Alkenes Flashcards
What are alkenes
Unsaturated hydrocarbons that contain at least one carbon double bond
What is the general formula for alkenes
What type of alkene is the exception
CnH2n
Cyclic alkenes
What is an electrophile
And electron deficient species (will accept a lone pair of electrons)
When do alkenes undergo addition reactions
What is the mechanism called
When they are attacked by electrophiles
Electrophilic addition
What is a carbocation
An ion with a positively charged carbon atom
How do you test for alkenes
Add a few drops of bromine water to the test liquid and shake it
If a carbon carbon double bond is present then it will turn from orange to colourless
What is an intermediate
Something that is formed in one step and then used up in another
What is the relation between a carbocation and the number of alkyl groups it is bonded to
The more alkyl groups it’s bonded to the more stable the carbocation is because alkyl groups are electron realising so stabilise the positive charge
How is a polymer formed
When thousands of repeating units made from small molecules called monomers join together to form a long chain molecule
What happens during addition polymerisation
Unsaturated molecules ie alkenes add together to form polymers
How are polymers named
Add the word poly as a prefix in front of monomer name for example Ethernet becomes polyethene
What is the repeating unit
The part of the polymer whose repetition would produce the complete polymer chains
What should you remember when drawing repeating units
Don’t include the n
Extend lines out of brackets
What is the reactivity of addition polymers
They tend to be unreactive because they are saturated and usually non polar as there is no C with a delta plus charge
For them to react the carbon carbon bonds would have to be broken which are extremely strong
What are the intermolecular forces between polymer chains
Usually weak intermolecular forces ie van der waals or permanent dipole dipole forces
