Question

why alkenes are called olefins

Answer 1

UNSATURATED hydrocarbons contain either double or triple bonds. Since the compound is unsaturated with respect to hydrogen atoms, the extra electrons are shared between 2 carbon atoms forming double bonds in alkenes. Alkenes are also called OLEFINS because they form oily liquids on reaction with chlorine gas.

Answer 2

Alkenes are alsocalled OLEFINS because they form oily liquids on reaction with chlorine gas.