Nanoparticles and Their Uses — AQA GCSE Chemistry (Separate)
Nanoparticles are extremely small particles with special properties because of their huge surface area to volume ratio.
Sizes of particles
- Coarse particles (dust) — 1 × 10⁻⁵ m to 2.5 × 10⁻⁶ m.
- Fine particles — 100 nm to 2500 nm.
- Nanoparticles — 1 to 100 nm (a few hundred atoms). They are far smaller than substances visible under a normal microscope.
Surface area to volume ratio
As a particle gets smaller, its surface area to volume ratio increases. For nanoparticles this ratio is very large. If the side of a cube decreases by a factor of 10, the surface area to volume ratio increases by a factor of 10.
This large ratio gives nanoparticles different properties from the same material in bulk, and means smaller quantities are needed to be effective (e.g. as catalysts).
Uses
- Catalysts — large surface area makes reactions efficient.
- Sun creams — give better skin coverage and UV protection than larger particles.
- Medicine — delivering drugs into the body.
- Electronics and cosmetics.
Risks
The effects of nanoparticles on health and the environment are not yet fully understood, so there are concerns about their use (e.g. in cosmetics) until more research is done.
Exam tips
- Nanoparticles are 1–100 nm.
- Their key feature is a very large surface area to volume ratio.
- Learn uses: catalysts, sun creams, medicine, electronics.
- Mention that the risks are not fully known.