Module 3 Halogens

Question 1

What group is referred to as halogens?

Answer 1

Group 7.

Question 2

List two properties of halogens?

Answer 2

• Low melting and boiling points.
• Exist as diatomic molecules.

Question 3

What is the trend in boiling point down group 7? Why?

Answer 3

Increases down the group because;
- size of atom increases as more occupied electron shells, meaning stronger London forces of attraction between molecules, take more energy to break.

Question 4

What is the trend in reactivity down group 7? Why?

Answer 4

Decreases because;
- atomic radius increases
- electron shielding increases
- ability to gain an electron and form 1- ions decreases.

Question 5

Trend in oxidising down group 7? Why?

Answer 5

Decreases. This is because Cl has the fewest occupied electron shells, greatest force of attraction between outer electrons and nucleus and thus is the easiest to gain electrons and be reduced, meaning best oxidising agent.

Question 6

When a more reactive halogen displaces a less reactive halide, what is this reaction called?

Answer 6

Displacement reaction.

Question 7

Out of Cl-, Br- and I- which of these can be oxidised by chlorine?

Answer 7

Br- and I- ions.

Question 8

Out of Cl-, Br- and I-, which of these can be oxidised by bromine?

Answer 8

I- ions.

Question 9

Out of Cl-, Br- and I-, which of these can be oxidised by iodine?

Answer 9

Does not oxidise Cl- or Br-.

Question 10

Define disproportionation?

Answer 10

The oxidation and reduction of the same element in a redox reaction.

Question 11

What type of reaction is the reaction of chlorine and water?

Answer 11

Disproportionation; chlorine is both oxidised and reduced.