The Group 7 Elements – Revision Pack (C4)
The Halogens:
The Group 7 Elements all have similar properties because they all have seven
electrons in their outer shells. They have similar properties because they are trying to
gain one electron when they react. In the reaction with Group 1 elements, the
halogens form a negative ion and gain a full electronic structure.
Group 7 Element
Chlorine
Bromine
Iodine
Colour and state at room temperature
Green gas
Orange liquid
Grey solid
It is possible to predict the properties of
group 7 elements if you know properties of
the other halogens because they follow a
particular trend.
The nearer the outer shell is to the nucleus, the easier it is for an atom to gain one
electron. Therefore, the easier it is to gain the electron, the more reactive the
halogen. Fluorine is more reactive than Chlorine.
Reactions of Halogens:
When a halogen reacts with an alkali metal, a
metal halide is made. For example, when
potassium reacts with iodine, the metal halide
formed is potassium iodide. Word equation:
Potassium + iodine  Potassium Iodide
OR
2K + I2  2KI
The ‘ide’ is always the group 7 element.
Another equation is:
2Li
+
Br 2
Lithium is the alkali metal.

2LiBr
Bromine is the halogen.
Lithium Bromide is the metal halide.
The Group 7 Elements – Revision Pack (C4)
Displacement Reaction:
Halogen
Gas (R)
Chlorine
Bromine
Chlorine
Metal Halide (R)
Metal Halide (P)
Potassium
Bromide
Potassium
Iodide
Potassium
Iodide
Potassium
Chloride
Potassium
Bromide
Potassium
Chloride
Halogen
Gas (P)
Bromine
Colour
Iodine
Red/Brown
Solution
Red/Brown
Solution
Iodine
Orange Solution
REMEMBER:
Bromine can displace iodine.
Chlorine can displace bromine and iodine.
Iodine cannot displace either because it is the least reactive out of the three.
BECAUSE displacement is dependent on reactivity, we can predict the reactions
between halogen and metal halides.
Reduction:
REMEMBER - Reduction Is Gain, as shown in this ionic equation:
Br 2
+
-
2e-

2Br-
A molecule of bromine gains two electrons (one for each atom)
It becomes two bromide ions that are negative ions
This is reduction
The Group 7 Elements – Revision Pack (C4)
Past Papers:
PPQ(1):
OCR Gateway C4 C5 C6 SPECIMEN PAPER
The Group 7 Elements – Revision Pack (C4)
PPQ(2):
OCR Gateway B4 C3 P4 June 2013
The Group 7 Elements – Revision Pack (C4)
Mark Schemes:
PPQ(1):
PPQ(2):