C=C Bond:

The C=C bond is stronger (152 kcal mol^-1) and shorter (1.33 Å) as compared to a C-C single bond (88 kcal mol^-1 and 1.54 Å correspondingly). A C=C bond consists of one σ bond and one π bond, with the π bond being weaker as compared to the σ bond. This is significant with respect to the reactivity of alkenes.

Bond rotation is not feasible for a C=C double bond because this would need the π bond to be broken. Hence, isomers of alkenes are possible relies on the relative position of the substituents. These can be described like cis or Trans, but are more correctly defined as (Z) or (E). Alkenes are described like mono-, di-, tri-, or tetrasubstituted relies upon the number of substituents that are present. The more substituents that are present, the more stable the alkene.