Module 4

Question 1

What are made in heterolytic fission?

Answer 1

Ions

Question 2

What is a radical?

Answer 2

A species with an unpaired electron

Question 3

What does the dot represent on a radical?

Answer 3

It shows the unpaired electron

Question 4

What are the conditions for radical substitution?

Answer 4

UV light or 300 degrees

Question 5

What is radical substitution?

Answer 5

Where a radical replaces a different atom or a group of atoms

Question 6

What is termination?

Answer 6

The final step in radical substitution where two radicals combine

Question 7

What are made in homolytic fission?

Answer 7

Radicals

Question 8

What is heterolytic fission?

Answer 8

One of the atoms takes both of the shared pair of electrons

Question 9

What is homolytic fission?

Answer 9

Each atom takes one of the shared pair of electrons

Question 10

Why are there several possible termination steps?

Answer 10

Because there is a large number of radicals in the reaction mixture

Question 11

Why is propagation a chain reaction?

Answer 11

The chlorine is used in the first step but made again in the second step. So the cycle will just keep going

Question 12

What is propagation?

Answer 12

The two repeated steps that build up the products in a chain reaction

Question 13

What is the first step called in free radical substitution?

Answer 13

Initiation

Question 14

What is the definition of a mechanism?

Answer 14

A sequence of steps showing the movement of electrons in a reaction

Question 15

What are nucleophiles?

Answer 15

Nucleophiles are electron pair donors.
They are attracted to positive charge.

Eg. Hydroxide ion in a molecule of water

Question 16

What are electrophiles?

Answer 16

They are electron pair acceptors.
They are attracted to negative charge.

Eg. Hydrogen in HBr

Question 17

What is markovnikoff’s rule?

Answer 17

Hydrogen is added to the carbon with the most hydrogens and the halide is attracted to the carbon with the least hydrogens.

Eg. Br will go to the carbon with the most alkyl groups attached

Question 18

What are intermediaries?

Answer 18

They are atoms, molecules, ions or free-radicals which do not appear in the overall equation but are instead formed during one step and the used up in the next

Question 19

What is a primary carbocation?

Answer 19

It’s a carbocation that has one alkyl group attached to C+. It’s also the most unstable

Question 20

What is a secondary carbocation?

Answer 20

A carbocation with two alkyl groups attached to C+. It is more stable than a primary carbocation

Question 21

What is a tertiary carbocation?

Answer 21

A carbocation with three alkyl groups attached to C+ and is more stable than a secondary or primary carbocation.

Question 22

What happens when a molecule such as HBr or HCl is added to an unsymmetrical alkene?

Answer 22

There will be two possible products; a major and a minor product.

Question 23

What is structural isomerism?

Answer 23

Same molecular formula but atoms are arranged differently

Question 24

Define photodegradable?

Answer 24

Where something is degraded by the sun

Question 25

Define biodegradable?

Answer 25

Where something is degraded by enzymes