General- Alkenes

Question 1

Describe the bonding in alkenes

Answer 1

Alkenes have a double bond of a strong sigma and 1 weak pi bond
The pi if formed from side on overlap of unhybridised py orbitals
The sigma is the end on overlap of sp2 orbital
Sp2 and s form C-H bond

Question 2

What hybridisation is the carbon atom

Answer 2

Sp2 hybridised

Question 3

What is the bond angle of the carbon atoms

Answer 3

120 degrees

Question 4

Can alkenes have isomers?

Answer 4

Yes they can have E or Z isomers due to the restrictive rotation around the double bond

Question 5

Are Z or E isomers easier to make?

Answer 5

E isomers are easier to make as they are more stable due to reduced steric strain
They are energetically favourable

Question 6

Other than sterics, what else affects compound stability

Answer 6

The electronic effects of the bonded substituents also affect stability
More ch3 bonded means more +I groups, these groups can stabilise a carbocation as they are electron donating

Question 7

How do you name an alkene?

Answer 7

1) select the longest continuous chain and add ene
2) begin numbering at the end of the chain closes to the double bond
3) assign stereochemistry