How to Measure the Size of an Atom

An atom is mostly empty space because you know what you would say is the size of it. The way that they probe this is two different ways. One is they shoot an electron at a proton, but sometimes also they just look at an atom. Sometimes the electron goes inside the proton. This happens more or less often. So you can measure like how often the electron is inside theproton. And that tells you how big the proton is.