Chemical symbols represent elements, while chemical formulas represent chemical compounds. Chemical symbols are also known as element symbols. Because compounds are formed by individual elements coming together, chemical formulas are composed of several chemical symbols.
There are three different varieties of chemical formulas. They include empirical formulas, molecular formulas and structural formulas. Molecular formulas show the number of atoms of a particular compound in each molecule of a compound. For example, the molecular formula for water is H20 and shows that every molecule of water always contains two hydrogen atoms and one oxygen atom.
Empirical formulas show the ratio of elements in the compound. They are most often associated with non-molecular substances that are ionically bonded, such as the chemical formula for table salt, NaCl. Showing the amounts of elements in ratio is useful because ions bond by charge only often form crystals or solids with overlapping bonds.
Structural formulas help show the shape of a molecule or ion by grouping atoms found in a particular location of the compound together. For example, the molecular formula for ethanol is C2H6O. This writing does not show the way the molecule is bonded and the functional groups that give it its name, chiefly the carbon chain surrounded by hydrogen atoms and the OH functional group at the end. Using the structural formula CH3CH2OH conveys this information.