Terpenes are special classes of lipids that are derived from isoprene units. An isoprene unit’s molecular formula is ; therefore, terpenes must contain a molecular formula that is derived from a empirical formula.

The molecular formula consists of seven isoprene units ( = ); therefore, is a type of terpene.

Pentene is an alkene with the molecular formula . () is derived from pentene units; however, terpenes do not have pentene units.