Summary notes for CIE IGCSE Chemistry Topic 10: Metals
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Course
Chemistry
Institution
GCSE
Complete revision notes for Topic 10 of the CIE IGCSE Chemistry course: Metals. Explanations with diagrams for every specification point. These notes are written for candidates taking the Extended paper.
High melting and boiling point (strong metallic bonds)
Good conductors of heat and electricity (delocalised electrons)
Malleable and ductile (layers can slide without disrupting electrostatic attractions)
Describe the general chemical properties of metals, e.g., reaction with dilute acids and
reaction with oxygen
The chemical properties of metals are studied by an observation of reactions with water,
dilute acid and oxygen. This allows a reactivity series to be formed.
Reactivity with water
Some metals react with water, either warm or cold, or with steam.
Metals that react with cold water form a metal hydroxide and hydrogen gas, for example
calcium:
Ca + 2H2O → Ca(OH)2 + H2
Metals that react with steam form metal oxide and hydrogen gas, for example zinc:
Zn + H2O → ZnO + H2
Why different products? This is because metal hydroxides thermally decompose (split up on
heating) to give the oxide and water.
Reactivity with acids
Most metals react with dilute acids such as HCl.
When acids and metals react, the hydrogen atom in the acid is replaced by the metal atom
to produce a salt and hydrogen gas, for example iron:
Fe + 2HCI → FeCl2 + H2
Unreactive metals such as gold and copper do not react with acids.
, Reactivity with oxygen
Some reactive metals such as the alkali metals react with oxygen.
Copper and iron can also react with oxygen although much more slowly.
When metals react with oxygen a metal oxide is formed, for example copper:
2Cu + O2 → 2CuO
Explain in terms of their properties why alloys are used instead of pure metals
An alloy is a mixture of two or more metals or a metal and a nonmetal.
Alloys often have properties that can be very different to the metals they contain, for
example they can have more strength, hardness or resistance to corrosion or
extreme temperatures.
Alloys contain atoms of different sizes, which distorts the normally regular arrangements of
atoms in metals.
This makes it more difficult for the layers to slide over each other, so alloys are usually much
harder than the pure metal.
Common alloys and their uses:
Brass is an alloy of copper and zinc and is much stronger than either metal
Alloys of iron with tungsten are extremely hard and resistant to high temperatures
Alloys of iron mixed with chromium or nickel are resistant to corrosion
Aluminium is mixed with copper, manganese and silicon for aircraft body production
as the alloy is stronger but still has a low density
REMEMBER that alloys are mixtures of substances, they are not chemically combined, and
an alloy is not a compound.
Identify representations of alloys from diagrams of structure
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