# Stainless steel is an alloy used to make surgical instruments. It contains iron, chromium and nickel. Explain why stainless steel is a more suitable material for surgical instruments than pure iron.

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

> Surgical instruments must be strong, durable and resistant to corrosion. Pure iron corrodes readily when exposed to water and oxygen. Stainless steel is an alloy made from iron, chromium and nickel.

## Mark scheme (4 marks)

1. Stainless steel is an alloy / made by combining two or more metals together
2. The different sized atoms disrupt the regular arrangement / layers of atoms cannot slide over each other as easily
3. This makes stainless steel harder / stronger than pure iron
4. Stainless steel has greater resistance to corrosion than pure iron / less likely to be destroyed by chemical reactions with water and oxygen

## 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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