Nanoparticle

A structure in this range is a nanoparticle and is typically of the order of a few hundred atoms. This places nanoparticles just above the scale of individual atoms and small molecules: an atom is typically about 0.1 nm across, while a small molecule may be around 0.5–2 nm. At the lower end of the range, a nanoparticle can therefore be only a few molecular dimensions across.

Nanoparticles are measured in nanometres, abbreviated to nm.

A nanoparticle is a particle on a larger, but still extremely small, scale: typically about 1–100 nm across. It can contain many atoms, even though it is much smaller than anything you could see unaided. The ranges overlap with the sizes of some molecules; the important distinction here is that an atom is one unit of an element, while a nanoparticle is a tiny particle of material.

Nanometres are useful because atoms, molecules and nanoparticles are far too small to measure conveniently in metres.