Group 7

Question 1

How does electronegativity change as you go down the group?

Answer 1

Decreases
More shells, more sheilding
Weaker attracting between nucleus and outer electrons

Question 2

How does boiling point change as you go down the group?

Answer 2

Increases
Larger atoms, more electrons
Stronger vdw forces meaning higher temperatures needed to overcome the forces

Question 3

Halogens
What type of agent?
What happens as you go down the group?
What reactions occurs?

Answer 3

Oxidising
Oxidising decreases
Displacement - more reactive halogen displaces a less reactive halide

Question 4

Halide ion
What type of agent?
What happens as you go down the group?

Answer 4

Reducing
Reducing ability decreases

Question 5

Equations for NaH2SO4 with
Cl
Be
I

Answer 5

NaH2SO4 + NaCl —> NaHSO4 + HCl
NaH2SO4 + NaBe —> NaHSO4 + HBe
NaH2SO4 + NaI—> NaHSO4 + HI

Question 6

NaH2SO4
Is it redox?
What does one of the products produce?

Answer 6

No it’s not redox as they all have the same oxidation states
HCl produces a white misty fume

Question 7

Equations for SO2 with
Br
I

Answer 7

2Br- + H2SO4 + 2H+ —> Br2 + SO2 + 2H2O

2I- + H2SO4 + 2H+ —> I2 + SO2 + 2H2O

Question 8

SO2
What does one of the elements form?

Answer 8

Br forms an orange vapour

Question 9

Equation for S with I
What does sulfur form

Answer 9

6H+ + H2SO4 + 6I- —> 3I2 + 4H2O + S

Yellow solid

Question 10

Equation for H2S with I
What smell?

Answer 10

8I- + 8H+ + H2SO4 —> 4I2 + H2S + 4H2O

Question 11

How to identify Group 7
What do you use?
What is the method?
What are the results?

Answer 11

Use acidified silver nitrate

Add any amount of halide
Acidify with nitric acid ( not HCl because we test for chlorine and not H2SO4 because it will form a white ppt)
Add silver nitrate

F = No test
Cl = dilute NH3 and a white ppt
Br = Concentrated NH3 and a cream ppt
I = Concentrated NH3 and a pale yellow ppt that is insoluble in the NH3