isomerism

• What are isomers?

  Molecules with the same molecular formula
• What are the two main categories of isomers?

  Structural isomers and stereoisomers
• What are structural isomers?

  Molecules with different connections of atoms
• What are stereoisomers?

  Molecules with the same connections but different arrangements
• What are the sub-types of structural isomers?

  • Chain isomers
  • Positional isomers
  • Functional group isomers
• What are chain isomers?

  Isomers differing in carbon skeleton arrangement
• What are positional isomers?

  Isomers with functional groups at different carbons
• What are functional group isomers?

  Isomers forming different functional groups
• What is the molecular formula of butane?

  C4H10
• What are the possible structures of butane?

  Butane and methylpropane
• What are the chain isomers of butane?

  • Butane (straight chain)
  • Methylpropane (branched chain)
• What is the molecular formula of chloropentane?

  C5H11Cl
• What are the positional isomers of chloropentane?

  1. chloropentane, 2-chloropentane, 3-chloropentane
• What is the molecular formula for C3H6O?

  C3H6O
• What functional groups can C3H6O form?

  Aldehydes or ketones
• What are the functional group isomers of C3H6O?

  Propanal and propanone
• What are the sub-types of stereoisomers?

  • Geometric (E/Z) isomers
  • Optical isomers
• What causes geometric (E/Z) isomers?

  Restricted rotation around carbon-carbon double bonds
• What is a Z-isomer?

  Higher priority groups on the same side
• What is an E-isomer?

  Higher priority groups across from each other
• How to identify E/Z isomers?

  1. Use Cahn-Ingold-Prelog priority rules
  2. Compare directly attached atoms
  3. Check arrangement of high priority groups
• What is the classification of the alkene with ethyl and bromine groups?

  It is the E-isomer
• What forms optical isomers?

  Molecules with a chiral centre
• What is an example of an optical isomer?

  1. chlorobutane
• What are the characteristics of enantiomers?

  • Non-superimposable mirror images
  • Different interactions with plane-polarised light