Hydrocarbon
a name given to compounds of one or more atoms of car- HYDROCEPHALUS bon, with atoms of hydrogen. Carbon is a tetrad element, capable of uniting with four atoms of H, as CH4 methane.
But carbon atoms can unite with each other, by one or more pair of bonds.
Hydrocarbons having the C atoms united by only one pair of bonds are called paraffins, Cn: H2n+2:, as ethane. Hydrocarbons having two C atoms united by two pairs of bonds are called olefines Cn H₂n:, as ethene. By three pairs of bonds, are called acetylenes CnH2n-2 as acetylene. Besides these there are hydrocarbons belonging to the aromatic series, having the carbon atoms arranged to form a closed ring, as BEN- ZENE, C.He (q. v.), and the naphthalene series containing two closed rings. The constitution of the other groups of hydrocarbons is described under their respective names.