Molecular formula is the simplest type of a molecular representation we use in chemistry.
Here are some examples:
What sort of information does molecular formulas give us?
First and foremost, molecular formulas give us the exact ratios of elements that make up the molecule. We know which elements, how many atoms of each, and what are the ratios between them.
Molecular formulas also allow us to calculate some important properties of molecules. Those properties are:
- Molecular mass
- Natural isotope composition
Molecular masses are important for chemical and stoichiometric calculations. While the natural isotope composition of the molecule can be potentially important for the mass spectrometric analysis of the compound.
What don’t molecular formulas tell us?
The important piece of information that molecular formulas hide from us is the molecular structures. While it is possible to reliably predict the structure of some simple inorganic molecules like sulfuric acid or carbon dioxide, it is very difficult to say what the molecular formula represents for an organic substance. The examples above show three organic molecules that would be impossible to identify without the compound names!