Answer:The major difference between atomic number and mass number is that the atomic number states the number of protons present in an atom whereas, the mass number indicates the total of the number of protons and the number neutrons present in an atom.i) Atomic number is the total number of protons present in the nucleus of an atom. It is also equal to the number of electrons for a neutral atom. Example, atomic number of sodium is 11. ii) Mass number is the number of protons and neutrons in the nucleus taken together. For example, mass number of sodium is 23 g/mol.
