High Quality Content by WIKIPEDIA articles! Walther Ludwig Julius Kossel (4 January 1888 in Berlin, Germany 22 May 1956 in Tübingen, Germany) was a German physicist known for his theory of the chemical bond (ionic bond/octet rule), Sommerfeld Kossel displacement law of atomic spectra, the Kossel-Stranski model for crystal growth, and the Kossel effect. Walther was the son of Albrecht Kossel who won the Nobel Prize in Physiology or Medicine in 1910.Kossel began studies at the University of Heidelberg in 1906, but was at the University of Berlin during 1907 and 1908. In 1910, he became assistant to Philipp Lenard, who was also his thesis advisor. Kossel was awarded his Ph.D. in 1910, and he stayed on as assistant to Leonard until 1913