Group 7 (17) - The Halogens (WIP)

Question 1

What happens to the atomic radius down group 7 and why?

Answer 1

It increases because there are more electron shells.

Question 2

What happens to the electronegativity down group 7 and why?

Answer 2

It decreases because the atoms get bigger and there is more electron shielding, therefore there is a weaker attraction between the nucleus and 2 electrons in a covalent bond.

Question 3

What happens to the melting and boiling points down group 7 and why?

Answer 3

They increase because the molecules get bigger, so there are more Van der Waals forces.

Question 4

What happens to the 1st ionisation energy down group 7 and why?

Answer 4

It decreases because the atoms get bigger and there is more electron shielding, therefore there is a weaker attraction between the nucleus and the outer shell electron.

Question 5

How do you test for a halide ion?

Answer 5

Add dilute nitric acid and silver nitrate.

Question 6

Why is dilute nitric acid added in the test for a halide ion?

Answer 6

In order to remove any other ions that could give a precipitate with silver nitrate ions.

Question 7

What are the results of the halide ions in the test for a halide ion?

Answer 7

Fluoride: no precipitate
Chloride: white precipitate
Bromide: cream precipitate
Iodide: yellow precipitate