isomerism

• Stereoisomers are molecules with the same structural formula but the atoms have a different arrangement in space.
• Alkanes are fully rotational so do not form stereoisomers.
• Cis/trans isomers are one naming system for geometric stereoisomerism.
• Any alkene can have cis/trans isomerism provided:

  • The carbon atoms on either side of the double bond are attached to two different groups
  • At least one of these two groups from either side are the same as one another.
• In a cis isomer, the two atoms/groups would be on the same side of the molecule as one another.

  
• In a trans isomer, the two same atoms/groups are on opposite sides of the molecules to one another.

  
• E/Z stereoisomerism is another naming system.
• Z ( zusammen ) isomer has the Same atoms or higher priority atoms on the same side of the molecule.
• E ( entgegen ) isomers have the same atoms or higher priority atoms on the opposite sides of the molecule.
• The EZ naming system can be used on molecules where the c=c double bonds are bonded to four different atoms. This is done using CIP priority rules.
• The element with the highest atomic number on one side of a carbon double bond is the higher priority element.
• If both of the atoms attached to the same carbon have the same atomic number, you would move to the next atom bonded to the previous atom until one has a higher atomic number.