John Clarke Slater was a noted American physicist and theoretical chemist, recognized for introducing exponential functions which describe atomic orbitals. He also made major contributions to microwave electronics. He was born on December 22, 1900 in Oak Park, Illinois, United States. He received a B.S. from the University of Rochester in 1920 and a Ph.D. in Physics from Harvard in 1923, then did post-doctoral work at the universities of Cambridge and Copenhagen. On his return to the U.S. he joined the Physics Department at Harvard. From 1940 to 1945 John Slater was a staff member of the government's radar research Radiation Laboratory housed on the MIT campus, and leader of Group 43, Theoretical Group. At MIT after the war he helped in the transformation of the Radiation Laboratory into the Research Laboratory of Electronics and helped to establish the Laboratory for Nuclear Science. His research focused on atomic and solid state physics, in which he made fundamental contributions to the science underlying the transistor. In 1970, he received the National Medal Of Science. Slater died in Sanibel Island, Florida in 1976.