Molecular formula

Formula For"mu*la, n.; pl. E. {Formulas}, L. {Formul[ae]}. [L., dim. of forma form, model. See{Form}, n.] 1. A prescribed or set form; an established rule; a fixed or conventional method in which anything is to be done, arranged, or said. [1913 Webster]

2. (Eccl.) A written confession of faith; a formal statement of foctrines. [1913 Webster]

3. (Math.) A rule or principle expressed in algebraic language; as, the binominal formula. [1913 Webster]

4. (Med.) A prescription or recipe for the preparation of a medicinal compound. [1913 Webster]

5. (Chem.) A symbolic expression (by means of letters, figures, etc.) of the constituents or constitution of a compound. [1913 Webster]

Note: Chemical formul[ae] consist of the abbreviations of the names of the elements, with a small figure at the lower right hand, to denote the number of atoms of each element contained. [1913 Webster]

{Empirical formula} (Chem.), an expression which gives the simple proportion of the constituents; as, the empirical formula of acetic acid is {C2H4O2}.

{Graphic formula}, {Rational formula} (Chem.), an expression of the constitution, and in a limited sense of the structure, of a compound, by the grouping of its atoms or radicals; as, a rational formula of acetic acid is {CH3.(C:O).OH}; -- called also {structural formula}, {constitutional formula}, etc. See also the formula of {Benzene nucleus}, under {Benzene}.

{Molecular formula} (Chem.), a formula indicating the supposed molecular constitution of a compound. [1913 Webster]