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Otto Hahn

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Otto Hahn was a pioneering German chemist who changed our understanding of the atom.

Otto Hahn (Frankfurt)
Otto Hahn (Frankfurt)

He is widely known as the father of nuclear chemistry. This title comes from his work in radiochemistry, the study of radioactive elements. His most famous achievement was the discovery of nuclear fission. Nuclear fission is the process where the nucleus of an atom splits into smaller parts. This process releases a massive amount of energy. This scientific breakthrough provided the foundation for both nuclear reactors and nuclear weapons.

Nuclear Fission Experimental Apparatus 1938 - Deutsches Museum - Munich
Nuclear Fission Experimental Apparatus 1938 - Deutsches Museum - Munich

Hahn's path to discovery began with rigorous academic training. He earned his doctorate from the University of Marburg in 1901.

München-2025-Deutsches Museum-Hahn
München-2025-Deutsches Museum-Hahn

To expand his expertise, he traveled to work with world-class scientists. In 1904, he moved to London to study under Sir William Ramsay. Ramsay was famous for discovering the noble gases. Later, Hahn moved to Montreal, Canada, to work at McGill University. There, he assisted the physicist Ernest Rutherford.

Ernest Rutherford 1905
Ernest Rutherford 1905

During this time, Rutherford noted that Hahn had a "special nose" for discovering new elements. These international experiences allowed Hahn to master the emerging field of radioactivity.

In the early 1900s, Hahn made several significant discoveries regarding radioactive isotopes. An isotope is a version of a chemical element with a different number of neutrons. While working in London in 1905, he identified radiothorium, which was actually an isotope of thorium.

William Ramsay
William Ramsay

After returning to Germany, he worked in a former woodworking shop at the University of Berlin. In this lab, he discovered mesothorium I and mesothorium II. Mesothorium I was particularly important because it could be used for medical radiation treatments. It was also much cheaper to manufacture than radium. Hahn also identified ionium, which was later identified as thorium-230.

Decay Chain of Uranium-238corrected
Decay Chain of Uranium-238corrected

A central part of Hahn's career was his thirty-year collaboration with Lise Meitner.

They worked together at the Kaiser Wilhelm Institute for Chemistry. In 1912, Hahn became the head of the Radioactivity Department there. Meitner and Hahn made many groundbreaking discoveries together. In 1918, Meitner successfully isolated the longest-lived isotope of protactinium. Their partnership was one of the most productive in the history of science.

Berliner Physiker u Chemiker 1920
Berliner Physiker u Chemiker 1920

They shared a deep professional respect that lasted their entire lives.

The most critical period of Hahn's research occurred between 1934 and 1938. During these years, Hahn worked with Meitner and Fritz Strassmann to study uranium. They used a process called neutron bombardment. This involves hitting heavy elements with neutrons to see how they change. Through this method, they discovered nuclear fission. They found that the uranium nucleus was actually splitting apart.

Otto Hahn's notebook 1938 - Deutsches Museum - Munich
Otto Hahn's notebook 1938 - Deutsches Museum - Munich

This discovery was so important that Hahn was awarded the 1944 Nobel Prize in Chemistry. While the discovery was a team effort, the Nobel Committee awarded the prize to Hahn alone.

Hahn's life was also shaped by the political turmoil of his time. He was an opponent of the Nazi Party and its persecution of Jewish people. This political climate forced many of his colleagues, including Lise Meitner, to flee Germany in 1938. During World War II, Hahn continued his research on the German nuclear weapons program. He spent time cataloging the fission products of uranium. After the war ended, Allied forces arrested him. From July 1945 to January 1946, he was detained at Farm Hall with other German scientists.

Farm Hall
Farm Hall

In his later years, Hahn focused on rebuilding the scientific community in Germany. He served as the last president of the Kaiser Wilhelm Society. He also became the founding president of the Max Planck Society, serving from 1948 to 1960.

Otto Hahn Nobelpreis 1945-a
Otto Hahn Nobelpreis 1945-a

Hahn was deeply concerned with the ethics of scientific work. In 1959, he co-founded the Federation of German Scientists. This organization promoted the ideal of responsible science. He became a highly respected figure in post-war West Germany. His legacy remains tied to the powerful energy found within the atom.

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🖼️ Images & Media (20)
File:William Ramsay.jpg
William Ramsay.jpg
File:Ernest Rutherford 1905.jpg
Ernest Rutherford 1905.jpg
File:Otto Hahn und Lise Meitner.jpg
Otto Hahn und Lise Meitner.jpg
File:Berliner Physiker u Chemiker 1920.jpg
Berliner Physiker u Chemiker 1920.jpg
File:Dahlem Thielallee Hahn-Meitner-Bau.JPG
Dahlem Thielallee Hahn-Meitner-Bau.JPG
File:Ottohahn1915.jpg
Ottohahn1915.jpg
File:Decay Chain of Actinium.svg
Decay Chain of Actinium.svg
File:Decay Chain of Uranium-238corrected.svg
Decay Chain of Uranium-238corrected.svg
File:München-2025-Deutsches_Museum-Hahn.jpg
München-2025-Deutsches_Museum-Hahn.jpg
File:Nuclear Fission Experimental Apparatus 1938 - Deutsches Museum - Munich.jpg
Nuclear Fission Experimental Apparatus...
File:Otto Hahn's notebook 1938 - Deutsches Museum - Munich.jpg
Otto Hahn's notebook 1938 - Deutsches...
File:Dahlem Thielallee Hahn-Meitner-Bau-2.JPG
Dahlem Thielallee Hahn-Meitner-Bau-2.JPG

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