# Silver nanoparticles are used as an antibacterial coating on some medical instruments. Describe two properties of silver nanoparticles that make them more useful for this purpose than bulk silver, and explain why silver nanoparticles have these properties.

> AQA GCSE Chemistry (8462) — 4.2.4 Bulk and surface properties including nanoparticles (Chem only) · Describe · 4 marks

> Silver nanoparticles have diameters between 1 nm and 100 nm. Bulk silver consists of much larger particles.

## Mark scheme (4 marks)

1. Silver nanoparticles have a much larger surface area to volume ratio than bulk silver
2. Because of this larger surface area to volume ratio, more silver atoms are exposed / in contact with bacteria, making the antibacterial effect more effective
3. Nanoparticles can exhibit different properties to the same material in bulk / nanoparticles may have different chemical or physical properties to bulk silver
4. Nanoparticles are very small (1–100 nm) so they can penetrate or access areas / surfaces that larger bulk particles cannot reach

## Key terms

- [nanoparticles](https://www.gradenine.co.uk/glossary/nanoparticles)
- [bulk](https://www.gradenine.co.uk/glossary/bulk)

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- [Revision notes for AQA GCSE Chemistry (8462)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/silver-nanoparticles-are-used-as-an-eddfeba2) · Published by Druglandscape Ltd.