Pentane is an organic compound with the chemical formula of . It is an alkane with five carbon atoms. Usually, "pentane" represents all three isomers ("n"-pentane, isopentane and neopentane). But in the IUPAC, pentane only represents "n"-pentane. In the IUPAC, the other two isomers is 2-methylbutane and 2,2-dimethylpropane. Cyclopentane's chemical formula is , so it is not an isomer of pentane.