James Chadwick's Nuclear Theory

James Chadwick was born 20 October 1891, Manchester, United Kingdom. He won the noble prize because he discovers the neutron in 1932, then few years later he got the noble prize for his work in 1935. He also led the British team in the Manhattan Project, in which the UK and Canada supported the USA’s World War 2 effort to build the world’s first nuclear bomb. James Chadwick parents were Joseph, a railway storekeeper, and Anne, a domestic servant. When he was aged 11, James won entry to the prestigious Manchester Grammar School. Unfortunately, his parents were too poor to afford the small amount of money they would need for fees. Instead, James Chadwick was educated at Manchester’s Central Grammar School for Boys; his favorite subjects

The extra protons were thought to provide the extra atomic mass, while the additional electrons would cancel out their positive charge, leaving the atom electrically neutral. Eventually, however, calculations using Heisenberg’s uncertainty principle showed it was not possible for electrons to be contained in the nucleus.
There were other ideas. Ernest Rutherford in 1921 postulated a particle called the “neutron,” having a similar mass as a proton but electrically neutral. Rutherford imagined a paired proton and electron somehow joined in one particle. One major problem with Rutherford’s “neutron theory”—not much evidence.
Evidence was difficult to come by. Such a “neutron” would prove difficult to detect with 1920s equipment. Detection methods of that day mainly relied on the electrical charges of particles revealing their presence—but neutrons, having no electrical charge, would leave no trace. In 1930, the physicists Walther Bothe and Herbert Becker bombarded beryllium with alpha particles (helium nuclei) emitted from the radioactive element polonium, and they found that the beryllium gave off an unusual, electrically neutral radiation. They interpreted this radiation to be high-energy gamma rays