Helium

Helium is a <a href="/facts/Chemical_element/0jducgWD">chemical element</a>; it has <a href="/facts/Chemical_symbol/2Fe1VAL0">symbol</a> He and <a href="/facts/Atomic_number/bgAr581S">atomic number</a> 2. It is a colorless, odorless, non-toxic, <a href="/facts/Inert_gas/3EkBEoYh">inert</a>, <a href="/facts/Monatomic/1cTX2U2g">monatomic</a> <a href="/facts/Gas/hVVAoodV">gas</a> and the first in the <a href="/facts/Noble_gas/j0yHMEAE">noble gas</a> group in the <a href="/facts/Periodic_table/umdGIfUb">periodic table</a>. Its <a href="/facts/Boiling_point/E2BK9QoS">boiling point</a> is the lowest among all the <a href="/facts/Chemical_element/0jducgWD">elements</a>, and it does not have a <a href="/facts/Melting_point/MY0w0h0k">melting point</a> at standard pressures. It is the second-lightest and second most <a href="/facts/Abundance_of_the_chemical_elements/CE9WehBl">abundant element</a> in the observable <a href="/facts/Universe/XbfpnDmM">universe</a>, after <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a>. It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the <a href="/facts/Sun/CadPCVHh">Sun</a> and <a href="/facts/Jupiter/95m7XjMT">Jupiter</a>, because of the very high <a href="/facts/Nuclear_binding_energy/PU8bREHW">nuclear binding energy</a> (per <a href="/facts/Nucleon/6fguU9Xk">nucleon</a>) of <a href="/facts/Helium-4/vNsL5qhC">helium-4</a> with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both <a href="/facts/Nuclear_fusion/hP0gLDqj">nuclear fusion</a> and <a href="/facts/Radioactive_decay/Ya6FVjt4">radioactive decay</a>. The most common isotope of helium in the universe is helium-4, the vast majority of which was formed during the <a href="/facts/Big_Bang/I5T1vTnv">Big Bang</a>. Large amounts of new helium are created by nuclear fusion of hydrogen in <a href="/facts/Stars/PFbd6ICx">stars</a>.
Helium was first detected as an unknown, yellow <a href="/facts/Spectral_line/HuI4Bj5f">spectral line</a> signature in sunlight during a <a href="/facts/Solar_eclipse_of_August_18,_1868/W3tzor0z">solar eclipse in 1868</a> by <a href="/facts/Georges_Rayet/gp8Lzbf0">Georges Rayet</a>, Captain C. T. Haig, <a href="/facts/N._R._Pogson/R7B0yo3C">Norman R. Pogson</a>, and Lieutenant John Herschel, and was subsequently confirmed by French astronomer <a href="/facts/Pierre_Janssen/nqYWwsIa">Jules Janssen</a>. Janssen is often jointly credited with detecting the element, along with <a href="/facts/Norman_Lockyer/Uh3no29f">Norman Lockyer</a>. Janssen recorded the helium spectral line during the solar eclipse of 1868, while Lockyer observed it from Britain. However, only Lockyer proposed that the line was due to a new element, which he named after the Sun. The formal <a href="/facts/Discovery_of_the_chemical_elements/QY4X2RP3">discovery of the element</a> was made in <a href="/facts/1895/q4F6bTdq">1895</a> by chemists <a href="/facts/Sir_William_Ramsay/fGzWlHlP">Sir William Ramsay</a>, <a href="/facts/Per_Teodor_Cleve/0KGIUxKW">Per Teodor Cleve</a>, and <a href="/facts/Nils_Abraham_Langlet/4kw7Hkfl">Nils Abraham Langlet</a>, who found helium emanating from the <a href="/facts/Uranium/n2sGWBzU">uranium</a> ore <a href="/facts/Cleveite/HVbWXInY">cleveite</a>, which is now not regarded as a separate mineral species, but as a variety of <a href="/facts/Uraninite/EsEwMErJ">uraninite</a>. In 1903, large reserves of helium were found in <a href="/facts/Natural_gas_field/wYoSQmGN">natural gas fields</a> in parts of the United States, by far the largest supplier of the gas today.
Liquid helium is used in <a href="/facts/Helium_cryogenics/ceqWI6mn">cryogenics</a> (its largest single use, consuming about a quarter of production), and in the <a href="/facts/Cryocooler/7cs7ygf2">cooling</a> of <a href="/facts/Superconducting_magnet/bRWH01s5">superconducting magnets</a>, with its main commercial application in <a href="/facts/MRI/Vh9yG9qq">MRI</a> scanners. Helium's other industrial uses—as a pressurizing and purge gas, as a protective atmosphere for <a href="/facts/Arc_welding/SFDgoY2g">arc welding</a>, and in processes such as growing <a href="/facts/Crystal/e2R2mk3E">crystals</a> to make <a href="/facts/Silicon_wafer/lCBJAoUL">silicon wafers</a>—account for half of the gas produced. A small but well-known use is as a <a href="/facts/Lifting_gas/yfMS1zJw">lifting gas</a> in <a href="/facts/Balloon/o9JQ2ykA">balloons</a> and <a href="/facts/Airship/8X3TSBdx">airships</a>. As with any gas whose density differs from that of air, inhaling a small volume of helium temporarily changes the timbre and quality of the <a href="/facts/Human_voice/RPzaPWwh">human voice</a>. In scientific research, the behavior of the two fluid phases of helium-4 (helium I and helium II) is important to researchers studying <a href="/facts/Quantum_mechanics/BRc3Mzgr">quantum mechanics</a> (in particular the property of <a href="/facts/Superfluidity/QuePDujN">superfluidity</a>) and to those looking at the phenomena, such as <a href="/facts/Superconductivity/pqQAlSzJ">superconductivity</a>, produced in <a href="/facts/Matter/osyc04UN">matter</a> near <a href="/facts/Absolute_zero/U3UyPl2K">absolute zero</a>.
On Earth, it is relatively rare—5.2 <a href="/facts/Parts_per_million/PozRuoLM">ppm</a> by volume in the <a href="/facts/Atmosphere/oUpLaGRF">atmosphere</a>. Most terrestrial helium present today is created by the natural <a href="/facts/Radioactive_decay/Ya6FVjt4">radioactive decay</a> of heavy radioactive elements (<a href="/facts/Thorium/ysdWH470">thorium</a> and uranium, although there are other examples), as the <a href="/facts/Alpha_particle/dzNMs9WP">alpha particles</a> emitted by such decays consist of helium-4 <a href="/facts/Atomic_nucleus/orpIm5Xl">nuclei</a>. This <a href="/facts/Radiogenic/KXP6MKk6">radiogenic</a> helium is trapped with <a href="/facts/Natural_gas/9MYQ7NAP">natural gas</a> in concentrations as great as 7% by volume, from which it is extracted commercially by a low-temperature separation process called <a href="/facts/Fractional_distillation/DdNf0k8I">fractional distillation</a>. Terrestrial helium is a non-renewable resource because once released into the atmosphere, it promptly <a href="/facts/Atmospheric_escape/lgjeWLCg">escapes into space</a>. Its supply is thought to be rapidly diminishing. However, some studies suggest that helium produced deep in the Earth by radioactive decay can collect in natural gas reserves in larger-than-expected quantities, in some cases having been released by volcanic activity.

Helium open-in-new

Helium