• Homologous series: related compounds that differ by the number of subgroups
o Methylene group (–CH –) 2 Methyl group (–CH )3
• Naming Alkanes:
1. Find the longest continuous chain of carbon atoms
to assign the parent name.
2. Find whatever groups are not a part of the longest continuous chain. Name
these as prefixes.
3. Assign numbers to the groups by counting from one end
of the chain. A chain has two ends so start with the end closest to the
4. If there are two or more identical groups, use prefixes to designate the
number: di (2), tri (3), tetra (4), penta (5), etc.
5. If there are two or more different groups, write them in the prefix in
o Stereoisomers − molecules with the same connectivity, but the same
bonds are oriented differently atoms in different positions (orientation
o Stereoisomerism due to restricted rotation about is called cis trans
o A cis isomer (or Z isomer) has two like groups on the same side of a line
drawn through a double bond (chain moves from up