• Isomers are molecules with the same mol. formula but with
different structures.
• Geometric Isomers in unsaturated compounds - the position of
groups about the double bond
varies between two isomers.
• Positional arrangement of highest
priority substituents across a double
bond; or opposite
sides of a ring.
• Priority is based on the atomic number of each substituent.
You compare each group
and look
for where they differ. Where they
differ you compare the atomic number.