The empirical formula of a compound represents the simplest whole-number ratio of the elements present in that compound. It gives the relative proportions of each element but does not provide information about the actual number of atoms or the molecular structure. For example, the empirical formula for benzene (C₆H₆) is CH, indicating a 1:1 ratio of carbon to hydrogen.
The molecular formula, on the other hand, provides the actual number of atoms of each element in a molecule of the compound. It can be the same as the empirical formula or a multiple of it. Using the same example, the molecular formula of benzene is C₆H₆, which tells us there are six carbon atoms and six hydrogen atoms in each benzene molecule.
In summary, the empirical formula shows the ratio of elements, while the molecular formula shows the actual number of atoms in a molecule.