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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-