Proton Number and Nucleon Number

Proton Number

1. The proton number (Z) represent the number of protons found in the nucleus of an atom.
2. Proton number = the number of protons
3. The proton number is also known as the atomic number.
4. In an atom of neutral charge, the number of electrons also equals the atomic number.
5. Hence, the proton number of an atom can also represent the number of electrons.

Nucleon Number

1. The nucleon number (A), also called atomic mass number or mass number, is the number of protons plus the number of neutrons in an atomic nucleus. (Nucleon number = Number of protons + Number of neutrons)
2. The nucleon number of an atom is about the same as the mass of the atom because the mass of an electron is very small and can be ignored.