A balanced equation representing a chemical reaction can be written using
(1) chemical formulas and mass numbers
(2) chemical formulas and coefficients
(3) first ionization energies and mass numbers
(4) first ionization energies and coefficients
The answer is (2) chemical formulas and coefficients. The balanced equation can represent the ratio of mol numbers of reactants and productions. So it is not the mass number counts but the mol number counts.
