Homologous Series

Six different types of homologous series: organic chemicals with similar chemical properties in which members differ by a constant relative atomic mass. For example, all the members of the alkane series differ by a relative atomic mass of 14.

In chemistry, any of a number of series of organic compounds with similar chemical properties in which members differ by a constant relative molecular mass.

Alkanes (paraffins), alkenes (olefins), and alkynes (acetylenes) form such series in which members differ in mass by 14, 12, and 10 atomic mass units respectively. For example, the alkane homologous series begins with methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), and pentane (C5H12), each member differing from the previous one by a CH2 group (or 14 atomic mass units).