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Kazimierz Fajans (Kasimir Fajans in many American publications; 1887-1975) was an American physical chemist of Polish origin and a pioneer in the science of radioactivity.

Education and career

He was born May 27, 1887, in Warsaw, Poland. After he had completed a secondary school in Warsaw (1904), he started studying chemistry in Germany: at first at the University in Leipzig, and then in Heidelberg and Zurich. In 1909 he was awarded a PhD degree for his research into the stereoselective synthesis of chiral compounds. In 1910 he undertook a job at the laboratory of Ernest Rutherford in Manchester, where the nucleus was discovered. Next Fajans returned to Germany where he took the position of an assistant and later became the assistant professor at the Technical University of Karlsruhe. He researched into radioactivity. In 1917 he took over the Faculty of Physical Chemistry at Munich University, and in 1932 became the Head of the Institute of Physical Chemistry established by the Rockefeller Foundation. In 1935 he left Germany due to the escalation of Nazi persecution. He stayed for a while in Cambridge and next returned to Ann Arbor, Michigan in the United States, where he joined the Faculty of the University of Michigan where he continued to work until the end of his life. He retired at age of seventy but never stopped working. He died May 18, 1975 in Ann Arbor, Michigan, USA.
Scientific work

When Fajans worked at the laboratory of Ernest Rutherford (with Henry G. Moseley) he was researching properties of the radioactive rows. He identified the periods of half-disappearance of the uranium-actinium row and thorium nuclides. He discovered the phenomenon of the electrochemical branching of the radioactive rows. Afterwards Fajans was working on the electrochemical properties of elements as a result of the radioactive changes, and he formulated the law of the radioactive moves which was later named the Soddy-Fajans Method (Frederick Soddy received the Nobel Prize in chemistry in 1921 for his isotopic research). In 1913, together with Otto Göhring, he discovered the radionuclide of a new element, which was later called protactinium. Fajans and Otto Hahn were the discoverers of the formula that defined the conditions of the precipitation and absorption of radioactive substances. It is very significant in the context of radiochemical methods of separating and cleaning radioactive substances found in the smallest number. In 1919, Fajans started researching the structure of particle and crystal by the thermochemical and refractometrical methods. The co-relation of Born, Fajans and Haber is one of the basic thermochemical rule. On the basis of his research data Fajans formulated the essential conclusions concerning chemical bonding strength and deformation of ions and particles, such as heat of ion hydration, refraction measurements and the heat of sublimation.

In the States he researched nuclear reactions using a cyclotron and discovered the radioactive lead isotope with Voigt, and a new rhenium isotope with Sullivan. He developed the quanticule theory which explained the rule of chemical bondings through electrostatic impacts between quanticules and nuclear cores. He was a member of the Polish Institute Of Arts and Sciences in America and of many societies and academies.

* 1913 - Radioactive Transformations and the Periodic System of the Elements
* ? - Application of the resonance theory to the structure of the water molecule
* 1941 - Artificial radioactive isotopes of Thallium, Lead and Bismuth
* 1948 - Electronic structure of molecules


* "Kasimir Fajans.", Journal of nuclear medicine : official publication, Society of Nuclear Medicine 7 (5): 402–4, May 1966, 1966 May, ISSN 0161-5505, PMID 5328478

See also

* Radioactivity
* Fajans rules

Chemistry Encyclopedia

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