Group 7 Halogens

Question 1

What are halogens?

Answer 1

Group 7 non metals that are poisonous and include: fluorine, chlorine, Bromine, Iodine and Astatine
They are diatomic

Question 2

Colours at room temp

Answer 2

Fluorine - yellow
Chlorine - pale green
Bromine - red-brown (readily evaporates to form a brown gas)
Iodine - grey solid (sublimes to form purple gas)

Question 3

Physical state (at room temp)

Answer 3

Fluorine - gas
Chlorine - gas
Bromine - liquid
Iodine - solid

Question 4

General properties of halogens

Answer 4

Non metals and so don’t conduct electricity
Brittle and crumbly when solid
Poisonous and smelly
Get darker as you go down the group

Question 5

Trends in melting point

Answer 5

Melting and boiling points increased down the group

Question 6

Trends in state at room temp

Answer 6

Physical states of halogens become more hard and set

Chlorine is a gas, bromine is a liquid and iodine is a solid

Question 7

Colour

Answer 7

Darker down the group

Question 8

Properties of other halogens (fluorine + astatine) melting and boiling point

Answer 8

Fluorine at the top so will have lowest melting + boiling point
Astatine at bottom so will have highest melting and boiling point

Question 9

States

Answer 9

Fluorine on top so will be a gas
Astatine on bottom so will be a solid
(States become more hard and set down the group)

Question 10

Colour

Answer 10

Fluorine at top so will be lighter (yellow)

Astatine on bottom so will be darker (black)

Question 11

Displacement reactions involving halogens

Answer 11

A more reactive halogen will displace a less reactive halogen from its compounds in solution

Question 12

How does electron structure affect reactivity?

Answer 12

Reactivity DECREASES down group

• atoms get larger down group
• -> outer shell gets further away from nucleus
• further outer shell is from pos attraction of nucleus, harder it is to attract another electron to complete outer shell

Question 13

What is the colour of the halide solution when chlorine and bromine react? What is the equation?

Answer 13

Yellow/orange
2KBr(aq) + Cl2 (aq) -> 2KCl (aq) + Br2 (aq)
Potassium bromide + chlorine -> potassium chloride + bromine

Question 14

What is the colour of the halide solution when potassium iodide is added to chlorine? +equation

Answer 14

Brown
2Kl (aq) + Cl2 (aq) -> 2KCl (aq) + I2 (aq)
Potassium iodide + chlorine -> potassium chloride + iodine

Question 15

What is the colour of the solution when potassium chloride is added to bromine?

Answer 15

No reaction (less reactive bromine cannot displace more reactive chlorine)
Colourless

Question 16

What is the colour of the solution when potassium iodide is added to bromine?

Answer 16

Brown
2KI (aq) + Br2 (aq) -> 2KBr (aq) + I2 (aq)
Potassium iodide + bromine -> potassium bromide + iodine

Question 17

Reaction with potassium chloride and and iodine?

Answer 17

No reaction , iodine less reactive so cannot displace chlorine

Question 18

Reaction : potassium bromide and iodine?

Answer 18

No reaction, iodine less reactive than bromine so cannot displace bromine

Question 19

What can we predict that astatine will do when reacted with iodine?

Answer 19

Will be displaced from solution by iodine