# Methane is a simple molecular substance. Nitrogen gas also exists as a simple molecule. Explain why methane and nitrogen both have low boiling points, and explain why methane and nitrogen are examples of different types of substance (one is a compound and one is an element).

> OCR A-Level Chemistry A (H432) — 2.1 Atoms, compounds, molecules and equations · Explain · 5 marks

> Methane has the molecular formula CH₄. Nitrogen gas exists as N₂ molecules. Both substances are gases at room temperature and have low boiling points.

## Mark scheme (5 marks)

1. Both methane and nitrogen have weak intermolecular forces between their molecules
2. Only a small amount of energy is needed to overcome these intermolecular forces, so the boiling point is low
3. Nitrogen (N₂) is an element because it contains only one type of atom
4. Methane is a compound because it contains two or more different types of atom (carbon and hydrogen) chemically bonded together
5. The atoms in methane are held together by covalent bonds (shared pairs of electrons between non-metals)

## Key terms

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

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](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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