Methods of Writing Constitutional Formulas

Chemical formulas, as well as any linguistic entity, have to fulfill two basic requirements – expressiveness and economy, i.e. they have to express the maximal meaning with minimal means. Besides, chemical formula, being a scientific notation, has not to convey vague and scientifically unapproved meanings. This article presents the development of various kinds of chemical formulas and discusses their meaning in the historical context. Special attention is paid to line notation, developed for computers (WLN, SMILES, InChI etc.). We also discuss Seymour B. Elk's "biparametric nomenclature", based on the concept of 3-simplex, which was claimed to be universally applicable to all classes of compounds.