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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 ...
For large-scale use, helium is extracted by fractional distillation from natural gas, which can contain as much as 7% helium. [148] Since helium has a lower boiling point than any other element, low temperatures and high pressure are used to liquefy nearly all the other gases (mostly nitrogen and methane). The resulting crude helium gas is ...
Helium is the smallest and the lightest noble gas and one of the most unreactive elements, so it was commonly considered that helium compounds cannot exist at all, or at least under normal conditions. [1] Helium's first ionization energy of 24.57 eV is the highest of any element. [2]
Hydrogen and helium are the most commonly used lift gases. Although helium is twice as heavy as (diatomic) hydrogen, they are both significantly lighter than air. The lifting power in air of hydrogen and helium can be calculated using the theory of buoyancy as follows: Thus helium is almost twice as dense as hydrogen.
Though all heavier helium isotopes decay with a half-life of <1 second, particle accelerator collisions have been used, to create unusual nuclei of elements such as helium, lithium and nitrogen. The unusual nuclear structures of such isotopes may offer insights into the isolated properties of neutrons and physics beyond the Standard Model. [28 ...
Helium-3 (3 He [1] [2] see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and protium (ordinary hydrogen) are the only stable nuclides with more protons than neutrons. It was discovered in 1939.
Helium is a chemical element with symbol He and atomic number 2. Helium may also refer to: In science. Helium dating, a method of determining the age of rocks;
The helium atom. Depicted are the nucleus (pink) and the electron cloud distribution (black). The nucleus (upper right) in helium-4 is in reality spherically symmetric and closely resembles the electron cloud, although for more complicated nuclei this is not always the case. Helium-4 (4 He) is a stable isotope of the element helium.