Number of Protons = Atomic Number of the Element. Number of Electrons = Number of Protons. Number of Neutrons = Mass Number - Atomic Number. Find the Number of Protons. Each element is defined by the number of protons found in each of its atoms. No matter how many electrons or neutrons an atom has, the element is defined by its number of protons.
The proton is, in effect, the index particle of any atom. It is the number of protons in an atom that determines the identity of the element an atom belongs to; in other words, if two atoms have a different number of protons, they are not the same element.
