How do alkanes differ from alkenes?

1 Answer
Apr 20, 2018

By their #"degree of unsaturation..."#


An alkane is proposed to be fully saturated, i.e. there are maximum number of #C-H# bonds....and alkanes thus have a general formula of #C_nH_(2n+2)#. By contrast, alkenes, olefins, have TWO hydrogens LESS than the saturated formula, i.e. #C_nH_(2n)#..and are said to have ONE degree of unsaturation...

See this old answer for more details. When given an organic formula, assessment of the degree of unsaturation should be the first thing you do. How many rings, how many double bonds, are in the molecule?

With respect to ethane or propane, how many degrees of unsaturation does acetylene have; what about cyclopropene?