Chapter 13 - Alkenes

Question 1

What is the bonding in alkenes?

Answer 1

σ bonds and π bond

Question 2

What is a π bond?

Answer 2

• Sideways overlap of two p-orbitals
• High electron density above and below plane of carbon atoms

Question 3

What is the bond angle and shape of an alkene?

Answer 3

120º
Trigonal planar

Question 4

What is stereoisomerism?

Answer 4

Same structural formula but a different arrangement of atoms in a space

Question 5

What conditions must a molecule meet to have E/Z isomerism?

Answer 5

• A C=C bond
• Different groups attached to each carbon atoms of the double bond

Question 6

What type of reaction do alkenes undergo?

Answer 6

Electrophilic addition

Question 7

Why are alkenes more reactive than alkanes?

Answer 7

Presence of π bond which readily breaks due to
- Lower bond enthalpy than σ bonds
- Electrons more exposed

Question 8

What is an electrophile?

Answer 8

Electron pair acceptor

Question 9

What type of polymerisation do alkenes undergo?

Answer 9

Addition

Question 10

What are uses of polymers?

Answer 10

• Recycling
• Energy production through combustion
• Chemical feedstocks

Question 11

What are the problems with burning polymers for the environment?

Answer 11

Combustion of halogenated plastics forms toxic waste products e.g. HCl gas