2020-03-16 Subclassed under pato:mass. [Allotrope] molecular mass 2020-03-16 Changed pref label. [Allotrope] molecular mass (molecular quality) Molecular mass is a molecular quality inhered in a molecular entity that expresses its mass relative to 1/12 of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. [Allotrope] atomic mass mass molecular quality