isomerism

  • Created by: Nataliagx
  • Created on: 31-01-19 10:19
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  • ISOMERISM
    • structural isomer
      • same molecular formula, but different arrangement of the atoms in space
      • CHAIN ISOMERISM
        • changing the position of branched chains
      • POSITION ISMOERISM
        • basic carbon chain stays same, but important groups move.
      • FUNCTIONAL GROUP ISOMERISM
        • same molecular formula but different functional groups
    • stereoisomer
      • same order of atoms, but different spatial arrangement
      • GEOMETRIC
        • restricted rotation
        • no  geometric isomers w/ 2 groups the same on one side of bond
      • TRANS
        • opposite sides of double bond
          • PHYSICAL PROPERTY
            • same side of double bond
            • TRANS higher mp
              • for IMF to work well, the molecules must pack together efficiently in the solid.
                • Trans pack better than cis isomers
                  • poorer packing in cis= IMF not as effective; less energy is needed to melt the molecule
            • CIS high bp
              • stronger IMF between the molecules of cis  than the  trans isomer
                • cis isomer is POLAR and trans isn't
                  • DIPOLE-DIPOLE INTRACTNS as well as LDN FORCES
                    • more energy needed to break these forces
      • CIS
        • same side of double bond
      • OPTICAL ISOMERISM
        • chiral carbon produces enoniometers that rotate plane of polarised light in opposite directions
          • If the solutions  equally concentrated, amount of rotation by two isomers is the same  but in opposite directions
        • (+)
          • rotates the plane of polarisation in clockwise
        • (-)
          • rotates the plane of polarisation anti-clockwise

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