What is "structural formula"

Formula \For"mu*la\, n.; pl. E. Formulas, L. Formul[ae].

1. A prescribed or set form; an established rule; a fixed or conventional method in which anything is to be done, arranged, or said.

2. (Eccl.) A written confession of faith; a formal statement of foctrines.

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

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

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

   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.

   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.

n. (context chemistry English) Any of various diagrammatic representations of the structure of a molecule that shows how its atoms are linked to each other, with what type of bonds, and the presence of any charges

n. an expanded molecular formula showing the arrangement of atoms within the molecule

The structural formula of a chemical compound is a graphic representation of the molecular structure, showing how the atoms are arranged. The chemical bonding within the molecule is also shown, either explicitly or implicitly. Unlike chemical formulas, which have a limited number of symbols and are capable of only limited descriptive power, structural formulas provide a complete geometric representation of the molecular structure. For example, many chemical compounds exist in different isomeric forms, which have different enantiomeric structures but the same chemical formula. A structural formula is able to indicate arrangements of atoms in three dimensional space in a way that a chemical formula may not be able to do.

Several systematic chemical naming formats, as in chemical databases, are used that are equivalent to, and as powerful as, geometric structures. These chemical nomenclature systems include SMILES, InChI and CML. These systematic chemical names can be converted to structural formulas and vice versa, but chemists nearly always describe a chemical reaction or synthesis using structural formulas rather than chemical names, because the structural formulas allow the chemist to visualize the molecules and the structural changes that occur in them during chemical reactions.