what is atomic number radiology
Nucleons are either protons or neutrons and the total number of nucleons is given the symbol A (also known as the mass number). The total number of protons within the nucleus is called the atomic number and given the symbol Z.Protons and neutrons have a mass of 1, protons are positively charged and neutrons have no charge. 1  A (mass number): total number of nucleons = protons + neutrons.2  Z (atomic number): number of protons. great many different configurations of the nucleus may occur. In each case, the atomic number defines the element, i.e. it is the number of protons that determines that carbon (having 6 protons) is carbon.