= Statistical weight of an atomic level
{title2=$g_J=2J+1$}
= Statistical weights of atomic levels
{synonym}
The statistical weight of an atomic level counts its degenerate quantum states. With no external field resolving magnetic substates, a specified total angular momentum $J$ gives $2J+1$ states. An unresolved term can have a larger summed weight. These weights enter the <Boltzmann distribution>, <Saha ionization equation> and detailed-balance relations; term and resolved-level weights must not be interchanged.
Back to article page
