Alkenes

• Are alkenes saturated or unsaturated ?

  unsaturated
• What is the general formula for alkenes ?

  CnH2n
• What does a C=C bond consist of ?

  a sigma bond and a pi bond
• How is a pi bond formed ?

  The sideways overlap of p orbitals formed above and below the plane of the carbon atoms.
• What does a pi bond prevent ?

  bond rotation
• What shape and bond angle does each C in the C=C bond have ?

  Shape= triganol planar

  Bond Angle =120
• Definition of stereoisomerism.

  Compounds with the same structural formula but a different arrangement of atoms in space.
• What are the two types of stereoisomerism ?

  E/Z and optical
• What is the criteria of E/Z isomerism ?

  C=C and each carbon on the double bond must be attached to two different atoms.
• What is the difference between E isomerism and Z isomerism ?

  In E isomerism the high priority groups are on opposite sides but for Z isomerism they are on the same side.
• What is the criteria for cis trans isomers ?

  Two different groups on each C on C=C bond and two of these substituent groups are hydrogen.
• What is the difference between cis and trans isomerism ?

  In cis isomerism the hydrogens are on the same side of the C=C and in trans isomerism the hydrogens are diagonally opposite.