Chemical formula is a term that describes the way elements are combined in a molecule. There are many synonyms for this term, including molecular formula, structural formula, empirical formula, and elemental formula. The molecular formula specifies the number and type of each atom in a molecule. Structural formula shows the way atoms are arranged and connected to each other in a molecule. Empirical formula denotes the simplest whole-number ratio of atoms in a molecule. Elemental formula represents the purest form of a substance, by listing the elemental composition of it. All these synonyms are used extensively in chemistry to describe various aspects of the composition and structure of chemical compounds.