Water for example is commonly known to be represented by the formula H 2 0. More complex molecules are simlarly described. Sucrose, for example, is written as C 6 H 12 O 6 . This describes the number of atoms in the molecule but tells us little about how they are arranged and arrangement, as we will see, can be critically important in understanding a chemicals properties.
Some chemical formulas attempt to describe the structure in the formula itself.
Let's look at another even more complicated example. This tells us that one of the hydrogens is distinguished from the other nine in some way. Neither of these formula really tell us much about the structure of this molecule and yet the actual shape of the molecule is very important in understanding it's properties. And to further complicate matters there are actually several different ways this chemical formula can and is represented in nature. All of these chemicals represent the same chemical family with the same number of atoms.