of Harvard University from 1933 to 1953, oversaw the Manhattan Project, winner of the Presidential Medal of Freedom. Joel Henry Hildebrand, Sigma 1913, (1962). Replaced nitrogen in scuba tanks with helium and oxygen, the American Chemical Society's Joel Henry Hildebrand is named for him, president of the Sierra Club from 1937 to 1940. Winner of virtually every chemical award except the Nobel Prize. Darleane Hoffman, Sigma 1988, (2000). Also winner of ACS Award in Nuclear Chemistry, US Medal of Science. Warren K. Lewis, Alpha Zeta 1925, (1947). Called Father of Modern Chemical Engineering. Also won first American Chemical Society of Award in Industrial and Engineering Chemistry, the AIChE Founders Award, and the Perkins Medal. Introduced the concept of the unit operation. M. Frederick Hawthorne, Beta Delta 1949 (2008) Noted Boron Chemist, Director of the International Institute of Nano and Molecular Medicine at the University of Missouri. Also won the King Faisal Award for Science. Other notable brothers Gilbert N. Lewis, Sigma 1913, known for dot diagrams of bonding, thermodynamic activity, and acid/base theory Frederick Gardner Cottrell, Sigma 1917, Director of the US Bureau of Mines. Arnold Orville Beckman, Zeta 1921, inventor of pH meter and ultraviolet spectrometer. Member of the National Inventors Hall of Fame, winner of the National Medal of Technology and the National Medal of Science. Wallace Carothers, Zeta 1926, Inventor of nylon and neoprene. Thomas Midgley Jr., Alpha Delta 1936, inventor of Freon Mary L. Good, Beta Phi 1976, 1993 Under Secretary of Technology, 1987 president of the American Chemical Society F. Albert Cotton, Beta Eta 1978, noted transition metal chemist Dr. Donna J. Nelson, Beta Nu 1982, 2016 American Chemical Society President, Science Advisor for the AMC television show Breaking Bad, 2022 Council of Scientific Society Presidents Board Chair-Elect, National Organization for Women "Woman of Courage Award" 2004, Society for Advancement of Chicanos and Native Americans in Science "Distinguished Scientist of the Year" 2006, Nelson Diversity Surveys author Collegiate chapters Professional chapters and groups See also Professional fraternities and sororities References Student organizations established in 1902 Professional fraternities and sororities in the United States Professional Fraternity Association 1902 establishments in Wisconsin