BACK TO mass number
mass number vs. atomic mass
- the integer nearest in value to the atomic weight of an atom and equal to the number of nucleons in the nucleus of the atom. Symbol: A
[ uh-tom-ik mas ]
- the mass of an isotope of an element measured in units formerly based on the mass of one hydrogen atom taken as a unit or on 1/16 (0.0625) the mass of one oxygen atom, but after 1961 based on 1/12 (0.0833) the mass of the carbon-12 atom.