Answer:
Protons
Explanation:
Atomic numbers are a count of the number of protons in an atom. Atoms can have varying numbers of electrons and neutrons, but the number of protons will always stay the same, otherwise, the atom would become a different element.
For example, oxygen has 8 protons, so its atomic number is 8. If oxygen gained a proton, it would become Fluorine. The number of protons is always equal to the atomic number.
