AQA GCSE Chemistry (8462), Higher tier · Bonding, structure and the properties of matter › Bonding, structure and properties
Practise Properties of metals and alloys. 14 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Metals and alloys are used for many purposes. What is an alloy?
A mixture of a metal with at least one other element (usually another metal).
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Metals and alloys are used for many purposes.
(a) Complete the sentence. Tick (✓) one box. In pure metals, the atoms are arranged in ................[1]
layers
pairs
a random mixture
small molecules
(b) What is an alloy?[1]
(c) Why are alloys used instead of pure metals for many purposes? Tick (✓) one box.[1]
Alloys are harder.
Alloys are softer.
Alloys are always cheaper.
Alloys conduct electricity better.
(d) Most metals have high melting points. Explain why.[2]
Show the answer and mark scheme
(a)Answer: layers
(b)Answer: A mixture of a metal with at least one other element (usually another metal).
a mixture of a metal with (at least) one other element / other metals
(c)Answer: Alloys are harder.
(d)Answer: Metals have giant structures with strong metallic bonding, which needs a lot of energy to overcome.
giant structure with strong metallic bonding / strong attraction between positive ions and delocalised electrons
a lot of energy is needed to overcome the metallic bonding
Question 2Medium8 marks
Duralumin is an alloy used to make aircraft. It contains 4.4% copper, 1.5% magnesium and 0.6% manganese by mass. The rest is aluminium.
(a) Calculate the percentage of aluminium in duralumin.[1]
(b) Calculate the mass of copper in 250 kg of duralumin.[2]
(c) Explain why duralumin is harder than pure aluminium.[3]
(d) Pure aluminium melts at 660 °C. Explain why aluminium has a high melting point.[2]
Show the answer and mark scheme
(a)Answer: 93.5%
(100 − 4.4 − 1.5 − 0.6 =) 93.5 (%)
(b)Answer: 11 kg
250 × 4.4 ÷ 100
11 (kg)
(c)Answer: The copper, magnesium and manganese atoms are different sizes from aluminium atoms; they distort the layers so the layers cannot slide easily.
atoms of copper / magnesium / manganese are a different size from aluminium atoms
(so) the layers of aluminium atoms are distorted
(so) the layers cannot slide over each other easily
(d)Answer: It has a giant structure with strong metallic bonding (attraction between positive ions and delocalised electrons), which needs a lot of energy to overcome.
strong electrostatic attraction between the positive ions and the delocalised electrons / strong metallic bonding (in a giant structure)
a lot of energy is needed to overcome it
Question 3Hard6 marks
Steel is an alloy of iron and carbon. Carbon atoms are much smaller than iron atoms. Relative atomic masses (Ar): C = 12, Fe = 56
(a) A student said: 'Alloys are harder than pure metals because the atoms that are added are bigger.' Use the information about steel to explain why the student is wrong.[2]
(b) A sample of steel contains 1.0% carbon by mass. Calculate the number of carbon atoms for every 100 iron atoms in this steel.[3]
(c) Suggest why a small percentage of carbon by mass has a large effect on the hardness of iron.[1]
Show the answer and mark scheme
(a)Answer: Carbon atoms are smaller than iron atoms, yet steel is harder than iron: atoms of any different size distort the layers so they cannot slide easily.
carbon atoms are smaller than iron atoms but steel is still harder than iron
atoms of a different size (larger or smaller) distort the layers so they cannot slide easily
(b)Answer: about 4.7
in 100 g: moles of C = 1.0 ÷ 12 = 0.0833 and moles of Fe = 99.0 ÷ 56 = 1.77
ratio C : Fe = 0.0833 ÷ 1.77 = 0.047
4.7 (carbon atoms per 100 iron atoms)
(c)Answer: Carbon atoms are light, so 1% by mass is about 5% of the atoms, and each carbon atom disrupts the layers around it.
carbon atoms are light so 1% by mass is a larger percentage of the atoms / each carbon atom distorts the layers around it