<P> Polycyclic aromatic hydrocarbons ( PAHs , also polyaromatic hydrocarbons or polynuclear aromatic hydrocarbons ) are hydrocarbons -- organic compounds containing only carbon and hydrogen -- that are composed of multiple aromatic rings ( organic rings in which the electrons are delocalized ) . Formally , the class is further defined as lacking further branching substituents on these ring structures . The simplest such chemicals are naphthalene , having two aromatic rings , and the three - ring compounds anthracene and phenanthrene . </P>
<P> Polycyclic aromatic hydrocarbons ( PAHs , also polyaromatic hydrocarbons or polynuclear aromatic hydrocarbons ) are hydrocarbons -- organic compounds containing only carbon and hydrogen -- that are composed of multiple aromatic rings ( organic rings in which the electrons are delocalized ) . Formally , the class is further defined as lacking further branching substituents on these ring structures . The simplest such chemicals are naphthalene , having two aromatic rings , and the three - ring compounds anthracene and phenanthrene . </P>
list the elements that make up polycyclic aromatic hydrocarbons
list the elements that make up polycyclic aromatic hydrocarbons
carbon hydrogen
carbon hydrogen