Group 7, The Halogens

Front 1

(Group 7) Atomic Radius

Back 1

1. increases

2. higher principal energy level

3. further from nucleous

more shielding

Front 2

(Group 7) Electronegativity

Back 2

1. decreases

2. size of atom increases

3. more PEL (shielding)

So, the ability of nucleus to attract electrons is reduced

Front 3

(Group 7) Boiling Point

Back 3

1. diatomic molecules have weak van der waals forces between molecules

2. boiling point increases down group

3. size of atom increases

4. more van der waals forces between molecules

Front 4

(Group 7) Oxidising Ability

Back 4

1. decreases down group

2. atomic radius increases

3. shielding

4. gains electron less readily

Front 5

(Group 7) displacement reactions

Back 5

1. aqueous solution of halogen

2. added drop wise to colourless solution containing halide ions

3. observations show trend in ability to act as oxidising agent

Front 6

Observations for iodine

Back 6

Brown solution and black precipitate

Front 7

Observations for bromine

Back 7

Yellow/ brown solution of bromine

Front 8

Observations for chlorine

Back 8

no visible change, bromine is not a strong enough oxidising agent to oxidise chloride

Front 9

trends in reducing properties of halide ions

Back 9

1. increases down group

2. size increases

3. outer electrons become further away from nucleus

4. less attraction

5. able to lose electron more readily

Front 10

Reactions of halide ions with sulphuric acid

Back 10

1. trend in reducing power is shown through reaction

2. Oxidation state of S in H2SO4 is +6

3. Can be reduced to +4, 0 or -2 depending on reducing power of halide ion

Front 11

Redox reactions of concentrated sulphuric acid with solid sodium FLUORIDE

Back 11

NO REDOX

Front 12

Redox reactions of concentrated sulphuric acid with solid sodium CHLORIDE

Back 12

NO REDOX

Front 13

Reactions of concentrated sulphuric acid with solid sodium BROMIDE

Back 13

Oxidation state +4

H2SO4 → SO2

2Br- → Br2 + 2e-

Front 14

Reactions of concentrated sulphuric acid with solid sodium IODIDE to give sulphur dioxide

Back 14

Oxidation state +4

H2SO4 → SO2

2I- → I2 + 2e-

Front 15

Generic acid-base reaction

Back 15

2NaX + H2SO4 → Na2SO4 + 2HX

Front 16

Reactions of concentrated sulphuric acid with solid sodium IODIDE to give S

Back 16

Oxidation state 0

H2SO4 → S + 4H2O

2I- → I2 + 2e-

Front 17

Reactions of concentrated sulphuric acid with solid sodium IODIDE to give H2S

Back 17

Oxidation state -2

H2SO4 → H2S + 4H2O

2I- → I2 + 2e

Front 18

What are the redox products of sodium IODIDE?

Back 18

Iodine, sulphur, sulphur dioxide and hydrogen sulphide

Front 19

What are the redox products of sodium bromide?

Back 19

Bromine and sulphur dioxide

Front 20

Observation for all acid- base products (HX)

Back 20

Misty fumes

Front 21

Observation for Br2

Back 21

Brown Gas

Front 22

Observation for SO2

Back 22

Choking Gas

Front 23

Observation for S

Back 23

yellow solid

Front 24

Observation for H2S

Back 24

smell of rotten eggs

Front 25

Observation for I2

Back 25

Black solid with purple gas

Front 26

Reacation of NaF with silver nitrate

Back 26

None because AgF is soluble

Front 27

Reaction of NaCl with silver nitate

Back 27

White precipitate

Front 28

Reaction of NaBr with silver nitrate

Back 28

Cream precipitate

Front 29

Reaction of NaI with silver nitate

Back 29

Yellow precipitate

Front 30

Solubility of AgI (yellow precipitate) in ammonia solution

Back 30

Insoluble

Front 31

Solubility of AgBr (cream precipitate) in ammonia solution

Back 31

Partially soluble in dilute ammonia, soluble in concentrated ammonia

Front 32

Solubility of AgCl (white precipitate in ammonia solution)

Back 32

Soluble in dilute ammonia (colourless solution)

Front 33

Before silver nitrate is used to test for halide ions, what must be done to the halide solutions?

Back 33

As an aqueous solution is used HNO3 must be added to remove carbonates and hydroxides that would form a precipitate. HCl must not be used because it contains chlorine ions.