 Functional group is an alkene, therefore suffix = ene
 The longest continuous chain is C3 therefore root = prop
 In order to give the alkene the lowest number, number from the right as drawn
 The C=C is unambiguously between C1 and C2 therefore the locant
isn't required
propene

CH_{3}CH=CH_{2} 

 Functional group is an alkene, therefore suffix = ene
 The longest continuous chain is C4 therefore root = but
 The C=C is between C2 and C3 so the locant is 2
but2ene
or 2butene

CH_{3}CH=CHCH_{3} 

 Functional group is an alkene, therefore suffix = ene
 The longest continuous chain is C4 therefore root = but
 In order to give the alkene the lowest number, number from the right as drawn
 The C=C is between C1 and C2 so the locant is 1
but1ene or 1butene 
CH_{3}CH_{2}CH=CH_{2} 

 Functional group is an alkene, therefore suffix = ene
 The longest continuous chain is C6 therefore root = hex
 The system is cyclic there prefix = cyclo
 The C=C is unambiguously between C1 and C2 therefore the locant
isn't required.
cyclohexene



 Functional group is an alkene, therefore suffix = ene
 The longest continuous chain is C5 therefore root = pent
 In order to give the alkene the lowest number, number from the right as drawn
 The C=C is between C2 and C3 so the locant is 2
 The substituent is a C1 alkyl group i.e. a methyl group
 The methyl group locant is 4
4methylpent2ene or
4methyl2pentene



 Functional group is an alkene, therefore suffix = ene
 The longest continuous chain is C6 therefore root = hex
 The C=C is between C3 and C4 so the locant is 3
 The substituent is a C1 alkyl group i.e. a methyl group
 The first point of difference rule requires numbering from the right
as drawn to make the methyl group locant 3
3methylhex3ene or 3methyl3hexene


