Metals and their uses
Mining for metals
What do I need to know
Must
Discuss the financial benefit and expense of
obtaining metals
Should
Describe how ores and metals are mined
Could
Explain that reactive metals need a chemical
reaction to turn them into the metal
What is a metal?
Ductile – means it can be pulled into wires
Malleable – means it can be bent into shape
These are the key properties of metals.
What is an ore?
• A metal ore is the rock that contains the
compound that the metal is found in.
• It looks very different to the metal.
• It is not usually native metal but a compound
such as iron oxide, copper oxide or lead oxide.
• The ore has different properties to metals. It
does not conduct electricity and cannot be
hammered into shape.
Mining
• Ores are extracted from the earth using
mining and quarrying.
• This can cause damage to the environment if
open quarrying is used and may be noisy and
dusty.
• There will also be lorries and trucks which
produce carbon dioxide as they carry the
mined ore away from the quarry or mine.
Test your understanding
Unreactive metals such as ______ are found in
the Earth as the _______ itself.
Most metals are mined as ___________ called
ores that require chemical reactions to _______
the metal.
Metals from ores
Reactivity series
What do I need to know?
Must
Recall the position of different elements on the
reactivity series
Should
Describe how the position of an element on the
reactivity series determines how to extract it
Could
Explain that carbon is used in a blast furnace to
reduce iron oxide to iron
Reactivity series
• All metal elements have a different reactivity.
• Some such as sodium are very reactive even in
air.
• Others such as gold are extremely unreactive
Recalling the reactivity series
More reactive
Sodium
Magnesium
Aluminium
Titanium
Carbon
Zinc
Iron
Lead
Copper
Gold
Extracting metals
• A metal can be extracted from a compound by
reacting with an element higher up in the
reactivity series.
• So for example copper is more reactive than
silver.
• If we add copper metal to silver nitrate
compound we make silver metal.
• This is called a DISPLACEMENT REACTION
Extracting iron
• Iron ore (haematite) is iron oxide.
• To make iron we need to remove the oxygen.
• This process is called REDUCTION
Copy down this equation and the symbol
equation. Be able to balance this equation!
Iron oxide + carbon  Iron + Carbon dioxide
2Fe2O3 + 3C  4Fe + 3CO2
Extracting Iron from its ore
• Carbon is part of the reactivity series and is
higher (more reactive) than iron.
• This means iron can be extracted from its ore
using carbon.
• This takes place inside a BLAST FURNACE
Test your knowledge
Metals that are ______ reactive than carbon in
the reactivity series can be ___________ from
their oxides by _________ with ________.
Iron oxide is reduced in the _________
________ to make iron.
[extracted, reduction, carbon, less, blast
furnace]
Summary
Recall the position of different elements on the
reactivity series
Describe how the position of an element on the
reactivity series determines how to extract it
Explain that carbon is used in a blast furnace to
reduce iron oxide to iron
Steelmaking and alloys
BOS Process
What do I need to know?
Recall that most iron is converted into steels.
Describe how steels are alloys since they are
mixtures of iron with carbon.
Explain that alloys can be designed to have
properties for specific uses.
Why make steel?
• Pure iron is relatively soft and not
very strong.
• The iron from the blast furnace is
very hard and brittle. It contains
about 4% carbon and is used as
cast iron.
• We need an iron that is in
between these two extremes.
Basic oxygen steelmaking
Carbon steels can be made by the following
processes:
• blowing oxygen into molten cast iron to
remove most of the carbon as carbon dioxide;
then…
• adding a calculated amount of carbon.
The BOS process
Test your knowledge
• _____ is made from cast iron by blowing _____ into
a large vessel containing molten iron.
• Oxygen reacts with _____ in the iron to make carbon
dioxide and carbon monoxide
• The steel has _____ carbon than cast iron.
• ____ _____ is added to cool the reaction.
Alloys
• An alloy is a metal that contains other
elements.
• Cast iron is an alloy
Alloys with carbon
• Low carbon steel is easily shaped (more
bendy).
• High carbon steel is hard and brittle (strong
but not easily shaped).
Hardness and tensile strength
• Carbon atoms get in the way of the iron atoms
making the steel harder and less malleable.
• The strength of the steel is also affected by
the amount of carbon in the steel. We call this
the TENSILE STRENGTH.
• It is important to get the right balance
between HARDNESS AND TENSILE STRENGTH.
Why alloy?
To change the properties for example to be:
• harder
• stronger
• rust less or not at all
• lighter
• heavier
• a different colour
Stainless steel
• This is an example of a very useful alloy of
iron. It contains lots of different elements in
small amounts.
• The most important addition is chromium and
this stops the metal from rusting.
Other alloys
Most metals in everyday use are alloys.
are
for many uses and so are mixed with small
amounts of similar metals to make them harder.
Why recycle?
You need to know three main reasons:
• Preserve raw materials and ores
• Save the energy used extracting new metal
from its ore
• Reduce the waste going to landfill.
Extracting reactive metals
Reduction of metals high in the
reactivity series
What do I need to know?
Recall that elements below carbon in the reactivity
series can be reduced from their ores using carbon
in a furnace.
Describe how more reactive metals can be obtained
using electrolysis.
Explain why this means that aluminium and
titanium are expensive metals to obtain and how
important it is to recycle them.
Recalling the reactivity series
Sodium
Magnesium
Aluminium
Titanium
Carbon
Zinc
Iron
Lead
Copper
Gold
Titanium manufacture
• Can you select a metal that could extract
titanium from its ore?
• In practice magnesium is used.
• http://www.youtube.com/watch?v=XsdRo5jv
nXo&feature=related
• This means that titanium is incredibly
expensive due to the many stages required.
Test your understanding
1. What is the chemical process called when
you obtain a metal from its ore?
2. Which metal is used to extract titanium?
3. Why is titanium so expensive?
Titanium Manufacture
1. What is the chemical process called when
you obtain a metal from its ore?
– Reduction
2. Which metal is used to extract titanium?
– Magnesium
3. Why is titanium so expensive?
– The process takes a long time, uses expensive
raw material, uses a lot of energy and
manpower.
Aluminium and electrolysis
• Aluminium is extracted using
• In electrolysis an electric current is used to
the aluminium when it is in molten
bauxite (aluminium oxide)
is added to lower the melting point of
bauxite so it can be more easily melted.
Aluminium and electrolysis
• Aluminium is formed at the negative
electrode or
Test your knowledge
1. What is the method used to extract
aluminium called?
2. What substance is added to help make the
aluminium ore (bauxite) molten?
3. Which electrode (positive or negative) does
the aluminium form at?
4. Why is making aluminium expensive?
Test your knowledge
1. What is the method used to extract aluminium
called? REDUCTION BY ELECTROLYSIS
2. What substance is added to help make the
aluminium ore (bauxite) molten? CRYOLITE
3. Which electrode (positive or negative) does the
aluminium form at? NEGATIVE CATHODE
4. Why is making aluminium expensive? HIGH
ENERGY COST TO MAKE ORE MOLTEN. ENERGY
USED FOR ELECTROLYSIS
Why do we bother?
• If electrolysis for aluminium and the
extraction of titanium with magnesium are so
expensive then why not just use steel?
• Aluminium and titanium are valuable metals
because of their properties.
• Aluminium is light and does not rust
• Titanium is hard and has a very high melting
point.
Copper mining and extraction
can be dug up (mined) via
traditional means
• Copper sulfide ore is turned into copper oxide.
This produces sulfur dioxide (SO2) that can
contribute to
.
• Copper oxides is then
(burned in a
furnace) with carbon.
• This
to copper in a
similar way to the blast furnace for iron, by
reacting with carbon to remove the oxygen as
CO2.
Copper electrolysis
• Copper is present in the solution as
.
• These positively charged copper ions move to
the
• Here they gain electrons to become Cu or
Copper which
.
• This
the copper as other impurities do
not travel to the cathode to be deposited.
Copper purification
Problems with traditional copper
mining
• Copper is extracted from its ores by chemical
processes that involve
• this contributes to greenhouse gases and
.
• copper-rich
and
• traditional mining and extraction have
.
Bioleaching
• Copper can also come from
• Bioleaching is the extraction of copper from
its ore through the use of living organisms
(
).
• This is much
than the traditional
leaching using cyanide or smelting as no
greenhouse gases are produced from burning
coal.
Phytomining
involves using plants to extract
the metal compounds present in
.
• Once the plants have been grown they are
burned to produce
.
• The metal can then be extracted using
.
• This is
.
Summary
Recall that elements below carbon in the reactivity
series can be reduced from their ores using carbon
in a furnace.
Describe how more reactive metals can be obtained
using electrolysis.
Explain why this means that aluminium and
titanium are expensive metals to obtain and how
important it is to recycle them.
Transition metals
Uses and properties
What do I need to know?
Must
Recall the general properties of metals and how
they differ from non metals
Should
Describe how the uses of metals are determined by
their properties
Could
Identify where transition metals are found on the
periodic table and identify three examples.
Transition metals
Transition metals are found in the middle section of
the periodic table.
Find this section on the periodic table in your
planner and write down at least three examples of
transition metals you have heard of. Two examples
are gold, Au and iron, Fe.
Some transition metals are very rare and very
valuable.
Identifying transition metals
Circle the elements you think are transition
metals.
Uses of transition metals
• Gold – precious metal, rare so very expensive yellow and
shiny, used for jewellery and electrical contacts
• Platinum – precious metal, rare so very expensive, silvery,
shiny, used for jewellery
• Iron – available in large quantities, strong, hard and high
tensile strength, can be made corrosion resistant, used in
building
• Copper – high electrical conductivity, ductile (can be made
into wires), malleable (can be made into pipes), used in
electrical wires and plumbing. Has coloured compounds.
• Zinc – corrosion resistant when galvanised or oxidised, can
be given an attractive finish, used in dustbins,
wheelbarrows and other outdoor applications.
• Tungsten – very high melting point, ductile and high tensile
strength, used in lightbulb filaments.
Complete the table
The first two have been done for you
Property
Use
Example metal
Good conductor of
electricity
Used to make electrical
wires
Copper
Shiny
Used to make mirrors and
jewellery
Silver
Good conductor of heat
Dense
Strong
High melting point
Magnetic
Test your understanding
Copper is used to make the electrical wires in
our houses. Silver is an even better conductor of
electricity than copper.
Why don’t we use silver to make the wires for
the electric circuits in our houses?