Strassmann, Fritz

In 1938 Niels Bohr had brought the astounding news from Europe that the radiochemists Otto Hahn and Fritz Strassmann in Berlin had conclusively demonstrated that one of the products of the bom-bardmeiit of uranium by neutrons was barium, with atomic number 56, in the middle of the periodic table of elements. He also announced that in Stockholm Lise Meitner and her nephew Otto Frisch had proposed a theory to explain what they called nuclear fission, the splitting of a uranium nucleus under neutron bombardment into two pieces, each with a mass roughly equal to half the mass of the uranium nucleus. The products of Fermi s neutron bombardment of uranium back in Rome had therefore not been transuranic elements, but radioactive isotopes of known elements from the middle of the periodic table. 

In 1938, Lise Meitner, Otto Hahn, and Fritz Strassmann realized that, by bombarding heavy atoms such as uranium with neutrons, they could split the atoms into smaller fragments in fission reactions, releasing huge amounts of energy. We can estimate the energy that would be released by using Einstein s equation, as we did in Example 17.5. 

The element was discovered in the pitchblende ores by the German chemist M.S. Klaproth in 1789. He named this new element uranium after the planet Uranus which had just been discovered eight years earlier in 1781. The metal was isolated first in 1841 by Pehgot by reducing the anhydrous chloride with potassium. Its radioactivity was discovered by Henry Becquerel in 1896. Then in the 1930 s and 40 s there were several revolutionary discoveries of nuclear properties of uranium. In 1934, Enrico Fermi and co-workers observed the beta radioactivity of uranium, following neutron bombardment and in 1939, Lise Meitner, Otto Hahn, and Fritz Strassmann discovered fission of uranium nucleus when bombarded with thermal neutrons to produce radioactive iso-... 

Fritze, K., u. F. Strassmann Zur geologischen Altersbestimmung nach der Kalium-Argon-Methode. Naturwissenschaften 39, 522 (1952). 

Two of these scientists in Berlin-Dahlem, Otto Hahn and Lise Meitner, had already confirmed Fermi s results, when Fritz Strassmann joined the team and together they continued with these experiments. On January 6, 1939, they observed a strange result which they published two months later in Die Naturwissenschaften. According to Hahn and Strassmann, the bombardment of uranium with neutrons had split the uranium atom almost in half The smash-up had produced what they had reason to believe were two different and lighter elements, isotopes of barium and krypton (U Ba -J-Kr88). Hitherto only bits of the heavier atoms had been chipped away. 

As World War II approached, two German chemists, Fritz Strassmann (1902-1980) and Otto Hahn (1879-1968), pointed a stream of neutrons at a sample of uranium and succeeded in splitting the nuclei of some of its atoms. This splitting of nuclei is termed nuclear fission. The energy released through nuclear fission was the source of power for the first atomic bomb, which was built in the United States by a large team of scientists lead by U.S. physicist J. Oppenheimer (1904-1967). This secret research and development program was termed the Manhattan Project. 

One of the leading research teams looking into the products of bombardment was composed of Otto Hahn (1879-1968), Lise Meitner (1878-1968), and Fritz Strassmann (1902-1980), working in Rerlin. They irradiated uranium with... 

When Fermi s group analyzed the products of the neutron bombardment, it appeared to them that radium had been produced, especially since they had no reason to even suspect that barium could be a product. Since radium is the daughter element formed by two successive alpha decays of a uranium atom, they decided their quest for a transuranium element was unsuccessful. Subsequently, Otto Hahn (1879-1968), Fritz Strassmann (1902-80), and Lise Meitner (1878-1968), all from Germany, reinterpreted the results to show that it was not radium atoms that had been formed, but barium atoms instead from the nuclear fission of uranium. Thus, Fermi and his group just missed discovering fission. 

German chemist Fritz Strassmann is born on February 22 in Boppard, Germany. 

Nuclear fission is discovered by Otto Hahn, Fritz Strassmann, and Lise Meitner. 

Marguerite Perey dies on May 13 in Louveciennes, France. 1980 Fritz Strassmann dies on April 22 in Mainz, Germany. 

In Germany in 1938, Otto Hahn and Fritz Strassmann, skeptical of claims by Enrico Fermi and Irene Johot-Curie that bombardment of uranium by neutrons produced new so-called transuranic elements (elements beyond uranium), repeated these experiments and chemically isolated a radioactive isotope of barium. Unable to interpret these findings, Hahn asked Lise Meitner, a physicist and former colleague, to propose an explanation for his observations. Meitner and her nephew, Otto Frisch, showed that it was possible for the uranium nucleus to be spfit into two smaller nuclei by the neutrons, a process that they termed fission. The discovery of nuclear fission eventually led to the development of nuclear weapons and, after World War II, the advent of nuclear power to generate electricity. Nuclear chemists were involved in the chemical purification of plutonium obtained from uranium targets that had been irradiated in reactors. They also developed chemical separation techniques to isolate radioactive isotopes for industrial and medical uses from the fission products wastes associated with plutonium production for weapons. Today, many of these same chemical separation techniques are being used by nuclear chemists to clean up radioactive wastes resulting from the fifty-year production of nuclear weapons and to treat wastes derived from the production of nuclear power. 

He closed by wishing his friend a somewhat bearable Christmas. Fritz Strassmann added very warm greetings and best wishes. Hahn posted the letter to Stockholm late at night on his way home. 

Hahn. Otto (1879-1968) German chemist, who studied in London (with William Ramsay) and Canada (with Ernest Rutherford) before returning to Germany in 1907. In 1917, together with Lise Meitner, he discovered protactinium. In the late 1930s he collaborated with Fritz Strassmann (1902- ) and in 1938 bombarded uranium with slow neutrons. Among the products was barium, but it was Meitner (now in Sweden) who the next year interpreted the process as nuclear fission. In 1944 Hahn received the Nobel Prize for chemistry. 

The following Christmas, Meitner s nephew, Otto Frisch, came to visit her. His visit coincided with a letter from Hahn in which he reported that he and their associate, Fritz Strassmann, had achieved such bizarre results that he would for the time communicate them only to her. He wrote... 

But rationalization is a way of surviving, too, and Meitner may have understood this. She and Hahn remained friends and correspondents until their deaths, months apart, when they were in their nineties. Recently though, Meitner s contribution has received some acknowledgment. The museum in Munich that displays the apparatus she designed for the neutron irradiation of uranium has changed the plaque from Worktable of Otto Hahn to Worktable of Otto Hahn, Lise Meitner, and Fritz Strassmann. ... 

Otto Hahn and Fritz Strassmann discover the process of fission in uranium. 

In nuclear fission a heavy nuclide splits into two or more intermediate-sized fragments when struck in a particular way by a neutron. The fragments are called fission products. As the atom splits, it releases energy and two or three neutrons, each of which can cause another nuclear fission. The first instance of nuclear fission was reported in January 1939 by the German scientists Otto Hahn (1879-1968) and Fritz Strassmann (1902-1980). Detecting isotopes of barium, krypton, cerium, and lanthanum after bombarding uranium with neutrons led scientists to believe that the uranium nucleus had been split. 

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