Question

difference between atomic number and mass number

Answer 1

Atomic number of an element is the number of protons it has in the nucleus. The symbol for denoting the atomic number is Z. 

Atoms are mainly composed of protons, neutrons and electrons. Atomic mass is simply the mass of an atom. Most of the atoms in the periodic table have two or more isotopes

Answer 2

Mass number is the number of protons and neutrons in an atom, and it tells us about the mass of the atom in amu, or atomic mass units. Atomic mass is the average mass of all the isotopes of a certain type. It is a weighted average that takes into account the abundances of all of the different isotopes.