# Iron is an element. Steel is an alloy made mostly from iron, with small amounts of carbon and other metals added. Explain why steel is described as a mixture rather than a compound, and describe one reason why steel is used in preference to pure iron in construction.

> OCR A-Level Chemistry A (H432) — 2.1 Atoms, compounds, molecules and equations · Explain · 5 marks

> Iron on its own is relatively soft and prone to corrosion. Steel is produced by combining iron with carbon and other metals to improve its properties.

## Mark scheme (5 marks)

1. A mixture contains at least two different elements or compounds that are not chemically bonded together
2. In a compound the atoms/elements are chemically bonded together, but in steel they are not
3. In a mixture the components can be present in variable/different proportions (unlike a compound which has a fixed ratio)
4. Steel has greater strength than pure iron (so it is used in construction)
5. Steel has greater resistance to corrosion than pure iron

## Key terms

- [mixture](https://www.gradenine.co.uk/glossary/mixture)
- [compound](https://www.gradenine.co.uk/glossary/compound)
- [alloy](https://www.gradenine.co.uk/glossary/alloy)
- [element](https://www.gradenine.co.uk/glossary/element)

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/iron-is-an-element-steel-is-20419ae7) · Published by Druglandscape Ltd.