Practice questions

Question 1

Explain why the boiling points in group 7 are low.

Answer 1

They are low because of the weak intermolecular forces which require little energy to overcome.

Question 2

Explain the trend in boiling points in group 7

Answer 2

As you go down the group the molecules are large so the forces between them increase thus the boiling points increase as you go down the group.

Question 3

What two substances does the molten mixture contain?

Answer 3

Cryolite and aluminium oxide

Question 4

Hot sodium is put in a gas jar of chlorine describe the observations made before during and after the reaction

Answer 4

Before - sodium is a metal
During - there is a yellow flame
after - sodium becomes a white solid/powder

Question 5

Explain why sodium is less reactive then potassium

Answer 5

Na has fewer energy levels/shells
Na outer shell electron is closer to the nucleus
forces of attraction are stronger
so electron is less likely given up

Question 6

What order did scientists use to arrange elements in the early periodic tables?

Answer 6

atomic weight

Question 7

Sate one difference and similarity in the electronic structure of sodium and of chlorine

Answer 7

Difference - Na has electrons one on outer shell and Cl has 7
Similarity - both have an incomplete outer shell of electrons

Question 8

Describe what happens when a sodium atom reacts with a chlorine atom

Answer 8

Sodium looses 1 electron to become positive

Chlorine gains 1 electronic to become negative