# What is the smallest whole number ratio of the atoms in a compound?

Why the $\text{empirical formula....}$
The $\text{empirical formula}$ is the simplest whole number ratio that defines constituent atoms in a species. The $\text{molecular formula}$ is always a whole number multiple of the $\text{empirical formula}$. And of course the multiple MIGHT be ONE....
By way of example, we could get an $\text{empirical formula}$ for hexane, ${C}_{3} {H}_{7}$, i.e. a whole number ratio. The $\text{molecular formula}$ is DOUBLE the $\text{empirical formula}$, $2 \times {C}_{3} {H}_{7} = {C}_{6} {H}_{14}$...