Homologous series

Homologous series

Groups of chemically related substances, the members of which differ from each other on the basis of a certain molecular fraction. In organic chemistry, this particularly refers to special groups of compounds in which each molecule differs from the previous one by one CH2 group. Such homologous series are formed by, for example, the alkanes (methane, CH4; ethane, C2H6; propane, C3H8; etc.) and also carboxylic acids (formic acid H-COOH; acetic acid, CH3-COOH; propionic acid, C2H5-COOH; etc.).