# Oxygen exists as simple molecules, O₂. Describe the bonding within an oxygen molecule and explain why oxygen has a low boiling point.

> Cambridge International IGCSE Chemistry (0620) — 2.5 Simple molecules and covalent bonds · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. Oxygen molecules are held together by a covalent bond / sharing of electrons between the two oxygen atoms
2. The covalent bond is a double bond / two pairs of electrons are shared
3. There are weak intermolecular forces between oxygen molecules
4. Only a small amount of energy is needed to overcome these intermolecular forces, so the boiling point is low

## Key terms

- [boiling point](https://www.gradenine.co.uk/glossary/boiling-point)
- [simple molecule](https://www.gradenine.co.uk/glossary/simple-molecule)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/oxygen-exists-as-simple-molecules-o-b1f7410c) · Published by Druglandscape Ltd.