Chemical equations are actually matrix equations, and this has important implications for their thermodynamic treatment. The fundamental equation for chemical thermodynamics for a chemical reaction system can be written in terms of species, but at chemical equilibrium, it has to be written in terms of components. The number of components is equal to the number of species minus the number of independent chemical reactions. The fundamental equation for the Gibbs energy of a system containing ethylene, methane, ethane, and propane is discussed. At chemical equilibrium there are two components, which can be taken to be carbon and hydrogen or ethylene and methane. There are advantages in using matrix notation.