Helion (chemistry)
{{short description|Helium-3 isotope nucleus}}
{{other uses|Helion (disambiguation)}}
A helion (symbol h) is the nucleus of a helium atom, a doubly positively charged cation. The term helion is a portmanteau of helium and ion, and in practice refers specifically to the nucleus of the helium-3 isotope, consisting of two protons and one neutron. The nucleus of the other (and far more common) stable isotope of helium, helium-4, consisting of two protons and two neutrons, is called an alpha particle or an alpha for short.
This particle is the daughter product in the beta-minus decay of tritium, an isotope of hydrogen:{{citation needed| date=November 2024}}
:
| border="0" | ||||||
| style="height:2em;"
|{{nuclide|link=no|Hydrogen|3}} | → | {{nuclide|link=yes|helium|3}} | + | {{SubatomicParticle|link=yes|Electron}} | + | {{SubatomicParticle|link=yes|Electron Antineutrino}} |
CODATA reports the mass of a helion particle as {{physconst|mh|symbol=yes}} = {{physconst|mh_Da|after=.}}
Helions are intermediate products in the proton–proton chain reaction in stellar fusion.
An antihelion is the antiparticle of a helion, consisting of two antiprotons and an antineutron.