# Magnesium burns in oxygen to form magnesium oxide. The word equation for this reaction is: magnesium + oxygen → magnesium oxide. Explain what is meant by the terms 'element' and 'compound', and state which substances in this reaction are elements and which is a compound.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.5 Chemical formulae, equations and calculations · Explain · 4 marks

> Magnesium burns in oxygen to form magnesium oxide. The word equation for this reaction is: magnesium + oxygen → magnesium oxide.

## Mark scheme (4 marks)

1. An element is a substance made up of only one type of atom
2. Magnesium and oxygen are both elements (both must be stated for the mark)
3. A compound is a substance made up of two or more types of atoms chemically combined together
4. Magnesium oxide is the compound

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](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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