sentences:  Homochain polymers have only one kind of atom in the main chain.One member is polymeric sulfur, which forms reversibly upon melting any of the cyclic allotropes, such as S8.Organic polysulfides and polysulfanes feature short chains of sulfur atoms, capped respectively with alkyl and H. Elemental tellurium and the gray allotrope of elemental selenium also are polymers, although they are not processable.