Hevesy, Georg von, 1885-1966, Hungarian physicist and chemist. He received the 1943 Nobel Prize in Chemistry for his work on the use of isotopes as tracers in studying chemical processes. Hevesy was the first to apply the radioactive tracer technique to biology, and he later used it in medical research. He also discovered X-ray fluorescence analysis. He was codiscoverer of hafnium, element 72 in the periodic table. Hevesy became an associate of the Institute of Theoretical Physics, Copenhagen, in 1920 and also of the Institute for Research in Organic Chemistry, Stockholm, in 1943.