tossellphotoed-250x300Jack was born in Norwalk, Ohio and attended the University of Chicago, where he was selected for Phi Beta Kappa and earned a B.S. in chemistry in 1966. He then moved to Harvard University, earning a Ph.D. in Chemistry in 1972 under the direction of chemistry Nobel laureate William Lipscomb.  An early interest in minerals led him to take up a post-doctoral appointment with Roger Burns in the Earth, Atmospheric and Planetary Science Department at MIT.  This set him on the path to a 40-year career as an inter-disciplinarian in the Chemistry and Biochemistry Department at the University of Maryland.  He became one of the first explorers and original pioneers in the application of quantum-based computational chemistry to geochemical and environmental problems.

When Jack began to explore the usefulness of computational chemistry in geochemistry, the capacity of available computers severely limited the complexity of problems that could be tackled.  Nonetheless, his papers from that time continue to be cited and used.  One of his most important late-career projects involved redetermination of the fractionation factor governing partitioning of 11B/10B between boric acid and borate.  Geochemists use the boron isotope ratio in calcium carbonate to infer the pH of ancient oceans.  When his computations suggested that the then-preferred fractionation factor was substantially too low, he organized a team to re-measure it by a method he proposed.  The team’s new value, in good agreement with the computational result, is now widely accepted.

During his career, Jack published about 250 papers, many of them singly authored.  He was elected Fellow of the Mineralogical Society of America in 1984 and received the American Chemical Society’s Geochemistry Medal in 2011.  He also received the Distinguished Young Scientist award of the Maryland Academy of Science in 1978.

In addition to his research, Jack taught thousands of University of Maryland undergraduates,  including chemistry and biochemistry, engineering, and life sciences majors, and mentored a number of interdisciplinary scientists who have gone on to successful academic and national-laboratory careers.  He was known for the high expectations that he set for himself, his students and his mentees, and for his generosity as a teacher and mentor.  He was also deeply interested in energy issues, and introduced energy concepts in many of his courses, to the appreciation of his students.

Jack will be well remembered and missed.  Condolences go to Jack’s wife, Julia, and his children, Beth and Ken.

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