A helium atom is an atom of the chemical element helium. Helium is composed of two electrons bound by the electromagnetic force to a nucleus containing...

50 atm, solid helium-4 may be a superglass (an amorphous solid exhibiting superfluidity). The helium atom is the second simplest atom (hydrogen is the...

Helium atom scattering (HAS) is a surface analysis technique used in materials science. It provides information about the surface structure and lattice...

environment, the alpha particle becomes a normal (electrically neutral) helium atom 4 2He. Alpha particles have a net spin of zero. When produced in standard...

conditions. Helium's first ionization energy of 24.57 eV is the highest of any element. Helium has a complete shell of electrons, and in this form the atom does...

Antiprotonic helium is a three-body atom composed of an antiproton and an electron orbiting around a helium nucleus. It is thus made partly of matter,...

hydrogen-4.1 atom can react with other atoms. Its chemical behavior behaves more like a hydrogen atom than an inert helium atom. A hadronic atom is an atom in which...

There are nine known isotopes of helium of which two, helium-3 and helium-4, are stable. In the Earth's atmosphere, one atom is 3 He for every million that...

The scanning helium microscope (SHeM) is a form of microscopy that uses low-energy (5–100 meV) neutral helium atoms to image the surface of a sample without...

function), the quantities can be varied in principle just one at a time. The helium atom consists of two electrons with mass m and electric charge −e, around...

approximately 1.33×1050 atoms. Although small numbers of independent atoms of noble gases exist, such as argon, neon, and helium, 99% of the atmosphere...

1913 that the electrons in atoms are arranged in shells surrounding the nucleus, and that for all noble gases except helium the outermost shell always...

helium hydride ion, hydridohelium(1+) ion, or helonium is a cation (positively charged ion) with chemical formula HeH+. It consists of a helium atom bonded...

of helium atoms. This condensation occurs in liquid helium-4 at a far higher temperature (2.17 K) than it does in helium-3 (2.5 mK) because each atom of...

neutrons.) Helium-3 and hydrogen-1 are the only stable nuclides with more protons than neutrons. It was discovered in 1939. Helium-3 atoms are fermionic...

electron, can bond with other atoms, and behaves more like a hydrogen atom than an inert helium atom. Muonic heavy hydrogen atoms with a negative muon may...

The helium dimer is a van der Waals molecule with formula He2 consisting of two helium atoms. This chemical is the largest diatomic molecule—a molecule...

cooled with 120 tonnes of liquid helium. A helium-3 atom is a fermion and at very low temperatures, they form two-atom Cooper pairs which are bosonic and...

Helium (2He) (standard atomic weight: 4.002602(2)) has nine known isotopes, but only helium-3 (3He) and helium-4 (4He) are stable. All radioisotopes are...

the helium atom, and achieve unusual stability for the same reason. Nuclei with 5 nucleons are all extremely unstable and short-lived, yet, helium-3, with...

helium atoms can be excited. The excited helium atoms collide with neon atoms, exciting some of them to the state that radiates 632.8 nm. Without helium, the...

model Hamiltonians including the hydrogen atom and the hydrogen molecular ion. Beginning with the helium atom—which contains just two electrons—numerical...

gravitational three-body problem in classical mechanics is the helium atom, in which a helium nucleus and two electrons interact according to the inverse-square...

of three atoms is much more stable than the two-atom helium dimer. The three-atom combination of helium-4 atoms is an Efimov state. Helium-3 is predicted...

A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral hydrogen atom contains a single positively charged proton in the...

formed by bosonic atoms under similar conditions. Examples of fermionic condensates include superconductors and the superfluid phase of helium-3. The first...

phenomenon called ZPE (zero-point energy). Though the atoms in, for instance, a container of liquid helium that was precisely at absolute zero would still jostle...

four hydrogen atoms are heavier than one helium atom. Thus in 1920, Arthur Eddington correctly predicted fusion of hydrogen into helium could be the primary...

know exactly how many electrons a helium atom had (nor atoms of other elements for that matter), so a helium atom stripped of two electrons might still...

quarks) and some atoms (such as helium-3) are fermions, and are therefore described by the Pauli exclusion principle as well. Atoms can have different...