Illustrated Glossary of Organic Chemistry

Skeletal formula (skeletal structure; line-angle formula): A representation of molecular structure in which covalent bonds are shown as lines. The symbols for all elements other than carbon and hydrogen are always drawn (unless part of a group abbreviation such as Ph). Carbon atoms can be represented with C, or the C omitted. Hydrogen atoms can be omitted only when bonded to carbon or if part of a group abbreviation; all other hydrogens must be shown as H. Lone pairs, where present, do not have to shown.

Skeletal formula representation of thalidomide.