Links Hydrocarbons Questions 
What is an Isomer?
Isomers are compounds
which have
the same molecular formula
but a different structural formula.
What is a Structural
Formula?
The structural formula (also
called the displayed formula)
shows how the atoms are joined
together in the molecule.
Isomers of hydrocarbons have the same
number
of carbon and
hydrogen atoms
but the carbon atoms are joined to each other in
different ways.
Simply changing
the shape of
the molecule does not make it a different isomer.
The isomers of butane are
shown on the next
page.
Different isomers are different
molecular compounds.
They will have different physical properties
(for
example different boiling
points).
The more carbon atoms a compound has,
the greater the number of isomers
there can be.
Propane (3
carbon atoms) has 0
isomers.
Butane
(4 carbon atoms) has 2 isomers.
Pentane
(5 carbon atoms) has 3 isomers.
Hexane (6 carbon
atoms) has 5 isomers.
Heptane (7
carbon atoms) has 9
isomers.
Octane (8 carbon
atoms) has 15
isomers.
There are also isomers of alkenes and alcohols.
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