The mass of an atom comes from
the protons and neutrons that is found in the nucleus. The number of protons is
the atomic number of an element. To find the number of neutrons, subtract the
atomic number from the mass of an atom. For example, sodium’s atomic number is
11. This will tell us that sodium has 11 protons in it. The atomic mass of
sodium is 23. So subtract 23 form 11 gives us 12. Therefore, there are 12
neutrons in sodium.
