Organic - 3.4 Alkenes Flashcards
Are alkenes saturated?
Yes
What is the general formula for alkenes?
CnH2n
Where is the centre of high electron density in an alkene?
Alkenes have a carbon carbon double bond with the centre of high electron density and as a result are more reactive than alkanes
What is a stereoisomer?
Molecules which have the same molecular formula and structural formula but a different 3D arrangement of the atoms in space
What do the E/Z isomers represent?
The prefix Z indicates the groups are on the same side of the double bond on different carbons
The prefix E indicates the groups are an opposite side of the double bond on different carbons
How are groups ranked using the Cahn Ingold Prelog (CIP) rules?
The higher atomic number of the element bonded to the carbon in the double bond the higher the ranking.
When the higher priority substituents are on the same side of the plane, the isomer is a Z isomer. When the higher priority substituents are on opposite sides of the plane that is is an E isomer.
What is addition polymerisation?
When alkenes react with other alkene molecules to form addition polymers.
What is a polymer?
Long chain of repeating monomer units joined together
why are addition polymers unreactive?
They are unreactive alkane molecules without the reactive carbon carbon double bond
Uses of poly(ethene)
- Plastic bags
- Bottles
- Clingfilm
- Kitchenware
Uses of poly(propene)
- Ropes
- Carpets
- Furniture
Uses of poly(chloroethene)
PVC
- Raincoats
- Drain pipes
- Window frames
Uses of poly(phenylethene)
- Expanded polystyrene is used for insulation in houses and packing
- Unexpanded polystyrene is used for toys and containers
What forces and bonds occur in polymers?
- strong covalent bonds join atoms to each other in individual polymer molecules
- weak VDW intermolecular forces occur between polymer molecules
Why do polymers have high melting and boiling point?
The hydrocarbon chains are often very long and the VDW forces between the chains are often very strong
