Alkenes Flashcards
What are alkenes?
general formula?
Unsaturated hydrocarbons (molecules made up of only hydrogen and carbon with at least one C=C double covalent bond).
general formula: CnH2n
What do you need to remember about unsaturated molecules?
They can make bonds with extra atoms in addition reactions.
Name and draw the displayed fomula for the following alkenes:
CH2CHCH3
CH2CHCHCH2
C5H8
What do you need to remember about cyclic alkenes?
A cyclic alkene has two fewer H’s than an open-chain alkene.
What is a double bond made up of?
a sigma bond and a pi bond.
Describe a sigma bond
Describe a pi bond
Why are alkanes so unreactive?
Why are alkenes more reactive than alkanes?
Why is it handy alkenes are so reactive?
What do you need to remember about double bonds?
Double bonds can’t rotate.
How does the double bond in an alkene affect its shape?
Why can’t double bonds rotate?
What do you need to remeber about the shape of larger alkenes?
What is a stereoisomer?
Molecules with the same molecular formula but a different arrangement in space.
What causes alkenes to form stereoisomers?
What causes alkenes to form stereoisomers?
Why do stereoisomers form?
stereoisomers occur when the two double-bonded carbon atoms each have two different atoms or groups attached to them.
What causes alkenes to form stereoisomers?
What are the two types of isomer formed from stereoisomerism?
an ‘E-isomer’ and a ‘Z isomer’ (hence the name E/Z isomerism).
What is characteristic of an ‘E isomer’/ a @Z isomer’?
Describe using the example but-2-ene.
What do you need to remember when naming stereoisomers?
you need to put an ‘E’ or ‘Z’ at the start of the name.
What is an easy wy to remeber the difference between an ‘E’ and a ‘Z’ isomer?
In the ‘Z’ isomer, the groups are on ‘ze zame zide’
In the ‘E’ isomer, they are ‘enemies’.
