Nanoscience refers to structures that are 1–100 nm in size, of the order…

The idea

Nanoscience studies structures with at least one dimension between 1 nm and 100 nm. A nanometre is 1 × 10⁻⁹ m, so these objects are far smaller than everyday particles but larger than single atoms. Because a typical atom is roughly 0.1–0.3 nm across, a 1–100 nm structure contains of the order of a few hundred atoms, which explains why nanoparticles behave differently from bulk solids.

For example: A gold nanoparticle about 10 nm wide contains thousands of atoms arranged in a tiny crystal, yet its surface atoms form a large fraction of the total.

What earns the marks

• States that nanoscience involves structures with at least one dimension from 1 nm to 100 nm.
• Recalls that 1 nm = 1 × 10⁻⁹ m and can convert a nanoscale length into metres.
• Explains that nanoscale structures contain of the order of a few hundred atoms, linking size to atomic scale.
• Compares nanoparticle dimensions with larger particles such as dust or a human hair to place the scale in context.
• Uses the nanometre scale to justify why nanoparticles have a very large surface area to volume ratio.

Common mistakes and how to put them right

• Treating 1–100 nm as a mass or volume range rather than a length range.

  Put it right by specifying that at least one dimension of the structure lies in that range.

• Confusing nanometres with micrometres or millimetres.

  Put it right by recalling 1 nm = 1 × 10⁻⁹ m and 1 µm = 1 × 10⁻⁶ m.

• Assuming a nanoparticle contains only a few atoms.

  Put it right by explaining that a few hundred atoms is the order of magnitude for structures in this size range.

Exam tips

• Quote the range 1–100 nm and define the nanometre in metres when a question asks for the scale of nanoscience.
• Use a familiar comparison, such as a human hair being about 100 000 nm wide, to show the tiny scale.
• When calculating, convert nanometres to metres before substituting into any surface area or volume formula.