Alkenes

• What is the general formula of alkenes?

  CnH2n
• What are the key features of alkenes?

  • they consist of carbon and hydrogen atoms
  • each alkenes molecule contains at least 1 carbon-carbon double bond
  • the double bond makes them ‘unsaturated’, enabling the to participate in addition reactions
• What s the general formula for cyclic alkenes?

  CnH2n-2
• Why are alkenes very reactive?

  They contain a double carbon-carbon bond which has a high electron density, allowing alkenes to attract electrophiles
• What are electrophiles?

  Electron pair acceptors
• What is the shape of alkenes?

  Trigonal planar
• What does the carbon-carbon double bond consist of?

  Pi bond and one sigma bond
• What is a stereoisomer?

  A stereoisomer is a molecule that has the same molecular formula and connectivity of atoms, but differs in the arrangement of atoms in space.
• When one’s E-Z stereoisomer is arise?

  • there is restricted rotation around the C=C bond
  • there are 2 different groups/ atoms attached to both ends of the double bond
• When is a molecule an E isomer?

  If the priority atom/molecule is on the opposite side of the double bond
• When is a molecule a Z isomer?

  If the priority atom is on the same side of the double bond
• What is an addition reaction?

  An addition reaction is a chemical reaction where two or more molecules combine to form a single product molecule.
• What is a carbocation?

  An intermediate formed which has a positive charge o a carbon atom
• What is a product of a reaction of bromine with an alkene?

  dihalogenoalkane