Atoms and small molecules are tiny. Their typical size is about 1 × 10-10 metres (m). A small molecule is made of a few atoms joined together, so it is about the same order of magnitude in size as an atom.
An order of magnitude is a power of ten. A length of 1 × 10-9 m is 10 times bigger than 1 × 10-10 m, so it is one order of magnitude larger. Something 100 times bigger is two orders of magnitude larger, and something 1000 times bigger is three orders of magnitude larger.
Because atoms are so small, their size is written in standard form. A grain of sand is about 1 × 10-3 m across. That is 7 orders of magnitude bigger than an atom, so an atom is far too small to see.
