Book 3 - Alkenes

• What type of bond does Alkanes have? All sigma bonds (σ)
• What is the shape and bond angle of all alkanes? Bond angle: 109.5o Shape: Tetrahedral
• What is a sigma bond? Overlap of orbitals directly between the bonding atoms
• What is a pie bond? Sideways overlap of p - orbitals
• How is a pie bond formed? Sidways overlap of p - orbitals above and below the bonding C atoms which restricts rotation
• What bond angle and shape does alkenes have? Bond angle = 120o Shape = Trigonal planar
• What are steroisomers? Compounds with the same structural formula, but with a different arrangement of atoms in space
• What are the categories of E/Z isomerism? C=C double bond which restricts rotation.

  Each C of the C=C double bond must be attached to two different groups
• What are E isomers? When the highest priority groups are on opposite sides.
• What is Z isomerism? When the highest priority group are on the same side. (On Zee same side)
• What is Cis isomerism? When 2 of the same substituent groups are on the same side
• What is Trans isomerism? When 2 of the same substituent groups are on opposite sides
• Why are alkenes more reactive than alkanes? Alkenes have a pie bond which has a lower bond enthalpy than alkanes so require more energy to overcome
• Hydrogenation ("Adding hydrogen""). Conditions? Reagents? Use?" Conditions: Nickel catalyst, 150oC.

  Reagent: Hydrogen.

  Use: Manufacture of margarine from unsaturated vegetable oils
• Bromination ("Adding halogen""). Conditions? Reagent? Mechansim? Use?" Conditions: Room temp

  Reagent: Bromine Water

  Mechanism: Electrophilic addition

  Use: Test for presence of C=C, bromine water goes from orange to colourless
• Adding HBr. Conditions? Reagent? Mechanism? Use? Condition: Room temp

  Reagent: Hydrogen Bromide

  Mechanism: Electrophilic addition

  Use: Manufacture of haloalkanes
• Hydration. Condition? Reagent? Mechanism? Use?

  Condition: Conc. phosphoric acid

  Reagent: H2O(g)

  Mechanism: Electrophilic addition

  Use: Formation of alcohol
• What is an electrophile? A species that accepts a pair of electrons
• What is addition reaction? 2 species which join together to form 1
• What is a Primary 1o? The positively charged carbon is attached to one other carbon
• What is secondary 2o? The positively charge carbon is attached to two other carbons
• What is Tertiary (3o) classification? The positively charged carbon is attached to three other carbons
• What is an addition polymer? A long chain, high molecular mass saturated molecule
• What is the problem with addition polymers? They are non - biodegradable
• What are the disposal options of polymers?

  Sort and recycle

  Combustion for energy production

  Use as organic feedstock
• What are two ways of reducing environmental damage of polymers? Biodegradable polymers

  Photodegradable polymers