Chapter 13 - Alkenes

Question 1

What is the definition of an alkene?

Answer 1

Hydrocarbon homologous series with one double carbon-to-carbon bonds and the general formula CnH2n

Question 2

What is the name given to hydrocarbons that have a carbon-to-carbon double bond?

Answer 2

Unsaturated

Question 3

What is a pi-bond?

Answer 3

Formed by the sideways overlap of two p-orbitals with the electron density concentrated above and below the line joining the nuclei of the bonding atoms

Question 4

Why can’t the two carbon atoms rotate in a double bond?

Answer 4

The pi bond locks them in position

Question 5

Explain why the shape around the double bond of carbon atoms is trigonal planar?

Answer 5

There are three regions of electron density around each of the carbon atoms
The three regions repel each other as far as possible until the bond angle is 120°
All of the atoms are in the same plane

Question 6

Give the definition of a stereoisomer

Answer 6

They have the same structural formula but a different spatial arrangement

Question 7

Name the two types of stereoisomerism

Answer 7

E/Z isomerism and optical isomerism

Question 8

In what compounds can E/Z isomerism occur?

Answer 8

carbon-to-carbon double bond