Hassel was born inKristiania (now Oslo), Norway. His parents were Ernst Hassel (1848–1905), agynaecologist, and Mathilde Klaveness (1860–1955). In 1915, he entered theUniversity of Oslo where he studiedmathematics,physics andchemistry, and graduated in 1920.Victor Goldschmidt was Hassel's tutor when he began studies in Oslo, whileHeinrich Jacob Goldschmidt, Victor's father, was Hassel's thesis advisor. Father and son were important figures in Hassel's life and they remained friends.[2][3] After taking a year off from studying, he went toMunich, Germany to work in the laboratory of ProfessorKasimir Fajans.[4]
His work was interrupted in October, 1943 when he and other university staff members were arrested by theNasjonal Samling and handed over to theoccupation authorities. He spent time in several detention camps, until he was released in November, 1944.[7]
Hassel originally focused oninorganic chemistry, but beginning in 1930 his work concentrated on problems connected withmolecular structure, particularly the structure ofcyclohexane and its derivatives. He introduced the Norwegian scientific community to the concepts of theelectric dipole moments andelectron diffraction. The work for which he is best known established the three-dimensionality ofmolecular geometry. He focused his research on ring-shapedcarbonmolecules, which he suspected filled three dimensions instead of two, the common belief of the time. By using the number ofbonds between the carbon and hydrogen atoms, Hassel demonstrated the impossibility of the molecules existing on only one plane. This discovery led to him being awarded theNobel Prize in Chemistry for 1969.
