a mole is the amount of pure substance containing the same number of chemical units as there are atoms in exactly 12 grams of carbon 12 i e 6 023 x 10 23 this involves the acceptance of two dictates the scale of atomic masses and the magnitude of the gram mole is the amount of pure substance containing the same number of chemical units as there are atoms in exactly 12 grams of carbon 12 i e 6 023 x 10 23 this involves the acceptance of two dictates the scale of atomic masses and the magnitude of the gram