Group 7

Question 1

Explain the power as oxidising agents of the halogens

Answer 1

Decreases down the group because oxidising agents are reduced so gain electrons. As you go down the group, shielding of the positive nucleus increases and so it is harder to gain electrons

Question 2

Explain the power of halide ions as reducing agents

Answer 2

Increases down the group. Reducing agents are oxidised so lose elcectrons. As you go down the group of halide ions, the shielding increases so the outermost electrons are more weakly attracted to the nucleus and therefore more easily lost.

Question 3

Describe the trend in electronegativity of the group 7 elements

Answer 3

Decreases
As you go down the group, the number of electron shells increases, which increases shielding of the +ve nucleus which means electrons are hearder to attract

Question 4

Explain the trend in the boiling point of the halogens

Answer 4

Increases
Larger molecules have more electrons which means VdWs forces are stronger. This means they require larger amounts of energy to overcome
VdWs are the only forces present in the simple molecular model of the halogens

Question 5

Explain the trend in reactivity of halogens

Answer 5

Increases as you go down the group
Shielding increases so electrons are lost more easily

Question 6

Give examples of displacement reactions of the halogens in aqueous solution

Answer 6

2KCl + Br2 > 2KBr + Cl2
2KBr + Cl2 > 2KBr + Cl2 NO REACTION

Question 7

Describe the physical state of fluorine

Answer 7

Yellow gas

Question 8

Describe the physical state of Chlorine

Answer 8

Yellow-green dense

Question 9

Describe the physical state of bromine

Answer 9

Red-brown volatile liquid

Question 10

Describe the physical state of IODINE

Answer 10

Grey-black solid
Purple gas sublimation

Question 11

Describe the physical state of Astatine

Answer 11

Has no stable isotope

Question 12

Name the reaction(s) of sodium fluoride with conc sulfuric acid

Answer 12

NaF + H2SO4 > NaHSO4 + HF
Acid-base
Misty white fumes

Question 13

Name the reaction(s) of sodium chloride with conc sulfuric acid

Answer 13

NaCl + H2SO4 > NaHSO4 + HCl
Acid-base
Misty white fumes

Question 14

Name the reaction(s) of sodium bromide with conc sulfuric acid

Answer 14

NaBr + H2SO4 > NaHSO4 + HBr
HBr + H2SO4 > Br2 + SO2 + 2H2O

Misty white fumes (HBr)
Red-brown vapour (Br2)

Question 15

Name the reaction(s) of sodium iodide with conc sulfuric acid

Answer 15

NaI + H2SO4> NaHSO4 +HI
2HI + H2SO4 > I2 + SO2 + 2H2O
6HI + H2SO4 > 3I2 +S + 4H2O
8HI + H2SO4 > 4I2 + H2S + 4H2O

Misty white fumes HI
Purple vapour / Black solid(I2)
Yellow solid forms (S)
Rotten egg smell (H2S)

Question 16

Write an equation for the reaction of chlorine wit cold water

Answer 16

Cl2+H2O >< HCl +HClO

Question 17

Write an equation for when chlorine decomposes water in the presence of UV light

Answer 17

2Cl2+2H2O»4HCl + O2

Question 18

Write an eqaution for when chlorine reacts with cold aqueous NaOH

Answer 18

Cl2+2NaOH» NaClO+NaCl+H2O