A chemical change is a process in which reactants are changed into one or more different products. A chemical change occurs whenever compounds are formed or decomposed. During this reaction, there is a rearrangement of atoms that makes or breaks chemical bonds. This change is usually not reversible.

There are several different types of chemical change. These include synthesis, decomposition , single displacement, double displacement, neutralization, precipitation and redox.

Indicators of a chemical change include a colour change, the formation of a precipitate, the formation of gas, or a change in temperature.