Protactinium was successfully identified in 1913 by Kazimierz Fajans and Oswald Helmuth Göhring, marking a significant milestone in the early understanding of radioactive elements. This discovery established Fajans as a central figure in physical chemistry, bridging the gap between traditional chemical inquiry and the rapidly evolving field of nuclear physics throughout the twentieth century.
Early Education and Scientific Foundation
Born in Warsaw in 1887, Kazimierz Fajans completed his secondary schooling in his home city before pursuing advanced scientific studies in Germany and Switzerland. He attended Leipzig University, Heidelberg University, and the University of Zurich, earning his PhD in 1909 for research involving the stereoselective synthesis of chiral compounds. His transition into the study of radioactivity began in 1910 when he joined the laboratory of Ernest Rutherford in Manchester.
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Fajans conducted extensive research into the periodic table's radioactive rows, identifying the half-lives of thorium nuclides and the uranium-actinium series. In collaboration with Frederick Soddy, he formulated the law of radioactive shifts. His research expanded to include electrochemical branching and the precipitation of radioactive substances, working alongside Otto Hahn. These studies provided the framework for separating and purifying rare radioactive materials.
Molecular Structure and Chemical Bonding
Beginning in 1919, Fajans applied thermochemical and refractometric methods to crystal structure analysis. He developed the Born-Fajans-Haber cycle and explored the relationship between ion deformation and chemical bond strength. In 1923, he formulated the eponymous Fajans' rules, providing a predictive method to classify chemical bonds as ionic or covalent based on ion polarization.
Academic Career and Displacement
Fajans held faculty positions at the Karlsruhe Institute of Technology and the Ludwig-Maximilians-Universität München, where he directed the Institute of Physical Chemistry starting in 1932. Due to the rise of Nazi persecution, he left Germany in 1935. After a period at the University of Cambridge, he relocated to the United States to join the University of Michigan. He remained there for the duration of his career, continuing his research into nuclear reactions and isotopes until his death in 1975.
Fast facts
- Born: 1887, Warsaw
- Died: 1975, Ann Arbor
- Field: Physical chemistry
- Notable discovery: Protactinium
- Key concept: Fajans' rules
- Academic appointments: University of Michigan, Ludwig-Maximilians-Universität München, Karlsruhe Institute of Technology
- Citizenship: Poland, United States
- Award: Fellow of the American Physical Society
Questions readers ask
What is the significance of Fajans' rules?
Formulated in 1923, these rules help predict the character of a chemical bond, determining whether it will exhibit primarily ionic or covalent properties based on the deformation and polarization of ions.
Did Kazimierz Fajans ever receive a Nobel Prize?
Despite being nominated four times—three times in Chemistry and once in Physics—he was never awarded the prize.
Achievements
- Held posts at Karlsruhe Institute of Technology, Ludwig-Maximilians-Universität München and University of Michigan
- Educated at Leipzig University and University of Zurich
- Fields of research: physical chemistry
