NanoparticlesOxford AQA IGCSE Chemistry: Revision notes
Section 1
What is nanoscience?
Nanoscience is the study of very small structures, typically 1–100 nanometres (nm) in size — roughly the size of a few hundred atoms. A nanometre is one-billionth of a metre.
Nanoparticles are particles in this size range, much smaller than particles you can see with the naked eye but larger than individual atoms or molecules.
Section 2
Why are nanoparticles different from bulk material?
Nanoparticles behave differently from the same material in bulk (large amounts) because of their size:
- They have a very high surface area to volume ratio compared with bulk material
- This means a much greater proportion of their atoms are on the surface, able to react or interact with their surroundings
- As a result, nanoparticles can show completely different chemical and physical properties from the bulk substance
If asked why nanoparticles behave differently to the bulk material, always mention the high surface area to volume ratio — this is the key reason examiners look for.
Section 3
What are nanoparticles used for?
The unusual properties of nanoparticles give them many potential applications:
- New computers — smaller, more efficient electronic components
- New catalysts — greater surface area speeds up reactions
- New coatings — e.g. self-cleaning or water-resistant surfaces
- Highly selective sensors — detecting very small amounts of a substance
- Stronger, lighter construction materials
- New cosmetics, such as suntan creams and deodorants
Some sun creams use nanoparticles of substances like zinc oxide, which give better UV protection while remaining transparent on skin, unlike the bulk material.
Must Know
- Nanoscience studies structures that are 1–100 nm in size, roughly a few hundred atoms
- Nanoparticles show different properties from the same material in bulk
- This is mainly due to their very high surface area to volume ratio
- Applications include: new computers, new catalysts, new coatings, selective sensors, stronger/lighter construction materials, and cosmetics such as suntan creams and deodorants
That's the notes covered.
Carry on to the next subtopic.