Properties, Uses and Alloys of Metals
CIE IGCSE ChemistryΒ· Unit 9.1, 9.2, 9.3Β· 12 min read
1. Core: Typical Physical and Chemical Properties of Metalsβ β ββββ± 3 min
Metals share a set of characteristic physical and chemical properties that distinguish them from non-metals, forming the basis for all their practical applications.
Typical Metal Properties
Physical properties: high melting/boiling points, high density, malleable, ductile, good conductor of heat and electricity, lustrous when cut. Chemical properties: form positive ions in reactions, react with oxygen to form basic oxides, many react with dilute acids to produce salt and hydrogen.
State two physical properties of aluminium that make it suitable for making food cooking foil.
- 1
- Identify properties needed for cooking foil: must be flexible, heat-resistant, good heat conductor.
- 2
- Select two relevant properties: Aluminium is malleable (can be rolled into thin sheets) and an excellent conductor of heat.
Exam tip:
When asked to link a property to a use, always pick the property directly related to the use, not a general metal property. For example, do not say 'good electrical conductor' for cooking foil.
2. Core: Relating Metal Properties to Real-World Usesβ β ββββ± 3 min
The choice of metal for a specific application is determined by its properties, with cost and abundance also factored into commercial decisions.
Copper is used for electrical wiring because it is an excellent conductor of electricity and ductile enough to be drawn into thin wires.
Iron (as steel) is used for construction girders because it has very high tensile strength and is relatively low cost.
Aluminium is used for aeroplane bodies because it has a low density (lightweight) and is resistant to corrosion.
Silver is used for high-end electrical contacts because it has the highest electrical conductivity of common metals, though high cost limits widespread use.
Explain why gold is used to make jewellery.
- 1
- List properties relevant to jewellery: lustrous, highly malleable for intricate designs, unreactive so does not tarnish, rare so has high perceived value.
- 2
- State two linked points: Gold is lustrous and highly unreactive, so it remains attractive for many years without tarnishing.
3. Core: Alloys - Composition and Common Usesβ β β βββ± 3 min
Alloy
A mixture of a metal with one or more other elements (usually another metal or carbon), designed to improve the properties of the pure metal for a specific use.
Alloy | Main Components | Key Improved Property | Common Use |
|---|---|---|---|
Brass | Copper + Zinc | Harder than pure copper, corrosion resistant | Door handles, musical instruments, plumbing fittings |
Bronze | Copper + Tin | Very hard, wear and corrosion resistant | Statues, bearings, ship propellers |
Stainless Steel | Iron + Chromium + Nickel | Rust resistant, very strong | Cutlery, surgical instruments, kitchen equipment |
Mild Steel | Iron + <0.25% Carbon | Malleable, strong, easy to weld | Car bodies, construction girders |
High Carbon Steel | Iron + 0.25-2% Carbon | Very hard, brittle | Cutting tools, drill bits |
Duralumin | Aluminium + Copper + Magnesium | Stronger than pure aluminium, low density | Aeroplane parts, bicycle frames |
Name the alloy used to make surgical instruments, and state the property that makes it suitable for this use.
- 1
- Recall alloy for medical use: Stainless steel.
- 2
- State relevant property: It is resistant to rusting, so it can be repeatedly sterilised without degrading.
4. Extended Only: Structure and Property Explanations for Alloysβ β β β βExtended onlyβ± 3 min
Extended tier learners are required to explain why alloys have different properties to pure metals using their understanding of metallic structure (covered in Unit 2.7, Extended only content).
In a pure metal, all atoms are the same size and arranged in regular layers. When a force is applied, these layers can slide over each other easily, which is why pure metals are soft, malleable and ductile.
In an alloy, the added element has atoms of a different size to the base metal atoms. This disrupts the regular arrangement of the metal layers, making it much harder for the layers to slide over each other. This is why almost all alloys are harder and less malleable than the pure metal they are made from.
Explain, in terms of structure, why mild steel is harder than pure iron.
- 1
- Describe pure iron structure: Pure iron has identical-sized atoms arranged in regular layers that can slide easily, making it soft.
- 2
- Describe alloy disruption: Mild steel contains small carbon atoms that are a different size to iron atoms, disrupting the regular layer arrangement and preventing layers from sliding easily.
- 3
- Link to property: This makes mild steel harder than pure iron.
Exam tip:
You must use the correct terminology for this question: reference to 'different sized atoms' and 'layers cannot slide' are mandatory marking points for Extended tier alloy explanation questions.
5. Common Pitfalls
Wrong move:
Stating a general metal property without linking it to the specific use asked (e.g. saying 'copper conducts heat' for its use in electrical wiring).
Why:
Examiners require explicit connection between the property and the use, not just a list of properties.
Correct move:
Always link directly: 'Copper is used for electrical wiring because it is a good conductor of electricity and ductile enough to be drawn into wires.'
Wrong move:
Confusing the components of brass and bronze.
Why:
These are two commonly tested alloys, and mixing up their components leads to lost marks.
Correct move:
Use the mnemonic: Brass = Copper + Zinc (B C Z), Bronze = Copper + Tin (Br C T) to remember the difference.
Wrong move:
Core learners attempting to explain alloy properties using metallic structure.
Why:
This content is exclusively for Extended tier; Core learners only need to recall composition and uses of alloys.
Correct move:
Core learners only answer questions that ask you to name, state or link properties, not explain structural reasons.
Wrong move:
Stating that all alloys are stronger than pure metals, without qualifying.
Why:
Some alloys are designed for other properties (e.g. lower melting point for solder), not just strength.
Correct move:
Only state strength as a property if it is relevant to the alloy; reference the specific improved property for the alloy asked.
Wrong move:
Writing that alloys are compounds, not mixtures.
Why:
Alloys are mixtures, they do not have a fixed chemical formula, unlike compounds.
Correct move:
Always define alloys as mixtures of a metal with other elements, not as compounds.
6. Quick Reference Cheatsheet
Concept | Core Required Knowledge | Extended Required Knowledge |
|---|---|---|
Metal Properties | Recall typical physical/chemical properties, link to uses | Same as Core, plus explain properties via metallic bonding |
Alloys | Define alloy, recall composition and uses of common listed alloys | Same as Core, plus explain alloy hardness using structure (different sized atoms, layers cannot slide) |
Exam Key Points | Always link property to use explicitly, memorise alloy component table | Include 'different sized atoms' and 'layers cannot slide' in all structural alloy explanations |
7. Frequently Asked
What is the difference between a pure metal and an alloy?
A pure metal consists of only one type of metallic atom, while an alloy is a mixture of a metal with another element (usually another metal or carbon) to modify its properties. Alloys are stronger and more corrosion-resistant than pure metals for most applications.
Do I need to know metallic bonding for this topic?
Metallic bonding explanations for alloy properties are only required for the Extended tier (Papers 2/4). Core learners only need to recall alloy uses and compositions.
Going deeper
What's Next
Now that you have mastered the properties, uses and alloys of metals, you can move on to the next topics in the Metals unit for CIE IGCSE Chemistry 0620. First, learn about the reactivity series of metals, which explains the chemical behaviour of metals in reactions with water, acids and other metal compounds. You can also study the extraction of metals from their ores, which relies heavily on the reactivity series to select the correct extraction method. For Extended tier learners, you can reinforce your understanding by reviewing the metallic bonding topic to ensure you can explain alloy properties fully in exam questions. All content is aligned to the 2026-2028 CIE 0620 syllabus to support your exam preparation.