A structural formula is a chemical formula that shows how atoms are bonded to each other. For example, we might write AlOHCl2 as shown here to emphasize the bonds.
However, in inorganic chemistry, the compounds are such that there is generally only one possible way to combine the atoms. This is not the case in organic chemistry, where very often there are many possible combinations for the atoms in the compound. Consider, for example, the formula C4H10. This formula could represent either of the following compounds
These compounds have slightly different properties. As the formulas become more complex, the differences are even greater. For this reason, it is often better to use a structural formula in organic chemistry rather than the simple chemical formula.