Formation of atomic nuclei.

Helium(He) is an inert gas, which is the second element of the periodic system of elements, as well as the second element in terms of lightness and prevalence in the Universe. It belongs to simple substances and under standard conditions (Standard temperature and pressure) is a monatomic gas.

Helium has no taste, color, smell and does not contain toxins.

Among all simple substances, helium has the lowest boiling point (T = 4.216 K). At atmospheric pressure, it is impossible to obtain solid helium, even at temperatures close to absolute zero - to go into a solid form, helium needs a pressure above 25 atmospheres. There are few chemical compounds of helium and all of them are unstable under standard conditions.
Naturally occurring helium consists of two stable isotopes, He and 4He. The “He” isotope is very rare (isotope abundance 0.00014%) with 99.99986% for the 4He isotope. In addition to natural, 6 artificial radioactive isotopes of helium are also known.
The appearance of almost everything in the Universe, helium, was the primary nucleosynthesis that took place in the first minutes after the Big Bang.
At present, almost all helium It is formed from hydrogen as a result of thermonuclear fusion occurring in the interior of stars. On our planet, helium is formed in the process of alpha decay of heavy elements. That part of the helium that manages to seep through the Earth's crust comes out as part of natural gas and can be up to 7% of its composition. What to highlight helium from natural gas, fractional distillation is used - the process of low-temperature separation of elements.

The history of the discovery of helium

On August 18, 1868, a total solar eclipse was expected. Astronomers around the world have been actively preparing for this day. They hoped to solve the mystery of prominences - luminous projections visible at the time of a total solar eclipse along the edges of the solar disk. Some astronomers believed that prominences are high lunar mountains, which, at the time of a total solar eclipse, are illuminated by the rays of the Sun; others thought that the prominences were mountains on the Sun itself; still others saw fiery clouds of the solar atmosphere in the solar projections. The majority believed that prominences were nothing more than an optical illusion.

In 1851, during a solar eclipse observed in Europe, the German astronomer Schmidt not only saw solar projections, but also managed to discern that their outlines change over time. Based on his observations, Schmidt concluded that prominences are incandescent gas clouds ejected into the solar atmosphere by giant eruptions. However, even after Schmidt's observations, many astronomers still considered fiery ledges to be an optical illusion.

Only after the total eclipse of July 18, 1860, which was observed in Spain, when many astronomers saw the solar projections with their own eyes, and the Italian Secchi and the Frenchman Dellar managed not only to sketch, but also photograph them, no one had any doubts about the existence of prominences .

By 1860, a spectroscope had already been invented - a device that makes it possible, by observing the visible part of the optical spectrum, to determine the qualitative composition of the body from which the observed spectrum is obtained. However, on the day of the solar eclipse, none of the astronomers used a spectroscope to view the spectrum of prominences. The spectroscope was remembered when the eclipse had already ended.

That is why, preparing for the solar eclipse of 1868, every astronomer included a spectroscope in the list of instruments for observation. Jules Jansen, a famous French scientist, did not forget this instrument when he went to India to observe prominences, where conditions for observing a solar eclipse, according to astronomers' calculations, were the best.

At the moment when the sparkling disk of the Sun was completely covered by the Moon, Jules Jansen, examining with a spectroscope the orange-red flames escaping from the surface of the Sun, saw in the spectrum, in addition to three familiar lines of hydrogen: red, green-blue and blue, a new, unfamiliar - bright yellow. None of the substances known to chemists of that time had such a line in the part of the spectrum where Jules Jansen discovered it. The same discovery, but at home in England, was made by astronomer Norman Lockyer.

On October 25, 1868, the Paris Academy of Sciences received two letters. One, written the day after the solar eclipse, came from Guntur, a small town on the east coast of India, from Jules Janssen; another letter dated 20 October 1868 was from England from Norman Lockyer.

The received letters were read out at a meeting of professors of the Paris Academy of Sciences. In them, Jules Jansen and Norman Lockyer, independently of each other, reported the discovery of the same "solar substance". This new substance, found on the surface of the Sun using a spectroscope, Lockyer proposed to call helium from the Greek word for "sun" - "helios".

Such a coincidence surprised the scientific meeting of professors of the Academies and at the same time testified to the objective nature of the discovery of a new chemical substance. In honor of the discovery of the substance of solar torches (prominences), a medal was knocked out. On one side of this medal, portraits of Jansen and Lockyer are engraved, and on the other, an image of the ancient Greek sun god Apollo in a chariot drawn by four horses. Under the chariot was an inscription in French: "Analysis of solar projections on August 18, 1868."

In 1895, the London chemist Henry Myers drew the attention of William Ramsay, the famous English physical chemist, to the then forgotten article of the geologist Hildebrand. In this article, Hildebrand argued that some rare minerals, when heated in sulfuric acid, emit a gas that does not burn and does not support combustion. Among these rare minerals was kleveite, found in Norway by Nordenskiöld, the famous Swedish explorer of the polar regions.

Ramsay decided to investigate the nature of the gas contained in kleveite. In all the chemical stores in London, Ramsay's assistants managed to buy only ... one gram of slander, paying only 3.5 shillings for it. Having isolated several cubic centimeters of gas from the amount of cleveite obtained and purified it from impurities, Ramsay examined it with a spectroscope. The result was unexpected: the gas released from kleveite turned out to be ... helium!

Not trusting his discovery, Ramsay turned to William Crookes, the then leading specialist in spectral analysis in London, with a request to investigate the gas released from cleveite.

Crookes investigated the gas. The result of the study confirmed Ramsay's discovery. Thus, on March 23, 1895, a substance was discovered on Earth that had been found on the Sun 27 years earlier. On the same day, Ramsay published his discovery, sending one message to the Royal Society of London and another to the famous French chemist Academician Berthelot. In a letter to Berthelot, Ramsay asked to inform the scientific meeting of professors of the Paris Academy about his discovery.

Fifteen days after Ramsay, independently of him, the Swedish chemist Langley isolated helium from kleveite and, like Ramsay, reported his discovery of helium to the chemist Berthelot.

For the third time, helium was discovered in the air, where, according to Ramsay, it should have come from rare minerals (kleveite, etc.) during destruction and chemical transformations on Earth.

Small amounts of helium were also found in the water of some mineral springs. So, for example, it was found by Ramsay in the healing spring Cotre in the Pyrenees, the English physicist John William Rayleigh found it in the waters of the springs in the famous resort of Bath, the German physicist Kaiser discovered helium in the springs gushing in the mountains of the Black Forest. However, most of all helium was found in some minerals. It is found in samarskite, fergusonite, columbite, monazite, and uranit. The mineral thorianite from the island of Ceylon contains a particularly large amount of helium. A kilogram of thorianite, when heated red-hot, releases 10 liters of helium.

It was soon established that helium is found only in those minerals that contain radioactive uranium and thorium. The alpha rays emitted by some radioactive elements are nothing more than the nuclei of helium atoms.

From the history...

Its unusual properties make it possible to widely use helium for a variety of purposes. The first, absolutely logical, based on its lightness, is the use in balloons and airships. Moreover, unlike hydrogen, it is not explosive. This property of helium was used by the Germans in the First World War on combat airships. The disadvantage of using it is that a helium-filled airship will not fly as high as a hydrogen one.

For the bombardment of large cities, mainly the capitals of England and France, the German command in the First World War used airships (zeppelins). Hydrogen was used to fill them. Therefore, the fight against them was relatively simple: an incendiary projectile that fell into the shell of the airship ignited hydrogen, which instantly flared up and the apparatus burned down. Of the 123 airships built in Germany during the First World War, 40 burned out from incendiary shells. But one day the general staff of the British army was surprised by a message of particular importance. Direct hits of incendiary shells on the German zeppelin did not produce results. The airship did not burst into flames, but slowly flowing out of some unknown gas, flew back.

Military experts were perplexed and, despite an urgent and detailed discussion of the issue of the non-flammability of the zeppelin from incendiary projectiles, they could not find the necessary explanation. The riddle was solved by the English chemist Richard Threlfall. In a letter to the British Admiralty, he wrote: "... I believe that the Germans invented some way to extract helium in large quantities, and this time they filled the shell of their zeppelin not with hydrogen, as usual, but with helium ..."

The persuasiveness of Threlfall's arguments, however, was reduced by the fact that there were no significant sources of helium in Germany. True, helium is contained in the air, but it is not enough there: one cubic meter of air contains only 5 cubic centimeters of helium. The refrigerating machine of the Linde system, converting several hundred cubic meters of air into liquid in one hour, could produce no more than 3 liters of helium during this time.

3 liters of helium per hour! And to fill the zeppelin, you need 5÷6 thousand cubic meters. m. To obtain such an amount of helium, one Linde machine had to work without stopping for about two hundred years, two hundred such machines would give the required amount of helium in one year. The construction of 200 plants for converting air into liquid to produce helium is economically very unprofitable, and practically meaningless.

Where did German chemists get helium from?

This issue, as it turned out later, was resolved relatively simply. Long before the war, German steamship companies shipping goods to India and Brazil were instructed to load returning steamships not with ordinary ballast, but with monazite sand, which contains helium. Thus, a reserve of "helium raw materials" was created - about 5 thousand tons of monazite sand, from which helium was obtained for zeppelins. In addition, helium was extracted from the water of the Nauheim mineral spring, which gave up to 70 cubic meters. m of helium daily.

The incident with the fireproof zeppelin was the impetus for a new search for helium. Chemists, physicists, geologists began to intensively look for helium. It has suddenly become of great value. In 1916, 1 cubic meter of helium cost 200,000 gold rubles, that is, 200 rubles per liter. If we take into account that a liter of helium weighs 0.18 g, then 1 g of it cost over 1000 rubles.

Helium has become an object of hunting for merchants, speculators, stock exchange dealers. Helium was found in significant quantities in natural gases coming out of the bowels of the earth in America, in the state of Kansas, where, after America entered the war, a helium plant was built near the city of Fort Worth. But the war ended, helium reserves remained unused, the cost of helium fell sharply and at the end of 1918 amounted to about four rubles per cubic meter.

The helium extracted with such difficulty was used by the Americans only in 1923 to fill the now peaceful Shenandoah airship. It was the world's first and only air cargo-passenger ship filled with helium. However, his "life" was short-lived. Two years after her birth, the Shenandoah was destroyed by a storm. 55 thousand cubic meters m, almost the entire world supply of helium, which had been collected for six years, dissipated without a trace in the atmosphere during a storm that lasted only 30 minutes.

Helium application

Helium in nature

Mostly terrestrial helium is formed during the radioactive decay of uranium-238, uranium-235, thorium and unstable products of their decay. Incomparably smaller amounts of helium are produced by the slow decay of samarium-147 and bismuth. All these elements give rise to only the heavy isotope of helium - He 4 , whose atoms can be considered as the remains of alpha particles, buried in a shell of two paired electrons - in an electron doublet. In the early geological periods, there probably also existed other naturally radioactive series of elements that had already disappeared from the face of the Earth, saturating the planet with helium. One of them was the now artificially recreated neptunian series.

By the amount of helium trapped in a rock or mineral, one can judge their absolute age. These measurements are based on the laws of radioactive decay: for example, half of uranium-238 in 4.52 billion years turns into helium and lead.

Helium accumulates slowly in the earth's crust. One ton of granite, containing 2 g of uranium and 10 g of thorium, produces only 0.09 mg of helium in a million years - half a cubic centimeter. The very few minerals rich in uranium and thorium contain quite a large amount of helium - a few cubic centimeters of helium per gram. However, the share of these minerals in natural helium production is close to zero, as they are very rare.

There is little helium on Earth: 1 m 3 of air contains only 5.24 cm 3 of helium, and each kilogram of terrestrial material contains 0.003 mg of helium. But in terms of prevalence in the Universe, helium ranks second after hydrogen: helium accounts for about 23% of the cosmic mass. Approximately half of all helium is concentrated in the earth's crust, mainly in its granite shell, which accumulated the main reserves of radioactive elements. The content of helium in the earth's crust is small - 3 x 10 -7% by weight. Helium accumulates in free gas accumulations of the bowels and in oils; such deposits reach an industrial scale. The maximum concentrations of helium (10-13%) were found in free gas accumulations and gases of uranium mines and (20-25%) in gases released spontaneously from groundwater. The older the age of gas-bearing sedimentary rocks and the higher the content of radioactive elements in them, the more helium is in the composition of natural gases.

Helium mining

Helium production on an industrial scale is carried out from natural and petroleum gases of both hydrocarbon and nitrogen composition. According to the quality of raw materials, helium deposits are divided into: rich (He content > 0.5% by volume); ordinary (0.10-0.50) and poor< 0,10). Значительные его концентрации известны в некоторых месторождениях природного газа Канады, США (шт. Канзас, Техас, Нью-Мексико, Юта).

World reserves of helium amount to 45.6 billion cubic meters. Large deposits are located in the USA (45% of world resources), followed by Russia (32%), Algeria (7%), Canada (7%) and China (4%).
The United States also leads in helium production (140 million cubic meters per year), followed by Algeria (16 million).

Russia ranks third in the world - 6 million cubic meters per year. The Orenburg helium plant is currently the only domestic source of helium production, and gas production is declining. In this regard, the gas fields of Eastern Siberia and the Far East with high concentrations of helium (up to 0.6%) are of particular importance. One of the most promising is the Kovykta ha zocondensate field located in the north of the Irkutsk region. According to experts, it contains about 25% of the world's x helium reserves.

Name of indicator	Helium (grade A) (according to TU 51-940-80)	Helium (grade B) (according to TU 51-940-80)	Helium of high purity, grade 5.5 (according to TU 0271-001-45905715-02)	Helium of high purity, brand 6.0 (according to TU 0271-001-45905715-02)
Helium, not less
Nitrogen, no more
Oxygen + argon
Neon, no more
Water vapor, no more
Hydrocarbons, no more
CO2 + CO, no more
Hydrogen, no more

Security

– Helium is non-toxic, non-flammable, non-explosive
- Helium is allowed to be used in any crowded places: at concerts, promotions, stadiums, shops.
– Gaseous helium is physiologically inert and does not pose a danger to humans.
– Helium is not dangerous for the environment either, therefore neutralization, utilization and elimination of its residues in cylinders is not required.
– Helium is much lighter than air and dissipates in the upper layers of the Earth's atmosphere.

Helium (grades A and B according to TU 51-940-80)
Technical name	Helium gaseous
Chemical formula
UN number
Transport hazard class
Physical properties
The physical state	Under normal conditions - gas
Density, kg/m³	Under normal conditions (101.3 kPa, 20 C), 1627
Boiling point, C at 101.3 kPa
Temperature of the 3rd point and its equilibrium pressure C, (MPa)
Solubility in water	minor
Fire and explosion hazard	fire and explosion proof
Stability and reactivity
Stability	stable
Reactivity	inert gas
Human danger
Toxic effect	Non toxic
environmental hazard	Has no harmful effect on the environment
Facilities	Any means are applicable.

Storage and transportation of helium

Gaseous helium can be transported by all modes of transport in accordance with the rules for the carriage of goods on a specific mode of transport. Transportation is carried out in special brown steel cylinders and helium containers. Liquid helium is transported in transport vessels such as STG-40, STG-10 and STG-25 with a volume of 40, 10 and 25 liters.

Rules for the transportation of cylinders with technical gases

Transportation of dangerous goods in the Russian Federation is regulated by the following documents:

1. "Rules for the transportation of dangerous goods by road" (as amended by the Orders of the Ministry of Transport of the Russian Federation of 11.06.1999 No. 37, of 10.14.1999 No. 77; registered with the Ministry of Justice of the Russian Federation on December 18, 1995, registration No. 997).

2. "European Agreement on the International Carriage of Dangerous Goods by Road" (ADR), to which Russia officially acceded on April 28, 1994 (Decree of the Government of the Russian Federation of 03.02.1994 No. 76).

3. "Rules of the road" (SDA 2006), namely article 23.5, establishing that "The carriage ... of dangerous goods ... is carried out in accordance with special rules."

4. "Code of the Russian Federation on Administrative Offenses", article 12.21 part 2 of which provides for liability for violation of the rules for the transport of dangerous goods in the form of an "administrative fine on drivers in the amount of from one to three times the minimum wage or deprivation of the right to drive vehicles for a period of one to three months; for officials responsible for transportation - from ten to twenty times the minimum wage.

In accordance with paragraph 3 of paragraph 1.2 "The Rules do not apply to ... transportation of a limited number of hazardous substances on one vehicle, the transportation of which can be considered as the transportation of non-dangerous goods." It also explains that "The limited quantity of dangerous goods is defined in the requirements for the safe transport of a specific type of dangerous goods. In determining it, it is possible to use the requirements of the European Agreement on the International Carriage of Dangerous Goods (ADR)". Thus, the question of the maximum amount of substances that can be transported as non-dangerous goods is reduced to the study of section 1.1.3 of ADR, which establishes exemptions from the European rules for the transport of dangerous goods associated with various circumstances.

So, for example, in accordance with paragraph 1.1.3.1 "The provisions of ADR do not apply ... to the transport of dangerous goods by private persons, when these goods are packaged for retail sale and are intended for their personal consumption, use in everyday life, leisure or sports, when provided that measures are taken to prevent any leakage of the contents under normal conditions of carriage."

However, the group of exemptions formally recognized by the rules for the carriage of dangerous goods are exemptions associated with the quantities transported in one transport unit (clause 1.1.3.6).

All gases are assigned to the second class of substances according to the ADR classification. Non-flammable, non-poisonous gases (groups A - neutral and O - oxidizing) belong to the third transport category, with a maximum quantity limit of 1000 units. Flammable (group F) - to the second, with a maximum limit of 333 units. By "unit" here is meant 1 liter of capacity of a vessel containing compressed gas, or 1 kg of liquefied or dissolved gas. Thus, the maximum amount of gases that can be transported in one transport unit as a non-dangerous cargo is as follows:

Helium is a truly noble gas. It has not yet been possible to force him to enter into any reactions. The helium molecule is monatomic.

In terms of lightness, this gas is second only to hydrogen, air is 7.25 times heavier than helium.

Helium is almost insoluble in water and other liquids. And in the same way, not a single substance noticeably dissolves in liquid helium.

Solid helium cannot be obtained at any temperature unless pressure is increased.

In the history of the discovery, research and application of this element, there are names of many prominent physicists and chemists from different countries. They were interested in helium, worked with helium: Jansen (France), Lockyer, Ramsay, Crookes, Rutherford (England), Palmieri (Italy), Keesom, Kamerling-Onnes (Holland), Feynman, Onsager (USA), Kapitsa, Kikoin, Landau ( Soviet Union) and many other prominent scientists.

The uniqueness of the appearance of the helium atom is determined by the combination of two amazing natural structures in it - absolute champions in terms of compactness and strength. In the helium nucleus, helium-4, both intranuclear shells are saturated - both proton and neutron. The electronic doublet framing this nucleus is also saturated. In these designs - the key to understanding the properties of helium. Hence its phenomenal chemical inertness and the record-breaking small size of its atom.

The role of the nucleus of the helium atom - alpha particles in the history of the formation and development of nuclear physics is enormous. If you remember, it was the study of the scattering of alpha particles that led Rutherford to the discovery of the atomic nucleus. When nitrogen was bombarded with alpha particles, the interconversion of elements was carried out for the first time - something that many generations of alchemists have dreamed of for centuries. True, in this reaction, it was not mercury that turned into gold, but nitrogen into oxygen, but this is almost as difficult to do. The same alpha particles were involved in the discovery of the neutron and the production of the first artificial isotope. Later, curium, berkelium, californium, and mendelevium were synthesized using alpha particles.

We have listed these facts for only one purpose - to show that element #2 is a very unusual element.

On a big balloon... Helium is used to prepare breathing mixtures, including for the atmosphere of manned spacecraft, for deep-sea diving, as well as for asthma treatment, for filling airships and balloons. It is non-toxic, so breathing in small amounts of helium along with air is completely harmless.

Colossus of Rhodes, a giant statue of the ancient sun god Helios. The element helium was discovered by the spectral method on the Sun and only later was discovered on Earth.

terrestrial helium

Helium is an unusual element, and its history is unusual. It was discovered in the atmosphere of the Sun 13 years earlier than on Earth. More precisely, a bright yellow D line was discovered in the spectrum of the solar corona, and what was hidden behind it became reliably known only after helium was extracted from terrestrial minerals containing radioactive elements.

Helium on the Sun was discovered by the Frenchman J. Jansen, who made his observations in India on August 19, 1868, and the Englishman J.H. Lockyer - October 20 of the same year. The letters of both scientists arrived in Paris on the same day and were read at a meeting of the Paris Academy of Sciences on October 26 with an interval of several minutes. Academicians, struck by such a strange coincidence, decided to knock out a gold medal in honor of this event.

In 1881, the discovery of helium in volcanic gases was reported by the Italian scientist Palmieri. However, his message, later confirmed, was taken seriously by few scientists. Secondary terrestrial helium was discovered by Ramsay in 1895.

There are 29 isotopes in the earth's crust, during the radioactive decay of which alpha particles are formed - highly active nuclei of helium atoms with high energy.

Basically, terrestrial helium is formed during the radioactive decay of uranium-238, uranium-235, thorium and unstable products of their decay. Incomparably smaller amounts of helium are produced by the slow decay of samarium-147 and bismuth. All these elements generate only the heavy isotope of helium - 4He, whose atoms can be considered as the remains of alpha particles buried in a shell of two paired electrons - in an electron doublet. In the early geological periods, there probably also existed other naturally radioactive series of elements that had already disappeared from the face of the Earth, saturating the planet with helium. One of them was the now artificially recreated neptunian series.

By the amount of helium trapped in a rock or mineral, one can judge their absolute age. These measurements are based on the laws of radioactive decay: for example, half of the uranium-238 turns into helium and lead in 4.52 billion years.

Helium in the earth's crust accumulates slowly. One ton of granite containing 2 g of uranium and 10 g of thorium produces only 0.09 mg of helium in a million years - half a cubic centimeter. In very few minerals rich in uranium and thorium, the helium content is quite high - a few cubic centimeters of helium per gram. However, the share of these minerals in natural helium production is close to zero, as they are very rare.

Natural compounds containing alpha active isotopes are only the primary source, but not the raw material for the industrial production of helium. True, some minerals with a dense structure - native metals, magnetite, garnet, apatite, zircon and others - firmly hold the helium contained in them. However, most minerals eventually undergo processes of weathering, recrystallization, etc., and helium leaves them.

The helium bubbles released from the crystalline structures set off on a journey through the earth's crust. A very small part of them dissolves in groundwater. The formation of more or less concentrated helium solutions requires special conditions, primarily high pressures. Another part of the nomadic helium enters the atmosphere through the pores and cracks of minerals. The remaining gas molecules fall into underground traps, where they accumulate for tens, hundreds of millions of years. Traps are layers of loose rocks, the voids of which are filled with gas. The bed for such gas reservoirs is usually water and oil, and from above they are blocked by gas-tight strata of dense rocks.

Since other gases also wander in the earth's crust (mainly methane, nitrogen, carbon dioxide), and, moreover, in much larger quantities, there are no purely helium accumulations. Helium is present in natural gases as a minor impurity. Its content does not exceed thousandths, hundredths, rarely - tenths of a percent. Large (1.5...10%) helium content of methane-nitrogen deposits is an extremely rare phenomenon.

An element symbol made of gas discharge tubes filled with helium. Helium glows a light peach color when an electric current is passed through it.

Natural gases turned out to be practically the only source of raw materials for the industrial production of helium. For separation from other gases, the exceptional volatility of helium associated with its low liquefaction temperature is used. After all other components of natural gas are condensed by deep cooling, helium gas is pumped out. Then it is purified from impurities. The purity of the factory helium reaches 99.995%.

Helium reserves on Earth are estimated at 5 1014 m3; judging by the calculations, it was formed in the earth's crust over 2 billion years ten times more. This discrepancy between theory and practice is understandable. Helium is a light gas and, like hydrogen (albeit more slowly), does not escape from the atmosphere into outer space. Probably, during the existence of the Earth, the helium of our planet was repeatedly updated - the old one escaped into space, and instead of it, fresh - “exhaled” by the Earth entered the atmosphere.

There is at least 200,000 times more helium in the lithosphere than in the atmosphere; even more potential helium is stored in the "womb" of the Earth - in alpha active elements. But the total content of this element in the Earth and the atmosphere is small. Helium is a rare and diffuse gas. For 1 kg of terrestrial material, there is only 0.003 mg of helium, and its content in the air is 0.00052 volume percent. Such a low concentration does not yet allow economical extraction of helium from the air.

Helium is formed from hydrogen as a result of a thermonuclear reaction. It is thermonuclear reactions that are the source of energy for our Sun and many billions of other stars.

Helium in the Universe

The bowels and atmosphere of our planet are poor in helium. But this does not mean that it is not enough everywhere in the Universe. According to modern estimates, 76% of the cosmic mass is hydrogen and 23% helium; only 1% remains on all other elements! Thus, the world matter can be called hydrogen-helium. These two elements predominate in stars, planetary nebulae, and interstellar gas.

Rice. 1. Curves of the abundance of elements on Earth (top) and in space.

The "cosmic" curve reflects the exceptional role of hydrogen and helium in the universe and the special significance of the helium group in the structure of the atomic nucleus. Those elements and their isotopes whose mass number is divisible by four have the highest relative abundance: 16О, 20Ne, 24Mg, etc.

Probably, all the planets of the solar system contain radiogenic (formed during alpha decay) helium, and large planets also contain relict helium from space. Helium is abundantly represented in the atmosphere of Jupiter: according to some data, it is 33% there, according to others - 17%. This discovery formed the basis of the plot of one of the stories of the famous scientist and science fiction writer A. Azimov. In the center of the story is a plan (possibly feasible in the future) for delivering helium from Jupiter, or even throwing it to the nearest satellite of this planet - Jupiter V - an armada of cybernetic machines on cryotrons (about them - below). Immersed in the liquid helium of Jupiter's atmosphere (ultra-low temperatures and superconductivity are necessary conditions for the operation of cryotrons), these machines will turn Jupiter V into the brain center of the solar system ...

The origin of stellar helium was explained in 1938 by the German physicists Bethe and Weizsacker. Later, their theory received experimental confirmation and refinement with the help of particle accelerators. Its essence is as follows.

Helium nuclei are synthesized at stellar temperatures from protons in a fusion process that releases 175 million kilowatt-hours of energy for every kilogram of helium.

Different cycles of reactions can lead to the fusion of helium.

Under the conditions of not very hot stars, such as our Sun, the proton-proton cycle seems to predominate. It consists of three consecutive transformations. First, two protons combine at great speeds to form a deuteron - a structure of a proton and a neutron; in this case, a positron and a neutrino are separated. Further, the deuteron is combined with a proton to form light helium with the emission of a gamma quantum. Finally, two 3He nuclei react, transforming into an alpha particle and two protons. An alpha particle, having acquired two electrons, will then become a helium atom.

The same end result gives a faster carbon-nitrogen cycle, the significance of which is not very large under solar conditions, but on stars hotter than the Sun, the role of this cycle is enhanced. It consists of six steps - reactions. Carbon plays here the role of a catalyst for the process of proton fusion. The energy released during these transformations is the same as in the proton-proton cycle - 26.7 MeV per helium atom.

The helium fusion reaction is the basis of the energy activity of stars, their glow. Consequently, helium synthesis can be considered the forefather of all reactions in nature, the root cause of life, light, heat and meteorological phenomena on Earth.

Helium is not always the end product of stellar fusion. According to the theory of Professor D.A. Frank-Kamenetsky, successive fusion of helium nuclei produces 3Be, 12C, 16O, 20Ne, 24Mg, and the capture of protons by these nuclei leads to the formation of other nuclei. For the synthesis of nuclei of heavy elements up to transuranium, exceptional superhigh temperatures are required, which develop on unstable "new" and "supernova" stars.

The famous Soviet chemist A.F. Kapustinsky called hydrogen and helium protoelements - elements of primary matter. Is it not this primacy that explains the special position of hydrogen and helium in the periodic system of elements, in particular the fact that the first period is essentially devoid of the periodicity characteristic of other periods?

Atomic structure of helium

The best...

The helium atom (aka molecule) is the strongest of molecular structures. The orbits of its two electrons are exactly the same and pass extremely close to the nucleus. To expose a helium nucleus, you need to spend a record high energy - 78.61 MeV. Hence the phenomenal chemical passivity of helium.

Over the past 15 years, chemists have managed to obtain more than 150 chemical compounds of heavy noble gases (compounds of heavy noble gases will be discussed in the articles "Krypton" and "Xenon"). However, the inertness of helium remains, as before, beyond suspicion.

Calculations show that if a way were found to obtain, say, fluoride or helium oxide, then during formation they would absorb so much energy that the resulting molecules would be “exploded” by this energy from the inside.

Helium molecules are non-polar. The forces of intermolecular interaction between them are extremely small - less than in any other substance. Hence - the lowest values ​​of critical quantities, the lowest boiling point, the lowest heats of evaporation and melting. As for the melting point of helium, at normal pressure it does not exist at all. Liquid helium at a temperature arbitrarily close to absolute zero does not solidify if, in addition to temperature, it is subjected to a pressure of 25 or more atmospheres. There is no other such substance in nature.

There is also no other gas so negligibly soluble in liquids, especially polar ones, and so little prone to adsorption, as helium. It is the best conductor of electricity among gases and the second, after hydrogen, conductor of heat. Its heat capacity is very high and its viscosity is low.

Helium penetrates amazingly quickly through thin partitions made of some organic polymers, porcelain, quartz and borosilicate glass. Curiously, helium diffuses through soft glass 100 times slower than through borosilicate glass. Helium can also penetrate many metals. Only iron and metals of the platinum group, even hot ones, are completely impenetrable to it.

A new method for extracting pure helium from natural gas is based on the principle of selective permeability.

Scientists show exceptional interest in liquid helium. Firstly, it is the coldest liquid in which, moreover, not a single substance noticeably dissolves. Secondly, it is the lightest of liquids with a minimum surface tension.

At a temperature of 2.172°K, there is an abrupt change in the properties of liquid helium. The resulting species is conventionally named helium II. Helium II boils quite differently from other liquids, it does not boil when boiling, its surface remains completely calm. Helium II conducts heat 300 million times better than ordinary liquid helium (helium I). The viscosity of helium II is practically zero, it is a thousand times less than the viscosity of liquid hydrogen. Therefore, helium II has superfluidity - the ability to flow without friction through capillaries of arbitrarily small diameter.

Another stable isotope of helium, 3He, passes into the superfluid state at a temperature that is only hundredths of a degree away from the absolute bullet. Superfluid helium-4 and helium-3 are called quantum liquids: quantum mechanical effects appear in them even before they solidify. This explains the very detailed study of liquid helium. And now they produce a lot of it - hundreds of thousands of liters a year. But solid helium has hardly been studied: the experimental difficulties in studying this very cold body are great. Undoubtedly, this gap will be filled, since physicists expect a lot of new things from the knowledge of the properties of solid helium: after all, it is also a quantum body.

Helium cylinders

Inert but very necessary

At the end of the last century, the English magazine Punch published a cartoon in which helium was depicted as a cunningly winking man - an inhabitant of the Sun. The text below the picture read: “Finally, they caught me on Earth! It's been long enough! I wonder how long it will be before they figure out what to do with me?”

Indeed, 34 years have passed since the discovery of terrestrial helium (the first report on this was published in 1881) before it found practical application. A certain role here was played by the original physical, technical, electrical and, to a lesser extent, chemical properties of helium, which required a long study. The main obstacles were absent-mindedness and the high cost of element No. 2.

The Germans were the first to use helium. In 1915, they began to fill their airships bombing London with it. Soon, light but non-flammable helium became an indispensable filler for aeronautic vehicles. The decline of the airship industry, which began in the mid-1930s, led to a slight decline in helium production, but only for a short time. This gas increasingly attracted the attention of chemists, metallurgists and machine builders.

Many technological processes and operations cannot be carried out in the air. To avoid the interaction of the resulting substance (or feedstock) with air gases, special protective environments are created; and there is no more suitable gas for these purposes than helium.

Helium cylinders

Inert, light, movable, good conductor of heat, helium is an ideal means for transferring flammable liquids and powders from one container to another; it is precisely these functions that it performs in rockets and guided missiles. In a helium protective environment, separate stages of obtaining nuclear fuel take place. Fuel elements of nuclear reactors are stored and transported in containers filled with helium.

With the help of special leak detectors, whose action is based on the exceptional diffusion ability of helium, they reveal the slightest possibility of leakage in nuclear reactors and other systems under pressure or vacuum.

Recent years have been marked by a renewed rise in airship building, now on a higher scientific and technical basis. In a number of countries, helium-filled airships with a carrying capacity of 100 to 3000 tons have been built and are being built. They are economical, reliable and convenient for transporting bulky cargo, such as gas pipelines, oil refineries, power transmission towers, etc. Filling with 85% helium and 15% hydrogen is fireproof and only reduces lift by 7% compared to hydrogen filling.

High-temperature nuclear reactors of a new type began to operate, in which helium serves as a coolant.

Liquid helium is widely used in scientific research and engineering. Ultra-low temperatures favor in-depth knowledge of matter and its structure - at higher temperatures, fine details of energy spectra are masked by the thermal motion of atoms.

There are already superconducting solenoids made of special alloys that create strong magnetic fields (up to 300,000 oersteds) at the temperature of liquid helium with negligible energy expenditure.

At the temperature of liquid helium, many metals and alloys become superconductors. Superconducting relays - cryotrons are increasingly used in the design of electronic computers. They are simple, reliable, very compact. Superconductors, and with them liquid helium, become essential for electronics. They are included in the design of infrared radiation detectors, molecular amplifiers (masers), optical quantum generators (lasers), and devices for measuring microwave frequencies.

Of course, these examples do not exhaust the role of helium in modern technology. But if it were not for the limited natural resources, not for the extreme dispersion of helium, he would have found many more applications. It is known, for example, that when preserved in a helium environment, food products retain their original taste and aroma. But “helium” canned food is still a “thing in itself”, because helium is not enough and it is used only in the most important industries and where it is indispensable. Therefore, it is especially insulting to realize that with combustible natural gas, much larger amounts of helium pass through chemical synthesis apparatuses, furnaces and furnaces and go into the atmosphere than those extracted from helium-bearing sources.

Now it is considered advantageous to separate helium only in cases where its content in natural gas is not less than 0.05%. The reserves of such gas are decreasing all the time, and it is possible that they will be exhausted before the end of our century. However, the problem of “helium deficiency” will probably be solved by this time - partly due to the creation of new, more advanced methods for separating gases, extracting the most valuable, albeit insignificant fractions from them, and partly due to controlled thermonuclear fusion. Helium will be an important, albeit by-product, product of "artificial suns."

Helium tube

Isotopes of helium

In nature, there are two stable isotopes of helium: helium-3 and helium-4. The light isotope is a million times less common on Earth than the heavy isotope. It is the rarest of the stable isotopes that exist on our planet. Three more helium isotopes have been artificially obtained. All of them are radioactive. The half-life of helium-5 is 2.4 10-21 seconds, helium-6 is 0.83 seconds, helium-8 is 0.18 seconds. The heaviest isotope, interesting in that there are three neutrons per proton in its nuclei, was first discovered in Dubna in the 60s. Attempts to obtain helium-10 have so far been unsuccessful.

Last solid gas

Helium was the last of all gases to be converted into a liquid and solid state. The special difficulties of liquefying and solidifying helium are explained by the structure of its atom and some features of its physical properties. In particular, helium, like hydrogen, at temperatures above -250°C, expanding, does not cool, but heats up. On the other hand, the critical temperature of helium is extremely low. That is why liquid helium was first obtained only in 1908, and solid - in 1926.

helium air

Air in which all or most of its nitrogen has been replaced by helium is no longer a novelty today. It is widely used on land, underground and underwater.

Helium air is three times lighter and much more mobile than ordinary air. It behaves more actively in the lungs - it quickly brings in oxygen and quickly evacuates carbon dioxide. That is why helium air is given to patients with respiratory disorders and some operations. It relieves suffocation, treats bronchial asthma and diseases of the larynx.

Breathing helium air practically eliminates nitrogen embolism (caisson disease), which divers and specialists of other professions, whose work takes place under conditions of high pressure, are susceptible to during the transition from high pressure to normal. The cause of this disease is quite significant, especially at high blood pressure, the solubility of nitrogen in the blood. As the pressure decreases, it is released in the form of gas bubbles that can clog blood vessels, damage nerve nodes ... Unlike nitrogen, helium is practically insoluble in body fluids, so it cannot cause decompression sickness. In addition, helium air eliminates the occurrence of "nitrogen anesthesia", outwardly similar to alcohol intoxication.

Sooner or later, mankind will have to learn how to live and work for a long time on the seabed in order to seriously take advantage of the mineral and food resources of the shelf. And at great depths, as the experiments of Soviet, French and American researchers have shown, helium air is still indispensable. Biologists have proven that prolonged breathing with helium air does not cause negative changes in the human body and does not threaten changes in the genetic apparatus: the helium atmosphere does not affect the development of cells and the frequency of mutations. There are works whose authors consider helium air to be the optimal air medium for spacecraft making long flights to the Universe. But so far, artificial helium air has not yet risen beyond the earth's atmosphere.

The asteroid (895) Helio, discovered in 1918, is named after helium.

The world around us consists of ~ 100 different chemical elements. How did they form in natural conditions? A hint for answering this question is provided by the relative abundance of chemical elements. Among the most significant features of the abundance of chemical elements in the solar system, the following can be distinguished.

1. Matter in the Universe mainly consists of hydrogen H - ~ 90% of all atoms.
2. In terms of abundance, helium He ranks second, accounting for ~ 10% of the number of hydrogen atoms.
3. There is a deep minimum corresponding to the chemical elements lithium Li, beryllium Be, and boron B.
4. Immediately after the deep minimum of Li, Be, B, there follows a maximum due to the increased abundance of carbon C and oxygen O.
5. Following the oxygen maximum, there is an abrupt drop in the abundance of elements up to scandium (A = 45).
6. There is a sharp increase in the abundance of elements in the region of iron A = 56 (iron group).
7. After A = 60, the decrease in the abundance of elements occurs more smoothly.
8. There is a noticeable difference between chemical elements with an even and odd number of protons Z. As a rule, chemical elements with even Z are more common.

Nuclear reactions in the universe

t = 0		Big Bang. Birth of the Universe
t = 10 -43 s		The era of quantum gravity. strings ρ = 10 90 g/cm 3 , T = 10 32 K
t = 10 - 35 s		Quark-gluon medium ρ = 10 75 g/cm 3 , T = 10 28 K
t = 1 µs		Quarks combine to form neutrons and protons ρ = 10 17 g/cm 3 , T = 6 10 12 K
t = 100 s		Formation of prestellar 4 He ρ = 50 g/cm 3 , T = 10 9 K
t = 380 thousand years		Formation of neutral atoms ρ = 0.5 10 -20 g/cm 3 , T = 3 10 3 K
t = 10 8 years	First stars	Burning hydrogen in stars ρ \u003d 10 2 g / cm 3, T \u003d 2 10 6 K Burning helium in stars ρ = 10 3 g/cm 3 , T = 2 10 8 K Burning carbon in stars ρ \u003d 10 5 g / cm 3, T \u003d 8 10 8 K Burning oxygen in the stars ρ = 10 5 ÷10 6 g/cm 3 , T = 2 10 9 K Burning silicon in stars ρ = 10 6 g/cm 3 , T = (3÷5) 10 9 K
t = 13.7 billion years		Modern Universe ρ \u003d 10 -30 g / cm 3, T \u003d 2.73 K

Prestellar nucleosynthesis. Education 4 He

Cosmological synthesis of helium is the main mechanism of its formation in the Universe. The synthesis of helium from hydrogen in stars increases the mass fraction of 4 He in baryonic matter by about 10%. The mechanism of pre-stellar formation of helium quantitatively explains the prevalence of helium in the Universe and is a strong argument in favor of the pre-galactic phase of its formation and the whole concept of the Big Bang.
Cosmological nucleosynthesis makes it possible to explain the prevalence in the Universe of such light nuclei as deuterium (2 H), isotopes 3 He and 7 Li. However, their numbers are negligible compared to the nuclei of hydrogen and 4 He. With respect to hydrogen, deuterium is formed in an amount of 10 -4 -10 -5 , 3 He - in an amount of ≈ 10 -5 , and 7 Li - in an amount of ≈ 10 -10 .
To explain the formation of chemical elements in 1948, G. Gamow put forward the theory of the Big Bang. According to Gamow's model, the synthesis of all chemical elements occurred during the Big Bang as a result of non-equilibrium capture of neutrons by atomic nuclei with the emission of γ-quanta and subsequent β - decay of the resulting nuclei. However, calculations showed that it is impossible to explain the formation of chemical elements heavier than Li in this model. It turned out that the mechanism of formation of light nuclei (A< 7) связан с условиями, существовавшими во Вселенной в течение первых трех минут. Более тяжелые ядра образовались в результате ядерных реакций, происходящих при горении звезд.

Prestellar stage of formation of the lightest nuclei. At the stage of evolution of the Universe 100 s after the Big Bang at a temperature of ~ 10 9 K, the matter in the Universe consisted of protons p, neutrons n, electrons e - , positrons e + , neutrinos ν, antineutrinos and photons γ. The radiation was in thermal equilibrium with electrons e - , positrons e + and nucleons.

Under conditions of thermodynamic equilibrium, the probability of formation of a system with energy E N equal to the rest energy of the nucleon is described by the Gibbs distribution . Therefore, under conditions of thermodynamic equilibrium, the ratio between the number of neutrons and protons will be determined by the difference in the masses of the neutron and proton

The formation of electron-positron pairs stops at T< 10 10 К, так как энергии фотонов становятся ниже порога образования e - e + -пар (~ 1 МэВ). К концу равновесной стадии на каждый нейтрон приходилось 5 протонов. Так как на этом этапе эволюции Вселенной плотность протонов и нейтронов была велика, сильное ядерное взаимодействие между ними привело к образованию 4 He и небольшого количества изотопов Li и Be.

The main reactions of prestellar nucleosynthesis are:

p + n → d + γ, d + p → 3 He + γ,		3 He + n → 3 He + p
d + d →	3 He + n,	3 He + n 3 H + p, 3 H + p 4 He + , 3 H + d 4 He + n.
	3H+p,

Since stable nuclei with BUT = 5 does not exist, nuclear reactions end mainly with the formation of 4He. 7 Be, 6 Li and 7 Li make up only ~ 10–9 – 10–12 of the formation of the 4 He isotope. Almost all neutrons disappear, forming 4 He nuclei. At a substance density ρ ~ 10–3 – 10–4 g/cm 3 the probability that a neutron and a proton do not interact during the primary nucleosynthesis is less than 10–4. Since at the beginning there were 5 protons per neutron, the ratio between the number of nuclei 4 He and p should be ~1/10. Thus, the ratio of the abundances of hydrogen and helium, observed at the present time, was formed during the first minutes of the existence of the Universe. The expansion of the Universe led to a decrease in its temperature and the termination of the primary prestellar nucleosynthesis.

Formation of chemical elements in stars. Since the process of nucleosynthesis at an early stage of the evolution of the Universe ended with the formation of hydrogen, helium and a small amount of Li, Be, B, it was necessary to find the mechanisms and conditions under which heavier elements could be formed.
G. Bethe and K. Weizsäcker showed that the corresponding conditions exist inside the stars. Heavier nuclei were formed only billions of years after the Big Bang in the process of stellar evolution. The formation of chemical elements in stars begins with the combustion of hydrogen to form 4 He .

G. Bethe, 1968: “From time immemorial, people have wanted to know what keeps the sun glowing. The first attempt at a scientific explanation was made by Helmholtz about a hundred years ago. It was based on the use of the most famous forces at that time - the forces of universal gravitation. If one gram of matter falls on the surface of the Sun, it acquires potential energy

E p \u003d -GM / R \u003d -1.91 10 15 erg / g.

It is known that at present the radiation power of the Sun is determined by the value

ε = 1.96 erg/g s.

Therefore, if gravity is the source of energy, the stock of gravitational energy can provide radiation for 10 15 s, i.e. over a period of about thirty million years...
At the end of the 19th century, Becquerel, Pierre and Marie Curie discovered radioactivity. The discovery of radioactivity made it possible to determine the age of the Earth. Somewhat later, it was possible to determine the age of meteorites, by which it was possible to judge when matter appeared in the solar system in the solid phase. From these measurements it was possible to establish that the age of the Sun, with an accuracy of 10%, is 5 billion years. Thus, gravity cannot provide the required supply of energy for all this time ...
Since the beginning of the 30s, they began to lean towards the fact that stellar energy arose due to nuclear reactions ... The simplest of all possible reactions will be the reaction

H + H → D + e + + v.

Since the process of primary nucleosynthesis ended mainly with the formation of 4 He nuclei as a result of the interaction reactions p + n, d + d, d + 3 He, d + 3 H and all neutrons were consumed, it was necessary to find the conditions under which heavier elements were formed . In 1937, G. Bethe created a theory explaining the origin of the energy of the Sun and stars as a result of fusion reactions of hydrogen and helium nuclei occurring in the center of stars. Since there were not enough neutrons in the center of the stars for reactions of the p + n type, only reactions could continue in them
p + p → d + e + + v. These reactions took place in stars when the temperature in the center of the star reached 10 7 K and the density reached 10 5 kg/m 3 . The fact that the reaction p + p → d + e + + ν occurred as a result of the weak interaction explained the features of the Hertzsprung–Russell diagram.

Nobel Prize in Physics
1967 − G. Bethe
For his contributions to the theory of nuclear reactions, and especially for the discovery of the source of stellar energy.

Having made reasonable assumptions about the strength of the reactions, based on the general principles of nuclear physics, I discovered in 1938 that the carbon-nitrogen cycle could provide the necessary release of energy in the Sun ... Carbon serves only as a catalyst; the result of the reaction is a combination of four protons and two electrons forming a nucleus 4 He . In this process, two neutrinos are emitted, carrying about 2 MeV of energy with them. The remaining energy of about 25 MeV per cycle is released and keeps the temperature of the Sun unchanged ... This was the basis on which Fowler and others calculated the reaction rates in the (C, N)-cycle ”.

Burning hydrogen. Two different sequences of hydrogen combustion reactions are possible - the conversion of four hydrogen nuclei into a 4 He nucleus, which can provide sufficient energy release to maintain the star's luminosity:

• proton-proton chain (pp-chain), in which hydrogen is converted directly into helium;
• carbon-nitrogen-oxygen cycle (CNO-cycle), in which C, N and O nuclei participate as catalysts.

Which of these two reactions plays a more significant role depends on the temperature of the star. In stars with a mass comparable to that of the Sun, or less, the proton-proton chain dominates. In more massive stars with higher temperatures, the main source of energy is the CNO cycle. In this case, naturally, it is necessary that C, N, and O nuclei be present in the composition of the stellar matter. The temperature of the inner layers of the Sun is 1.5∙10 7 K, and the proton-proton chain plays a dominant role in energy release.

Temperature dependence of the logarithm of the rate V of energy release in the hydrogen (pp) and carbon (CNO) cycles

Burning hydrogen. Proton-proton chain. nuclear reaction

p + p → 2 H + e + + v e + Q,

begins in the central part of the star at densities of ≈100 g/cm3. This reaction stops the further contraction of the star. The heat released during the hydrogen fusion reaction creates pressure that counteracts gravitational contraction and prevents the star from collapsing. There is a qualitative change in the mechanism of energy release in the star. If before the onset of the nuclear reaction of hydrogen combustion, the heating of the star occurred mainly due to gravitational compression, now another dominant mechanism appears - energy is released due to nuclear fusion reactions.

The star acquires a stable size and luminosity, which for a star with a mass close to the sun, does not change for billions of years, while the "burning" of hydrogen occurs. This is the longest stage of stellar evolution. As a result of the combustion of hydrogen, one helium nucleus is formed out of every four hydrogen nuclei. The most probable chain of nuclear reactions on the Sun leading to this is called proton-proton cycle and looks like this:

p + p → 2 H + e + + ν e + 0.42 MeV,
p + 2 H → 3 He + 5.49 MeV,
3 He + 3 He → 4 He + p + p + 12.86 MeV

or in a more compact form

4p → 4He + 2e + 2νe + 24.68 MeV.

Neutrinos are the only source providing information about events occurring in the interior of the Sun. The spectrum of neutrinos produced on the Sun as a result of hydrogen combustion in the 4p → 4 He reaction and in the CNO cycle extends from an energy of 0.1 MeV to an energy of ~12 MeV. Observation of solar neutrinos makes it possible to directly verify the model of thermonuclear reactions on the Sun.
The energy released as a result of the pp chain is 26.7 MeV. Neutrinos emitted by the Sun were registered by ground-based detectors, which confirms the fusion reaction on the Sun.
Burning hydrogen. CNO cycle. A feature of the CNO cycle is that, starting from the carbon nucleus, it reduces to the sequential binding of 4 protons with the formation of a 4He nucleus at the end of the CNO cycle.

l2 C + p → 13 N + γ
13 N → 13 C + e + + v
13 C + p → 1 4 N + γ
14 N + p → 15 O + γ
15 O → 15 N + e + + v
15 N + p → 12 C + 4 He

CNO cycle

Reaction chain I

12 C + p → 13 N + γ (Q = 1.94 MeV),
13 N → 13 C + e + + ν e (Q = 1.20 MeV, T 1/2 = 10 min),
13 C + p → 1 4 N + γ (Q = 7.55 MeV),
14 N + p → 15 O + γ (Q = 7.30 MeV),
15 O → 15 N + e + + ν e (Q = 1.73 MeV, T 1/2 = 124 s),
15 N + p → 12 C + 4 He (Q = 4.97 MeV).

Reaction chain II

15 N + p → 16 O + γ (Q = 12.13 MeV),
16 O + p → 17 F + γ (Q = 0.60 MeV),
17 F → 17 O + e + + ν e (Q = 1.74 MeV, T 1/2 =66 s),
17 O + p → 14 N + ν (Q = 1.19 MeV).

Reaction chain III

17 O + p → 18 F + γ (Q = 6.38 MeV),
18 F → 18 O + e + + ν e (Q = 0.64 MeV, T 1/2 = 110 min),
18 O + p → 15 N + α (Q = 3.97 MeV).

The main time of the evolution of a star is associated with the burning of hydrogen. At densities typical for the central part of the star, hydrogen burning occurs at a temperature of (1–3)∙10 7 K. At these temperatures, it takes 10 6 – 10 10 years for a significant part of the hydrogen in the center of the star to be converted into helium. With a further increase in temperature, heavier chemical elements Z > 2 can be formed in the center of the star. Main sequence stars burn hydrogen in the central part, where, due to higher temperature, nuclear reactions occur most intensively. As hydrogen burns out in the center of the star, the hydrogen combustion reaction begins to move to the periphery of the star. The temperature in the center of the star continuously increases, and when it reaches 10 6 K, combustion reactions of 4 He begin. The reaction 3α → 12 C + γ is the most important for the formation of chemical elements. It requires the simultaneous collision of three α-particles and is possible due to the fact that the energy of the reaction 8 Be + 4 He coincides with the resonance of the excited state 12 C. The presence of resonance sharply increases the probability of fusion of three α-particles.

Formation of middle nuclei A< 60. What nuclear reactions will take place in the center of the star depends on the mass of the star, which must provide high temperature due to gravitational compression in the center of the star. Since nuclei with large Z are now involved in the fusion reactions, the central part of the star is compressed more and more, the temperature in the center of the star rises. At temperatures of several billion degrees, the previously formed stable nuclei are destroyed, protons, neutrons, α-particles, high-energy photons are formed, which leads to the formation of chemical elements of the entire Periodic Table of Mendeleev up to iron. The formation of chemical elements heavier than iron occurs as a result of successive capture of neutrons and subsequent β - decay.
Formation of medium and heavy nucleiA > 60. In the process of thermonuclear fusion, atomic nuclei are formed in stars up to iron. Further synthesis is impossible, since the cores of the iron group have the maximum specific binding energy. The formation of heavier nuclei in reactions with charged particles - protons and other light nuclei - is hindered by the increasing Coulomb barrier of heavy nuclei.

Formation of elements 4 He → 32 Ge.

Evolution of a massive star M > M

As elements with increasing values ​​are involved in the combustion process Z temperature and pressure in the center of the star increase at an ever-increasing rate, which in turn increases the rate of nuclear reactions. If for a massive star the reaction of burning hydrogen lasts several million years, then the burning of helium occurs 10 times faster. The combustion process of oxygen lasts about 6 months, and the combustion of silicon occurs in a day.
The abundance of elements located in the region behind iron depends relatively weakly on the mass number A. This indicates a change in the mechanism of formation of these elements. It must be taken into account that most heavy nuclei are β - radioactive. In the formation of heavy elements, the reactions of neutron capture by nuclei (n, γ) play a decisive role:

(A, Z) + n → (A+1, Z) + γ.

As a result of a chain of alternating processes of capture by nuclei of one or more neutrons, followed by β - decay, the mass numbers increase BUT and charge Z nuclei and from the initial elements of the iron group, increasingly heavier elements are formed until the end of the Periodic Table.

In the supernova stage, the central part of the star consists of iron and an insignificant fraction of neutrons and α-particles, the products of iron dissociation under the action of γ - quants. Near
M/M = 1.5 is dominated by 28 Si. 20 Ne and 16 O make up the bulk of the substance in the region from 1.6 to 6 M/M. The outer envelope of the star (M/M > 8) consists of hydrogen and helium.
At this stage, in nuclear processes, not only the release of energy, but also its absorption takes place. The massive star is losing stability. A supernova explosion occurs, in which a significant part of the chemical elements formed in the star is ejected into interstellar space. If the stars of the first generation consisted of hydrogen and helium, then in the stars of subsequent generations, heavier chemical elements are already present at the initial stage of nucleosynthesis.

Nuclear reactions of nucleosynthesis. E. Burbidge, G. Burbidzh, V. Fowler, F. Hoyle in 1957 gave the following description of the main processes of stellar evolution in which the formation of atomic nuclei takes place.

1. The combustion of hydrogen, as a result of this process, 4He nuclei are formed.

Helium burning. As a result of the reaction 4 He + 4 He + 4 He → 12 C + γ 12 C nuclei are formed.

2. α-process. As a result of successive capture of α-particles, α-particle nuclei 16 O, 20 Ne, 24 Mg, 28 Si, ...
3. e-process. When a temperature of 5∙10 9 K is reached, a large number of various reactions proceed in stars under conditions of thermodynamic equilibrium, resulting in the formation of atomic nuclei up to Fe and Ni. Kernels with BUT~ 60 are the most strongly bound atomic nuclei. Therefore, they end the chain of nuclear fusion reactions, accompanied by the release of energy.
4. s-process. Nuclei heavier than Fe are formed in reactions of successive neutron capture. Very often, the nucleus that captured the neutron turns out to be β - -radioactive. Before the nucleus captures the next neutron, it can decay as a result of β - decay. Each β - -decay increases the serial number of the resulting atomic nuclei by one. If the time interval between successive neutron captures is greater than the periods of β - decay, the neutron capture process is called the s-process (slow). Thus, as a result of neutron capture and subsequent β - decays, the nucleus becomes progressively heavier, but at the same time it does not deviate too far from the stability valley on the N-Z diagram.
5. r-process. If the successive capture rate of neutrons is much greater than the rate of β - decay of an atomic nucleus, then it manages to capture a large number of neutrons at once. As a result of the r-process, a neutron-rich nucleus is formed, which is far from the stability valley. Only then does it, as a result of a successive chain of β - decays, turn into a stable nucleus. It is usually believed that r-processes occur as a result of supernova explosions.
6. R-process. Some stable neutron-deficient nuclei (the so-called bypassed nuclei) are formed in proton capture reactions, in reactions ( γ ,n) or in reactions driven by neutrinos.

Synthesis of transuranic elements. Only those chemical elements have survived in the solar system, the lifetime of which is longer than the age of the solar system. These are 85 chemical elements. The remaining chemical elements were obtained as a result of various nuclear reactions in accelerators or as a result of irradiation in nuclear reactors. Synthesis of the first transuranium elements in the laboratory was carried out using nuclear reactions under the action of neutrons and accelerated α-particles. However, further advancement to heavier elements turned out to be practically impossible in this way. For the synthesis of elements heavier than mendelevium Md ( Z= 101) use nuclear reactions with heavier multiply charged ions - carbon, nitrogen, oxygen, neon, calcium. To accelerate heavy ions, multiply charged ion accelerators began to be built.

Nobel Prize in Physics
1983 - W. Fowler
For theoretical and experimental studies of nuclear processes important in the formation of chemical elements in the Universe.

Opening year	Chemical element	Z	Reaction
1936	Np, Pu	93, 94
1945	Am	95
1961	cm	96
1956	bk	97
1950	cf	98
1952	Es	99
1952	fm	100
1955	md	101
1957	no	102
1961	lr	103
1964	RF	104
1967-1970	Db	105
1974	Sg	106
1976	bh	107
1984-1987	hs	108
1982	Mt	109
1994	Ds	110
1994	Rg	111
1996	Cn	112
2004		113, 115
1998		114
2000		116
2009		117
2006		118

E. Rutherford: “If there are elements heavier than uranium, then it is likely that they will turn out to be radioactive. The exceptional sensitivity of chemical analysis methods, based on radioactivity, will make it possible to identify these elements, even if they are present in negligible amounts. Therefore, it can be expected that the number of radioactive elements in trace amounts is much greater than the three currently known radioactive elements. Purely chemical research methods will prove to be of little use at the first stage of the study of such elements. The main factors here are the constancy of the radiation, their characteristics, and the existence or absence of emanations or other decay products.”

The chemical element with the maximum atomic number Z = 118 was synthesized in Dubna in collaboration with the Livermore Laboratory in the USA. The upper limit of the existence of chemical elements is associated with their instability with respect to radioactive decay. Additional stability of atomic nuclei is observed near magic numbers. According to theoretical estimates, there should be doubly magic numbers Z = 108, N = 162 and Z = 114, N = 184. The half-life of nuclei with such numbers of protons and neutrons can be hundreds of thousands of years. These are the so-called "islands of stability". The problem of the formation of nuclei of the "island of stability" is the complexity of the selection of targets and accelerated ions. The currently synthesized isotopes of 108-112 elements have too few neutrons. As follows from the measured half-lives of isotopes of 108 - 112 elements, an increase in the number of neutrons by 6 - 10 units (ie, approaching the island of stability) leads to an increase in the α-decay period by 10 4 - 10 5 times.
Since the number of superheavy nuclei Z > 110 is calculated in units, it was necessary to develop a method for their identification. The identification of newly formed chemical elements is carried out by the chains of their successive α-decays, which increases the reliability of the results. This method of identifying transuranium elements has an advantage over all other methods, since is based on the measurement of short periods of α-decay. At the same time, according to theoretical estimates, the chemical elements of the island of stability can have half-lives exceeding months and years. To identify them, it is necessary to develop fundamentally new registration methods based on the identification of a single number of nuclei over several months.

G. Flerov, K, Petrzhak:“Prediction of the possible existence of a new region in the periodic system of elements by D.I. Mendeleev - the field of superheavy elements (SHE) - is for the science of the atomic nucleus one of the most significant consequences of experimental and theoretical studies of the process of spontaneous fission. The sum of our knowledge of the atomic nucleus, obtained over the past four decades, makes this prediction quite reliable and. which is important, independent of the choice of one or another particular variant of the shell model. The answer to the question about the existence of SHE would mean, perhaps, the most critical test of the very concept of the shell structure of the nucleus - the main nuclear model that has so far successfully withstood many tests in explaining the properties of known atomic nuclei.
More specifically, the stability of the heaviest nuclei is determined mainly by their spontaneous fission, and therefore a necessary condition for the existence of such nuclei is that they have barriers to fission. For nuclei from uranium to fermium, the shell component in the fission barrier, although leading to some very interesting physical phenomena, still does not have a critical effect on their stability and manifests itself in superposition with the liquid-drop component of the barrier. In the SHE region, the drop component of the barrier completely disappears, and the stability of superheavy nuclei is determined by the permeability of the purely shell barrier.
At the same time, if the presence of a barrier is sufficient for the fundamental existence of SHE nuclei, then experimental verification of such a prediction requires knowledge of the lifetime of SHE nuclei relative to spontaneous fission, since with any particular setting of the experiment to search for them, it is impossible to cover the entire range of lifetimes - from 10 10 years up to 10 -10 s. The choice of the experimental technique essentially depends on the lifetime interval in which the study is carried out.
As already mentioned, the uncertainty in the theoretical calculation of the period of spontaneous fission T SF is too large, no less than 8–10 orders of magnitude. This uncertainty a priori does not exclude any of the possibilities of obtaining or detecting SHE, and as directions for the experimental solution of the problem, one can choose both the search for SHE in nature (on Earth, in objects of cosmic origin, as part of cosmic radiation, etc.), and artificial production of elements at accelerators (in nuclear reactions between complex nuclei).
Obviously, the search for SHE in terrestrial objects can lead to success only under a happy combination of two circumstances. On the one hand, there must be an effective mechanism of nucleosynthesis, which leads to the formation of SHE atomic nuclei with sufficient probability. On the other hand, it is necessary that there be at least one nuclide belonging to the new region of stability, which would have a lifetime comparable to that of the Earth, 4.5· 10 9 years old.
If we are talking about the presence of SHE in objects of extraterrestrial origin - in meteorites, cosmic radiation, etc., then such searches can lead to success even if the lifetime of SHE nuclei is significantly less than 10 10 years: such objects can be significantly younger than terrestrial samples (10 7 -10 8 years).

Helium is an inert gas of the 18th group of the periodic table. It is the second lightest element after hydrogen. Helium is a colorless, odorless and tasteless gas that becomes liquid at -268.9 °C. Its boiling and freezing points are lower than those of any other known substance. It is the only element that does not solidify when cooled at normal atmospheric pressure. It takes 25 atmospheres for helium to solidify at 1 K.

Discovery history

Helium was discovered in the gaseous atmosphere surrounding the Sun by the French astronomer Pierre Jansen, who in 1868 during an eclipse discovered a bright yellow line in the spectrum of the solar chromosphere. This line was originally thought to represent the element sodium. In the same year, the English astronomer Joseph Norman Lockyer observed a yellow line in the solar spectrum that did not correspond to the known D 1 and D 2 lines of sodium, and so he named it the D 3 line. Lockyer concluded that it was caused by a substance in the Sun unknown on Earth. He and the chemist Edward Frankland used the Greek name for the sun, helios, to name the element.

In 1895, British chemist Sir William Ramsay proved the existence of helium on Earth. He received a sample of the uranium-bearing mineral cleveite, and after examining the gases formed when it was heated, he found that the bright yellow line in the spectrum coincided with the D 3 line observed in the spectrum of the Sun. Thus, the new element was finally installed. In 1903, Ramsay and Frederic Soddu determined that helium is a spontaneous decay product of radioactive substances.

Distribution in nature

Helium makes up about 23% of the entire mass of the universe, and the element is the second most abundant in space. It is concentrated in stars, where it is formed from hydrogen as a result of thermonuclear fusion. Although helium is found in the earth's atmosphere at a concentration of 1 part per 200 thousand (5 ppm) and is found in small amounts in radioactive minerals, meteorite iron, and mineral springs, large amounts of the element are found in the United States (especially in Texas, New York). Mexico, Kansas, Oklahoma, Arizona and Utah) as a component (up to 7.6%) of natural gas. Small reserves have been found in Australia, Algeria, Poland, Qatar and Russia. In the earth's crust, the concentration of helium is only about 8 parts per billion.

isotopes

The nucleus of each helium atom contains two protons, but like other elements, it has isotopes. They contain one to six neutrons, so their mass numbers range from three to eight. The stable ones are the elements in which the mass of helium is determined by the atomic numbers 3 (3 He) and 4 (4 He). All the rest are radioactive and decay very quickly into other substances. Terrestrial helium is not the original component of the planet, it was formed as a result of radioactive decay. Alpha particles emitted by the nuclei of heavy radioactive substances are nuclei of the 4 He isotope. Helium does not accumulate in large quantities in the atmosphere because the Earth's gravity is not strong enough to prevent it from gradually escaping into space. Traces of 3 He on Earth are explained by the negative beta decay of the rare element hydrogen-3 (tritium). 4 He is the most common of the stable isotopes: the ratio of the number of atoms 4 He to 3 He is about 700 thousand to 1 in the atmosphere and about 7 million to 1 in some helium-containing minerals.

Physical properties of helium

The boiling and melting points of this element are the lowest. For this reason, helium exists except under extreme conditions. Gaseous He dissolves less in water than any other gas, and the rate of diffusion through solids is three times that of air. Its refractive index comes closest to 1.

The thermal conductivity of helium is second only to that of hydrogen, and its specific heat capacity is unusually high. At ordinary temperatures, it heats up during expansion, and cools down below 40 K. Therefore, at T<40 K гелий можно превратить в жидкость путем расширения.

An element is a dielectric unless it is in an ionized state. Like other noble gases, helium has metastable energy levels that allow it to remain ionized in an electrical discharge when the voltage remains below the ionization potential.

Helium-4 is unique in that it has two liquid forms. The regular one is called helium I and exists at temperatures ranging from a boiling point of 4.21 K (-268.9 °C) to about 2.18 K (-271 °C). Below 2.18 K, the thermal conductivity of 4 He becomes 1000 times greater than that of copper. This form is called helium II to distinguish it from the normal form. It is superfluid: the viscosity is so low that it cannot be measured. Helium II spreads into a thin film on the surface of whatever it touches, and this film flows without friction even against gravity.

Less abundant helium-3 forms three distinct liquid phases, two of which are superfluid. Superfluidity in 4 He was discovered by a Soviet physicist in the mid-1930s, and the same phenomenon in 3 He was first noticed by Douglas D. Osherov, David M. Lee, and Robert S. Richardson from the USA in 1972.

A liquid mixture of two isotopes of helium-3 and -4 at temperatures below 0.8 K (-272.4 °C) is divided into two layers - almost pure 3 He and a mixture of 4 He with 6% helium-3. The dissolution of 3 He into 4 He is accompanied by a cooling effect, which is used in the design of cryostats, in which the helium temperature drops below 0.01 K (-273.14 °C) and is maintained at this temperature for several days.

Connections

Under normal conditions, helium is chemically inert. In extreme conditions, you can create element connections that are not stable at normal temperatures and pressures. For example, helium can form compounds with iodine, tungsten, fluorine, phosphorus, and sulfur when subjected to an electrical glow discharge when bombarded with electrons or in the plasma state. Thus, HeNe, HgHe 10 , WHe 2 and molecular ions He 2 + , He 2 ++ , HeH + and HeD + were created. This technique also made it possible to obtain neutral He 2 and HgHe molecules.

Plasma

In the Universe, ionized helium is predominantly distributed, the properties of which differ significantly from molecular helium. Its electrons and protons are not bound, and it has a very high electrical conductivity even in a partially ionized state. Charged particles are strongly affected by magnetic and electric fields. For example, in the solar wind, helium ions, along with ionized hydrogen, interact with the Earth's magnetosphere, causing the aurora borealis.

Discovery of deposits in the USA

After drilling a well in 1903 in Dexter, Kansas, non-flammable gas was obtained. Initially, it was not known that it contained helium. What gas was found was determined by state geologist Erasmus Haworth, who collected samples of it and at the University of Kansas, with the help of chemists Cady Hamilton and David McFarland, found that it contains 72% nitrogen, 15% methane, 1% hydrogen and 12% was not identified. After further analysis, the scientists found that 1.84% of the sample was helium. So they learned that this chemical element is present in huge quantities in the bowels of the Great Plains, from where it can be extracted from natural gas.

industrial production

This made the United States the world leader in helium production. At the suggestion of Sir Richard Threlfall, the US Navy funded three small experimental plants to produce the substance during World War I to provide barrage balloons with a light, non-flammable lifting gas. A total of 5,700 m 3 of 92% He was produced under this program, although only less than 100 liters of gas had previously been produced. Part of this volume was used in the world's first helium airship C-7, which made its first flight from Hampton Roads to Bolling Field on December 7, 1921.

Although the low-temperature gas liquefaction process was not advanced enough at the time to be significant during World War I, production continued. Helium was mainly used as a lift gas in aircraft. Demand for it grew during World War II, when it was used in shielded arc welding. The element was also important in the Manhattan atomic bomb project.

US National Reserve

In 1925, the United States government established the National Helium Reserve at Amarillo, Texas for the purpose of providing military airships in times of war and commercial airships in times of peace. The use of gas declined after World War II, but the supply was increased in the 1950s to provide, among other things, its supply as a coolant used in the production of oxyhydrogen rocket fuel during the space race and the Cold War. U.S. helium use in 1965 was eight times the peak wartime consumption.

Since the Helium Act of 1960, the Bureau of Mines has contracted 5 private companies to extract the element from natural gas. For this program, a 425-kilometer gas pipeline was built connecting these plants to a partially depleted government gas field near Amarillo, Texas. The helium-nitrogen mixture was pumped into an underground storage and remained there until it was needed.

By 1995, a billion cubic meters of stock had been built and the National Reserve was $1.4 billion in debt, prompting the US Congress to phase it out in 1996. Following the adoption of the helium privatization law in 1996, the Ministry of Natural Resources began to liquidate the storage facility in 2005.

Purity and production volumes

Helium produced before 1945 was about 98% pure, with the remaining 2% being nitrogen, which was sufficient for airships. In 1945, a small amount of 99.9% gas was produced for use in arc welding. By 1949, the purity of the resulting element reached 99.995%.

For many years, the United States produced over 90% of the world's commercial helium. Since 2004, 140 million m 3 has been produced annually, 85% of which is in the United States, 10% in Algeria, and the rest in Russia and Poland. The main sources of helium in the world are the gas fields of Texas, Oklahoma and Kansas.

Receipt process

Helium (purity 98.2%) is isolated from natural gas by liquefying other components at low temperatures and high pressures. The adsorption of other gases with chilled activated carbon achieves a purity of 99.995%. A small amount of helium is produced by liquefying air on a large scale. About 3.17 cubic meters can be obtained from 900 tons of air. m of gas.

Applications

Noble gas has found application in various fields.

• Helium, whose properties make it possible to obtain ultra-low temperatures, is used as a cooling agent in the Large Hadron Collider, superconducting magnets in MRI machines and nuclear magnetic resonance spectrometers, satellite equipment, as well as for liquefying oxygen and hydrogen in Apollo rockets.
• As an inert gas for welding aluminum and other metals, in the production of optical fibers and semiconductors.
• To create pressure in the fuel tanks of rocket engines, especially those that operate on liquid hydrogen, since only gaseous helium retains its state of aggregation when hydrogen remains liquid);
• He-Ne are used to scan barcodes at checkouts in supermarkets.
• A helium-ion microscope produces better images than an electron microscope.
• Due to its high permeability, noble gas is used to check for leaks in, for example, car air-conditioning systems, as well as to quickly inflate airbags in a collision.
• Low density allows you to fill decorative balloons with helium. Inert gas has replaced explosive hydrogen in airships and balloons. For example, in meteorology, helium balloons are used to lift measuring instruments.
• In cryogenic technology, it serves as a coolant, since the temperature of this chemical element in the liquid state is the lowest possible.
• Helium, whose properties provide it with low reactivity and solubility in water (and blood), mixed with oxygen, has found application in breathing compositions for scuba diving and caisson work.
• Meteorites and rocks are analyzed for this element to determine their age.

Helium: element properties

The main physical properties of He are as follows:

• Atomic number: 2.
• Relative mass of a helium atom: 4.0026.
• Melting point: no.
• Boiling point: -268.9 °C.
• Density (1 atm, 0 °C): 0.1785 g/p.
• Oxidation states: 0.

In a few generations, balloons may be history. Buy a balloon. Release it and watch it shrink into a tiny dot and disappear into the stratosphere. Then it will either fly too far and crack, or components that are lighter than air will slowly come out of it. One way or another, helium will escape from the balloon and from the atmosphere. Terrestrial helium literally flies into space.

This is the future of global helium in the next hundred years, scientists say. Such is the fate of a gas that is lighter than air: gravity simply cannot hold it. The earth's crust releases some helium, but it quickly escapes from the atmosphere. The amount of helium in it is stable at 0.00052 volume percent. Extracting such a small amount from the air would be very expensive. The helium that can be bought and used comes from natural gas reserves, mostly in the US.

Used (in balloons, MRI or rockets) helium rises up, up and away. As helium supplies are slowly depleted, prices are already starting to rise and balloons are giving way to more serious uses. In a hundred years, a balloon might cost more than a solid gold ring. Although scientists knew about the impending helium shortage decades ago, it has only become news in the last five years.

Why? The reasons lie in the complex political history of helium.

How did we get there?

Helios on the chariot of the Sun. Nicola BertinNicolas Bertin

In 1868, helium was first seen as a line in the spectrum of light during a solar eclipse. The name "helium" is associated with the Greek god Helios, who every day drove the sun across the sky in a golden chariot. In 1895, Scottish chemist William Ramsay first discovered this gas on Earth. In the same year, Swedish chemists Per Theodor Kleve and Abram Lengle collected enough gas to determine its atomic number, 2.

The element is present in solar energy because the Sun is a huge ball of hydrogen and helium. The attraction of the sun is so strong that at its center hydrogen atoms (with one proton) fuse and become helium atoms (with two protons). This process is called a thermonuclear reaction, and it releases enough energy to make us see sunlight and feel heat at a distance of 150,000,000 km. But we don't get solar helium. This gas, first isolated by scientists, was a by-product of dissolving pitchblende (the most common uranium mineral) in acid, a process that is both radioactive and expensive.

In 1903, an oil rig in Kansas discovered a geyser of disappointingly non-flammable gas. This gas went to the laboratory for analysis and turned out to be 1.8% helium - much more concentrated than that found in the atmosphere. Engineers began to study gas from other wells in the country, and as a result, in 1906, scientists declared: "Helium is not a rare, but a common element, and we have to find a use for its vast reserves."

Why is helium so much more than hydrogen suitable for airships

Once common, helium became the natural solution for rubber balloons and airships that used to be filled with equally light but flammable hydrogen. Helium is less common outside the US and the government wanted to keep that advantage. In 1925, Congress approved the Federal Reserve of Helium for military and commercial airships, and a law passed in 1927 prohibited the export of helium. As a result, the airships of other countries, such as the Hindenburg, were still refueled with hydrogen, which led to the well-known disaster.

Soon other ways of using the resource were found. Helium has the lowest boiling point of all known substances - minus 269 degrees Celsius, so in the liquid state, helium is an ideal refrigerant. A boiling liquid maintains the temperature at which it boils as long as it remains a liquid—it does not get hotter. Water cannot be hotter than a hundred degrees, and liquid helium cannot be hotter than -269. The resource began to be used to isolate welding arcs, and later - in superconductors, nuclear reactors and cryogenics. Now this gas is most often used as a coolant.

Since the days of the Manhattan Project, helium has been used to find leaks: it is an inert gas that does not react with other substances and penetrates holes very quickly. It is used to measure radiation and in medical imaging.

The temperature of the magnets in the MRI machine is maintained with helium.

federal reserve

Although the use of helium-filled airships ceased, the Federal Helium Reserve continued to exist and expand in the second half of the twentieth century because the gas was useful for government needs, mainly for the space and defense industries.

In 1996, the Federal Reserve stood at a billion cubic meters but was no longer of interest to the US government, due in part to poor financial management. The Washington Post wrote: “In 1996, a helium supply looks like a waste. Airships are no longer a vital part of the air force, and, most importantly, by paying drillers to extract helium from natural gas, the storage facility owes $1,400,000,000.”

Both Reagan and Clinton promised to solve this problem, and in 1996 Congress passed legislation to privatize helium. Starting in 2005, the stock was to be sold at a fixed price, rather than market value, and by 2015 it was planned to end sales and close the vault.

Balloon at Macy's Thanksgiving Day Parade (Macy's Thanksgiving Day Parade)

Therefore, the market was filled with helium, its price fell sharply, and consumption, according to conservationists, rose sharply. “Because of this law, helium has become too cheap and is not perceived as a valuable resource. They squander it. [...] Helium has not been able to sell as quickly as desired, and world prices for it are ridiculously low,” Nobel laureate Robert Richardson said in 2010.

Professor Richardson believes helium prices should be increased 20 to 50 times to encourage recycling. For example, NASA doesn't even try to reuse helium after cleaning the rocket fuel tanks, which consumes a lot of this gas. Professor Richardson also believes that helium-filled balloons are too cheap. Each of them should cost about $ 100 - such is the value of the gas that is in them.

Richardson believes that if current consumption rates continue, the world's helium reserves will last about a hundred years.

Instead of encouraging the private sector to produce helium, the sell-off of stocks had the exact opposite effect. Gas became so cheap that no one saw the need or the benefit of extracting it on their own. In anticipation of 2015, scientists sounded the alarm: if the stocks are sold according to the plan, they will no longer be restored. The United States, which produces about 70% of all helium on the planet, remains the world leader in its production, which means that its shortage in the United States can cause problems around the world.

In 2013, the Helium Strategic Control Act was approved, allowing it to be auctioned until 2021, so the price will soon approach the market after a huge part of the stock sold for pennies.

Helium today

Even if the auction gradually solves the price problem, helium is a non-renewable resource. The reserves are expected to deplete by 2020, and even if this does not happen, under current laws, the storage of this gas must be closed by 2021. At the same time, alternative refrigerants, levitators and helium sources are desperately sought all over the world.

The US Geological Survey writes: “By the end of the decade, international helium production facilities are likely to become the world's main source of helium. Such installations have already been created in Algeria and Qatar.” China plans to extract helium-3, which is now mostly only produced, on the moon.

Many consumers, looking at rising prices, began to look for ways to reuse helium. Depending on where these efforts lead, we may be postponing the day when a bunch of balloons becomes as insane a luxury as silver cutlery or ivory-lined piano keys.