2-butene is a colorless gas that belongs to the family of hydrocarbons known as alkenes. It has the chemical formula C4H8 and features a double bond between the second and third carbon atoms in its chain. This structure allows it to participate in various chemical reactions, making it useful in organic synthesis. There are two isomers of 2-butene: cis and trans, which differ in the arrangement of their hydrogen atoms around the double bond. Cis-2-butene has both hydrogen atoms on the same side, while trans-2-butene has them on opposite sides. These isomers exhibit different physical properties and reactivities.