What distinguishes an empirical formula from a molecular formula?

The distinction between an empirical formula and a molecular formula is fundamental in chemistry. An empirical formula represents the simplest whole-number ratio of the elements in a compound. This means that it conveys the proportions of each type of atom in the compound without detailing the actual number of atoms present. For instance, the empirical formula for glucose, which is C6H12O6, would be CH2O, indicating that for every carbon atom, there are two hydrogen atoms and one oxygen atom.

In contrast, a molecular formula specifies the actual number of each type of atom in a molecule of the compound. Therefore, while the empirical formula provides a simplified version of the composition, the molecular formula gives a complete picture.

Choosing the second option highlights the key aspect that distinguishes the two types of formulas: the empirical formula's focus on the ratio rather than specific quantities plays a crucial role in understanding chemical compositions and stoichiometry in reactions.