What is "skeletal formula"

n. (context chemistry English) A diagrammatic representation of a molecule (especially that of an organic compound) in which lines represent bonds between atoms that are represented by their symbols

The skeletal formula, sometimes called line-angle formula, of an organic compound is a type of molecular structural formula that serves as a shorthand representation of a molecule's bonding and some details of its molecular geometry. It is represented in two dimensions, as on a page of paper. It employs certain conventions to represent carbon and hydrogen atoms, which are the most common in organic chemistry.

The technique was developed by the organic chemist Friedrich August Kekulé von Stradonitz. Skeletal formulae have become ubiquitous in organic chemistry, partly because they are relatively quick and simple to draw. Carbon atoms are usually depicted as line ends or vertices with the assumption that all carbons have a valence of 4 and carbon-hydrogen bonds, usually not shown explicitly, are assumed to complete each C valence. A skeletal formula shows the skeletal structure or skeleton of a molecule, which is composed of the skeletal atoms that make up the molecule.

Although Haworth projections and Fischer projections look somewhat similar to skeletal formulae, there are differences in the conventions used, which the reader needs to be aware of in order to understand the details of a molecule.