C2 Group 7 Elements

Question 1

What are group 7 elements known as?

Answer 1

Halogens

Question 2

What type of elements make up group 7?

Answer 2

Non metals

Question 3

List the elements in group 7 (5)

Answer 3

Fluoride
Chlorine
Bromine
Iodine
Astatine

Question 4

How many electrons are in the outer shell of all group 7 elements?

Answer 4

7

Question 5

Complete the sentence

All group 7 elements have 7 electrons in their outer shells, so they all have similar ……

Answer 5

…..chemical properties

Question 6

Halogens exist as diatomic molecules. Explain

Answer 6

Sharing one pair of electrons in a covalent bond gives both atoms a full outer shell

Question 7

What happens to the melting and boiling points as you go down group 7 elements?

Answer 7

They increase

Question 8

What is fluorine like at room temperature and pressure?

Answer 8

Highly reactive, toxic, pale yellow gas

Question 9

What is chlorine like at room temperature and pressure?

Answer 9

Fairly reactive, poisonous, green gas

Question 10

What is bromine like at room temperature and pressure?

Answer 10

Poisonous, red-brown liquid, which gives off an orange vapour at room temperature

Question 11

What is iodine like at room temperature and pressure?

Answer 11

A dark grey crystalline solid which gives off a purple vapour when heated.

Question 12

Why do the melting and boiling points increase as you go down group 7?

Answer 12

Due to the increase in the number of electrons in each atom as you go down the group.

Question 13

Why is more energy needed to overcome the molecules as you go down group 7?

Answer 13

More electrons mean there are greater intermolecular forces between the molecules, so more energy is needed to overcome them.

Question 14

What happens to the reactivity as you go down group 7?

Answer 14

The halogens become less reactive.

Question 15

Why do the halogens become less reactive as you move down group 7?

Answer 15

It gets harder to attract the extra electron to fill the outer shell when it’s further away from the nucleus

Question 16

What are the salts formed from a reaction between halogens and alkali metals called?

Answer 16

Metal halides

Question 17

See p 24 for equations for halogens reacting with alkali metals

Answer 17

All reactions between group 1 and group 7 elements follow this pattern - make sure you can write equations for any of them.

Question 18

Why do halogens higher up group 7 react more vigorously with alkali metals?

Answer 18

Because they are more reactive.

Question 19

Why do all halogens have a similar reaction?

Answer 19

Because they have the same number of electrons in their outer shells.

Question 20

Why does knowing how one halogen reacts help you to predict how other halogens will react?

Answer 20

Because they have similar reactions, since all halogens have the same number of electrons in their outer shell.

Question 21

To know what type of salt is formed by a halogen, just replace ‘ine’ with what?

Answer 21

‘ide’

Question 22

What type of salt does fluorine form?

Answer 22

Fluoride salts

Question 23

What type of salt does iodine form?

Answer 23

Iodide salts

Question 24

The melting point of chlorine (Cl2) is -101.5 degree C.

Predict whether bromine (Br2) would be a solid, a liquid or a gas at -101.5 degree C. Explain your answer.

(2 marks)

Answer 24

Bromine would be a solid at this temperature (1 mark)

The melting point of the halogens increase as you go down the group, so at the melting point of chlorine, bromine would still be solid (1 mark)

Question 25

Writ a balanced symbol equation for the reaction between sodium metal (Na) and iodine (I2)

Answer 25

2Na + l2 -> 2Nal

1 mark for correct reactants and products, 1 mark for correctly balanced equation