# Ammonia has the molecular formula NH₃. State the meaning of this molecular formula and explain why the empirical formula and the molecular formula of ammonia are the same.

> Cambridge International IGCSE Chemistry (0620) — 3.1 Formulae · State and Explain · 4 marks

## Mark scheme (4 marks)

1. The molecular formula shows the actual number of atoms of each element in one molecule of the compound
2. One molecule of ammonia contains one nitrogen atom and three hydrogen atoms
3. The empirical formula shows the simplest whole-number ratio of atoms of each element in the compound
4. The ratio 1:3 (N:H) in NH₃ cannot be simplified further / is already the simplest whole-number ratio, so the empirical formula is also NH₃

## Key terms

- [molecular formula](https://www.gradenine.co.uk/glossary/molecular-formula)
- [empirical formula](https://www.gradenine.co.uk/glossary/empirical-formula)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](https://www.gradenine.co.uk/learn)
- [How to answer "State and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/ammonia-has-the-molecular-formula-nh-336d3b53) · Published by Druglandscape Ltd.