page_title: Aromatic hydrocarbon
section_title: Polycyclics
hierarchical_section_title: Aromatic hydrocarbon / Types of aromatic compounds / Polycyclics
context_page_description: An aromatic hydrocarbon, or arene, is a hydrocarbon ring compound. It has alternating double and single bonds between carbon atoms forming rings. Many of the compounds have a sweet scent, hence the term 'aromatic'. The ring of six carbon atoms in aromatic compounds is known as a benzene ring, after the simplest possible hydrocarbon ring, benzene. Aromatic hydrocarbons can be monocyclic or polycyclic.
  Some non-benzene-based compounds called heteroarenes, which follow Hückel's rule, are also aromatic compounds. In these compounds, at least one carbon atom is replaced by one of oxygen, nitrogen, or sulfur.
context_section_description: Polycyclic aromatic hydrocarbons are molecules with two or more simple aromatic rings fused together by sharing two neighboring carbon atoms. Examples are naphthalene, anthracene and phenanthrene.
caption: Nathlalene has two rings.