The atomic number is exactly the same as the charge number of the nucleus, and it is the unique number that identifies a chemical element. When an atom is uncharged, or does not have a positive or negative charge, the atomic number is also the same as the number of electrons. The atomic number is sometimes confused with the atomic mass, which is the total number of protons and neutrons that can be found in the nucleus of the atom.
Every element on the periodic table has a specific set of chemical properties that can be distinguished due to the number of electrons present in the atom, or the atomic number. The atomic number is also referred to as the Z-number. The symbol Z comes from the German word Atomzahl, which also means atomic number.
The number of neutrons in an atom is referred to as the N-number, or the neutron number. Both the neutron number and the atomic number are expressed as whole numbers. When an atom has the same atomic number but a different neutron number, it is called an isotope.Learn more about Atoms & Molecules