Group 7

Question 1

Halogens

Answer 1

At room temperature:
Fluorine- pale yellow gas
Chlorine- green gas
Bromine- red brown liquid
Iodine- black or grey solid

Question 2

Boiling point

Answer 2

Increases down the group due to:
More mass and more electrons so greater size and surface area.
Stronger van der waals forces.
More energy needed to overcome these forces.

Question 3

Oxidising ability of the halogens

Answer 3

Halogens act as oxidising agents as they themselves get reduced.
Oxidising ability decreases down the group (fluorine is most reactive)

Question 4

Reducing ability of halides

Answer 4

Increases down the group (iodine most reactive).

Question 5

Reaction with silver nitrate

Answer 5

Fluoride- silver fluoride, no ppt
Chloride- silver chloride, white ppt
Bromide- silver bromide, cream ppt
Iodide- silver iodide, pale yellow ppt
To ensure these are pure solution must first be acidified using dilute nitric acid.
As differences are hard to see further testing using ammonia is required, in dilute silver chloride will dissolve and in concentrated silver bromide will dissolve.