Group 7

Question 1

Describe the trend in electro negativity down the group

Answer 1

It decreases as
-nuclear charge increases
-atomic radius increases
-shielding increases
-the abliity to attract an electron decreases

Question 2

Describe the trend in boiling point down the group

Answer 2

-simple covelant molecules
- the number of electrons increases therefore induced dipole dipole forces increase down the group
- more energy is needed to overcome these forces

Question 3

Describe halogens as oxidising agents

Answer 3

F2 (g) + 2e- = 2F- (g)

Question 4

Describe the trend in reactivity and oxidiser agents down the group

Answer 4

-less reactive +weaker oxidising agents
-nuclear charge decreases
-atomic radius decreases
-shielding increases as more shells
-nuclear attraction decreases and the ability to attract electrons decreases

Question 5

What is a displacement reaction

Answer 5

More reactive element displaces less reactive element from a solution of the latters ions

Question 6

What colours are the halogens

Answer 6

Cl = pale green
Br = orange
I = brown (violet in hyclohexane or organic solution)

Question 7

Give the equation for chlorine displacing I for KI

Answer 7

KI + Cl2 = KCl + I2

Question 8

What are the 2 chlorine ions

Answer 8

Chlorate (1) OCl - (cl is in +1 state)
Chlorate (5) Cl03- (cl is in +5 state)

Question 9

What is a disproportionating reaction

Answer 9

The oxidation and reduction of the same element in a redox reaction

Question 10

The reaction of chlorine and water

Answer 10

Chlorine + water = hydrochloric acid + chloric (1) acid

Cl2(aq) + H20 (l) = HCl (aq) + HClO (aq)

Question 11

Chlorine in an alkaline environment in normal heat

Answer 11

Chlorine + sodium hydroxide
Cl2 (aq) + 2NaOH (aq) = Nacl (aq) + NaCl0 (aq) + H2O

Question 12

Chlorine in alkaline environment in heat

Answer 12

3cl2 + 6NaOH = 5NaCl +NaClO3 + 3H2O

Question 13

Describe the test for halide ions

Answer 13

•silver nitrate will form precipitate
• AgNO3
• KF + AgNO3 = AgF + KNO3
• dissolve in dilute it conc ammonia (NH3)

Question 14

Describe the carbonate test

Answer 14

•CO3 2-
• add acid (most likely nitric)
•effervescence as co2 is produced
• Na2Co3 + HNO3 = NaNo3 + H2O + CO2

Question 15

Sulphate test

Answer 15

•so4 2-
Add barium ions
Most likey barium nitrate
Forms precipitate as barium sulphate is insoluble
Ba (no3) 2 + na2so4 = baso4 (s) + nano3

Question 16

What is the correct test order

Answer 16

Carbonate
Sulphate
Halide ion
Ammonium /cation

Question 17

Describe the test for cations

Answer 17

Testing for nh4 +
Naoh is added
Nh3 (ammonium is produced)
Heat and use red litmus paper which turns blue as it is alkaline