Non-binary compounds are compounds that contain more than two different elements. Binary compounds are formed when two elements react together; for example, the compound CH4 is a binary compound because it contains two elements: carbon and hydrogen. Therefore, compounds that have less than or more than two elements are non-binary compounds.
Types of non-binary compounds include some ionic compounds that contain a metal and a polyatomic ion. For example, the compound NaOH is a non-binary compound composed of the metal sodium and the polyatomic ion hydroxide. Since the compound contains atoms of the three elements sodium, oxygen and hydrogen, it is not binary. These types of compounds are named in the same manner as binary compounds.
Other types of non-binary compounds are some acid salts, such as sodium hydrogen sulfate and sodium hydrogen carbonate. The compound sodium hydrogen carbonate, or NaHCO3, is composed of the four elements sodium, hydrogen, carbon and oxygen - two more elements than a binary compound can contain. Some acids, such as hydrogen chlorate and hydrogen sulfate, may also be non-binary, as hydrogen sulfate (H2SO4) is made up of the three elements hydrogen, sulfur and oxygen. Other examples of non-binary compounds include magnesium acetate, iron(III) hydroxide and potassium phosphate.