Helium: properties, characteristics, applications

2024 Author: Angel Austin | [email protected]. Last modified: 2024-01-02 17:39

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

Discovery history

Helium was discovered in the gaseous atmosphere surrounding the Sun by the French astronomer Pierre Jansen, who in 1868 during an eclipse discovered a bright yellow line in the spectrum of the solar chromosphere. This line was originally thought to represent the element sodium. In the same year, the English astronomer Joseph Norman Lockyer observed a yellow line in the solar spectrum that did not correspond to the known sodium lines D₁ and D₂, and so he named her line D_{3. Lockyer concluded that it was caused by a substance in the Sun unknown on Earth. He and the chemist Edward Frankland used in the name of the elementthe Greek name for the Sun is Helios.}

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

Spread in nature

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

Isotopes

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

Physical properties of helium

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

The thermal conductivity of helium is second only to that of hydrogen, and its specific heat capacity is unusually high. At ordinary temperatures, it heats up during expansion, and cools down below 40 K. Therefore, at T<40 K, helium can be converted intoliquid by expansion.

An element is a dielectric if it is not in an ionized state. Like other noble gases, helium has metastable energy levels that allow it to remain ionized in an electrical discharge when the voltage remains below the ionization potential.

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

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

A liquid mixture of two isotopes of helium-3 and -4 at temperatures below 0.8 K (-272.4 °C) is divided into two layers - almost pure ³He and a mixture of⁴He with 6% helium-3. The dissolution of ³He into ^{4He is accompanied by a cooling effect, which is used in the design of cryostats, in which the helium temperature dropsbelow 0.01 K (-273.14 °C) and maintained there for several days.}

Connections

Under normal conditions, helium is chemically inert. In extreme conditions, you can create element connections that are not stable at normal temperatures and pressures. For example, helium can form compounds with iodine, tungsten, fluorine, phosphorus, and sulfur when subjected to an electrical glow discharge when bombarded with electrons or in the plasma state. Thus, HeNe, HgHe₁₀, WHe₂ and He₂ molecular ions were created +^{, Not}2++^{, HeH}+ ^{and HeD +}. This technique also made it possible to obtain neutral molecules He² and HgHe.

Plasma

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

US discovery

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

Industrial production

This has made the United States the world leader in helium production. At the suggestion of Sir Richard Threlfall, the US Navy funded three small experimental plants to produce the substance during World War I to provide barrage balloons with a light, non-flammable lifting gas. The program produced a total of 5,700 m3 92% He, although less than 100 liters of gas had previously been produced. Part of this volume was used in the world's first helium airship, the US Navy C-7, which made its first flight from Hampton Roads, Virginia to Bolling Field, Washington, DC on December 7, 1921.

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

US National Stock

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

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

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

Purity and production volumes

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

For many years, the United States produced over 90% of the world's commercial helium. Since 2004, it has produced 140 million m3 annually, 85% of which comes from the United States, 10% from Algeria, and the rest from Russia and Poland. The main sources of helium in the world are the gas fields of Texas, Oklahoma and Kansas.

Receive process

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

Application areas

Noble gas has been used in various fields.

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