AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
Steels are alloys of iron that contain specific amounts of carbon and…
Full specification wording
Alloys as useful materials: Steels are alloys of iron that contain specific amounts of carbon and other metals.
Steel is an alloy based on iron.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 5 of 10
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Steel is an alloy based on iron. It always contains iron as the main metal, together with a controlled, specific amount of carbon and often other metals added for particular properties. The carbon content is chosen deliberately: low carbon steel and high carbon steel have different properties because their carbon percentages differ. Other metals may be added to make alloy steels with extra strength, hardness or resistance to corrosion; stainless steel, for example, contains chromium. Because the amounts are specific, steel is not a single substance but a family of alloys whose composition is adjusted for a purpose.
What earns the marks
- State that steel is a mixture of iron with carbon and possibly other metals.
- Explain that the carbon content is a controlled, specific amount rather than a random or unlimited quantity.
- Recognise that changing the amount of carbon or the identity of other added metals changes the properties of the steel.
- Give a named example of an alloy steel, such as stainless steel containing chromium, and link the added metal to a property.
- Distinguish steel from pure iron by noting that pure iron is an element while steel is an alloy.
Common mistakes and how to put them right
Describing steel as pure iron.
Put it right by stating that steel is an alloy of iron with carbon and often other metals.
Thinking any amount of carbon can be present.
Put it right by explaining that the carbon content is deliberately controlled to give specific properties.
Assuming all steels have identical properties.
Put it right by linking differences in composition, such as carbon content or added chromium, to differences in properties.
Exam tips
- Name the main metal first, then the added elements, when describing the composition of a steel.
- Use comparative language such as higher carbon content or added chromium when explaining property differences.
- Link each composition feature to a use, for example corrosion resistance for stainless steel.
Try the lesson
The start of the Alloys as useful materials: Steels are alloys of iron that contain specific amounts of carbon and other metals. lesson, made from checked teaching notes for this specification point.
Have a go first
Which metal is the main component of all steels?
Listen
Steel is an alloy based on iron. It always contains iron as the main metal, together with a controlled, specific amount of carbon and often other metals added for particular properties. The carbon content is chosen deliberately: low carbon steel and high carbon steel have different properties because their carbon percentages differ. Other metals may be added to make alloy steels with extra strength, hardness or resistance to corrosion; stainless steel, for example, contains chromium. Because the amounts are specific, steel is not a single substance but a family of alloys whose composition is adjusted for a purpose. A strong answer earns marks for these points. State that steel is a mixture of iron with carbon and possibly other metals. Explain that the carbon content is a controlled, specific amount rather than a random or unlimited quantity. Recognise that changing the amount of carbon or the identity of other added metals changes the properties of the steel. Give a named example of an alloy steel, such as stainless steel containing chromium, and link the added metal to a property. A common slip: Describing steel as pure iron. Instead, stating that steel is an alloy of iron with carbon and often other metals. Exam tip: Name the main metal first, then the added elements, when describing the composition of a steel.
See it
Key words
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Steel
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Stainless steel
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Composition
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See every definition
- Steel
- An alloy based on iron that always contains iron as the main metal, together with a controlled, specific amount of carbon and often other metals added for particular properties.
- Stainless steel
- An alloy steel that contains chromium, which is added to give resistance to corrosion.
- Composition
- The specific amounts of carbon and other metals in a steel, which are adjusted for a purpose.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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