Minerals, elements and the Earth’s crust:
teachers’ notes
Level
This activity is suitable for students aged 11-14.
Topic
The activity uses questions about the composition of minerals and ores to reinforce
work on elements, compounds, symbols and formulae.
Description
The activity includes two tables. One gives information about the most common
elements in the Earth’s crust and the other the chemical composition of some
minerals. Students answer questions based upon the information in these tables.
This would be a useful exercise for homework or to be used in the case of teacher
absence.
Context
Students need to be familiar with chemical elements, symbols, compounds and
formulae.
Teaching points
Reference books and / or internet access should be available to help students
tackle the research questions. Alternatively, teachers may wish to make the
questions that refer to Table 2 easier, and less dependent on reference sources, by
filling in some more of the cells in the table.
Timing
About half an hour.
Resources
Each student will need a copy of the Periodic Table.
The activity
Students tackle a series of questions based on tables giving information about the
most common elements in the Earth’s crust and about the chemical composition of
some minerals.
Answers to questions
Q 1. Appropriate bar chart.
Q 2. Oxygen.
Q 3. Magnesium.
Q 4. They are found combined because they are relatively reactive elements and
combine with oxygen from the atmosphere and with other elements to form
compounds.
Q 5. A compound.
Q 6. Magnesium (because it is the rarest). No definite answer is possible
because there is no information about the ease of extraction of any of the
elements.
Q 7. See Table 1
Mineral name
Chemica
l formula
How many
atoms of
each element
are present in
the formula
Useful
elemen
t
Uses of
this
element
Galena PbS Lead x 1
Sulfur x1
Lead
Flashing
(rainproof
strips) on
roofs, car
batteries
Pyrite FeS
2
Iron x 1
Sulfur x
2
Sulfur
(pyrite
is
not
used
as
an ore of iron)
Making
sulfuric acid
Chalcopyrite CuFeS
2
Copper x
1 Iron x 1
Sulfur x 2
Copper Plumbing
pipes and
electrical
wires. Coinage
Chalcocite Cu
2
S
Copper x 2
Sulfur x 1
Copper Plumbing
pipes and
electrical
wires. Coinage
Bauxite Al
2
O
3
Aluminium x 2
Oxygen x 3
Aluminium Making alloys
for aircraft,
packaging,
electrical use
Magnetite Fe
3
O
4
Iron x 3
Oxygen x 4
Iron Making steel
for
construction,
transport,
packaging
Haematite Fe
2
O
3
Iron x 2
Oxygen x 3
Iron Making steel
for
construction,
transport,
packaging
Rutile TiO
2
Titanium x 1
Oxygen x 2
Titanium Making alloys
for aircraft
parts
Table 1 Answers