Frederick Soddy (1877-1956), British radiochemist & Nobel Laureate. Soddy was the youngest of seven children. He graduated in chemistry at Oxford, then moved to Canada. There, working with Rutherford, he proposed the disintegration theory to explain what radioactivity is. Soddy predicted that helium was a decay product of radium, proving this in London in 1903. In 1913 he proposed the radioactive displacement law; this states that in alpha decay the atomic number of the atom drops by two, but in beta decay increases by one. It was Soddy who first used the term 'isotope'. He was appointed Professor of Chemistry at Oxford in 1919, and was awarded the 1921 Nobel Prize.