# Explain why adding small amounts of other metals to iron to form an alloy can make it more useful for construction purposes than pure iron alone.

> Edexcel GCSE Chemistry (1CH0) — 5.1 Transition metals, alloys and corrosion (Chem only) · Explain · 4 marks

> Steel is an alloy of iron widely used in the construction of bridges and buildings. Unlike pure iron, steel can be engineered to have a range of different properties depending on which metals are added to it.

## Mark scheme (4 marks)

1. An alloy is made by combining two or more metals together
2. The different-sized atoms disrupt the regular arrangement of atoms in pure iron
3. This makes the alloy harder/stronger than pure iron
4. Alloys can also give greater resistance to corrosion compared to pure iron

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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