# A student writes the following word equation for the reaction between magnesium and oxygen: magnesium + oxygen → magnesium oxide. Describe what a balanced symbol equation shows that a word equation does not, and explain why it is important that a symbol equation is balanced.

> Edexcel GCSE Chemistry (1CH0) — 0 Formulae, equations and hazards · Describe · 4 marks

## Mark scheme (4 marks)

1. A balanced symbol equation shows the chemical symbols / formulae of the reactants and products (rather than just their names)
2. A balanced symbol equation shows the ratio / number of moles / number of molecules of each reactant and product
3. A balanced equation is important because atoms are not created or destroyed during a chemical reaction (conservation of mass / atoms)
4. Therefore the number of each type of atom must be the same on both sides of the equation

## Key terms

- [balanced symbol equation](https://www.gradenine.co.uk/glossary/balanced-symbol-equation)
- [word equation](https://www.gradenine.co.uk/glossary/word-equation)

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-writes-the-following-word-113e3aaa) · Published by Druglandscape Ltd.