Nanoparticles
nanoscienceThe study of structures between 1 and 100 nanometres (nm) in size. is the study of structures that are between 1 and 100 nanometres (nm) in size. Most nanoparticlesTiny particles which are between 1 and 100 nanometres (nm) in size. are made up of a few hundred atomThe smallest part of an element that can exist..
Learn more on nanoparticles in this podcast.
Listen to the full series on ±«Óătv Sounds.
Comparing sizes
The table shows the sizes of nanoparticles compared to other types of particles.
| Particle | Diameter |
| Atoms and small molecules | 0.1 nm |
| Nanoparticles | 1 to 100 nm |
| Fine particles (also called particulate matter - PM2.5) | 100 to 2,500 nm |
| Coarse particles (PM10, or dust) | 2500 to 10,000 nm |
| Thickness of paper | 100,000 nm |
| Particle | Atoms and small molecules |
|---|---|
| Diameter | 0.1 nm |
| Particle | Nanoparticles |
|---|---|
| Diameter | 1 to 100 nm |
| Particle | Fine particles (also called particulate matter - PM2.5) |
|---|---|
| Diameter | 100 to 2,500 nm |
| Particle | Coarse particles (PM10, or dust) |
|---|---|
| Diameter | 2500 to 10,000 nm |
| Particle | Thickness of paper |
|---|---|
| Diameter | 100,000 nm |
Worked example
A zinc oxide nanoparticle has a diameter of 32 nm. The diameter of a zinc atom is 0.28 nm. Estimate how many times larger the nanoparticle is compared to a zinc atom.
Worked example answer
Round each number to 1 significant figure:
30 nm and 0.3 nm
Number of times larger â \(\frac{30}{0.3}\) = 100
The nanoparticle is about 100 times larger than the zinc atom. This is an example of an order of magnitudeAn order of magnitude estimate approximates a number to the nearest power of ten. calculation.
Surface area to volume ratios
Nanoparticles have very large surface areaThe total area of all sides on a 3D shape. to volumeThe volume of a three-dimensional shape is a measure of the amount of space or capacity it occupies, eg an average can of fizzy drink has a volume of 330 ml. ratios compared to the same material in bulk, as powders, lumps or sheets.
For a solid, the smaller its particles, the greater the surface area to volume ratio. If the length of the side of a cube gets 10 times smaller, the surface area to volume ratio gets 10 times bigger.
Worked example
A cube-shaped nanoparticle has sides of 10 nm. Calculate its surface area to volume ratio.
Worked example answer
Surface area = 6 Ă 10 Ă 10 = 600 nm2 (remember that a cube has six sides)
Volume = 10 Ă 10 Ă 10 = 1000 nm3
Surface area to volume ratio = \(\frac{600}{1000}\) = 0.6