Who discovered electrons, energy levels and neutrons?

In 1897 Scientist, J.J Thompson discovered atoms contained tiny negative particles, known as electrons and this discovery showed atoms aren't tiny spheres that can't be divided, but rather; atoms have an internal structure. While Niels Bohr allowed for the development of energy levels by theorising electrons orbit the nucleus at specific distances rather than in a general area. And the scientist James Chadwick discovered the nucleus contains neutral particles called neutrons.