The best way is on your fingers. But you need a very small finger!
Quite precisely atoms can be „counted” by X-rays: they are diffracted on crystal planes, like the light on a CD disk. Thighter are placed the atoms – more distant are light spots on the screen.There are others ways of counting atoms (i.e. calculation of the Avogadro or Loschmidt number). For example as dependence of slime sedimentation in a liquid* (J. Perrin) or as dependence of their brewery** motion (A. Einstein).Today is possible to count on „fingers” leading it on the crystal surface. But... the finger must be quite small and precise. This finger can be a sharp tip of the tungsten needle – when it touches an atom (or better: approaching it, then needle gets slightly bent. Ask at the University - they will show you how it works***.
* Elements distribution of the slime with mass m in function
of height h is defined by formula e-mgh/kT ,where
k=R/NA is Boltzmann
constant
** or better: Brownian motions
*** Gdansk Technical University, for example (and mamy, many other) are equipped with atomic force microscope.
