All mass number synonyms
mass num·ber
M m noun mass number
- atomic mass — the mass of an isotope of an element in atomic mass units
- atomic number — the number of protons in the nucleus of an atom of an element
- atomic volume — the atomic weight (relative atomic mass) of an element divided by its density
- atomic weight — the weight of one atom of an element expressed in atomic mass units: it is the average weight of all the isotopes of the element