About Walther Kossel
Walther Ludwig Julius Kossel (German: [ˈvaltɐ ˈkɔsl̩]; 4 January 1888 – 22 May 1956) was a German theoretical physicist known for his theory of the chemical bond (ionic bond/octet rule), the Sommerfeld–Kossel displacement law of atomic spectra, and the Kossel–Stranski model for crystal growth. == Education and research == Walther Ludwig Julius Kossel was born on 4 January 1888 in Berlin, Germany, the son of biochemist and Nobel laureate Albrecht Kossel. In 1910, he became an assistant to Philipp Lenard at Heidelberg University. The following year, he received his Ph.D., and remained at Heidelberg University until 1913. In 1913, the year in which Niels Bohr introduced the Bohr model of the atom, Kossel went to the Ludwig-Maximilians-Universität München as an assistant to Arnold Sommerfeld, under whom he did his habilitation. Under Sommerfeld, Munich was a theoretical center for the developing atomic theory, especially from the interpretation of atomic spectra. Kossel worked with Bohr and Sommerfeld on the Bohr–Sommerfeld model. In 1916, Kossel put forth his theory of the ionic chemical bond (octet rule), also independently advanced in the same year by Gilbert N. Lewis. In papers published in 1914, 1916, and 1920, Kossel was the first to explain the theory of absorption limits in X-ray spectra. The edge appears at a critical frequency where absorption of the radiation largely begins with the resultant ejection of photoelectrons.
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