Now that you are familiar with atoms and molecules and how they make up the solids, liquids, and gases we see around us, let’s discuss what happens when two molecules meet: namely, chemical reactions. A chemical reaction is defined as a process by which one or more substances are changed into one or more new substances. Chemical reactions are usually portrayed in this way:
is read as “yields” or “produces.” You will often see the states of matter in parentheses as subscripts after the chemical formulas of the reactants and products. The symbols for the states of matter and some other chemical reaction symbols you should be familiar with are given in the table below.