Consider the data obtained by analyzing a compound. A chemist determines that the substance contains potassium, chlorine and oxygen. Here is some sample data:

element

mass, g

 potassium

0.479

chlorine

0.434

oxygen

0.588

What is the chemical formula of this compound? It might be tempting to say K0.479Cl0.434O0.588 but of course that is not correct.

The numbers in chemical formulas are always integers since they represent actual whole atoms which combine. The fact that they represent the numbers of atoms and not their masses should suggest a direction to follow.