How small a nanoparticle is, nanometres in standard form, surface area to volume ratios, and the uses and risks of nanoparticles.
What you will learn
- Convert between nanometres and metres in standard form
- Calculate the surface area to volume ratio of a cube and compare particles
- Give uses of nanoparticles and weigh up their risks
How small is nano?
1 nm (nanometre) = 1 × 10−9 m, a thousandth of a micrometre (μm).
Atoms are about 0.1 nm across.
- Nanoparticles: 1 to 100 nm across, a few hundred atoms.
- Fine particles (PM2.5): 100 to 2500 nm.
- Coarse particles (PM10, dust): 2500 to 10 000 nm.
- A particle is 45 nm across
- 45 × 10⁻⁹ m = 4.5 × 10⁻⁸ m
- 1 μm = 1000 nm, so 2.5 μm = 2500 nm
Before you compare two sizes, write both in the same unit, usually nm.
To go back from metres to nanometres, divide by 1 × 10⁻⁹: 6.0 × 10⁻⁸ m ÷ 10⁻⁹ = 60 nm, a nanoparticle. 0.6 μm = 600 nm, a fine particle.
The rest of this lesson and its 9 practice questions are locked.
In this lesson
- How small is nano?
- Surface area to volume ratio
- Try it: Your first ratio
- Uses and risks
9 practice questions, marked as you go; about 20 minutes in all.
In this unit: Bonding, structure and the properties of matter
Ionic, covalent and metallic bonding, the structures they make, and how structure explains melting points, conduction and hardness, with nanoparticles for separate Chemistry.