Recent Event Highlights: General Theory Of Relativity, Plum Pudding Disaproved and Nobel Prize Won, Special Theory of Relativity, Alpha rays and Plum pudding, Discovery of Radium Emmiting Rays, and 8 more...
Rutherford bombards nitrogen gas with alpha particles and obtains atoms of an oxygen isotope and protons. This transmutation of nitrogen into oxygen was the first artificially induced nuclear reaction.
Ernest O. Lawrence conceives idea for the first cyclotron, a device that greatly increased the speed with which protons could be hurled at atomic nuclei. He was awarded the 1939 Nobel Prize in Physics for the invention and development of the cyclotron and for results obtained with it.
John Crockcroft and E. T. S. Walton develop a high-voltage apparatus ("linear accelerator") for accelerating protons. With this they study nuclear reactions (atomic transmutation) and are awarded the 1951 Nobel Prize in Physics.
The "plum-pudding" is disproved by the gold foil experiment by Ernest Rutherford, when he discovered the nucleus of the atom.
Marie Curie receives a second Nobel Prize, this time in Chemistry, for the isolation of radium and polonium and for her investigation of their chemical properties.
Rutherford discovers that alpha rays are heavy positively charged particles.
J. J. Thomson proposes the "plum-pudding" model of the atom. In it the atom is envisioned as electrons surrounded by a soup of positive charge, like plums surrounded by pudding.
French physicist Antoine Henri Becquerel's experiments led to the discovery of radioactivity. He observed that the element uranium can blacken a photographic plate, even though separated from it by glass or black paper. He also observed that the rays that produce the darkening are capable of discharging an electroscope, indicating that the rays possess an electric charge.