Atoms are extremely small. A typical atom has a radius of about 0.1 nanometres (nm), which is 0.0000000001 m. We write this as 10-10 m, or 10 to the power -10 metres. An order of magnitude is the nearest power of ten, so atomic radii are of the order of 10-10 m.
Bond lengths, the distances between the nuclei of two bonded atoms, are also of the order of 10-10 m, and so are the sizes of small molecules. The nucleus is much smaller still. It is about ten thousand times smaller than the atom, at around 10-14 m, so most of an atom is empty space.
To get a feel for the scale, a human hair is about 0.0001 m (10-4 m) wide. Dividing 10-4 by 10-10 gives 106. Taking an atom as of the order of 10-10 m across (to the nearest power of ten), roughly one million atoms fit side by side across the width of a hair. Nanoparticles are larger than single atoms but still tiny, with sizes of roughly 1 to 100 nm.