Rutherford’experiment
In 1909 the New Zealand Scientist, Earnest Rutherford
discovered that the nucleus only takes up a very small
fraction of the space inside an atom. In his famous
experiment he fired a beam of
helium nuclei at a sheet of gold
foil. He found that most of
them went straight through
and only a few bounced back.
If the atom was solid most of
them should have bounced
back. He concluded the atom
was mostly empty space!
https://www.youtube.com/watch?v=U83swkcL32w
Ernest Rutherford’s experiment