C3e Group 7 – The Halogens

Group 7 elements are known as the ______________________.

They include:

Physical appearances at room temperature:

Halogen Formu

la

Colour and Physical

State

Use

Chlorine

•

•

Bromine

Iodine

What physical appearance would you predict for:

Fluorine –

Astatine (As) -

Sodium Chloride, NaCl

A very common compound of chlorine is sodium chloride. You need to learn it’s

formula, __________, and 3 important uses:

1.

2.

3.

Chemical Reactions of the halogens

The Reaction of the halogens with alkali metals:

The halogens react _______________ with the alkali metals

e.g. sodium + chlorine sodium

chloride

2Na Cl2 2NaCl

sodium + bromine

sodium + iodine

Fluorine and Astatine are also in group 7; can you predict how they would react

with sodium?

Displacement Reactions

The reaction of potassium bromide with chlorine is an example of a

_____________ reaction:

Potassium bromide + chlorine bromine + potassium

chloride

We call this a _______________ reaction because bromine has been

displaced and replaced by ______________

This happens because chlorine is ___________ reactive than bromine

A less reactive halogen cannot displace one which is _______ reactive

Investigating Displacement Reactions

The halogens can be placed in order of reactivity by investigating these

displacement reactions. You will now carry out this investigation and record the

results in the table below:

Analysis

Write word and symbol equations for the successful displacement reactions:

Conclusion

The halogen which displaced the most was ______________

The halogen which displaced the least was ______________

The most reactive halogen tested was _____________ and the least

reactive was _______________

The halogens get ___________ reactive down the group

Using this information, put a tick or a cross if your think that there would be

displacement in the following situations:

Potassium iodide + fluorine

Potassium chloride + fluorine

Potassium fluoride + chlorine

Potassium bromide + astatine (At)

Electronic Structure of the Halogens

The halogens all react in a similar way because of the similarities in their

electronic structure:

The chlorine, bromine and iodine are all in group ___ so they have ___

electrons in their outer shell

To achieve a full outer shell they need to _______ an electron from a

__________ atom and become a _____________ ion

Complete the following table:

Halogen Atom Electron structure Ion Electron

structure

Fluorine F 2,7 F- 2,8

Chlorine Cl Cl-

Bromine Br 2,8,18,7 Br-

Reduction (Remember OIL RIG)

When atoms gain an electron to become ____________ ions we say they

have been _____________

e.g.

Chlorine- Cl2 + 2e- 2Cl-

Bromine- Br +

Iodine-