Atoms are tiny. Yes, you already know that, but you may not know exactly how tiny. You can line up one thousand million atoms side-by-side in one little millimeter. This size makes the fact that we even know that there are atoms at all is somewhat surprising. We didn't find out about atom's existence by looking at them, instead we found out about atoms through a number of experiments and speculation. In the fourth century, two Latin scientists (Democritus and Leucippus) independently thought of the atom and even named it "atom" (meaning indivisible). Several centuries later, in 1803, John Dalton came up with the idea that there were indivisible particles that made up everything. Though many people had the idea of atoms and had done experiments to prove their ideas, no one had seen atoms.
It's different now. Using an electron microscope we have seen larger atoms and now smaller atoms, too. Simply put, an electron microscope works by sending a beam of electrons at a target to see what is deflected. Seeing larger atoms is much easier, as a result, because larger atoms are easier targets than smaller atoms (because smaller targets require more accuracy.)
It's different now. Using an electron microscope we have seen larger atoms and now smaller atoms, too. Simply put, an electron microscope works by sending a beam of electrons at a target to see what is deflected. Seeing larger atoms is much easier, as a result, because larger atoms are easier targets than smaller atoms (because smaller targets require more accuracy.)
See sources and the articles on these pictures on the "Resources & Notes" Page.