Molecular Formula
Tells you how many atoms of each element are in a compound. This is the “default”; it is what most people think of when hearing chemical formulas.
Empirical Formula
Tells you the simplest ratio of elements in a compound. Sometimes a substance’s molecular and empirical formula are the same, but sometimes they are different.
Ex. A compound with the molecular formula C₂H₅O₃ has the same empirical formula. You cannot simplify the 2 carbon:5 hydrogen:3 oxygen ratio.
Ex. A compound with the molecular formula C₆H₁₂O₆ has an empirical formula of CH₂O because each of those subscripts can be divided by 6.
Structural Formula
Structural formulas provide a visual representation of how a molecule looks. You will learn about how to create them in later units, but here’s an example with H₂O ↴
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