Developed 1st atomic theory - Billiard Ball Model. Elements consisted of atoms. All atoms of an element are identical. Atoms of each element are different from one another. Compounds consisted of atoms are different elements combined together. Chemical reactions involved the rearrangement of combinations of those atoms. http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm
He invented the cyclotron and recognized the potential for medical isotopes. Isotopes are used to make medicines. When radioactive isotopes are introduced to the body, they give off an energy or radiation that can be tracked by imaging equipment.