Just before the First World War two German scientists, James Franck and Gustav Hertz carried out experiments where they bombarded mercury atoms with electrons and traced the energy changes that resulted from the collisions. Their experiments helped to substantiate they theory put forward by Nils Bohr that an atom can absorb internal energy only in precise and definite amounts. In 1921 Otto Hahn and Lise Meitner, discovered nuclear isomers. Over the next few years they devoted …showed first 75 words of 768 total…

…showed last 75 words of 768 total…S. Truman, the USA's new president, and he decided to use the bomb on Japan. On 6th August 1945, a B29 bomber dropped an atom bomb on Hiroshima. It has been estimated that over the years around 200,000 people have died as a result of this bomb being dropped. Japan did not surrender immediately and a second bomb was dropped on Nagasaki three days later. On 10th August the Japanese surrendered. The Second World War was over.