Finding the size of atoms
The fact that matter is made of particles is perhaps the most powerful idea in science. Understanding the scale of the particles is important. This collection shows how students can estimate the size of molecules and atoms for themselves.
In a classic experiment, first performed by Lord Rayleigh, a small drop of oil spreads out to form a circular patch on the surface of water. Simple measurements lead to the length of the oil molecule, from which the diameter of carbon atoms can be deduced.