2.11.1 Group 7

Question 1

What is the formula, colour and standard state of fluorine?

Answer 1

F2, pale yellow, gas

Question 2

What is the formula, colour and standard state of chlorine?

Answer 2

Cl2, green-yellow, gas

Question 3

What is the formula, colour and standard state of bromine?

Answer 3

Br2, red-brown, liquid

Question 4

What is the formula, colour and standard state of iodine?

Answer 4

I2, black, solid

Question 5

What is produced when iodine is heated?

Answer 5

A purple vapour is produced

Question 6

What are the group 7 elements called?

Answer 6

The halogens

Question 7

What is the trend in boiling points down group 7?

Answer 7

The boiling point decreases down the group

• the atoms get larger
• the strength of the Van der Waals’ forces increase

Question 8

What is the trend in electronegativity down group 7?

Answer 8

All the halogens are strongly electronegative, with fluorine being the most, and iodine the least

Question 9

What is the trend in polarity of the hydrogen halides?

Answer 9

Hydrogen fluoride is strongly polar, and hydrogen iodide is almost non-polar

Question 10

Are halogens reducing or oxidising agents?

Answer 10

All halogens gain electrons to make the halide ions, so all the halogens are oxidising agents

Question 11

What is the trend in oxidising power down group 7?

Answer 11

The halogens get larger down the group, meaning their oxidising powers get weaker as they lose the ability to attract electrons

Question 12

What is a displacement reaction?

Answer 12

A redox reaction in which one halogen replaces another

Question 13

What is the trend in reducing power down the halide ions?

Answer 13

Halide ions become stronger reducing agents down the group

• more shielding
• less attraction between the nucleus and outer electrons
• the electrons are donated more easily

Question 14

Describe the process of the silver nitrate test to identify halide ions

Answer 14

1- add silver nitrate solution and look for a precipitate

2- add ammonia solution to see if the precipitate dissolves

Question 15

Why is a precipitate formed when silver nitrate is added to halide ions?

Answer 15

Silver nitrate is soluble in water and reacts with halide ions in solution to form silver halides

Question 16

Why should you add a few drops of dilute nitric acid to your test solution when doing the silver nitrate test?

Answer 16

To prevent the formation of other silver compounds such as silver carbonate

Question 17

What happens when silver nitrate is added to the fluoride ion?

Answer 17

There is no observable change

Question 18

What happens when you add silver nitrate to chloride ions?

Answer 18

A white precipitate is formed

Question 19

What happens when you add silver nitrate to bromide ions?

Answer 19

A cream precipitate is formed

Question 20

What happens when you add silver nitrate to iodide ions?

Answer 20

A yellow precipitate is formed?

Question 21

What is the trend in solubility from AgCl to AgI?

Answer 21

It decreases from AgCl to AgI