1. Isomers and polymers

2. Structural Isomers Pentane and 2-methylbutane are both C5H12. 1-butene
2-methylpropene
cyclobutane
methylcyclopropane
C4H10 has 2 isomers (2-methylpropane, butane). C4H8 has more isomers because the position of the double affects the name and because ring structures can be drawn.

3. Geometric Isomers cis = same side, trans = opposite sides
1,2-dichloroethene requires cis or trans.
1,2-dichloroethane does not require cis or trans because they would both represent the same molecule (to move chlorine from the same side to opposite sides only requires that the C – C single bond be rotated).
cis-1,2-dimethylcyclopentane
trans-1,2-dimethylcyclopentane

4. 1,1-dimethylcyclopentane
A molecule is relatively inflexible when a multiple (double or triple) bond is present or if a ring structure (including benzene) exists.
a) not isomers (they don’t have the same chemical formula: C5H12 vs. C5H10)
b) structural isomers (same as question #1)
c) geometric isomers
d) not isomers (both diagrams represent the exact same molecule)

5. Polymers
Monomer: the smallest repeating unit of a polymer (propene in polypropylene).
Polymer: a long chain molecule made up of many small identical units (monomers).
Addition polymerization: a reaction in which unsaturated monomers combine with each other to form a polymer.
Teflon, polypropylene, polyester, polyethylene (pop bottles, grocery bags), polystyrene (packing material), Plexiglas, polyvinyl chloride (vinyl), natural rubber, etc.

6. Geometric Isomers cis-1,2-dichloroethene trans-1,2-dichloroethene
cis-1,2-dichlorocyclopentane trans-1,2-dichlorocyclopentane
cis-1,2-dichloroethene trans-1,2-dichloroethene
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