IGCSE CHEMISTRY
SECTION 2 LESSON 4
Content
The iGCSE
Chemistry
course
Section 1 Principles of Chemistry
Section 2 Chemistry of the Elements
Section 3 Organic Chemistry
Section 4 Physical Chemistry
Section 5 Chemistry in Society
Content
Section 2
Chemistry
of the
Elements
a)
b)
c)
d)
e)
f)
g)
The Periodic Table
Group 1 Elements
Group 7 Elements
Oxygen and Oxides
Hydrogen and Water
Reactivity Series
Tests for ions and gases
Lesson 4
f) Reactivity
Series
f) Reactivity series
2.29 understand that metals can be arranged in a reactivity series
based on the reactions of the metals and their compounds:
potassium, sodium, lithium, calcium, magnesium, aluminium, zinc,
iron, copper, silver and gold
2.30 describe how reactions with water and dilute acids can be
used to deduce the following order of reactivity: potassium,
sodium, lithium, calcium, magnesium, zinc, iron and copper
2.31 deduce the position of a metal within the reactivity series
using displacement reactions between metals and their oxides, and
between metals and their salts in aqueous solutions
2.32 understand oxidation and reduction as the addition and
removal of oxygen respectively
2.33 understand the terms redox, oxidising agent, reducing agent
2.34 describe the conditions under which iron rusts
2.35 describe how the rusting of iron may be prevented by grease,
oil, paint, plastic and galvanising
2.36 understand the sacrificial protection of iron in terms of the
reactivity series
What is the
REACTIVITY
SERIES?
The REACTIVITY
SERIES places metals in
order of their reactivity
based on how vigorously
they react with water and
dilute acids.
The Reactivity Series
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
INCREASING REACTIVITY
ELEMENT
The Reactivity Series
Very
reactive
{
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
INCREASING REACTIVITY
ELEMENT
The Reactivity Series
Very
reactive
Quite
reactive
{
{
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
INCREASING REACTIVITY
ELEMENT
The Reactivity Series
Very
reactive
Quite
reactive
Not so
reactive
{
{
{
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
INCREASING REACTIVITY
ELEMENT
The Reactivity Series
Very
reactive
Quite
reactive
Not so
reactive
Unreactive
{
{
{
{
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
INCREASING REACTIVITY
ELEMENT
Reaction with water
ELEMENT
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Very vigorous reaction with water,
forming the hydroxide. Fizzes, and
hydrogen is released.
2K(s) + 2H20(l)  2KOH(aq) + H2(g)
2Na(s) + 2H20(l)  2NaOH(aq) + H2(g)
2Li(s) + 2H20(l)  2LiOH(aq) + H2(g)
Reaction with water
ELEMENT
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Slow reaction with cold water (very slow
in the case of magnesium) to form the
hydroxide. Bubbles of hydrogen gas will
be seen.
Ca(s) + 2H2O(l)  Ca(OH)2(aq) + H2(g)
Mg(s) + 2H2O(l)  Mg(OH)2(aq) + H2(g)
Reaction with water
ELEMENT
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Do not react with cold water, but will
react with steam to form the oxide.
Hydrogen gas is produced.
Al(s) + 3H2O(l)  Al2O3(s) + 3H2(g)
Zn(s) + H2O(l)  ZnO(s) + H2(g)
Fe(s) + H2O(l)  FeO(s) + H2(g)
Reaction with water
ELEMENT
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
No reaction with water
or steam
Reaction with dilute acid
ELEMENT
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
These elements react with acid in a very
violent and dangerous manner. These
experiments would not normally be
attempted in the school laboratory.
Examples:
2K(s) + 2HCl(aq)  2KCl(ag) + H2(g)
2Na(s) + H2SO4(aq)  Na2SO4(aq) + H2(g)
Ca(s) + 2HNO3(aq)  Ca(NO3)2(aq) + H2(g)
Reaction with dilute acid
ELEMENT
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
These elements react reasonably well
with acid, and the reactivity decreases
as we go down the series.
Examples:
Mg(s) + 2HCl(aq)  MgCl2(ag) + H2(g)
Zn(s) + H2SO4(aq)  ZnSO4(aq) + H2(g)
Sn(s) + 2HNO3(aq)  Sn(NO3)2(aq) + H2(g)
Reaction with dilute acid
ELEMENT
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
No reaction with dilute
acids
Displacement reactions
What is a
DISPLACEMENT
REACTION?
A DISPLACEMENT
REACTION is one in which
a more reactive metal
displaces a less reactive
metal from a compound.
In other words, a metal
higher up in the reactivity
series will ‘push out’ a
metal that is lower in the
series.
“deduce the position of a metal within the
reactivity series using displacement
reactions between metals and their
oxides, and between metals and their
salts in aqueous solutions.”
“deduce the position of a metal within the
reactivity series using displacement
reactions between metals and their
oxides, and between metals and their
salts in aqueous solutions.”
Displacement reactions
Magnesium
ribbon fuse
Aluminium
powder +
iron oxide
Iron plug
A very violent
displacement reaction
occurs
Displacement reactions
Magnesium
ribbon fuse
Iron plug
Aluminium
powder +
iron oxide
Aluminium + Iron oxide  Aluminium oxide + Iron
Displacement reactions
Magnesium
ribbon fuse
Iron plug
Aluminium
powder +
iron oxide
Aluminium + Iron oxide  Aluminium oxide + Iron
Al(s) +
FeO(s) 
Al2O3(s) + Fe(s)
“deduce the position of a metal within the
reactivity series using displacement
reactions between metals and their
oxides, and between metals and their
salts in aqueous solutions.”
Displacement reactions
Iron
nail
Copper
sulphate
solution
Copper
deposit
Displacement
reaction
occurs
Iron
sulphate
solution
Displacement reactions
A displacement reaction occurs because iron is
higher than copper in the reactivity series
Iron
nail
Copper
sulphate
solution
Copper
deposit
Displacement
reaction
occurs
Iron
sulphate
solution
Displacement reactions
A displacement reaction occurs because iron is
higher than copper in the reactivity series
Iron
nail
Copper
sulphate
solution
Copper
deposit
Displacement
reaction
occurs
Iron
sulphate
solution
Copper sulphate + Iron  Iron sulphate + Copper
Displacement reactions
A displacement reaction occurs because iron is
higher than copper in the reactivity series
Iron
nail
Copper
sulphate
solution
CuSO4(aq) + Fe(s)
Copper
deposit
Displacement
reaction
occurs

Iron
sulphate
solution
FeSO4(aq) +
Cu(s)
Displacement reactions
Will displacement reactions occur?
Displacement reactions
Will displacement reactions occur?
METAL
SOLUTION
Lead
Iron sulphate
Lead
Copper sulphate
Iron
Zinc sulphate
Tin
Copper sulphate
WILL
DISPLACEMENT
HAPPEN?
Displacement reactions
Will displacement reactions occur?
METAL
SOLUTION
WILL
DISPLACEMENT
HAPPEN?
Lead
Iron sulphate
NO
Lead
Copper sulphate
YES
Iron
Zinc sulphate
NO
Tin
Copper sulphate
YES
Oxidation and Reduction
Understand oxidation and
reduction as the addition
and removal of oxidation
respectively
Oxidation and Reduction
Understand oxidation and
reduction as the addition
and removal of oxidation
respectively
Oxidation may be defined in three
ways:
1. Oxidation is the addition of
oxygen to a substance
2. Oxidation is the removal of
hydrogen from a substance
3. Oxidation is the loss of
electrons from a substance
Oxidation and Reduction
Understand oxidation and
reduction as the addition
and removal of oxidation
respectively
Examples of oxidation:
S(s) + O2(g)  SO2(g)
2CO(g) + O2(g)  2CO2(g)
Oxidation and Reduction
Understand oxidation and
reduction as the addition
and removal of oxidation
respectively
Reduction may be defined in three
ways:
1. Reduction is the removal of
oxygen from a substance
2. Reduction is the addition of
hydrogen to a substance
3. Reduction is the gain of
electrons by a substance
Oxidation and Reduction
Understand oxidation and
reduction as the addition
and removal of oxidation
respectively
Examples of reduction:
2Pb3O4(s)  6PbO(s) + O2(g)
2NaNO3(s)  2NaNO2(s) + O2(g)
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
What is
redox?
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
?
What is
redox?
In a redox reaction, both
reduction and oxidation occur.
For example, when hydrogen is
passed over heated copper
oxide, copper and water vapour
are formed.
Oxidation and Reduction
Copper oxide
Dry
hydrogen
Anhydrous
copper
sulphate
Excess
hydrogen
HEAT
In a redox reaction, both
reduction and oxidation occur.
The water vapour can be
trapped by the anhydrous
copper sulphate, turning it from
white to blue.
The excess hydrogen is burnt.
In a redox reaction, both
reduction and oxidation occur.
HEAT
CuO(s) + H2(g)  Cu(s) + H2O(g)
In a redox reaction, both
reduction and oxidation occur.
OXIDATION
HEAT
CuO(s) + H2(g)  Cu(s) + H2O(g)
In a redox reaction, both
reduction and oxidation occur.
OXIDATION
HEAT
CuO(s) + H2(g)  Cu(s) + H2O(g)
REDUCTION
In a redox reaction, both
reduction and oxidation occur.
OXIDATION
HEAT
CuO(s) + H2(g)  Cu(s) + H2O(g)
REDUCTION
REDOX
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
An oxidising agent is a substance
which brings about oxidation.
Eg. by adding oxygen to something
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
Eg. hydrogen peroxide
as an oxidising agent:
H2O2(l) + Na2SO3(aq)  Na2SO4(aq) + H2O(l)
An oxidising agent is a substance
which brings about oxidation.
Eg. by adding oxygen to something
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
reducing agent
A reducing agent is a substance which
brings about reduction.
Eg. by removing oxygen from
something
Oxidation and Reduction
Understand the terms
redox, oxidising agent,
agent
Eg. carbon monoxidereducing
as
a reducing agent:
3CO(g) + Fe2O3(s)  2Fe(s) + 3CO2(g)
A reducing agent is a substance which
brings about reduction.
Eg. by removing oxygen from
something
Oxidation and Reduction
Describe the conditions under
which iron rusts.
Describe how the rusting of
iron may be prevented by
grease, oil, paint, plastic and
galvanising.
Understand the sacrificial
protection of iron in terms of
the reactivity series
Oxidation and Reduction
Describe the conditions under
which iron rusts.
Describe how the rusting of
iron may be prevented by
grease, oil, paint, plastic and
galvanising.
Understand the sacrificial
protection of iron in terms of
the reactivity series
The corrosion of iron and steel is known as
rusting
Oxidation and Reduction
Describe the conditions under
which iron rusts.
Describe how the rusting of
iron may be prevented by
grease, oil, paint, plastic and
galvanising.
Understand the sacrificial
protection of iron in terms of
the reactivity series
Rusting is an oxidation process as it
results it the formation of iron oxide,
Fe2O3
Oxidation and Reduction
Describe the conditions under
which iron rusts.
Describe how the rusting of
iron may be prevented by
grease, oil, paint, plastic and
galvanising.
Understand the sacrificial
protection of iron in terms of
the reactivity series
Rusting requires both oxygen and water.
In the absence of either, iron does not
rust.
Rusting experiment
No rusting
Slow
rusting
Fast
rusting
Vaseline
Anhydrous
calcium
chloride
Cotton
wool
Dry air
Boiled water
Water
Dilute sodium
chloride
solution
Moisture
excluded
Air excluded
Air and water
Air, water and
salt
Prevention of Rusting
Prevention of Rusting
Surfaces can be painted, greased,
covered in oil or plastic.
Prevention of Rusting
Galvanizing :- iron or steel object is
dipped into molten zinc. Zinc is
higher in the reactivity series, so if
the surface is scratched, the zinc is
oxidised in preference to the iron.
Prevention of Rusting
Sacrificial metal,
eg magnesium
Prevention of Rusting
Sacrificial metal,
eg magnesium
The sacrificial metal is attached to the steel object.
Since magnesium is higher than iron in the reactivity
series of metals, magnesium is oxidised in preference to
iron. The magnesium is used up in this process, but can be
renewed.
End of Section 2 Lesson 4
In this lesson we have covered:
The Reactivity Series of Metals
Displacement reactions
Oxidation and reduction
Rusting