSv per year for any consecutive 5 years, but not more than 5 mSv per year). That's a lot, but it's unlikely that you've been wearing compasses on your body 24/7. If you know the dose from the compasses at the point where you were during work (2-3 meters is a sufficiently large distance for the dose to be small), then you can calculate the likely effective dose for the year yourself, taking into account the actual time spent there. As for the manifestations of overexposure, there are two types of biological effects from exposure high levels radiation:
- deterministic effects - they necessarily appear and depend on the dose; the higher the dose, the worse the health status (according to the severity of radiation sickness)
- stochastic effects are probabilistic and unpredictable, they are assessed by the degree of increase in risk, that is, the higher the dose, the greater the risk of developing such effects, but no one can say when they will develop, or whether they will develop at all.
It seems that radon baths are only absolutely beneficial healthy people. It’s unlikely that radiation, although in small doses, is useful, no one knows how this dose of radon will affect the body in the future... And so all around we have radiation from household electronics... Maybe they were useful in the ancient centuries, when there were not so many factors of everyday radiation as now.
Answer
The child went to kindergarten. Later they found out that as a result of the earthquake, a crack appeared and radon was coming into the group, they made an exhaust hood and the commission checks it every six months.
Then we find out that the hood has not worked since September, my child has developed a strong cough since December. They are diagnosed with bronchial hyperactivity
Could radon have accumulated since September and harm children?
Is it possible to use a hood to solve the problem?
In August, before accepting children, measurements showed the norm
Answer
The housing departments are killing us with radon. All the vents are bricked up. Incompetent management! The residents are completely unaware. What about radon
Answer
/mol)
(first electron)
(according to Pauling)
(liquid, at -62 °C) 4.4 /cm³
face-centered
| Rn | 86 |
| 4f 14 5d 10 6s 2 6p 6 | |
| Radon | |
Radon- element main subgroup eighth group, sixth period periodic table chemical elements of D. I. Mendeleev, with atomic number 86. Indicated by the symbol Rn(Radon). Simple substance radon(CAS number: 10043-92-2) under normal conditions - a colorless inert gas; radioactive and may pose a danger to health and life. At room temperature it is one of the heaviest gases. The most stable isotope (222 Rn) has a half-life of 3.8 days.
The English scientist E. Rutherford noted in 1899 that thorium preparations emit, in addition to α-particles, some previously unknown substance, so that the air around the thorium preparations gradually becomes radioactive. He proposed to call this substance an emanation (from the Latin emanatio - outflow) of thorium and give it the symbol Em. Subsequent observations showed that radium preparations also emit a certain emanation, which has radioactive properties and behaves like an inert gas.
Initially, the emanation of thorium was called Thoron, and the emanation of radium by Radon. It was proven that all emanations are actually radionuclides of a new element - an inert gas, which corresponds to atomic number 86. It was first isolated in its pure form by Ramsay and Gray in 1908, they also proposed to call the gas niton (from the Latin nitens, luminous ). In 1923, the gas was finally named radon and the symbol Em was changed to Rn.
Being in nature
It is part of the radioactive series 238 U, 235 U and 232 Th. Radon nuclei constantly arise in nature during the radioactive decay of parent nuclei. Equilibrium content in earth's crust 7·10−16% by mass. Due to its chemical inertness, radon relatively easily leaves the crystal lattice of the “parent” mineral and enters groundwater. natural gases and air. Since the longest-lived of the four natural isotopes of radon is 222 Rn, it is its content in these environments that is maximum.
The concentration of radon in the air depends primarily on the geological situation (for example, granites, which contain a lot of uranium, are active sources of radon, while at the same time there is little radon above the surface of the seas), as well as on the weather (during rain, microcracks through which radon comes from the soil and is filled with water; snow cover also prevents radon from entering the air). Before the earthquakes, an increase in radon concentration in the air was observed, probably due to a more active exchange of air in the ground due to an increase in microseismic activity.
Receipt
To obtain radon through aqueous solution any radium salt is blown through air, which carries with it radon formed during the radioactive decay of radium. Next, the air is carefully filtered to separate microdroplets of the solution containing the radium salt, which can be captured by the air current. To obtain radon itself, chemically active substances (oxygen, hydrogen, water vapor, etc.) are removed from a mixture of gases, the residue is condensed with liquid nitrogen, then nitrogen and other inert gases (argon, neon, etc.) are distilled from the condensate.
Physical properties
Radon is a radioactive monatomic gas, colorless and odorless. Solubility in water 460 ml/l; in organic solvents and in human adipose tissue, the solubility of radon is tens of times higher than in water. Gas penetrates well through polymer films. Easily adsorbed by activated carbon and silica gel.
Radon's own radioactivity causes it to fluoresce. Gaseous and liquid radon fluoresces with blue light; in solid radon, when cooled to nitrogen temperatures, the fluorescence color becomes first yellow, then red-orange.
Chemical properties
"Noble Gas" Radon forms clathrates, which, although they have a constant composition, chemical bonds with the participation of radon atoms they do not contain. With fluorine radon high temperatures forms compounds of the composition RnF n, where n = 4, 6, 2. Thus, radon difluoride RnF 2 is white non-volatile crystalline substance. Radon fluorides can also be produced by the action of fluorinating agents (for example, halogen fluorides). The hydrolysis of tetrafluoride RnF 4 and hexafluoride RnF 6 produces radon oxide RnO 3 . Compounds with the RnF + cation were also obtained.
Application
Radon is used in medicine to prepare radon baths. Radon is used in agriculture to activate animal feed, in metallurgy as an indicator in determining the speed of gas flows in blast furnaces and gas pipelines. In geology, measuring radon content in air and water is used to search for deposits uraniumAndthorium, in hydrology - to study the interaction of groundwater and river waters. Dynamics of radon concentration in groundwater can be used to predict earthquakes.
Background
The discovery of radioactivity and radon coincided with increased interest in the biological effects of radiation. It has been found that the water of many mineral water sources is rich in radium emanation(that’s what radon was called at that time). This discovery was followed by a wave of fashion for radiation. In particular, in advertising of that time, the radioactivity of mineral waters was presented as the main indicator of their usefulness and effectiveness.
Natural radiation background of building premises (NRBP)
The main components of indoor radiation levels largely depend on human activity. This is caused primarily by factors such as choice building materials, design solutions of buildings and ventilation systems used in them. Measurements do not always confirm the established conclusion that radon accumulates in higher concentrations in basements and on the lower floors of buildings than on the upper floors.
Biological effects
When radon enters the human body, it contributes to processes leading to lung cancer. The decay of radon nuclei and its daughter isotopes in lung tissue causes a microburn, since all the energy of the alpha particles is absorbed almost at the point of decay. The combination of exposure to radon and smoking is especially dangerous (increases the risk of disease). It is believed that radon is the second most common factor (after smoking) cancer-causing lungs. Lung cancer caused by radon exposure is the sixth leading cause of cancer death.
Radon radionuclides account for more than half of the total radiation dose that the average human body receives from natural and man-made radionuclides in the environment.
Currently, many countries carry out environmental monitoring of radon concentrations in buildings, since in areas of geological faults its concentrations in buildings can be hurricane-like and significantly exceed the average values for other regions.
The maximum permissible intake of radon through the respiratory system is 146 MBq/year.
Isotopes
Radon has no stable isotopes. The most stable is 222 Rn ( T 1/2 =3.8235 days), which is part of the natural radioactive family of uranium-238 (uranium-radium family) and is a direct product of the decay of radium-226. Sometimes the name “radon” refers specifically to this isotope. The thorium-232 family includes 220 Rn ( T 1/2 =55.6 s), sometimes called thoron (Tn). The uranium-235 (uranium-actinium) family includes 219 Rn ( T 1/2 =3.96 s), it is called actinon(An). One of the side branches (branching factor 2×10 −7) of the uranium-radium family also includes a very short-lived ( T 1/2 =35 ms) radon-218. All noted isotopes of radon undergo alpha decay.
These four nuclides complete the list of natural isotopes of radon. Another 30 artificial isotopes of Rn are known with a mass number from 195 to 228. Some neutron-deficient isotopes of radon also have excited metastable states; 13 such states are known. The predominant decay modes of light Rn isotopes are alpha decay, positron decay, and electron capture. Starting from mass number A=212 alpha decay becomes dominant. Heavy isotopes radon (starting from A=223) decay predominantly through beta-minus decay.
Radon(lat. Radonum), Rn, radioactive chemical element VIII group Mendeleev's periodic system; atomic number 86, belongs to the noble gases. Three α-radioactive isotopes of Radon occur in nature as members of the natural radioactive series. 219 Rn (member of the actinouranium series; half-life T ½ = 3.92 sec); 220 Rn (thorium series, T ½ = 54.5 sec) and 222 Rn (uranium - radium series, T ½ = 3.823 days). The isotope 219 Rn is also called actinon (symbol An), 220 Rn is thoron (Tn), and 222 Rn is called true Radon and is often designated simply by the symbol Rn. Artificially, with the help nuclear reactions over 20 isotopes of Radon with mass numbers between 201 and 222 were obtained. To synthesize neutron-deficient isotopes of Radon with mass numbers 206-212, a special gas chromatographic installation was created at the Joint Institute for Nuclear Research (Dubna, USSR), which makes it possible to obtain the sum of these isotopes in radiochemical terms in half an hour pure form.
The discovery of Radon is the result of early work on the study of radioactivity. In 1899, the American physicist R.B. Owens discovered that the decay of Th produces a certain radioactive substance that can be removed from solutions containing Th by a stream of air. E. Rutherford called this substance emanation (from the Latin emano - flow out). In 1899, Rutherford, then working in Canada, proved that the emanation of thorium discovered by Owens was a radioactive gas. In the same year, E. Dorn in Germany and A. Debierne in France reported that the decay of radium also produces an emanation (radium emanation, radon). In 1903, an emanation of actinium, actinon ( natural isotopes Radon is still often called emanations). Thus, in the case of Radon, scientists practically for the first time encountered the existence of several varieties of atoms in one element, which were later called isotopes. E. Rutherford, W. Ramsay, F. Soddy and others showed that the emanation of radium is a new chemical element related to inert gases. For its ability to luminesce in a condensed state, Radon was supposed to be called niton (from the Latin nitens - shining).
Radon is one of the rarest elements. Its content in the earth's crust up to 1.6 km deep is about 115 tons. Radon, formed in radioactive ores and minerals, gradually enters the earth's surface, the hydrosphere and the atmosphere. The average concentration of Radon in the atmosphere is about 6·10 -17% (by mass); in sea water - up to 0.001 pcurie/l.
Under normal conditions, Radon is a colorless, odorless, and tasteless gas; boiling temperature -61.8°С, melting temperature -71°С. Density at 0°C is about 9.9 g/l. About 0.5 volumes of Radon are dissolved in 1 volume of water at 0°C (much more in organic solvents). There are 8 electrons on the outer electron shell of the Radon atom (configuration 6s 2 6p 6), which is why chemically Radon is very inactive. Like xenon, Radon produces fluoride (probably of the composition RnF 2), which at 500 °C is reduced by hydrogen to elemental Radon. As B.A. Nikitin established, Radon can form clathrates with water, phenol, toluene, etc.
To obtain Radon (its isotope 222 Rn), a current of gas (nitrogen, argon, etc.) is passed through an aqueous solution of radium salt. The gas passing through the solution contains about 10 -5% Radon. To extract Radon, they use either its ability to sorb well on porous bodies (activated carbon and others), or special chemical methods. Available quantities of pure Radon do not exceed 1 mm 3 .
Radon is highly toxic due to its radioactive properties. The decay of Radon produces non-volatile radioactive products (isotopes Po, Bi and Pb), which are removed from the body with great difficulty. Therefore, when working with Radon, it is necessary to use sealed boxes and take precautions.
Radon is used mainly in medicine. Waters containing Radon are used in the treatment of diseases of the nervous and cardiovascular systems, respiratory and digestive organs, bones, joints and muscles, gynecology, diseases, metabolic diseases and others.
Emanation methods of geological exploration are based on determining the concentration of Radon in the surface layer of air, allowing one to estimate the content of U and Th in soils, in rocks adjacent to the surface, etc. Radon is also used in scientific research. The radioactivity of Radon, which is in equilibrium with U or Th, is sometimes used to determine the content of these elements, for example, in rock samples. The study of changes in the structure of solids by the emanation method is based on measuring the rate of release of Radon when heated from solid samples containing radioactive isotopes- Radon precursors in the radioactive series 232 Th or 235 U.
radon, radium emanation ; German Radon n) - Radioactive chemical element of the periodic table. Symbol Rn. Opened in 1900 in Germany. scientists F. Dore and English. physicist E. Rutherford. Belongs to inert gases, at. n. 86, at. 222.0176. R. is a monatomic gas, colorless and odorless. Radioactive. Toxic. Chemically inactive. Forms inclusion compounds with water, phenol, toluene, etc., chemical compounds- lithium. It is formed in radioactive ores and minerals during the decay of radium (hence the name of the element). Artificially obtained from radium salts. More than 25 isotopes of Rn are known. The isotope 222 Rn is stable (half-life - 3.824 days). Density 9.73 kg/m3; tpl = - 71? WITH; t kip = - 61.9? S.R. is used in geochemistry for the qualitative assessment of the preservation of the crystalline structure of radioactive minerals used in isotope geochronology. A radon-xenon method for determining the age of uranium minerals has also been proposed. In addition, they are used in the exploration of uranium deposits (behind Rn emanations in the surface layer of the atmosphere), in medicine (radon baths, radiation therapy), and technology (Rn-Be neutron source).2. History
Opened in 1900 in Germany. scientists F. Dore and English. physicist E. Rutherford.
3. Origin of the name
The English scientist E. Rutherford noted in 1899 that thorium preparations release, in addition to α-particles, some previously unknown substance, so that the air around the thorium preparations becomes radioactive. He proposed to call this substance emanation (from lat. emanatio- Outflow) of thorium and give it the symbol Em. Further observations showed that the preparations also release some kind of emanation, which has radioactive properties and behaves like an inert gas. At first, the emanation of thorium was called thoron, and the emanation of radium was called radon. It was proven that all emanations are actually radionuclides of a new element - an inert gas, which corresponds to atomic number 86. It was first isolated in its pure form by Ramsay and Gray in 1908, they also proposed to call the gas nitone (lat. Nitens- Glowing). In 1923, the gas was finally named radon and the symbol Em was changed to Rn.
4. Distribution
One of the rarest elements on Earth. The total amount of R. in the earth's crust up to 1.6 km deep is approx. 115 t. Wed. R. concentration in the atmosphere is approx. 6? 10 -17% (mass.).
5. Receipt
To obtain radon, air is blown through an aqueous solution of any radium salt, which carries with it radon formed during the radioactive decay of radium. Further air is carefully filtered to separate microdroplets of the solution containing radium salt and which can be captured by the air stream. To obtain radon itself, chemically active substances (oxygen, hydrogen, water vapor, etc.) are removed from a mixture of gases, the residue is condensed with liquid nitrogen, then nitrogen and other inert gases are fractionally distilled from the condensate (
