3 - Group 7 (17), the halogens

Question 1

State the four halogens

Answer 1

Fluorine, chlorine, bromine, iodine

Question 2

What colour is fluorine at rtp?

Answer 2

Pale yellow gas

Question 3

What is colour is chlorine at rtp?

Answer 3

Green gas

Question 4

What colour is bromine at rtp?

Answer 4

Red liquid that gives off dense orange fumes

Question 5

What colour is iodine at rtp?

Answer 5

Shiny grey solid

Question 6

What is the trend in boiling points down group 7?

Answer 6

Bp increases

Question 7

Why does boiling point increase down group 7?

Answer 7

Molecules become larger which allows for stronger VdW forces between molecules requiring more energy to overcome

Question 8

What is the trend in electronegativity down group 7?

Answer 8

Electronegativity decreases

Question 9

Why does electronegativity decrease down group 7?

Answer 9

Atomic radii increases due to increasing number of shells and is less able to attract bonding pair of electrons

Question 10

What is the trend of reactivity down group 7?

Answer 10

Reactivity decreases

Question 11

Why does reactivity decrease down group 7?

Answer 11

Less likely to gain an electron due to greater distance between the nucleus and electron

Question 12

Are halogens oxidising or reducing agents?

Answer 12

Oxidising agents

Question 13

Why are halogens oxidising agents?

Answer 13

They accept an electron

Question 14

What is the trend in oxidising ability down group 7?

Answer 14

Oxidising ability decreases

Question 15

What halide ions can chlorine displace?

Answer 15

• Bromide
• Iodide

Question 16

What are the 2 half equations and overall equation of when chlorine displaces bromide ions?

Answer 16

Oxidation
2Br^- → Br₂ + 2e^-

Reduction
Cl₂ + 2e^- → 2Cl^-

Overall
Cl₂ + 2Br^- → 2Cl^- + Br₂

Question 17

What are the 2 half equations and overall equation of when chlorine displaces iodide ions?

Answer 17

Oxidation
2I^- → I₂ + 2e^-

Reduction
Cl₂ + 2e^- → 2Cl^-

Overall
Cl₂ + 2I^- → 2Cl^- + I₂

Question 18

What halide ion can bromine displace?

Answer 18

Iodide

Question 19

What are the 2 half equations and overall equation of when bromine displaces iodide ions?

Answer 19

Oxidation
2I^- → I₂ + 2e^-

Reduction
Br₂ + 2e^- → 2Br^-

Overall
Br₂ + 2I^- → 2Br^- + I₂

Question 20

When bromide is displaced to form bromine, what colour change is observed?

Answer 20

Solution turns from colourless to orange/yellow

Question 21

When iodide is displaced to form iodine, what colour change is observed?

Answer 21

Solution turns from colourless to brown