Sizes of Particles & their Properties (OCR GCSE Chemistry A (Gateway Science Suite)): Revision Notes
📚 Revision Notes
2.4.1 Sizes of Particles & their Properties
What are Nanoparticles?
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Nanoparticles are extremely small particles that range in size from 1 to 100 nanometres (nm). A nanometer is a billionth of a metre, which is incredibly tiny! Nanoparticles are usually made up of just a few hundred atoms.
Comparing Particle Sizes:
- Nanoparticles: 1 - 100 nm
- Fine particles: 100 – 2,500 nm (also known as PM2.5)
- Coarse particles: 2,500 – 10,000 nm (often referred to as dust)
Surface Area to Volume Ratio:
- Nanoparticles have a very high surface area-to-volume ratio compared to larger particles. This means that even though they are tiny, they have a lot of surface area relative to their size.
- Why is this important? Because the larger surface area allows nanoparticles to be more reactive or more effective at doing things like acting as catalysts or being absorbed by the body.
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Example: Imagine a cube made of nanoparticles. If you shrink the size of the cube by 10 times, its surface area to volume ratio increases by 10 times. This means you can use smaller amounts of nanoparticles to achieve the same effect as larger particles, making them very efficient.