The chemical element helium was first discovered on the Sun and only then on Earth.

A key role in the history of the discovery of helium was played by Norman Lockyer, the founder of one of the world's leading scientific publications - the journal Nature. In preparation for the publication of the magazine, he became acquainted with the London scientific establishment and became interested in astronomy. This was a time when, inspired by the Kirchhoff-Bunsen discovery, astronomers were just beginning to study the spectrum of light emitted by stars. Lockyer himself managed to make a number of important discoveries - in particular, he was the first to show that sunspots are colder than the rest of the solar surface, and he was also the first to point out that the Sun has an outer shell, calling it chromosphere. In 1868, while studying the light emitted by atoms in prominences—huge ejections of plasma from the surface of the Sun—Lockyer noticed a number of previously unknown spectral lines ( cm. Spectroscopy). Attempts to obtain the same lines in the laboratory failed, from which Lockyer concluded that he had discovered a new chemical element. Lockyer called it helium, from the Greek helios- "Sun".

Scientists were perplexed as to how to react to the appearance of helium. Some suggested that an error had been made in interpreting the spectra of the prominences, but this point of view received fewer and fewer supporters as more and more astronomers were able to observe the Lockyer lines. Others argued that the Sun contains elements that do not exist on Earth - which, as already mentioned, contradicts the main point about the laws of nature. Still others (there was a minority) believed that someday helium would be found on Earth.

In the late 1890s, Lord Rayleigh and Sir William Ramsay conducted a series of experiments that led to the discovery of argon. Ramsay modified his setup to use it to study the gases released by uranium-containing minerals. Ramsay discovered unknown lines in the spectrum of these gases and sent samples to several colleagues for analysis. Upon receiving the sample, Lockyer immediately recognized the lines that he had observed in sunlight more than a quarter of a century earlier. The helium mystery has been solved: the gas is undoubtedly found on the Sun, but it also exists here on Earth. Nowadays, this gas is best known in everyday life as a gas for inflating airships and balloons ( cm. Graham's Law), and in science - thanks to its application in cryogenics, technologies for achieving ultra-low temperatures.

Coronium and nebulium

The question of whether there are chemical elements somewhere in the Universe that are not found on Earth has not lost its relevance in the 20th century. When studying the outer solar atmosphere - solar crowns, consisting of hot, highly rarefied plasma, astronomers discovered spectral lines that they could not identify with any of the known terrestrial elements. Scientists have suggested that these lines belong to a new element, which is called coronium. And when studying the spectra of some nebulae- distant accumulations of gases and dust in the Galaxy - another mysterious lines were discovered. They were attributed to another “new” element - nebulia. In the 1930s, the American astrophysicist Ira Sprague Bowen (1898-1973) came to the conclusion that the nebulium lines actually belong to oxygen, but acquired this appearance due to extreme conditions existing on the Sun and in nebulae, and these conditions cannot be reproduced in earthly laboratories. Coronium turned out to be highly ionized iron. And these lines got the name prohibited lines.

Joseph Norman LOCKYER
Joseph Norman Lockyer, 1836-1920

English scientist. Born in the town of Rugby in the family of a military doctor. Lockyer came to science in an unusual way, starting his career as an official in the War Ministry. To earn extra money, he took advantage of public interest in science and began publishing a popular science magazine. The first issue of the magazine was published in 1869 Nature, and for 50 years Lockyer remained its editor. He participated in many expeditions observing total solar eclipses. One of these expeditions led him to the discovery of helium. Lockyer is also known as the founder of archaeoastronomy - the science that studies the astronomical meaning of ancient structures such as Stonehenge - and the author of many popular science books.

We all know helium, a very light gas that helps balloons and airships rise into the air. Helium has a very important safety advantage - it does not burn or explode like hydrogen. This gas is also an integral part of air mixtures for use in breathing by deep-sea divers - unlike nitrogen, it is almost insoluble in blood or lipids (fatty components) even under very high pressure conditions.

Helium helps you do without nitrogen narcosis, in which the nervous system (which is 60% lipid) is infused with nitrogen, leaving divers feeling like they've had a single martini at a depth of 30 meters. This gas also helps to avoid the onset of decompression sickness, also known as decompression sickness. This is a painful and dangerous condition in which nitrogen bubbles form in the diver's blood, nervous system, joints and under the skin when pressure drops too quickly as the diver rises to the surface. The mixture of helium and oxygen (called heliox) makes the voice very squeaky - this is due to the fact that sound travels through helium much faster than through air, and it is precisely this property of helium that makes it a favorite joke during the holidays when balloons are inflated with helium. .

Helium is the second lightest chemical element, which has many amazing properties. This gas got its name because it was first detected in a light image on the sun (helios in Greek) before it was discovered on Earth. All gases, when sufficiently cooled, condense into a liquid state, and helium has the lowest condensation temperature of any known substance (–269°C or –452°F). Unlike other chemical elements, helium never freezes, no matter how cold it is, except under very high pressure conditions. Additionally, the liquid form of helium, when cooled to temperatures below –271°C (–456°F) forms a unique phase called a superfluid – this superfluid It flows just perfectly, without any resistance (viscosity).

It is believed that helium in the sun was formed by nuclear fusion . It is a process in which the nuclei of hydrogen, the lightest element, combine to form helium, releasing enormous amounts of energy.

On Earth, this gas is formed mainly as a result of radioactive alpha(a)-decay. Renowned New Zealand physicist Ernest Rutherford (1871–1937) first discovered that alpha particles were actually the nuclei of helium atoms. This is how helium is formed by radioactive elements contained in rock, such as uranium or thorium, and from them it enters the air.

Scientists can determine how quickly helium is formed, how quickly it leaves the rock and how much of it enters the air, and how much helium may be lost from the air to space. They can also measure the amount of helium in rock and air. Based on this, scientists can calculate the maximum age of rocks and air. The results are puzzling to those who believe in billions of years. Of course, all such calculations are based on propositions about the past, such as assumptions about the initial conditions and constant coefficients of various processes. They'll never be able to prove the age of something. For this you need an eyewitness who saw everything with his own eyes ( look Job 38:4 ).

Helium in the atmosphere

Air mainly consists of nitrogen (78.1%) and oxygen (20.1%). The amount of helium in it is very small (0.0005%). But this is still a lot of helium, namely 3.71 billion tons. However, since every second Since 67 grams of helium enters the atmosphere from the earth's crust, then to accumulate the helium existing in the atmosphere today would require about two million years , even if at the very beginning it was not there at all.

Evolutionists believe that our earth is 2500 times older, that is, it 4.5 billion years. Of course, the earth could have been created with most of the observed helium, so two million years is maximum age . (This age could be much less, such as 6000 years.)

In addition, it should be noted that in the past, helium formation would have occurred faster than in the present, as radioactive sources decayed. This would further reduce the age range of the Earth.

The only way to eliminate this problem is to assume that the helium simply leaks into space. But for this to happen, the helium atoms must move fast enough to escape the Earth's gravity (that is, at a speed higher than escape velocity). Collisions between atoms slow down their movement, but above a critical height ( exobase), approximately 500 kilometers above the earth, collisions occur very rarely. Atoms that cross this height have a chance of escaping if they travel fast enough - at least 10.75 kilometers per second. Note that although the helium in the balloon will float, when open it will simply mix evenly with all the other gases, as is the case with all normal gases.

The average speed of atoms can be calculated if the temperature is known, since it is directly related to the average energy of the atoms or molecules. Renowned physicist (and creationist) James Clerk Maxwell calculated how many gas atoms (or molecules) would have a given speed at any temperature and mass. This way we can calculate how many atoms would cross the exobase fairly quickly in order to escape into space.

The exobase is very hot. But even if we assume a temperature of 1500 K (1227°C or 2241°F), which is higher than the average temperature, the most common speed of helium atoms is only 2.5 kilometers per second (5625 m/h), or less than a quarter of the flow rate. Few atoms move faster than the average speed, and yet the amount of helium that flows into space is approximately 1/40 the amount of helium which enters the atmosphere. Other escape mechanisms also fail to account for the small amount of helium in the air, which is about 1/2000 of the amount that would be present in the air after expected billions of years.

This is an unsolved problem for the atmospheric physicist who believes in the long epochs of earth's history, K.G. Walker, who said the following: “...with regard to the level of helium in the atmosphere, here we are faced with a problem”. Another specialist, D.W. Chamberlain also said that this problem regarding helium accumulation “... will not go away on its own, and will remain unresolved”.

The evolutionary community is desperately trying to find other explanations for this lack of helium, but none of them are suitable. A simple solution to the problem can be found if we accept that the earth is not at all as old as evolutionists believe! Creationist, scientist Larry Vardiman, who studied the atmosphere, studied this issue more deeply and wrote a more detailed study of this issue.

Helium in rocks

As we have already said, most of the helium on earth is formed as a result of radioactive decay in rocks. Small atoms of helium gas flow freely from rocks into the atmosphere.

We also said above that the rate at which helium enters the atmosphere has been established. But we can also measure the rate at which helium flows out of rocks. This process happens faster in hotter rocks, and the deeper you go into the earth, the hotter the rocks become.

Creation physicist Robert Gentry has been researching deep-lying granite as a possible way to safely store hazardous radioactive waste from nuclear power plants. Safe storage requires that the elements do not pass through the rock too quickly.

Granite contains mineral crystals called zircons(zirconium silicate, ZrSiO 4), which often contain radioactive elements. This means that they must form helium, which must flow into the atmosphere.

But Gentry found that even deep-lying zircons (197°C or 387°F) contained too much helium- that is, if they had billions of years to flow out.

However, if in reality only a few thousand years passed during which this helium entered the atmosphere, then it is not surprising that there is so much helium left there.

[October 2002 News: See data on accelerated nuclear decay in the article Nuclear Decay: Evidence of the World's Youth , written by a creationist nuclear physicist Dr Russell Humphreys .]

Conclusion

The amount of helium in the air and rocks is completely inconsistent with the idea that our earth is billions of years old, as evolutionists and progressive creationists claim. This amount of helium is rather scientific proof of a small age, as clearly and clearly stated in the book of Genesis.

Helium(lat. Helium), symbol He, chemical element of group VIII of the periodic system, refers to inert gases; serial number 2, atomic mass 4.0026; colorless and odorless gas. Natural Helium consists of 2 stable isotopes: 3 He and 4 He (the content of 4 He sharply predominates).

Historical reference. For the first time, Helium was discovered not on Earth, where it is scarce, but in the atmosphere of the Sun. In 1868, the Frenchman J. Jansen and the Englishman J. N. Lockyer studied the spectroscopic composition of solar prominences. The images they obtained contained a bright yellow line (the so-called D3 line), which could not be attributed to any of the elements known at that time. In 1871, Lockyer explained its origin by the presence of a new element in the Sun, which was called helium (from the Greek helios - Sun). On Earth, Helium was first isolated in 1895 by the Englishman W. Ramsay from the radioactive mineral kleveite. The spectrum of the gas released when heating kleveite showed the same line.

Distribution of Helium in nature. There is little Helium on Earth: 1 m 3 of air contains only 5.24 cm 3 of Helium, and every kilogram of earthly material contains 0.003 mg of Helium. In terms of abundance in the Universe, Helium ranks second after hydrogen: Helium accounts for about 23% of cosmic mass.

On Earth, Helium (more precisely, the isotope 4 He) is constantly formed during the decay of uranium, thorium and other radioactive elements (in total, the earth's crust contains about 29 radioactive isotopes that produce 4 He).

Approximately half of all Helium is concentrated in the earth's crust, mainly in its granite shell, which has accumulated the main reserves of radioactive elements. The content of Helium in the earth's crust is low - 3·10 -7% by mass. Helium accumulates in free gas accumulations in the subsurface and in oil; Such deposits reach industrial scale. Maximum concentrations of Helium (10-13%) were found in free gas accumulations and gases of uranium mines and (20-25%) in gases spontaneously released from groundwater. The older the age of gas-bearing sedimentary rocks and the higher the content of radioactive elements in them, the more Helium in the composition of natural gases. Volcanic gases are usually characterized by a low content of Helium.

Helium is produced on an industrial scale from natural and petroleum gases of both hydrocarbon and nitrogen composition. Based on 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). В СССР природный Гелий содержится во многих нефтегазовых месторождениях. Значительные его концентрации известны в некоторых месторождениях природного газа Канады, США (штаты Канзас, Техас, Нью-Мексико, Юта).

Isotopes, atom and molecule of Helium. In natural Helium of any origin (atmospheric, from natural gases, from radioactive minerals, meteorite, etc.), the 4 He isotope predominates. The content of 3 He is usually low (depending on the source of Helium, it ranges from 1.3·10 -4 to 2·10 -8%) and only in Helium isolated from meteorites reaches 17-31.5%. The rate of formation of 4 He during radioactive decay is low: in 1 ton of granite containing, for example, 3 g of uranium and 15 g of thorium, 1 mg of Helium is formed in 7.9 million years; however, since this process occurs constantly, during the existence of the Earth it would have to provide a content of Helium in the atmosphere, lithosphere and hydrosphere that significantly exceeds the existing one (it is about 5 10 14 m 3). This deficiency of Helium is explained by its constant evaporation from the atmosphere. Light atoms of Helium, falling into the upper layers of the atmosphere, gradually acquire a speed there higher than the second cosmic speed and thereby gain the opportunity to overcome the forces of gravity. The simultaneous formation and volatilization of helium leads to the fact that its concentration in the atmosphere is almost constant.

The 3 He isotope, in particular, is formed in the atmosphere during the β-decay of the heavy isotope of hydrogen - tritium (T), which, in turn, arises from the interaction of neutrons from cosmic radiation with nitrogen in the air:

14 7 N + 3 0 n → 12 6 C + 3 1 T.

The nuclei of the 4 He atom (consisting of 2 protons and 2 neutrons), called alpha particles or helions, are the most stable among compound nuclei. The binding energy of nucleons (protons and neutrons) in 4 He has a maximum value compared to the nuclei of other elements (28.2937 MeV); therefore, the formation of 4 He nuclei from hydrogen nuclei (protons) 1 H is accompanied by the release of a huge amount of energy. This nuclear reaction is believed to be:

4 1 H = 4 He + 2β + + 2n

[simultaneously with 4 He, two positrons (β +) and two neutrinos (ν) are formed] serves as the main source of energy for the Sun and other stars similar to it. Thanks to this process, very significant reserves of Helium accumulate in the Universe.

Physical properties of Helium. Under normal conditions, Helium is a monatomic gas, colorless and odorless. Density 0.17846 g/l, boiling point -268.93°C, melting point -272.2°C. Thermal conductivity (at 0°C) 143.8·10 -3 W/(cm·K). The radius of the Helium atom, determined by various methods, ranges from 0.85 to 1.33 Å. About 8.8 ml of helium dissolves in 1 liter of water at 20°C. The primary ionization energy of Helium is greater than that of any other element - 39.38·10 -13 J (24.58 eV); Helium does not have an affinity for electrons. Liquid Helium, consisting only of 4 He, exhibits a number of unique properties.

Chemical properties of Helium. Until now, attempts to obtain stable chemical compounds of Helium have ended in failure.

Obtaining Helium. In industry, Helium is obtained from helium-containing natural gases (currently, mainly deposits containing > 0.1% Helium are exploited). Helium is separated from other gases by deep cooling, using the fact that it liquefies more difficult than all other gases.

Application of Helium. Due to its inertness, Helium is widely used to create a protective atmosphere when melting, cutting and welding active metals. Helium is less electrically conductive than another inert gas, argon, and therefore an electric arc in a Helium atmosphere produces higher temperatures, which significantly increases the speed of arc welding. Due to its low density combined with its non-flammability, helium is used to fill stratospheric balloons. The high thermal conductivity of Helium, its chemical inertness and extremely low ability to enter into a nuclear reaction with neutrons make it possible to use Helium for cooling nuclear reactors. Liquid Helium is the coldest liquid on Earth and serves as a coolant in various scientific research. One of the methods for determining their absolute age is based on determining the Helium content in radioactive minerals. Due to the fact that Helium is very poorly soluble in the blood, it is used as a component of artificial air supplied for breathing to divers (replacing nitrogen with Helium prevents the occurrence of decompression sickness). The possibilities of using Helium in the atmosphere of a spacecraft cabin are also being studied.

Helium is liquid. The relatively weak interaction of helium atoms causes it to remain gaseous to lower temperatures than any other gas. The maximum temperature below which it can be liquefied (its critical temperature Tk) is 5.20 K. Liquid Helium is the only non-freezing liquid: at normal pressure, Helium remains liquid at arbitrarily low temperatures and solidifies only at pressures exceeding 2. 5 Mn/m2 (25 at).

Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, first in the group of noble gases in the periodic table. Its boiling point is the lowest of all elements. After hydrogen, helium is the second lightest and second most abundant element in the observable universe, present at about 24% of the total mass of the elements, more than 12 times the mass of all heavier elements combined. Its abundance is due to the very high nuclear binding energy (per nucleon) of helium-4 relative to the next three elements after helium. This helium-4 binding energy also explains why helium is a product of both nuclear fusion and radioactive decay. Most of the helium in the universe is in the form of helium-4, and is believed to have formed during the Big Bang. Large amounts of new helium are created by nuclear fusion of hydrogen in stars. Helium is named after the Greek god of the sun, Helios. Helium was first discovered as an unknown yellow spectral line signature in sunlight during a solar eclipse in 1868 by Georges Rayet, Captain C.T. Haig, Norman R. Pogson and Lieutenant John Herschel.

This observation was subsequently confirmed by French astronomer Jules Janssen. Janssen is often credited with discovering this element along with Norman Lockyer. Janssen recorded the spectral line of helium during the 1868 solar eclipse, while Lockyer observed the phenomenon from Britain. Lockyer was the first to suggest that this line was associated with a new element, to which he gave the name helium. The formal discovery of the element was made in 1895 by two Swedish chemists, Per Theodor Cleave and Niels Abraham Langlet, who discovered helium coming from the uranium ore kleveite. In 1903, large reserves of helium were discovered in natural gas fields in parts of the United States. Today, the USA is the largest gas supplier. Liquid helium is used in cryogenics (its largest single use, consuming about a quarter of production), particularly in cooling superconducting magnets, with the main commercial use being in MRI scanners. Other industrial uses of helium are as a pressurization and purge gas, as a protective atmosphere for arc welding, and in processes such as crystal growth to make silicon wafers. A well-known but minor use of helium is as a lifting gas for balloons and airships. As with any gas whose density is different from that of air, inhaling a small volume of helium temporarily changes the timbre and quality of the human voice. In scientific research, the behavior of the two liquid phases of helium-4 (helium I and helium II) is important to researchers studying quantum mechanics (in particular the property of superfluidity) and to scientists studying phenomena such as superconductivity in matter near absolute zero. On Earth, helium is relatively rare - 5.2 ppm. by volume in the atmosphere. Today, most of the helium present on Earth is created through the natural radioactive decay of heavy radioactive elements (thorium and uranium, although there are other examples), since the alpha particles emitted by such decays are composed of helium-4 nuclei. This radiogenic helium is captured in natural gas in concentrations of up to 7% by volume, from which it is extracted commercially by a low-temperature separation called fractional distillation. Terrestrial helium used to be a non-renewable resource because, once released into the atmosphere, it could easily travel into space, and the element was thought to be increasingly scarce. However, recent research suggests that helium, formed on Earth from radioactive decay, may be collecting in natural gas reserves in larger quantities than expected, in some cases released by volcanic activity.

Story

Scientific discoveries

The first evidence of the existence of helium was made on August 18, 1868. A bright yellow line with a wavelength of 587.49 nanometers was observed in the spectrum of the solar chromosphere. This line was discovered by French astronomer Jules Janssen during a total solar eclipse in Guntur, India. This line was originally thought to be sodium. On October 20 of the same year, English astronomer Norman Lockyer observed a yellow line in the spectrum of the Sun, which he called the D3 Fraunhofer line because it was close to the famous D1 and D2 lines of sodium. The scientist concluded that this line was caused by an element of the Sun, unknown on Earth. Lockyer and the English chemist Edward Frankland named the element from the Greek word for sun, ἥλιος (helios). In 1881, Italian physicist Luigi Palmieri first discovered helium on Earth through its D3 spectral line, while analyzing material that was sublimated during the eruption of Mount Vesuvius. On March 26, 1895, Scottish chemist Sir William Ramsay isolated helium on Earth by treating the mineral cleveite (a range of uraninites with at least 10% rare earth elements) with mineral acids. Ramsay was looking for argon, but after separating the nitrogen and oxygen from the gas produced by the sulfuric acid, he noticed a bright yellow line that matched the D3 line seen in the spectrum of the Sun. These samples were identified as helium by Lockyear and British physicist William Crookes. Helium was independently isolated from kleveite in the same year by chemists Per Theodor Kleve and Abraham Langlet in Uppsala, Sweden, who collected enough of the gas to accurately determine its atomic weight. Helium was also isolated by American geochemist William Francis Hillebrand before Ramsey's discovery, when he noticed unusual spectral lines while testing a sample of the mineral uraninite. Hillebrand, however, attributed these lines to nitrogen. In 1907, Ernest Rutherford and Thomas Royds demonstrated that alpha particles were helium nuclei by allowing the particles to penetrate the thin glass wall of an evacuated tube and then creating a discharge in the tube to study the spectra of the new gas inside. In 1908, helium was first liquefied by Dutch physicist Heike Kamerlingh Onnes by cooling the gas to a temperature of less than one kelvin. He tried to make the gas solid by lowering the temperature further, but failed because helium does not solidify at atmospheric pressure. Onnes's student, Willem Hendrik Keesom, was eventually able to cause 1 cm3 of helium to solidify in 1926 by adding additional external pressure. In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that helium-4 has virtually no viscosity at temperatures near absolute zero, a phenomenon now called superfluidity. This phenomenon is associated with Bose-Einstein condensation. In 1972, the same phenomenon was observed for helium-3, but at temperatures much closer to absolute zero, by American physicists Douglas D. Osheroff, David M. Lee and Robert C. Richardson. The phenomenon in helium-3 is thought to be due to the pairing of helium-3 fermions to form bosons, analogous to Cooper pairs of electrons that produce superconductivity.

Extraction and Use

After an oil drilling operation in 1903, Dexter, Kansas, produced a gas geyser that did not burn, and Kansas State Geologist, Erasmus Haworth, collected samples of the escaping gas and took them to the University of Kansas at Lawrence, where, with the help of chemists Hamilton Cady and David McFarland, he found that the gas consisted of 72% nitrogen, 15% methane (the flammable percentage with only enough oxygen), 1% hydrogen and 12% unidentifiable gas. Upon further analysis, Cady and McFarland found that 1.84% of the gas sample was helium. This showed that, despite its general rarity on Earth, helium was concentrated in large quantities beneath the American Great Plains, available for extraction as a byproduct of natural gas. This allowed the United States to become the world's leading supplier of helium. Following a suggestion by Sir Richard Threlfall, the United States Navy sponsored three small experimental helium plants during the First World War. The goal was to supply barrage balloons with a non-flammable gas lighter than air. During this program, 5,700 m3 (200,000 cu ft) of 92% helium was produced, although less than one cubic meter of this gas had previously been produced. Some of this gas was used in the world's first helium airship, the US Navy's C-7, which made its maiden voyage from Hampton Roads, Virginia, to Bolling Field in Washington, D.C., on December 1, 1921, nearly two years before it was built. the first helium-filled rigid airship in September 1923 at the Shenandoah plant. Although the extraction process using low-temperature gas liquefaction was not developed at the time, production continued during World War I. Helium was primarily used as a lifting gas in lighter-than-air aircraft. During World War II, the demand for helium as a lifting gas and for shielded arc welding increased. The helium mass spectrometer was also of great importance in the Manhattan Project (the code name for the work to create the first atomic bomb in the United States during the Second World War). The United States government established the National Helium Reserve in 1925 in Amarillo, Texas, for the purpose of supplying military airships in times of war and commercial airships in times of peace. Because of the Helium Control Act (1927), which prohibited the export of rare helium, the production of which the United States then had a monopoly on, coupled with the prohibitive cost of gas, the Hindenburg, like all German Zeppelins, was forced to use hydrogen as a lift gas. The market for helium was suppressed after World War II, but supplies were expanded in the 1950s to provide liquid helium as a coolant to create oxyhydrogen rocket fuel (among other uses) during the Space Race and the Cold War. Helium use in the United States in 1965 was more than eight times peak wartime consumption. Following the Helium Act Amendments of 1960 (Public Law 86-777), the United States Bureau established five private plants to recover helium from natural gas. For this helium conservation program, the Bureau constructed a 425-mile (684-kilometer) pipeline from Bushton, Kansas, to connect these plants to the government's partially depleted Cliffside gas field near Amarillo, Texas. This helium-nitrogen mixture was injected and stored in the Cliffside gas field until it was needed, during which time it was further purified. By 1995, a billion cubic meters of gas had been collected and the reserve was $1.4 billion in debt, prompting the United States Congress to eliminate the reserve in 1996. The Helium Privatization Act of 1996 (Public Law 104-273) forces the United States Department of the Interior to release the reserve and begin sales in 2005. Helium produced between 1930 and 1945 was approximately 98.3% pure (2% nitrogen), sufficient for airships. In 1945, small amounts of 99.9% helium were produced for welding. By 1949, commercial quantities of 99.95% Class A helium were available. For many years, the United States produced more than 90% of the world's commercially used helium, with mining plants in Canada, Poland, Russia and other countries producing the rest. In the mid-1990s, a new plant in Argeve, Algeria, began operating, producing 17 million cubic meters (600 million cubic feet of helium), with enough production to cover all of Europe's needs. Meanwhile, by 2000, helium consumption in the United States increased to more than 15 million kg per year. In 2004-2006, additional plants were built in Ras Laffan, Qatar and Skikda, Algeria. Algeria quickly became the second leading producer of helium. During this time, both helium consumption and helium production costs increased. From 2002 to 2007 Helium prices have doubled. As of 2012, the United States National Helium Reserve accounted for 30 percent of the world's helium reserves. The reserve is expected to run out in 2018. Despite this, proposed legislation in the United States Senate would allow the reserve to continue selling gas. Other large helium reserves were located in the Hugoton State of Kansas, USA, and nearby gas fields in Kansas, as well as in the Texas and Oklahoma salients. New helium plants were due to open in 2012 in Qatar, Russia and the US state of Wyoming, but were not expected to ease the shortage. In 2013, construction began on the world's largest helium plant in Qatar. 2014 was widely considered a year of oversupply in the helium business, after years of shortages.

Characteristics

Helium atom

Helium in quantum mechanics

From a quantum mechanics perspective, helium is the second simplest atom to model, following the hydrogen atom. Helium consists of two electrons in atomic orbitals surrounding a nucleus containing two protons and (usually) two neutrons. As in Newtonian mechanics, no system consisting of more than two particles can be solved using a precise analytical mathematical approach, and helium is no exception. Thus, numerical mathematical methods are required, even to solve a system consisting of one nucleus and two electrons. Such computational chemistry techniques have been used to create a quantum mechanical picture of helium's electronic binding that is accurate to less than 2% of the correct value across multiple computational steps. Such models show that each electron in helium partially shields one nucleus from the other, so that the effective nuclear charge Z that each electron sees is about 1.69 units, rather than the 2 charge of a classical "naked" helium nucleus.

Relative stability of the helium-4 nucleus and electron shell

The nucleus of a helium-4 atom is identical to an alpha particle. High-energy electron scattering experiments show that its charge decreases exponentially from a maximum at the central point, just like the charge density of helium's own electron cloud. This symmetry reflects similar underlying physics: a pair of neutrons and a pair of protons in a helium nucleus obey the same quantum mechanical rules as a pair of helium electrons (although the nuclear particles are subject to a different nuclear binding potential), so that all of these fermions completely occupy the 1s orbitals in the pairs , and neither of them has orbital momentum, and each of them cancels the other’s own spin. Adding any other of these particles would require angular momentum and release substantially less energy (in fact, no nucleus with five nucleons is stable). So this scheme is energetically extremely stable for all these particles, and this stability explains many important facts about helium in nature. For example, the stability and low energy state of the electron cloud in helium explains the chemical inertness of the element, as well as the lack of interaction of helium atoms with each other, creating the lowest melting and boiling points of all elements. Likewise, the special energetic stability of the helium-4 nucleus, created by similar effects, explains the ease of production of helium-4 in atomic reactions that involve either the release of heavy metals or their synthesis. Some stable helium-3 (2 protons and 1 neutron) is produced in fusion reactions from hydrogen, but this amount is very small compared to the highly sensitive energy of helium-4. The unusual stability of the helium-4 nucleus is also important cosmologically: it explains the fact that in the first few minutes after the Big Bang, during the creation of the "mash of free protons and neutrons" that were originally created in a ratio of about 6:1, cooled to such a to the extent that nuclear bonding became possible, almost all of the first compound atomic nuclei formed were helium-4 nuclei. helium-4 binding was so tight that helium-4 production consumed almost all of the free neutrons within minutes before they could be beta-decayed, leaving little to form heavier atoms such as lithium, beryllium or boron . The nuclear binding of helium-4 per nucleon is stronger than that of any of these elements, and thus, when helium was formed, there was no energetic drive to create elements 3, 4 and 5. It was of little energetic benefit for helium to fuse into the next element with less energy per nucleon, carbon. However, due to the lack of intermediate elements, this process requires three helium nuclei striking each other almost simultaneously. Thus, in the minutes after the Big Bang, there was no time for significant amounts of carbon to form before the early expanding Universe cooled to a temperature and pressure at which fusion of helium with carbon would be impossible. Because of this, the early universe had a hydrogen/helium ratio similar to today's (3 parts hydrogen to 1 part helium-4 by mass), with almost all of the neutrons in the universe captured by helium-4. All heavier elements (including elements needed for rocky planets like Earth and for carbon-based or other life forms) were thus created after the Big Bang in stars that were hot enough to fuse helium itself. All elements except hydrogen and helium today make up only 2% of the mass of atomic matter in the Universe. Helium-4, by contrast, makes up about 23% of the universe's ordinary matter—almost all the ordinary matter that is not hydrogen.

Gas and plasma phases

Helium is the second least reactive noble gas after neon and therefore the second least reactive of all the elements. It is inert and monoatomic under all standard conditions. Because of helium's relatively low molar (atomic) mass, its thermal conductivity, specific heat capacity, and speed of sound in the gas phase are greater than those of any other gas except hydrogen. For these reasons and because of the small size of monatomic helium molecules, helium diffuses through solid particles at a speed three times the speed of air and about 65% of the speed of hydrogen. Helium is the least water-soluble monatomic gas and one of the less water-soluble gases (CF4, SF6 and C4F8 have lower molar solubilities: 0.3802, 0.4394 and 0.2372 x2/10-5 respectively versus 0.70797 x2/10-5 5 for helium), in addition, the refractive index of helium is closer to unity than the refractive index of any other gas. Helium has a negative Joule-Thomson coefficient at normal ambient temperatures, which means it heats up when it is allowed to expand freely. Just below its Joule-Thomson inversion temperature (about 32 to 50 K at 1 atmosphere), helium cools as it expands freely. Once supercooled below this temperature, the helium can be liquefied by refrigeration. Most extraterrestrial helium is in a plasma state and has properties completely different from those of atomic helium. In plasma, helium's electrons are not bound to its nucleus, resulting in very high electrical conductivity even when the gas is only partially ionized. Charged particles are strongly influenced by magnetic and electric fields. For example, in the solar wind, along with ionized hydrogen, the particles interact with the Earth's magnetosphere, leading to Birkeland currents and aurora.

Liquid helium

Unlike any other element, helium will remain liquid to absolute zero at normal pressures. This is a direct influence of quantum mechanics: in particular, the zero point energy of the system is too high to allow freezing to occur. Solid helium requires a temperature of 1-1.5 K (about -272 °C or -457 °F) at a pressure of about 25 bar (2.5 MPa). It is often difficult to distinguish solid from liquid helium because the refractive index of the two phases is almost the same. The solid has a distinct melting point and a crystalline structure, but it is highly compressible; applying pressure in the laboratory can reduce its volume by more than 30%. With a bulk modulus of about 27 MPa, helium is 100 times more compressible than water. Solid helium has a density of 0.214 ± 0.006 g/cm3 at 1.15 K and 66 atm; the predicted density at 0 K and 25 bar (2.5 MPa) is 0.187 ± 0.009 g/cm3. At higher temperatures, helium will solidify with sufficient pressure. At room temperature, this requires about 114,000 atm.

Helium state I

Below its boiling point of 4.22 kelvin and above its lambda point of 2.1768 kelvin, the isotopic helium-4 exists in a normal colorless liquid state called helium I. Like other cryogenic liquids, helium I boils when it is heated and contracts when his temperature decreases. However, below the lambda point, helium does not boil and it expands as the temperature drops further. Helium I has a gaseous refractive index of 1.026, making its surface so difficult to view that pop-up polystyrene foams are often used to view its surface. This colorless liquid has a very low viscosity and a density of 0.145-0.125 g/ml (about 0-4 K), which is only one-fourth of the value expected from classical physics. Quantum mechanics is needed to explain this property, and so both states of liquid helium (helium I and helium II) are called quantum liquids, meaning that they exhibit atomic properties on a macroscopic scale. This may be due to the fact that helium's boiling point is so close to absolute zero that it prevents random molecular motion (thermal energy) from masking its atomic properties.

Helium state II

Liquid helium below its lambda point (called helium II) has very unusual characteristics. Due to its high thermal conductivity, when it boils, it does not bubble but evaporates directly from the surface. Helium-3 also has a superfluid phase, but only at much lower temperatures; as a result, little is known about the properties of this isotope. Helium II is a superfluid liquid and a quantum mechanical state with strange properties. For example, when it flows through capillaries 10-7 to 10-8 m thick, it has no measurable viscosity. However, when measurements were taken between two moving disks, a viscosity comparable to that of helium gas was observed. The present theory explains this using a two-fluid model for helium II. In this model, liquid helium below the lambda point is considered to contain a portion of ground-state helium atoms that are superfluid and flow with zero viscosity, and a portion of excited-state helium atoms that behave like an ordinary liquid. In the gushing effect, a chamber is constructed that is connected to the helium II reservoir by a sintered disk through which superfluid helium easily flows, but through which non-superfluid helium cannot pass. If the inside of the container heats up, the superfluid helium changes to non-superfluid helium. To maintain an equilibrium proportion of superfluid helium, superfluid helium flows and increases pressure, causing liquid to release from the container. The thermal conductivity of helium II is greater than that of any other known substance, a million times greater than that of helium I and several hundred times greater than that of copper. This is due to the fact that thermal conduction occurs due to an exceptional quantum mechanism. Most materials that conduct heat have a valence band of free electrons that serve to transfer heat. Helium II does not have such a valence band, but nevertheless conducts heat well. Heat flow is determined by equations that are similar to the wave equation used to characterize the propagation of sound in air. When exposed to heat, it travels at 20 meters per second at 1.8 K through Helium II in the form of waves in a phenomenon known as second sound. Helium II also has a creeping effect. When a surface passes through a Helium II level, Helium II moves across the surface, against gravity. Helium II will exit the unsealed container, sliding down the sides until it reaches a warmer area where it will evaporate. It moves in a 30 nm thick film regardless of the surface material. This film is called Rollin film in honor of the scientist who first characterized this quality, Bernard W. Rollin. As a result of this "creeping" behavior and Helium II's ability to quickly flow through tiny holes, it is very difficult to confine liquid helium. Unless the container is carefully constructed, Helium II will creep along the surface and through the valves until it reaches a warmer area, where it will evaporate. Waves propagating through a Rollin film are governed by the same equation as gravitational waves in shallow water, but instead of gravity, the restoring force is the van der Waals force. These waves are known as third sound.

Isotopes

There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. In the Earth's atmosphere, there is one 3He atom per million 4He atoms. Unlike most elements, the isotopic abundance of helium varies greatly in origin due to different formation processes. The most common isotope, helium-4, is produced on Earth through the alpha decay of heavier radioactive elements; the resulting alpha particles are fully ionized helium-4 nuclei. Helium-4 is an unusually stable nucleus because its nucleons are arranged in complete shells. It was also formed in huge quantities in big bang nucleosynthesis. Helium-3 is present on Earth only in trace amounts; Most helium-3 has been present since Earth's formation, although some ends up on Earth captured in cosmic dust. Trace amounts of helium are also produced by tritium beta decay. Rocks in the Earth's crust have isotopic ratios that vary by a factor of ten, and these ratios can be used to study the origins of rocks and the composition of the Earth's mantle. 3He is much more common in stars as a product of nuclear fusion. Thus, in the interstellar medium the ratio of 3He to 4He is approximately 100 times higher than on Earth. Extraplanetary material such as lunar and asteroidal regolith has trace amounts of helium-3 from bombardment by solar winds. The Moon's surface contains helium-3 in concentrations on the order of 10 ppm, much higher than the approximately 5 ppm found in the Earth's atmosphere. A number of scientists, starting with Gerald Kulcinski in 1986, have proposed exploring the moon, collecting lunar regolith, and using helium-3 for fusion. Liquid helium-4 can be cooled to about 1 kelvin using evaporative cooling in a pot that reaches 1 K. Similar cooling of lower boiling point helium-3 can reach about 0.2 kelvin in a helium-3 refrigerator. Equal mixtures of liquid 3He and 4He with temperatures below 0.8 K separate into two immiscible phases due to their dissimilarity (they have different quantum statistics: helium-4 atoms are bosons, while helium-3 atoms are fermions). In refrigeration machines operating on a mixture of cryogenic substances, this immiscibility is used to achieve temperatures of several millikelvins. It is possible to produce exotic isotopes of helium that quickly decay into other substances. The shortest-lived heavy isotope of helium is helium-5, with a half-life of 7.6×10-22 s. Helium-6 decays by emitting a beta particle and has a half-life of 0.8 seconds. Helium-7 also emits a beta particle as well as a gamma ray. Helium-7 and helium-8 are formed in some nuclear reactions. Helium-6 and helium-8 are known to have a nuclear halo.

Helium compounds

Helium has a valency of 0 and is chemically inactive under all normal conditions. Helium is an electrical insulator unless it is ionized. Like other noble gases, helium has metastable energy levels that allow it to remain ionized in an electrical discharge at a voltage below its ionization potential. Helium can form unstable compounds known as excimers with tungsten, iodine, fluorine, sulfur, and phosphorus when it is subjected to glow discharge, electron bombardment, or reduced to plasma by other means. In this way the molecular compounds HeNe, HgHe10 and WHe2 and the molecular ions He+2, He2+2, HeH+ and HeD+ were created. HeH+ is also stable in its ground state, but is extremely reactive - it is the strongest Brønsted acid, and therefore can only exist in isolation, as it will protonate any molecule or protianion it comes into contact with. This method also created the neutral He2 molecule, which has a large number of band systems, and HgHe, which appears to be held together only by polarization forces. Van der Waals helium compounds can also form with cryogenic helium gas and atoms of some other substance, such as LiHe and He2. It is theoretically possible that there are other true compounds, such as helium fluorohydride (HHeF), which would be similar to HArF discovered in 2000. Calculations show that two new compounds containing a helium-oxygen bond may be stable. The two new molecular species predicted using the theory, CsFHeO and N(CH3)4FHeO, are derivatives of the metastable FHeO anion first proposed in 2005 by a group in Taiwan. If this is confirmed by experiment, the only remaining element with no known stable compounds will be neon. Helium atoms were inserted into molecules of hollow carbon frameworks (fullerenes) by heating under high pressure. The created endohedral fullerene molecules are stable at high temperatures. When chemical derivatives of these fullerenes are formed, helium remains inside. If helium-3 is used, it can be easily observed using helium nuclear magnetic resonance spectroscopy. Many fullerenes containing helium-3 have been reported. Although helium atoms are not linked by covalent or ionic bonds, these substances have certain properties and a certain composition, like all stoichiometric chemical compounds. At high pressures, helium can form compounds with various other elements. Crystals of helium-nitrogen clathrate (He(N2)11) were grown at room temperature at pressures of ca. 10 GPa in a high pressure chamber with diamond anvils. The Na2He insulating electrolyte has been shown to be thermodynamically stable at pressures above 113 GPa. It has a fluorite structure.

Origin and production

Natural abundance

Although helium is rare on Earth, it is the second most abundant element in the known Universe (after hydrogen), accounting for 23% of its baryon mass. The vast majority of helium was formed by Big Bang nucleosynthesis one to three minutes after the Big Bang. Thus, measurements of its abundance contribute to cosmological models. In stars, helium is formed by the nuclear fusion of hydrogen in proton-proton chain reactions and the CNO cycle, part of stellar nucleosynthesis. In the Earth's atmosphere, the concentration of helium by volume is only 5.2 parts per million. The concentration is low and fairly constant despite the continuous production of new helium, because most of the helium in Earth's atmosphere enters space through several processes. In the earth's heterosphere, part of the upper atmosphere, helium and other lighter gases are the most abundant elements. Most of the helium on Earth is the result of radioactive decay. Helium is found in large quantities in uranium and thorium minerals, including kleveite, resin, carnotite and monazite, because they release alpha particles (helium nuclei, He2+), with which electrons immediately bind as soon as the particle is stopped by a stone. Thus, about 3000 metric tons of helium are generated throughout the lithosphere. In the earth's crust, the concentration of helium is 8 parts per billion. In seawater the concentration is only 4 parts per trillion. Small amounts of helium are also present in mineral springs, volcanic gas and meteoric iron. Because helium is trapped in the ground under conditions that also trap natural gas, the largest natural concentrations of helium on the planet are found in natural gas, from which most commercial helium is extracted. Helium concentrations vary widely, from a few ppm to over 7% in a small gas field in San Juan County, New Mexico. As of 2011, global helium reserves were estimated at 40 billion cubic meters, with a quarter of these reserves located in the South Pars/North Dome Gas-Condensate field, jointly owned by Qatar and Iran. In 2015 and 2016, more probable reserves were announced in the North American Rocky Mountains and East Africa.

Modern production and distribution

For large-scale use, helium is extracted by fractional distillation from natural gas, which can contain up to 7% helium. Because helium has a lower boiling point than any other element, low temperature and high pressure are used to liquefy almost all other gases (mainly nitrogen and methane). The resulting raw helium gas is purified by successive steps of lowering the temperature, at which time almost all of the remaining nitrogen and other gases are precipitated from the gas mixture. Activated carbon is used as the final purification step, typically producing 99.995% pure Class A helium. The main impurity in class A helium is neon. At the final stage of production, most of the helium produced is liquefied through a cryogenic process. This is essential for applications requiring liquid helium and also allows helium suppliers to reduce the cost of transporting helium over long distances, as the largest liquid helium containers have more than five times the capacity of the largest gas helium trailers. In 2008, approximately 169 million standard cubic meters of helium were extracted from natural gas or withdrawn from helium reserves, approximately 78% from the United States, 10% from Algeria, and most of the remainder from Russia, Poland and Qatar. By 2013, increased helium production in Qatar (RasGas under Air Liquide) increased Qatar's share of global helium production to 25% and made the country the second largest helium exporter after the United States. It is estimated that about 54 billion cubic feet (1.5×109 m3) of helium were discovered in Tanzania in 2016. In the United States, most helium is extracted from natural gas in Hugoton and nearby gas fields in Kansas, Oklahoma, and the Panhandle field in Texas. Much of this gas was once piped to the National Helium Reserve, but the reserve has been depleted and sold off since 2005, and is expected to be largely depleted by 2021, according to the Responsible Helium and Stewardship Act. passed in October 2013 (HR 527). Diffusion of raw natural gas through special semi-permeable membranes and other barriers is another way to recover and purify helium. In 1996, the United States discovered reserves of helium in such gas well complexes, about 147 billion standard cubic feet (4.2 billion SCM). At the rate of use at the time (72 million SCM per year in the US), there would be enough helium to last for about 58 years in the US, and less than that (perhaps 80% of the time) in the world, but factors affecting the economy and processing, affect effective reserve indicators. Helium must be extracted from natural gas because it is only a fraction of the fraction of neon in the air, but the demand for it is much greater. It is estimated that if all neon products were converted to store helium, 0.1% of the world's helium demand would be met. Likewise, only 1% of the world's helium needs can be met by reinstalling all air distillation plants. Helium can be synthesized by bombarding lithium or boron with high-speed protons or by bombarding lithium with deuterons, but these processes are completely uneconomical. Helium is commercially available in either liquid or gaseous form. As a liquid, it can be supplied in small insulated containers called dewars, which hold up to 1,000 liters of helium, or in large ISO containers, which have a nominal capacity of up to 42 m3 (about 11,000 US gallons). In gaseous form, small quantities of helium are sold in high-pressure cylinders holding up to 8 m3 (about 282 standard cubic feet) of helium, while large quantities of high-pressure gas are supplied in tubular trailers that have a capacity of 4,860 m3 (about 172,000 standard cubic feet) of helium. cubic feet).

Helium safety protection

According to helium conservation advocates, such as Nobel Prize-winning physicist Robert Coleman Richardson, writing in 2010, the free market price of helium has contributed to its "wasteful" use (such as for helium balloons). In the 2000s, prices were lowered by a decision by the US Congress to sell large reserves of helium in the country by 2015. The price would have to be multiplied by 20 to eliminate excessive helium depletion, Richardson said. In their book The Future of Helium as a Natural Resource (Routledge, 2012), Nuttall, Clarke & Glowacki (2012) also proposed the creation of an International Helium Agency (IHA) to create a sustainable market for this precious commodity.

Areas of use

While balloons are perhaps the best known way to use helium, they make up a small portion of all helium use. Helium is used for many purposes that require some of its unique properties, such as low boiling point, low density, low solubility, high thermal conductivity, or inertness. Of the 2014 total world helium production, about 32 million kg (180 million standard cubic meters) of helium per year, the largest use (about 32% of the 2014 total) is in cryogenic applications, most of which involve cooling superconducting magnets in medical MRI scanners and NMR spectrometers. Other major applications were pressurization and purge systems, welding, controlled atmosphere maintenance and leak detection. Other uses by category accounted for relatively small fractions.

Controlled Atmospheres

Helium is used as a shielding gas in the growing of silicon and germanium crystals, in the production of titanium and zirconium, and in gas chromatography because it is inert. Due to its inertness, thermal and calorically perfect nature, high speed of sound and high heat capacity ratio, it is also useful in supersonic wind tunnels and impulse plants.

Gas tungsten arc welding

Helium is used as a shielding gas in arc welding processes on materials that are contaminated and weakened by air or nitrogen at welding temperatures. Gas tungsten arc welding uses a range of inert shielding gases, but uses helium instead of cheap argon, especially for higher thermal conductivity welding materials such as aluminum or copper.

Less common uses

Industrial Leak Detection

One industrial use of helium is leak detection. Because helium diffuses through solids three times faster than air, it is used as a tracer gas to detect leaks in high-vacuum equipment (such as cryogenic tanks) and high-pressure containers. The test substance is placed in a chamber, which is then evacuated and filled with helium. Helium that passes through a leak is detected by a sensitive device (helium mass spectrometer) even at leak rates of 10-9 mbar l/s (10-10 Pa m3/s). The measurement procedure is usually performed automatically and is called the integral helium test. The simple procedure is to fill the test object with helium and search for leaks manually using a hand-held device. Helium leakage through cracks should not be confused with gas penetration through bulk material. While helium has documented permeation constants (thus estimated permeation rates) through glasses, ceramics, and synthetic materials, noble gases such as helium will not penetrate most large metals.

Flying

Because helium is lighter than air, airships and balloons are pumped with this gas to lift them into the air. While hydrogen gas is more able to adhere to a surface and penetrates the membrane at a slower rate, helium has the advantage of being non-flammable and truly fire retardant. Another minor use of helium is in rockets, where helium is used as a cushion of air to replace fuel and oxidizers in storage tanks and to condense hydrogen and oxygen to produce rocket fuel. It is also used to purify fuel and oxidizer from ground support equipment prior to launch and to pre-cool liquid hydrogen on spacecraft. For example, the Saturn V rocket used in the Apollo program required about 370,000 m3 (13 million cubic feet) of helium to launch.

Minor commercial and recreational uses

Helium as a breathing gas does not have any narcotic properties, so helium mixtures such as Trimix, Heliox and Heliair are used for deep diving to reduce the effects of anesthesia, which worsen with increasing depth. As pressure increases at depth, the density of the breathing gas also increases, and the low molecular weight of helium significantly reduces the breathing effort, reducing the density of the mixture. This reduces the number of Reynolds flows, which results in less turbulent flow and more laminar flow, which requires less work to breathe. At depths below 150 meters (490 feet), divers inhaling helium-oxygen mixtures begin to experience tremors and decreased psychomotor function, a nervous syndrome caused by high blood pressure. To some extent, this effect may be facilitated by the addition of some narcotic gases, such as hydrogen or nitrogen, to the helium-oxygen mixture. Helium-neon lasers, a type of low-power gas laser that produces a red beam, had a variety of practical applications, including bar code readers and laser pointers, before they were almost universally replaced by cheaper diode lasers. Because of its inertness and high thermal conductivity, neutron transparency, and lack of formation of radioactive isotopes under reactor conditions, helium is used as a coolant in some gas-cooled nuclear reactors. Helium mixed with a heavier gas such as xenon is useful for thermoacoustic cooling due to the resulting high heat capacity coefficient and low Prandtl number. Helium's inertia has environmental advantages over traditional refrigeration systems, which contribute to ozone depletion or global warming. Helium is also used in some hard drives.

Scientific Applications

The use of helium reduces the distorting effects of temperature changes in the space between lenses in some telescopes due to its extremely low refractive index. This method is especially used in solar telescopes, where the vacuum insulated telescope tube would be too heavy. Helium is a widely used carrier gas for gas chromatography. The age of rocks and minerals containing uranium and thorium can be estimated by measuring helium levels in a process known as helium dating. Helium at low temperatures is used in cryogenics and some cryogenics applications. As examples of such applications, liquid helium is used to cool some metals to the extremely low temperatures required for superconductivity, such as in superconducting magnets for magnetic resonance imaging. The Large Hadron Collider at CERN uses 96 metric tons of liquid helium to maintain a temperature of 1.9 kelvin.

Inhalation and safety

Effects

Neutral helium is non-toxic under standard conditions, does not play any biological role, and is found in trace amounts in human blood. The speed of sound in helium is almost three times the speed of sound in air. Because the fundamental frequency of a gas-filled cavity is proportional to the speed of sound in the gas, when helium is inhaled, there is a corresponding increase in the resonant frequencies of the vocal tract. The fundamental frequency (sometimes called tone) does not change, as this occurs through direct vibration of the vocal folds, which does not change. However, higher resonant frequencies cause a change in timbre, resulting in a thin, duck-like sound. The opposite effect, lowering resonant frequencies, can be obtained by inhaling a dense gas such as sulfur hexafluoride or xenon.

Dangers

Inhaling excess amounts of helium can be dangerous because helium is a simple asphyxiant that displaces the oxygen needed for normal breathing. Deaths have been reported, including a young man who suffocated in Vancouver in 2003 and two adults who suffocated in South Florida in 2006. In 1998, an Australian girl (her age unknown) from Victoria fell unconscious and temporarily turned blue after inhaling the entire contents of a helium tank. Inhaling helium directly from pressurized cylinders or even cylinder filling valves is extremely dangerous, as the high flow rates and pressures can cause barotrauma, fatal damage to lung tissue. Death caused by helium is rare. The first reported case was that of a 15-year-old Texas girl who died in 1998 from helium inhalation at a friend's party. In the United States, only two deaths were reported between 2000 and 2004, including a man who died in North Carolina from barotrauma in 2002. A young man suffocated in Vancouver in 2003, and a 27-year-old man in Australia had an embolism after inhaling gas from a cylinder in 2000. Since then, two adults suffocated in South Florida in 2006, several cases were reported in 2009 and 2010, one involving a California youth found with a bag over his head attached to a helium tank, and another involving a teenager in Northern Ireland. , died of suffocation. In Eagle Point, Oregon, a teenage girl died in 2012 from barotrauma at a party. A Michigan girl died of hypoxia later that year. On February 4, 2015, it was revealed that on January 28, during a taping of Japanese girl group 3B Junior's television show, a 12-year-old member of the group (whose name was kept secret) suffered an embolism, lost consciousness and fell into a coma as a result of air bubbles blocking blood flow in the brain. after inhaling huge amounts of helium. The incident was not made public until the following week. TV Asahi staff held an emergency press conference to report that the girl had been taken to the hospital and that she was showing signs of rehabilitation, such as eye and limb movements, but her consciousness had not yet been fully recovered. The police launched an investigation due to the neglect of security measures. Safety concerns for cryogenic helium are similar to those for liquid nitrogen; its extremely low temperatures can cause cold burns, and its liquid-to-gas expansion ratio can cause explosions unless pressure relief devices are installed. Containers of helium gas at 5-10 K should be treated as if they contained liquid helium due to the rapid and significant thermal expansion that occurs when helium gas at less than 10 K is warmed to room temperature. At high pressures (more than about 20 atm or two MPa), a mixture of helium and oxygen (heliox) can lead to high pressure nervous syndrome, a kind of reverse anesthetic effect; adding a small amount of nitrogen to the mixture may alleviate the problem.

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List of used literature:

Rayet, G. (1868) "Analyse spectral des protuberances observées, pendant l"éclipse totale de Soleil visible le 18 août 1868, à la presqu"île de Malacca" (Spectral analysis of the protuberances observed during the total solar eclipse, seen on 18 August 1868, from the Malacca peninsula), Comptes rendus…, 67: 757–759. From p. 758: "... je vis immédiatement une série de neuf lignes brillantes qui... me semblent devoir être assimilées aux lignes principales du spectre solaire, B, D, E, b, une ligne inconnue, F, et deux lignes du groupe G." (... I saw immediately a series of nine bright lines that... seemed to me should be classified as the principal lines of the solar spectrum, B, D, E, b, an unknown line, F, and two lines of the group G.

Helium is the second order element of the periodic system of chemical elements of D.I. Mendeleev, with atomic number 2. It is located in the main subgroup of the eighth group, the first period of the periodic system. Heads the group of noble gases in the periodic table. Denoted by the symbol He (lat. Helium). The simple substance helium (CAS number: 7440-59-7) is an inert monatomic gas without color, taste or smell. Helium is one of the most common elements in the Universe, second only to hydrogen. Helium is also the second lightest chemical element (after hydrogen). Helium is extracted from natural gas by a process of low-temperature separation - the so-called fractional distillation

On August 18, 1868, the French scientist Pierre Jansen, while during a total solar eclipse in the Indian city of Guntur, first examined the chromosphere of the Sun. Jansen managed to configure the spectroscope in such a way that the spectrum of the solar corona could be observed not only during an eclipse, but also on ordinary days. The very next day, spectroscopy of solar prominences, along with the hydrogen lines - blue, green-blue and red - revealed a very bright yellow line, initially taken by Jansen and other astronomers who observed it to be the sodium D line. Jansen immediately wrote about this to the French Academy of Sciences. It was subsequently found that the bright yellow line in the solar spectrum does not coincide with the sodium line and does not belong to any of the previously known chemical elements.

Two months later, on October 20, English astronomer Norman Lockyer, not knowing about the developments of his French colleague, also conducted research on the solar spectrum. Having discovered an unknown yellow line with a wavelength of 588 nm (more precisely 587.56 nm), he designated it D3, since it was very close to the Fraunhofer lines D 1 (589.59 nm) and D 2 (588.99 nm) sodium Two years later, Lockyer, together with the English chemist Edward Frankland, with whom he worked, proposed giving the new element the name “helium” (from the ancient Greek ἥλιος - “sun”).

It is interesting that the letters from Jansen and Lockyer arrived at the French Academy of Sciences on the same day - October 24, 1868, but Lockyer's letter, written four days earlier, arrived several hours earlier. The next day, both letters were read out at a meeting of the Academy. In honor of the new method of studying prominences, the French Academy decided to mint a medal. On one side of the medal there were portraits of Jansen and Lockyer over crossed laurel branches, and on the other there was an image of the mythical Sun god Apollo, driving a chariot with four horses galloping at full speed.

In 1881, the Italian Luigi Palmieri published a report on his discovery of helium in volcanic gases (fumaroles). He examined a light yellow oily substance that settled from gas jets on the edges of the crater of Vesuvius. Palmieri calcined this volcanic product in the flame of a Bunsen burner and observed the spectrum of gases released. Scientific circles greeted this message with disbelief, since Palmieri described his experience unclearly. Many years later, small amounts of helium and argon were actually found in fumaroles.

Only 27 years after its initial discovery, helium was discovered on Earth - in 1895, Scottish chemist William Ramsay, examining a sample of the gas obtained from the decomposition of the mineral kleveite, discovered in its spectrum the same bright yellow line found earlier in the solar spectrum. The sample was sent for additional research to the famous English spectroscopist William Crookes, who confirmed that the yellow line observed in the spectrum of the sample coincided with the D3 line of helium. On March 23, 1895, Ramsay sent a message about his discovery of helium on Earth to the Royal Society of London, as well as to the French Academy through the famous chemist Marcelin Berthelot.

In 1896, Heinrich Kaiser, Siegbert Friedländer, and two years later Edward Beley finally proved the presence of helium in the atmosphere.

Even before Ramsay, helium was also isolated by the American chemist Francis Hillebrand, but he mistakenly believed that he had obtained nitrogen and in a letter to Ramsay recognized his priority of discovery.
While examining various substances and minerals, Ramsay discovered that helium in them accompanies uranium and thorium. But it was only much later, in 1906, that Rutherford and Royds discovered that the alpha particles of radioactive elements were helium nuclei. These studies laid the foundation for the modern theory of atomic structure.

Only in 1908, the Dutch physicist Heike Kamerlingh Onnes managed to obtain liquid helium by throttling (see Joule-Thomson effect), after the gas was pre-cooled in liquid hydrogen boiling under vacuum. Attempts to obtain solid helium remained unsuccessful for a long time, even at a temperature of 0.71 K, which was achieved by Kamerlingh Onnes's student, the German physicist Willem Hendrik Keesom. Only in 1926, by applying pressure above 35 atm and cooling the compressed helium in liquid helium boiling under rarefaction, he managed to isolate the crystals.

In 1932, Keesom studied the nature of the change in the heat capacity of liquid helium with temperature. He found that around 2.19 K, a slow and gradual rise in heat capacity gives way to a sharp drop and the heat capacity curve takes the shape of the Greek letter λ (lambda). Hence, the temperature at which a jump in heat capacity occurs is given the conventional name “λ-point.” A more accurate temperature value at this point, established later, is 2.172 K. At the λ-point, deep and abrupt changes in the fundamental properties of liquid helium occur - one phase of liquid helium is replaced at this point by another, without releasing latent heat; a phase transition of the second order takes place. Above the temperature of the λ-point there is so-called helium-I, and below it - helium-II.

In 1938, Soviet physicist Pyotr Leonidovich Kapitsa discovered the phenomenon of superfluidity of liquid helium-II, which consists of a sharp decrease in the viscosity coefficient, as a result of which helium flows practically without friction. This is what he wrote in one of his reports about the discovery of this phenomenon.

origin of name

From Greek ἥλιος - “Sun” (see Helios). It is curious that the name of the element used the ending “-i”, characteristic of metals (in Latin “-um” - “Helium”), since Lockyer assumed that the element he discovered was a metal. By analogy with other noble gases, it would be logical to give it the name “Helion”. In modern science, the name “helion” is assigned to the nucleus of a light isotope of helium - helium-3.

Prevalence

In the Universe
Helium ranks second in abundance in the Universe after hydrogen - about 23% by mass. However, helium is rare on Earth. Almost all the helium in the Universe was formed in the first few minutes after the Big Bang, during primordial nucleosynthesis. In the modern Universe, almost all new helium is formed as a result of thermonuclear fusion from hydrogen in the interior of stars (see proton-proton cycle, carbon-nitrogen cycle). On Earth, it is formed as a result of the alpha decay of heavy elements (the alpha particles emitted during alpha decay are helium-4 nuclei). Part of the helium that appears during alpha decay and seeps through the rocks of the earth’s crust is captured by natural gas, the concentration of helium in which can reach 7% of the volume and higher.

Earth's crust
Within the eighth group, helium ranks second in content in the earth's crust (after argon). The helium content in the atmosphere (formed as a result of the decay of Ac, Th, U) is 5.27×10−4% by volume, 7.24×10−5% by mass. Helium reserves in the atmosphere, lithosphere and hydrosphere are estimated at 5×1014 m³. Helium-bearing natural gases usually contain up to 2% helium by volume. Extremely rare are accumulations of gases, the helium content of which reaches 8 - 16%. The average helium content in terrestrial matter is 3 g/t. The highest concentration of helium is observed in minerals containing uranium, thorium and samarium: kleveite, fergusonite, samarskite, gadolinite, monazite (monazite sands in India and Brazil), thorianite. The helium content in these minerals is 0.8 - 3.5 l/kg, and in thorianite it reaches 10.5 l/kg

Definition

Helium is determined qualitatively by analyzing emission spectra (characteristic lines 587.56 nm and 388.86 nm), quantitatively by mass spectrometric and chromatographic analysis methods, as well as by methods based on measuring physical properties (density, thermal conductivity, etc.

Chemical properties

Helium is the least chemically active element of the eighth group of the periodic table (inert gases). Many helium compounds exist only in the gas phase in the form of so-called excimer molecules, in which the excited electronic states are stable and the ground state is unstable. Helium forms diatomic molecules He 2 +, HeF fluoride, HeCl chloride (excimer molecules are formed by the action of an electric discharge or ultraviolet radiation on a mixture of helium with fluorine or chlorine). The chemical compound of helium LiHe is known (perhaps the compound LiHe 7 was meant

Receipt

In industry, helium is obtained from helium-containing natural gases (currently, mainly deposits containing > 0.1% helium are exploited). Helium is separated from other gases by deep cooling, taking advantage of the fact that it liquefies more difficult than all other gases. Cooling is carried out by throttling in several stages, purifying it from CO 2 and hydrocarbons. The result is a mixture of helium, neon and hydrogen. This mixture, the so-called. crude helium (He - 70-90% vol.) is purified from hydrogen (4-5%) using CuO at 650-800 K. Final purification is achieved by cooling the remaining mixture with N2 boiling under vacuum and adsorption of impurities on active carbon in adsorbers, also cooled with liquid N2. They produce helium of technical purity (99.80% helium by volume) and high purity (99.985%). In Russia, helium gas is obtained from natural and petroleum gases. Currently, helium is extracted at the helium plant of Gazprom Dobycha Orenburg LLC in Orenburg from gas with a low helium content (up to 0.055% vol.), so Russian helium has a high cost. An urgent problem is the development and comprehensive processing of natural gases from large deposits of Eastern Siberia with a high helium content (0.15-1% vol.), which will significantly reduce its cost. The USA leads in helium production (140 million m³ per year), followed by Algeria (16 million m³). Russia ranks third in the world - 6 million m³ per year. World helium reserves amount to 45.6 billion m³.