You almost won a Nobel Prize ;-) @ 4:46 From Wikipedia: Under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or between 0.3 and 3 ångströms. Therefore, the radius of an atom is more than 10,000 times the radius of its nucleus (1-10 fm),[2] and less than 1/1000 of the wavelength of visible light (400-700 nm).