Let's quickly review chemical symbols and chemical formulas.

Identify each of the following as a chemical symbol or chemical formula by clinking in the correct column.

Interactive exercise. Assistance may be required.

Remember, a chemical reaction is a change in matter that produces one or more new substances. For example, sodium and chlorine combine to form sodium chloride, or salt. If we wrote out all the words for each element or compound every time we wanted to discuss a chemical reaction, it would be quite confusing. A chemical equation is a symbolic representation of a chemical reaction. The equation below shows sodium and chloride reacting to produce salt.

2Na + Cl2 → 2NaCl

Chemical equations have a definite structure. Click on each question mark to learn more about the structure of a chemical equation.

Interactive exercise. Assistance may be required.