Each element in a given compound comprises a fixed percent by

This fixed percent is called the definite proportion. Specifically, this phenomenon is states in the Law of Definite Proportions. According to John Dalton, all the individual elements making up the compound has a fixed ratio, whether in mass or in moles. For example, for any amount of H₂O, there will always be a fixed proportion of 2 H atoms: 1 O atom.