Originally, alkenes were named olefins. The name derives from the French oléfiant which in turn originated from the Latin oleum facere, maker of oil. The name gaz oléfiant for ethene was introduced by Dutch chemists because the product from the reaction of ethene with chlorine is the very oily 1,2-dichloroethane. This compound had already been produced in The Netherlands since the 18. century and, therefore, was called "Oil of the Dutch Chemists".
Lower alkenes with up to four C atoms are gaseous at room temperature with characteristically penetrating smells. Alkenes with four to twelve C atoms are liquids.