The compound C₆H₅-HC=CH₂, also known as styrolene, cinnamene and phenethylene. The phenyl radical, C₆H₅^-, replaces one of the hydrogen atoms on ethylene. Styrene polymers are analogous to vinyl polymers in structure except that phenyl radicals replace the corresponding H atom. (Due to larger size of the phenyl radical as compared to the H atom, not all corresponding polymers are possible. ) A phenyl radical has the benzene ring structure-missing one H-with alternating double bonds between adjacent carbons. It is an aromatic group that is nonionic.