Molecular Formulas Versus Empirical Formulas

One definition of a Molecular Formula is "a formula indicating the actual number of atoms of each element *** up a molecule."1 In other words, the molecular formula must accuratly state the exact number of atoms of all of the elements in one molecule of the substance.
One definition of an Empirical Formula is "the formula giving the simplest ratio between the atoms of the elements present in a compound."2 In other words, in an empirical formula, you must find the ratio of atom to atom, in a molecule, and then reduce it.

Other Important Information:

The formulas for Ionic Compounds are empirical formulas.
A molecular formula is "a whole number multiple of an empirical formula."3
Converting to Emprirical Formula from Molecular Formulas is slightly more difficult than vice versa.