Helium

Helium (from Greek: ἥλιος, Roman: helios, lit. 'Sun') is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monoatomic gas. In the group of noble gases in the periodic table [a] and its boiling and melting point is the lowest among all elements. It is the second lightest and second most abundant element in the observable universe (hydrogen being the lightest and most abundant element). It is present in about 24% of the total mass of the element, which is more than 12 times the mass of the heavier elements. Its abundance is similar in both the Sun and Jupiter, due to the very high nuclear binding energy (per nucleon) of helium-4, higher than the next three elements after helium. The binding energy of helium-4 is also the reason why it is a product of nuclear fusion and radioactive decay. Most of the helium in the universe is helium-4, the vast majority of which was formed during the big bang. Large amounts of new helium are created from the nuclear fusion of hydrogen in stars.

Scientific discoveries the first evidence of helium was observed on August 18, 1868 as a bright yellow line with a wavelength of 587.49 nm in the spectrum of the Sun's chromosphere. French astronomer Jules Jansen spotted this line during a total solar eclipse in Guntur, India. This line was initially assumed sodium. On October 20 of the same year, English astronomer Norman Lockyer observed a yellow line in the solar spectrum, which he named D3 because it was close to Fraunhofer's known sodium lines D1 and D2. He concluded that it was caused by an element in the sun unknown on Earth. Lockyer and English chemist Edward Frankland named this element after the Greek word for sun, ἥλιος (helios).

History

In 1907, Ernest Rutherford and Thomas Royds showed that alpha particles were helium nuclei by allowing particles to penetrate the thin, glass wall of an evacuated tube and then creating a discharge in the tube to study the spectrum of the new gas inside the tube. In 1908, helium was first liquefied by the Dutch physicist Heike Kamerling Ons by cooling the gas to a temperature below 5 K (−268.15 °C; −450.67 °F). He tried to solidify it by lowering the temperature further, but failed because helium does not solidify at atmospheric pressure. Ounce's student Willem Hendrik Kissom was finally able to solidify 1 cubic centimeter of helium in 1926 by applying additional external pressure. In 1913, Niels Bohr published his "Trilogy" on atomic structure, which included a revision of the Pickering–Fowler series as the main evidence in support of his model of the atom. The collection is named after Edward Charles Pickering, who in 1896 published observations of previously unknown lines in the spectrum of the star ζ Puppis. Half-correct ratio transmission levels. In 1912, Alfred Fowler succeeded in producing similar lines from a mixture of hydrogen and helium, supporting Pickering's conclusion about their origin. Bohr's model did not allow for half-correct transitions (and neither did quantum mechanics), and Bohr concluded that Pickering and Fowler were mistaken and instead attributed these spectral lines to ionized helium He+. Fowler was initially skeptical but eventually became convinced that Bohr was right, and by 1915, "the spectrographers had moved the [Pickering–Fowler] series definitively [from hydrogen] to helium. Bohr's theoretical work in the Pickering series had shown the need to "re-examine problems which seemed to be already solved in classical theories" and provided important confirmation of his atomic theory. In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that helium-4 has almost no viscosity at temperatures near absolute zero, a phenomenon now called superfluidity. This phenomenon is related to the Bose-Einstein density. In 1972, American physicists Douglas D. Oshroff, David M. Lee and Robert C. Richardson observed the same phenomenon in helium-3, but at a temperature very close to absolute zero. The helium-3 phenomenon is thought to be related to the pairing of helium-3 fermions to make bosons, in contrast to the Cooper electron pairs that produce superconductivity.

Extraction and application

After an oil drilling operation in 1903 in Dexter, Kansas produced a gas geyser that did not burn, Kansas State Geologist Erasmus Haworth collected samples of the fugitive gas and took it to the University of Kansas in Lawrence, where, with the help of chemist Hamilton Cady, and David McFarland, who discovered that the gas consisted by volume of 72% nitrogen, 15% methane (a percentage combustible only with sufficient oxygen), 1% hydrogen, and 12% an unidentified gas.

Upon further analysis, Cady and McFarland discovered that 1.84% of the sample was helium gas. This showed that despite its overall rarity on Earth, helium was concentrated in large quantities beneath the American Great Plains and was available for extraction as a byproduct of natural gas. This enabled the United States to become the world's leading supplier of helium. Following Sir Richard Threlfall's suggestion, the US Navy sponsored three small helium experimental plants during World War I. The goal was to supply the barrage balloons with a non-flammable, lighter-than-air gas. A total of 5,700 cubic meters (200,000 cubic feet) of 92% helium was produced in the program, even though less than one cubic meter of the gas had already been recovered.

Some of this gas was used in the world's first helium-filled airship, the US Navy C-7, which made its maiden voyage from Hampton Roads, Virginia, to a bowling alley in Washington, D.C., on December 1, 1921.

Almost two years before the Navy's first helium-filled rigid airship, the Naval Aircraft Factory-built USS Shenandoah, flew in September 1923. Although the extraction process using low-temperature gas liquefaction was not developed in time to be significant during World War I, production continued. Helium was primarily used as a lift gas in lighter-than-air ships. During World War II, the demand for helium increased for lifting gas and for shielded arc welding.

The helium mass spectrometer was also vital in the Manhattan Atomic Bomb Project. The US government established the National Helium Reserve in Amarillo, Texas in 1925 to supply military airships in wartime and commercial airships in peacetime. Due to the Helium Act of 1925, which prohibited the export of rare helium, which the United States had a monopoly on at the time, along with the exorbitant cost of the gas, the Hindenburg, like all German zeppelins, had to use hydrogen gas as fuel. Use a lift. The helium market stagnated after World War II, but its stockpile expanded in the 1950s to ensure the supply of liquid helium as a coolant for creating oxygen/hydrogen rocket fuel (among other things) during the space race and the Cold War. To be Helium use in the United States in 1965 was more than eight times its wartime peak.

Following the "Helium Act Amendments of 1960" (Public Law 777-86), the US Bureau of Mines arranged for five private plants to recover helium from natural gas. For this helium conservation program, the administration built a 425-mile (684 km) pipeline from Boston, Kansas, to connect the plants with the state's partially depleted Cliffside gas field near Amarillo, Texas. This helium-nitrogen mixture was injected and stored at the Cliffside gas field until needed, at which time it was further purified.

Specification

helium atom

Helium in quantum mechanics

From the point of view of quantum mechanics, helium is the second simplest atom to model after the hydrogen atom. The model 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 by a rigorous analytical mathematical approach, and helium is no exception. Therefore, numerical mathematical methods are needed even to solve the system of one nucleus and two electrons.

The stability associated with the helium-4 nucleus and the electron shell of the nucleus of the helium-4 atom is the same as that of the alpha particle. High-energy electron scattering experiments show that its charge decreases exponentially from a maximum at a central point, much like the charge density of the electron cloud of helium itself. This symmetry reflects the same underlying physics: the neutron pair and the proton pair in the helium nucleus obey the same quantum mechanical laws as the electron pairs in helium (although the nuclear particles are subject to different nuclear binding potentials), so that all obey quantum mechanical laws. They follow Fermions completely occupy 1s orbitals in pairs, neither has orbital angular momentum, and each cancels the other's intrinsic spin. Adding another one of these particles requires momentum that is more angular and releases much less energy, (no nucleus with five nucleons is actually stable). Thus, this arrangement is energetically very stable for all of these particles, and this stability reveals many vital facts about helium in nature.

Gas and plasma phases

Helium is the second least reactive noble gas after neon, and thus the second least reactive gas of all the elements. It is chemically inert and monoatomic under all standard conditions. Due to helium's relatively low molar (atomic) mass, its thermal conductivity, specific heat, and speed of sound in the gas phase are all greater than any other gas except hydrogen. For these reasons and the small size of helium monoatomic molecules, helium diffuses in solids at three times the rate of air and about 65% of hydrogen.

Liquid helium

Liquefied helium is not only liquid, but also supercooled. The drop of liquid at the bottom of the glass indicates the spontaneous release of helium from the container at the side to drain from the container. The energy to drive this process is provided by the potential energy of the falling helium.

Liquid Helium Unlike any other element, helium remains liquid at normal pressures down to absolute zero. This is a direct effect of quantum mechanics: in particular, the zero-point energy of the system is too high to allow freezing. 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).

Distinguishing solid helium from liquid is often difficult because the refractive index of the two phases is almost identical. The solid has a sharp melting point and crystalline structure, but is highly compressible. Applying pressure in the laboratory can reduce its volume by more than 30%. With a bulk modulus of about 27 MPa, it 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 zero K and 25 bar (2.5 MPa) is 0.009±0.187 g/cm3. At higher temperatures, helium solidifies under sufficient pressure. At room temperature, this requires about 114,000 atmospheres.

Occurrence and production

Natural Abundance although helium is rare on Earth, helium is the second most abundant element known in the universe, accounting for 23% of its baryonic mass. Only hydrogen is more abundant. The vast majority of helium was formed by the Big Bang one to three minutes after the Big Bang. In this way, measuring its abundance helps cosmological models. In stars, it is formed by nuclear fusion of hydrogen in proton-proton chain reactions and the CNO cycle, part of the synthesis of stellar nuclei.

In the Earth's atmosphere, the concentration of helium by volume is only 2.5 parts per million. Despite the constant production of new helium, the concentration is low and relatively constant because most of the helium in the Earth's atmosphere escapes into space through several processes. In the Earth's heterosphere, part of the upper atmosphere, helium and other lighter gases are the most abundant elements.

Modern extraction and distribution

For large-scale use, helium is extracted by fractional distillation of natural gas, which can contain up to 7% helium. Because helium has a lower boiling point than any other element, low temperatures and high pressures are used to liquefy almost all other gases (mostly nitrogen and methane). The resulting raw helium gas is purified by successive exposure to lower temperatures, where almost all-residual nitrogen and other gases are precipitated from the gas mixture. Activated charcoal is used as the final purification step, typically yielding 99.995% pure grade a helium. The main impurity in grade a helium is neon. In the final stage of production, most of the helium produced is converted to liquid through a cryogenic process. This is essential for applications that require liquid helium and allows helium suppliers to reduce the cost of long-distance shipping, as the largest liquid helium containers have more than five times the capacity of the largest helium tube gas trailers.

In 2008, approximately 169 million standard cubic meters (SCM) 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 (under RasGas, managed by Air Liquide). It increased Qatar's helium production sector to 25%, making it the second largest exporter after the United States. About 54 billion cubic feet (1.5 x 109 cubic meters) of helium reserves were found in Tanzania in 2016. A large-scale helium plant opened in Ningxia, China in 2020.

Scientific applications

The use of helium reduces its effects due to temperature changes in the space between the lenses in some telescopes due to its very low refractive index. This method is especially used in solar telescopes where the vacuum telescope tube is very heavy.

Medical expenses

Helium was approved for medical use in the United States in April 2020 for humans and animals.

 As a pollutant, while helium contamination is chemically inert, it disrupts the performance of micro-electromechanical systems (MEMS), causing iPhones to malfunction.

Effects

Neutral helium is non-toxic under standard conditions, does not play a biological role and is found in small amounts in human blood.

The effect of helium on the human voice

The speed of sound in helium is about three times the speed of sound in air. Since the natural resonant 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, which amplifies the vocal sound. This increase in the resonant frequency of the amplifier (sound device) compared to the case where the sound box is filled with air, gives more amplification to the high frequency components of the sound wave produced by the direct vibration of the vocal cords. When a person speaks after inhaling helium gas, the muscles that control the voice box continue to move as they did when the voice box is filled with air, so the direct vibration of the vocal cords produces the fundamental frequency (sometimes called the pitch). It is created, it does not change. However, preferential high-frequency amplification causes a change in the amplified sound, resulting in a duck-like vocal quality. The opposite effect, lowering the resonant frequencies, can be achieved by inhaling a dense gas such as sulfur hexafluoride or xenon.

Helium production methods

Membrane separation

The helium content of a gas can be concentrated or purified using high-pressure membranes that selectively diffuse relatively smaller gas molecules through microscopic pores in the medium.

PSA or TSA

Pressure swing absorption (PSA) or temperature swing absorption (TSA). These technologies use temperature or pressure to induce selective adsorption of gas molecules of different sizes into a large surface area composed of uniformly sized pore spaces. These technologies are time-tested, reliable and can be applied on a small scale. The downside is that this process is less efficient than cryogenic separation in terms of energy consumption and product losses during the process.

Cryogenic isolation

Similar to Air Separation Units (ASUs) deployed worldwide in the industrial gas business, this technology uses low temperatures to condense various gases into liquids in a fractionation tower. This process is ideally suited for helium, which has the lowest condensation point of any gas, but requires large scale for efficiency and has a higher initial capital cost.

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