closed chain - (chemistry) a chain of atoms in a molecule that forms a closed loopchemical science, chemistry - the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions chemical chain, chain - (chemistry) a series of linked atoms (generally in an organic molecule) heterocyclic ring, heterocycle - a ring of atoms of more than one kind; especially a ring of carbon atoms containing at least one atom that is not carbon open chain - a chain of atoms in a molecule whose ends are not joined to form a ring |