Formulas of CompoundsObjective ■ To learn how a formula describes a compound’s composition.A compound is a distinct substance that is composed of the atoms of two or more elements and always contains exactly the same relative masses of those elements. In light of Dalton’s atomic theory, this simply means that a compound always contains the same relative numbers of atoms of each element. For example, water always contains two hydrogen atoms for each oxygen atom. In this context, the term relativerefers to ratios