RUTHERFORD, ERNEST, BARON RUTHERFORD OF NELSON, OF ...

born Aug. 30, 1871, Spring Grove, N.Z. died Oct. 19, 1937, Cambridge, Cambridgeshire, Eng. British physicist who laid the groundwork for the development of nuclear physics. After receiving a master's degree from Canterbury College, Christchurch, in 1893, Rutherford went to the University of Cambridge in 1895 to work with Sir J.J. Thomson at the Cavendish Laboratory. In 1897 Rutherford showed that the radiation emitted by uranium differs from X rays and consists of two distinct types, which he named alpha rays and beta rays. In 1898 Rutherford was appointed to the chair of physics at McGill University, Montreal. There, in 1902, while studying the radioactivity of thorium, he and the English chemist Frederick Soddy concluded that radioactivity was a process in which atoms of one element spontaneously disintegrate into atoms of an entirely different element. Together the two men created a modern theory of radioactivity, which was set forth in Rutherford's book Radio-activity (1904). In 1903 Rutherford showed that alpha rays are composed of positively charged particles. In 1907 he went to the Victoria University of Manchester to continue his research, and in 1908 he proved that alpha particles are in fact helium atoms. Rutherford was awarded the Nobel Prize for Chemistry in 1908. In 1911 he made his greatest contribution to science with his nuclear theory of the atom. From the scattering of swift alpha particles as they were directed against thin metal foils, such as gold leaf, Rutherford concluded that the alpha particles sometimes encounter strong centres of repulsion in the gold, and that most of the mass and all of the positive charge of gold atoms must be concentrated in a very small central nucleus around which electrons circle. The positive charge on the nucleus would be balanced by an equal charge on all the electrons somehow distributed around it. In 1913 the Danish physicist Niels Bohr adapted the nuclear structure postulated by Rutherford to the quantum theory of Max Planck and thereby explained how electrons could have stable orbits around the nucleus of the atom. Rutherford was knighted in 1914. In 1919 he produced the first artificial disintegration of an element when he bombarded nitrogen with alpha particles and transmuted it into an isotope of oxygen. That same year Rutherford was invited to succeed Thomson in the Cavendish chair at the University of Cambridge. Honours now came in rapid succession. The Copley Medal of the Royal Society was bestowed on him in 1922 and the presidency of the British Association for the Advancement of Science in 1923, to be followed two years later by the presidency of the Royal Society. In 1925 he was appointed to the Order of Merit. In 1931 he was created Baron Rutherford of Nelson. Rutherford wrote Radiations from Radioactive Substances (1930), Radioactive Transformations (1906), Radioactive Substances and Their Radiations (1913), and The Newer Alchemy (1937).