Oxidising power of halogens

Question 1

oxidation number of an element

Answer 1

always 0

Question 2

oxidation number of ions

Answer 2

same as its charge (NaCl has no charge, so Na is +1 and Cl is -1)

Question 3

trend in oxidation numbers

Answer 3

the more positive the number, the more it has been oxidised (the more negative electrons it has lost). The more negative, the more reduced

Question 4

rule exceptions

Answer 4

H is usually +1, but in metal hydrides its -1
O, -2 (peroxides -1, and the compound OF2, where its +2)
F, -1
Cl, -1 (except for with F or O where its positive)

Question 5

Which halogen has the strongest oxidising power (i.e which is best at stealing electrons?)

Answer 5

Chlorine, bromine then ikodine

Question 6

Explanation of trend in oxidising power

Answer 6

Down the group it becomes harder to gain an electron because atoms are larger and there is more shielding (due to extra electron shell).

Question 7

Colour of;
Bromide
Iodide

Answer 7

Yellow

Brown

Question 8

Which halogen has the strongest reducing power?

Answer 8

Iodine
Bromine
Chlorine

Question 9

Explanation of reducing power

Answer 9

When a halide acts as a reducing agent it is losing electrons. Down the group it becomes easier to lose an electron because ions are larger and there is more shielding due to an extra electron shell.