2 Group 7 (The halogens)

Question 1

What do all elements in group 7 have?

Answer 1

7 valence electrons.

Question 2

What do halogens form when they react with metals?

Answer 2

A wide range of salts.

Question 3

What are the halogens?

Answer 3

They are non-metallic elements with diatomic molecules.

Question 4

What is f2 (fluorine)’s physical state and colour at room temperature?

Answer 4

Gas, and it is yellow.

Question 5

What is Cl2 (chlorine)’s physical state and colour at room temperature?

Answer 5

Gas, and it is green.

Question 6

What is Br2 (bromine)’s physical state and colour at room temperature?

Answer 6

Liquid, and it is either a red-brown liquid or an orange/brown vapour.

Question 7

What is I2 (iodine)’s physical state and colour at room temperature?

Answer 7

Solid, and it is either a grey solid or a purple vapour.

Question 8

What happens to the melting and boiling points as we go down the group?

Answer 8

They increase due to the molecular mass increase.

Question 9

What happens because the halogens are non-metals?

Answer 9

They are poor conductors of heat and energy.

Question 10

How do halogens react with hydrogen?

Answer 10

To form hydrogen hallides.

Question 11

What is a hydrogen hallide?

Answer 11

It is a compound formed between hydrogen and a halogen with the formula HX where X stands for a halogen atom.

Question 12

What is an example of a hydrogen hallide?

Answer 12

Hydrogen fluoride.

Question 13

What are the properties of hydrogen hallides?

Answer 13

• Acidic, poisonous gases.
• The gases are covalently bonded.
• Very soluble in water and produce solutions of acids.

Question 14

What happens when we react a solution of a halogen with a solution containing hallide ions?

Answer 14

A displacement reaction occurs.

Question 15

What do the displacement reactions show us?

Answer 15

The fall in reactivity as we go down the group.

Question 16

How does the displacement reaction take place?

Answer 16

A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.

Question 17

There is a spectator ion in displacement reactions, what does it do?

Answer 17

It does nothing, and it just stays the same.

Question 18

What do they form with metals?

Answer 18

Ionic salts.

Question 19

What do they form with non-metals?

Answer 19

Covalent compounds.

Question 20

What are the main features of the halogens?

Answer 20

• They have coloured poisonous vapours, the colours of the elements get darker as you go down the group.
• They form ionic salts with metals and covalent compounds with non-metals.
• Will displace elements lower down the group from their salts.

Question 21

What are some predicted properties?

Answer 21

• Will be diatomic.
• Will be less reactive than iodine.
• Will be a very dark colour like very dark grey or black.