Elements of the Sea: Group 7

Question 1

What are the solutions of chlorine bromine and iodine and why ( in terms of redox )

Answer 1

Oxidising agents because the elements gain electrons ( get reduced )

Question 2

What are the solutions of chloride bromide and iodide and why ( in terms of redox )

Answer 2

Reducing agents because the ions lose electrons

Question 3

Definition of halogen

Answer 3

Group 7 diatomic molecules

Question 4

Examples of halogens

Answer 4

Chlorine, Cl2
Bromine, Br2
Fluorine, F2

Question 5

Definition of halide ions

Answer 5

Group 7 ions

Question 6

Examples of halide ions

Answer 6

Chloride, Cl-
Bromide, Br-
Fluoride, F-

Question 7

Appearance of chlorine at room temp

Answer 7

Pale green gas

Question 8

Appearance of bromine at room temp

Answer 8

Dark red liquid

Question 9

Appearance of iodine at room temp

Answer 9

Shiny grey solid

Question 10

Appearance of aqueous solution of chlorine at room temp ( chlorine in water )

Answer 10

Pale green

Question 11

Appearance of aqueous solution of bromine at room temp ( bromine in water )

Answer 11

Orange/ yellow

Question 12

Appearance of aqueous solution of iodine at room temp ( iodine in water )

Answer 12

Brown

Question 13

Appearance of cyclohexane solution of chlorine at room temp

Answer 13

Pale green

Question 14

Appearance of cyclohexane solution of bromine at room temp

Answer 14

Red/ brown/ orange

Question 15

Appearance of cyclohexane solution of iodine at room temp

Answer 15

Violet

Question 16

What happens to the solubility of silver halides when you add ammonia ( give examples )

Answer 16

Sobulitt decreases as you go down the group

Eg. AgCl = soluble
AgBr = partly soluble
AgI = insoluble

Question 17

What happens when you mix Chlorine (aq) and bromide ion (aq)

-give equation & explanation

Answer 17

Yellow solution forms

Cl2 + 2Br- —> 2Cl- + Br2

= chlorine displaces bromide ion because chlorine has stronger oxidising power

Question 18

What happens when you mix Chlorine (aq) and iodide ions (aq)

-give equation & explanation

Answer 18

Brown solution forms

Cl2 + 2I- —> 2Cl- + I2

= chlorine displaces iodide ion because chlorine has stronger oxidising power

Question 19

What happens when you mix Bromine (aq) and iodide ions (aq)

-give equation & explanation

Answer 19

Brown solution forms

Br2 + 2I- —> 2Br- + I2

= bromine displaces iodide ion because bromine has stronger oxidising power

Question 20

What happens when you mix a halogen that has a weaker oxidising power than the halide

Eg. Bromine & chloride ions

Answer 20

No reaction

Question 21

Give the order of halogens in strongest to weakest of oxidising power

Answer 21

Chlorine
Bromine
Iodine

Question 22

What is the trend of oxidising power of halogens ad you go down the group

Answer 22

Decreases as you go down the group

Question 23

Explain why oxidising power decreases as you go down the group

Answer 23

1. Halogen atom gains an electron when it oxides the halide ion

• atomic radius increases
• increase shells
• increase shielding
• decrease ability to attract electrons ( gets weaker )

Question 24

Appearance of fluorine at room temp

Answer 24

Pale yellow gas

Question 25

What happens to the melting and boiling point as you go down the group

Answer 25

Increase

Question 26

Reason for trend in physical properties ( colour, mpt, bpt )as you go down the group

Answer 26

Strength of intermolecular forces increases as you go down the group

Question 27

What happens to reactivity as you go down the group

Answer 27

Decreases

Question 28

Why does group 7 reactivity decrease as you go down the group

Answer 28

• increase atomic radius
• increased shielding
• nuclear charge is further away from the outer shell to attract electrons

Question 29

What happens to ionisation energy as you go down the group

Answer 29

Decreases

Question 30

Why does ionisation energy decreases as you go down the group

Answer 30

• increase atomic radius
• increased shielding
• nuclear charge is further away from the outer shell
• less energy required to remove electrons