By: Dajanay, Chloe, Bella and Stephanie James Chadwick By: Dajanay, Chloe, Bella and Stephanie

Evidence that led to change the ‘previous atom’ Chadwick and his colleague Rutherford saw that almost every element had an atomic number that was less than its atomic mass. In other words, an atom of any given element seemed to have more mass than could be accounted for by the number of protons in its nucleus. Rutherford initially thought that the extra mass was made up of proton-electron pairs, which would add mass but no additional charge to the nucleus. However, the nucleus did not seem to have room enough for such pairs.

the discovery of the neutron Chadwick discovered the neutron when physicists Frederic and Irene Joliot- Curie found the answer to why beryllium showed emission pattern and and why their other hypothesis was not matching up. Chadwick then realized that it was the presence of a neutron since only a neutral particle can move a proton. Chadwick did different examples to why the gamma-ray hypothesis was incorrect. neutrons is the only thing that had enough energy to eject protons so fast.

More evidence that led to a change in the atom Chadwick found a lot of evidence in his work. He first started with a hypothesis stating that neutral particles were responsible for the emissions. Chadwick observed a lot of the work from the Curie’s from which they found that gamma rays emitted by beryllium knocked hydrogen protons out of the paraffin. And from that conclusion, chadwick knew neutrons were present. He started experimenting and concluded that gamma rays would not have enough energy to eject protons so quickly. Chadwick then went on to show that the beryllium nucleus combined with an alpha particle could be transmuted to a carbon nucleus, which then releases a particle with a mass similar to that of a proton with a neutral charge. This is when Chadwick had finally tracked down the neutron.

How Chadwick's Work Changed the Atomic Model James Chadwick's work changed the atomic model with the discovery of the neutron and the further discovering of the essential properties of the proton. Chadwick partnered with Ernest Rutherford on attempting to break up the nucleus. In this work, the pair were able to lead experiments that helped gauge the size and map the structure of the atomic nucleus which also helped the with the development of the atomic model. His most famous discovery was the revelation of the existence of the neutrally charged Neutron. This discovery than helped lead to the development of the atomic bomb.