Group 7- The Halogens

Question 1

Electronegativity down Group 7

Answer 1

Electronegativity decreases down the group
Atomic Radius incresases
Electron Shielding increases
Electrons in the neighbouring orbitals are less attracted to the nucleus

Question 2

Boiling Point down Group 7

Answer 2

Boiling point increase down the group
Simple molecules ger larger
More Van Der Waals forces between molecules

Question 3

Trend in Oxidising Ability / Reactivity

Answer 3

Decreases down the group
AR Increases
ES Increases
NC Increases (outweighed)

Attraction of nucleus to outside shell decreases, attracting incoming electrons decreases

Question 4

Trend in Reducing Ability

Answer 4

Reducing ability down the group Increase
Ions get bigger so are further away from the nucleus
Extra inner electron shells so greater shielding effect

Question 5

NaF or NaCl with H2SO4

Answer 5

NaF (s) + H2SO4 (l) —-> NaHSO4 (s) + HF (g)
NaCl (s) + H2SO4 (l) —-> NaHSO4 (s) + HCl (g)

Obs: Steamy fumes

Question 6

NaBr with H2SO4

Answer 6

NaBr (s) + H2SO4 (l) —-> NaHSO4 (s) + HBr (g)
2HBr (aq) + H2SO4 (l) —-> Br2 (g) + SO2 (g) + 2H2O (l)

Obs: HBr- Misty fumes
SO2- Choking gas

Question 7

NaI with H2SO4

Answer 7

NaHSO4 (s) + HI (g)
2HI (g) + H2SO4 (l) —-> I2 (g) + SO2 (g) + 2H2O (l)

Obs: Solid black iodine is formed
H2S (g) is a smells of bad eggs

Question 8

Silver nitrate with F-

Answer 8

AgF- No Precipitate

Question 9

Silver nitrate with Cl-

Answer 9

AgCl- White Precipitate

Question 10

Silver nitrate with Br-

Answer 10

AgBr- Cream Precipitate

Question 11

Silver nitrate with I-

Answer 11

AgI- Pale yellow precipitate

Question 12

What does adding HNO3 do beforehand?

Answer 12

Removes impurities such as hydroxides and carbonates

Question 13

F-

Answer 13

No Precipitate
Soluble in Water
Soluble in Dilute Ammonia
Soluble in Conc Ammonia

Question 14

Cl-

Answer 14

White precipitate
Soluble in Dilute Ammonia
Soluble in Conc Ammonia

Question 15

Br-

Answer 15

Cream precipitate
Soluble in Conc Ammonia

Question 16

I-

Answer 16

Pale Yellow Precipitate
Not Soluble in water, dil. ammonia or conc. ammonia

Question 17

Reaction of Chlorine with Water

Answer 17

Cl2(g) + H2O (l) ——> 2H+ (aq) + Cl- (aq) + ClO- (aq)
<——

• Disproportionation reaction

Question 18

Reaction of Chlorine and Water in Sunlight

Answer 18

2Cl2 (g) + 2H2O (l) ——> 4H+ (aq) + 4Cl- (aq) + O2 (g)
<—–

Question 19

Advantages of Chlorination

Answer 19

Kills bacteria preventing diseases

Question 20

Disadvantages of Chlorination

Answer 20

Toxic if not managed
Wasteful

Question 21

2Reaction of Chlorine and Sodium Hydroxide to make Bleach

Answer 21

2NaOH(aq) + Cl2 (g) —-> NaClO (aq) + NaCl (aq) + H2O (l)

• Sodium (i) chlorate kills bacteria