A3 - Group 7

Question 1

What is the state of fluorine?

Answer 1

Gas

Question 2

What is the state of chlorine?

Answer 2

Gas

Question 3

What is the state of bromine?

Answer 3

Liquid

Question 4

What is the state of iodine?

Answer 4

Solid

Question 5

What is the state of astatine?

Answer 5

Solid

Question 6

What is the trend in electronegativity as you go down group 7?

Answer 6

As you go down group 7:
- Electronegativity decreases because…
- The number of protons increases
- The atomic radius increases
- Shielding increases
- These factors outweigh the increasing number of protons
- Meaning there is a weaker attraction between the nucleus and outer electron
- So there is less tendency to attract another electron to fill the outer shell

Question 7

What happens when group 7 elements react?

Answer 7

They are reduced, but can also be called oxidising agents.

Question 8

What is the colour of chlorine in an aqueous solution?

Answer 8

Pale green (almost colourless)

Question 9

What is the colour of chlorine in an organic solution?

Answer 9

Pale green (almost colourless)

Question 10

What is the colour of bromine in an aqueous solution?

Answer 10

Orange

Question 11

What is the colour of bromine in an organic solution?

Answer 11

Orange

Question 12

What is the colour of iodine in an aqueous solution?

Answer 12

Brown

Question 13

What is the colour of iodine in an organic solution?

Answer 13

Violet

Question 14

What is the oxidising power of chlorine, bromine and iodine in order of strongest oxidising agent to the weakest?

Answer 14

Strongest: Chlorine
Bromine
Weakest: Iodine

Question 15

Explain the trend in reactivity as you go down group 7:

Answer 15

As you go down group 7 the electron affinity decreases because:
- Atomic radius increases
- Shielding increases
- Nuclear attraction decreases so it becomes harder to gain an electron

Question 16

What is the observation of chloride ions with silver nitrate?

Answer 16

White ppt

Question 17

What is the observation of bromide ions with silver nitrate?

Answer 17

Cream ppt

Question 18

What is the observation of iodide ions with silver nitrate?

Answer 18

Yellow ppt

Question 19

What is the observation of chloride ions with dilute ammonia?

Answer 19

Ppt disappears

Question 20

What is the observation of bromide ions with dilute ammonia?

Answer 20

No change

Question 21

What is the observation of iodide ions with dilute ammonia?

Answer 21

No change

Question 22

What is the observation of chloride ions with concentrated ammonia?

Answer 22

Ppt disappears

Question 23

What is the observation of bromide ions with concentrated ammonia?

Answer 23

Ppt disappears

Question 24

What is the observation of iodide ions with concentrated ammonia?

Answer 24

No change

Question 25

What is the trend in electronegativity as you go down group 7?

Answer 25

As you go down group 7, electronegativity decreases because: - the number of protons increases - however atomic radius increases - and shielding increases - the last 2 factors outweigh the increasing number of protons - leading to a weaker attraction between the nucleus and outer electrons - this means that down the group, atoms are less able to attract a pair of electrons in a covalent bond