(*8 March 1879 ; + 28 July 1968) was a chemist and Nobel laureate who pioneered the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry" and the "founder of the atomic age". Hahn was the youngest son of Heinrich Hahn (1845-1922) and Charlotte Hahn (1845-1905). At the age of 15, he developped a special interest in chemistry and started out with simple experiments the familiy´s laundry room. In 1897, after taking his Abitur at the Klinger Oberrealschule in Frankfurt, Hahn went to the University of Marburg to study chemistry and mareology. His subsidiary subjects were physics and philosophy. Hahn joined the Students' Association of Natural Sciences and Medicine, which was then a student fraternity and resulted as a forerunner of today's Nibelungia Fraternity. Hahn spent his third and fourth semester studying under Adolf von Baeyer at the University of Munich. In 1901, Hahn received his doctorate in Marburg for a dissertation wth the title On Bromine Derivates of Isoeugenol, a topic adherent to classical organic chemistry. After completing military service, he returned to the University of Marburg, where he would work as assistant to his doctoral supervisor, Geheimrat Professor Theodor Zincke for two years. Early Research: Hahn's intention had been to work in industry. With this in mind, he accepted an office at University College London in 1904, working under Sir William Ramsay, who was known for having discovered the inert gases. Here Hahn worked on radiochemistry, which was a very unexplored field at that time. In 1905, in the course of his work with salts of radium, Hahn discovered a substance he called radiothorium (thorium 228), which was held for being a new radioactive element. (In fact, it was a still undiscovered isotope of the known element thorium). In 1905, Hahn transferred to McGill University in Canada, in order to pursue further research under Sir Ernest Rutherford. It was then that Hahn discovered the new radioactive elements thorium C, radium D and radioactinium. In 1906 Hahn returned to Germany to collaborate with Emil Fischer at the University of Berlin. Hahn discovered mesothorium I, mesothorium II and - independently from Bertram Boltwood - the mother substance of radium, ionium. In subsequent years, mesothorium I (radium-228) assumed great importance because, like radium-226 (discovered by Pierre and Marie Curie), it was ideally suited for use in medical radiation treatment, costing half as much to manufacture. After the physicist Harriet Brooks had observed a radioactive recoil in 1904, Otto Hahn succeeded, in the winter of 1908/09, in demonstrating the radioactive recoil incident to alpha particle emission and interpreting it correctly. In June 1911, while attending a conference in Stettin (today Szczecin, Poland) Otto Hahn met Edith Junghans (1887-1968), who he married only two years later. In 1917/18 Hahn and Lise Meitner isolated a long-lived activity, which they named "proto-actinium". In 1949, the International Union of Pure and Applied Chemistry (IUPAC) named this new element protactinium and confirmed Hahn and Meitner as discoverers. In February 1921, Otto Hahn published the first report on his discovery of uranium Z (later known as 234Pa),which constituted the first example of nuclear isomerism. In the early 1920s, Otto Hahn created a new field of work. Using the "emanation method", which he had recently developed, and the "emanation ability", he founded what became known as "Applied Radiochemistry" for the researching of general chemical and physical-chemical questions. In 1933 he published a book entitled "Applied Radiochemistry". and specifies on lectures given by Hahn when he was a visiting professor at Cornell University in Ithaca, New York in 1933. On 15 November 1945 the Royal Swedish Academy of Sciences announced that Hahn had been awarded the 1944 Nobel Prize in Chemistry "for his discovery of the fission of heavy atomic nuclei. Max Planck Society From 1948 to 1960 Otto Hahn was the founding President of the newly formed Max Planck Society for the Advancement of Science. Immediately after the Second World War, Hahn reacted to the dropping of the atomic bombs on Hiroshima and Nagasaki by stating against the use of nuclear energy for military purposes. He considered the use of his scientific discoveries with this purpose as a misuse, or even a crime. Consequently he initiated the Mainau Declaration of 1955, in which a large number of Nobel Prize-winners called attention to the dangers of atomic weapons and warned the nations of the world urgently against the use of "force as a final resort". Source: Wikipedia