Structural Isomers
C - C - C - C - C - C - C - C
CC
C - C - C - C - C - C - C
C
C
C
• Name, draw, and construct structural models of alkanes
Include: branched alkanes, structural isomers
Additional KEY Termscycloalkanes
Structural isomers:Compounds with same molecular formula but different structural formula.
Isomers differ in their properties such as boiling point and melting point.
More branched the structure, lower its boiling point - compounds can’t stack, weaker the IMFs.
branched unbranched
butane 2-methylpropane
C4H10isomers
More carbon atoms - more structural isomers.
Octane - 18 different structural isomersDecane - 75Eicosane - 366 319(20 carbon alkane)
3-methyl-5-ethylheptane decane
C - C - C - C - C - C - C
C
C
CC - C - C - C - C
CC
C C
C
Draw and name 2 structural isomers of pentane.
C - C
C
C - C - C - C
C
C -
C2-methylbutane
2,2-dimethylpropane C - C
C
C - C -
C - C
C
C - C - pentane2-methylbutane
Take care when naming your isomers to be sure you don’t have the same thing.
3-ethyl-2-methylhexane is a structural isomer of which straight chained alkane?
6 carbons + 2 carbons + 1 carbon = 9 carbons
The alkane with 9 carbons is nonane.
hexane ethyl methyl
C - C - C - C
C
C
C - C - 1 2 3 4 5 6
C
CYCLOALKANES
• Same naming rules – but add prefix“cyclo” • Name the carbon ring first, then number the carbons so
as to give the alkyl groups the lowest set of numbers.
1,2-dimethylcyclopentane
1-methylcyclobutane
C
CC
C
C
C
CC
C
C
C
C
CC
CC
C
C
cyclohexane
CAN YOU / HAVE YOU?
• Name, draw, and construct structural models of alkanes
Include: branched alkanes, structural isomers
Additional KEY Termscycloalkanes
