# Explain how an ionic bond is formed between sodium and chlorine atoms.

> Cambridge International IGCSE Chemistry (0620) — 2.4 Ions and ionic bonds · Explain · 4 marks

> Sodium has one electron in its outer shell. Chlorine has seven electrons in its outer shell.

## Mark scheme (4 marks)

1. Sodium transfers/loses one electron to chlorine
2. Sodium forms a positive ion (Na⁺) because it loses a negative charge
3. Chlorine forms a negative ion (Cl⁻) because it gains a negative charge
4. The oppositely charged ions are attracted to each other by electrostatic attraction

## Key terms

- [ionic bond](https://www.gradenine.co.uk/glossary/ionic-bond)
- [ion](https://www.gradenine.co.uk/glossary/ion)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-an-ionic-bond-is-49aacd86) · Published by Druglandscape Ltd.