The total number of protons and neutrons in the nucleus of an atom. For example, nitrogen has 7 protons and 7 neutrons in its nucleus, giving it a mass number of 14. Isotopes of elements are distinguished by their mass number; for example, carbon-12 and carbon-14 have mass numbers of 12 and 14 respectively.
Find another word for atomic-mass. In this page you can discover 3 synonyms, antonyms, idiomatic expressions, and related words for atomic-mass, like: atomic-weight, mass-number and relative-atomic-mass.