The first twelve linear 1-alkenes are shown below, together with their systematic names.

Straight chain 1-alkenes

ethene 2
propene 3
butene 4
pentene 5
hexene 6
heptene 7
octene 8
nonene 9
decene 10
undecene 11
dodecene 12

There is a simple relationship between the number of carbons and hydrogens in these molecules that allow us to easily tell whether a compound is an alkane or an alkene from its formula - an alkane with n carbons will have 2n+2 hydrogens, while an alkene with n carbons will have 2n hydrogens.

For example, C7H16 is an alkane (16 = 2×(7) + 2), while C8H16 is an alkene (16 = 2×8).