What is the number of protons and neutrons in the nucleus of an atom?
Well, their sum is the atomic mass of the nuclide.
Nuclei are conceived to contain
The number of
Individual elements can have various numbers of neutrons, and this variability gives rise to the existence of isotopes; the same element that has different number of neutrons. For instance, most hydrogen nuclei contain the one nuclide, the proton, to give the protium isotope,
As the nucleus gets bigger, a greater range of isotopes becomes possible, and the atomic masses quoted on the Periodic Table are the weighted average of the individual isotopes.