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Helium is a commonly used carrier gas for gas chromatography. The age of rocks and minerals that contain uranium and thorium can be estimated by measuring the level of helium with a process known as helium dating. [28] [30] Helium at low temperatures is used in cryogenics and in certain cryogenic applications.
Helium is composed of two electrons bound by the electromagnetic force to a nucleus containing two protons along with two neutrons, depending on the isotope, held together by the strong force. Unlike for hydrogen , a closed-form solution to the Schrödinger equation for the helium atom has not been found.
Helium's first ionization energy of 24.57 eV is the highest of any element. [2] Helium has a complete shell of electrons, and in this form the atom does not readily accept any extra electrons nor join with anything to make covalent compounds. The electron affinity is 0.080 eV, which is very close to zero. [2]
Helium is inert - it does not react with other substances or combust - and its atomic number is 2, making it the second lightest element after hydrogen. Rockets need to achieve specific speeds and ...
The inertness of noble gases makes them useful whenever chemical reactions are unwanted. For example, argon is used as a shielding gas in welding and as a filler gas in incandescent light bulbs. Helium is used to provide buoyancy in blimps and balloons. Helium and neon are also used as refrigerants due to their low boiling points.
Helium-4 makes up about one quarter of the ordinary matter in the universe by mass, with almost all of the rest being hydrogen. While nuclear fusion in stars also produces helium-4, most of the helium-4 in the Sun and in the universe is thought to have been produced during the Big Bang, known as "primordial helium". However, primordial helium-4 ...
The U.S. is currently experiencing the fourth in a series of helium shortages since 2006, according to helium consultant Phil Kornbluth. “The world has experienced eight years of helium shortage ...
The most widely studied heavy helium isotope is 8 He. 8 He and 6 He are thought to consist of a normal 4 He nucleus surrounded by a neutron "halo" (of two neutrons in 6 He and four neutrons in 8 He). Halo nuclei have become an area of intense research. Isotopes up to 10 He, with two protons and eight neutrons, have been confirmed.