What Are the Things Required to Write the Molecular Formula of a Compound?

To write the molecular formula of a compound, you need to know:

1. The elements present in the compound.
2. The number of atoms of each element in one molecule of the compound.

The molecular formula shows the exact number of each type of atom present in a single molecule. For example, the molecular formula for water is H₂O. This tells us that one molecule of water has two hydrogen atoms and one oxygen atom.

You usually find the molecular formula using the empirical formula and the compound’s molar mass. Once the molar mass is known, you can calculate how many units of the empirical formula are present in the actual molecule.