|Fig. 1: Otto Hahn is referred to the father of nuclear chemistry. (Source: Wikimedia Commons)|
Otto Hahn, who is often known as the "father" of nuclear chemistry, was born on March 8, 1879 in Germany. Hahn was the son of a businessman, but took an early interest in chemistry. Although his father waned him to study architecture, he was able to convince his father to let him study chemistry as that was his true passion. He enrolled to study chemistry and physics at the University of Marburg from 1897 to 1901, when he received his doctorate. 
Hahn wanted to become a chemistry professor at a university, and so moved to England to the University College London, where he served as an assistant to Sir William Ramsay. In 1905, he was studying salts of radium and discovered an unknown isotope of the element thorium, which he called radiothorium. Motivated by this new finding and Sir William Ramsay, Hahn decided to continue study radioactivity instead. Hahn then moved back to Germany to the University of Berlin in 1906, where he continued his research and discovered mesothorium I. This discovery would turn out to be incredibly important, as mesothorium I became a huge component of medical radiation treatment. Hahn would make many more important contributions to the study of radioactivity for the next 20 years (with a brief hiatus of four years to serve in World War I), including the discovery of radioactive recoil, protactinium, nuclear isomerism, and further research into beta-rays and the electromagnetic spectrum, all leading him up to his big discovery in 1938. 
In 1934, Hahn decided to elaborate on the work of Enrico Fermi. Fermi had discovered earlier that when hit with neutrons, the element uranium sent off radioactive products. Fermi believed that these products were small particles from the uranium atom, and so were composed very similar to Uranium. Hahn decided to test this theory, as he thought maybe the uranium atom was being broken down into something else. What he found ended up changing nuclear chemistry forever. He found convincing evidence that the products that came from the bombardment of uranium with neutrons was actually a radioactive form of barium, a much smaller and lighter element. This suggested that the uranium atom actually split into two much smaller atoms, and the idea that atoms could be split was born. This was the discovery of nuclear fission, a process that split heavier elements into multiple lighter elements and released an enormous amount of energy in accordance to Einstein's famous equation, E = mc2, in the process. In the case of Hahn's uranium to barium breakdown, about one-fifth of a neutron's mass got converted into energy.
The discovery of nuclear fission had many implications. Scientists immediately realized the possible military development of nuclear fission, and the Germans set up a group to study and develop a weapon. Hahn, however, wanted no part of the military implications, and actually condemned the use of nuclear fission in warfare. He was happy to be able to continue his research on uranium fission reactions, which he did throughout World War II.  After the war, Hahn was sent to England. He was suspected of working with the Germans to create a nuclear weapon, but was eventually cleared of all charges as he only discovered nuclear fission, but denied helping the military. The next year he received the 1944 Nobel Prize in Chemistry, and soon after that, the Enrico Fermi award. After this, Hahn spent his life continuing nuclear fission research, advocating against using nuclear fission to develop nuclear weapons, and serving as president of the Max Planck Society. Hahn died in 1968 at the age of 89. His legacy will forever be carried on as the founder of the atomic age. 
© Sameer Kumar. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 W. R. Shea et al., Otto Hahn and the Rise of Nuclear Physics (Springer, 1983).