A chemical formula that shows exact number of atoms of all the elements present in a molecule is called ‘Molecular Formula’ of that compound. It also explains actual ratio between the atoms of elements.
For example: Glucose C6H12O6
Common Salt NaCI
Sulfuric acid H2SO4
A chemical formula which shows the simplest ratio between the atoms of elements present in a molecule is called “Empirical Formula’. Example: Glucose CH2O