Ralph G. Pearson

Professor Emeritus

Office Location

4619 PSB-N


Inorganic Chemistry


The Department of Chemistry and Biochemistry regretfully reports the passing of Professor emeritus Ralph G. Pearson on October 12, 2022 at the age of 103.  Ralph joined the UCSB Chemistry Faculty in 1976 after distinguished teaching and research for 30 years at Northwestern University.  He retired from teaching at UCSB in 1991, but continued to come into his office in the Department until he was in his 90’s, where he carried out theoretical studies. His last journal publication appeared in 2011.  Ralph was a highly cited researcher in Inorganic and Physical Chemistry, particularly well known for his introduction of the concept of Hard and Soft Acids and Bases. The high regard held toward him was demonstrated by election to the National Academy of Sciences and receiving the American Chemical Society National Award for Distinguished Service to Inorganic Chemistry and numerous other awards.  Ralph was also well known for his authorship of “Mechanisms of Inorganic Reactions” (with Basolo), of “Kinetics and Mechanisms” (with Frost) and “Symmetry Rules for Chemical Reactions”; texts that helped train several generations of graduate students and more senior researchers. 



Current Research

Mechanisms of chemical reactions; theory of chemical bonding; applications of density functional theory to chemistry.

My main field of research is in the application of the new concepts of absolute electronegativity and absolute hardness. These are the first and second derivatives, respectively, of a plot of electronic energy vs the number of electrons in a atom or molecule. These determine the direction of electron flow and the amount of charge transferred in a reaction between two molecules. They may be used to predict the rate of reaction, or in some cases, the coordinate bond energy. At equilibrium, chemical systems are in a state of maximum hardness.


Selected Research Publications

Pearson, RG Chemical hardness and density functional theory J CHEM SCI 117 (5): 369-377 SEP 2005.

Pearson, RG Self-consistent shielding in atoms and molecules INT J QUANTUM CHEM 101 (3): 239-245 2005.

Pearson, RG Improving the energies of approximate wave functions using the concepts of density functional theory INT J QUANTUM CHEM 86 (3): 273-279 JAN 20 2002.

Maximum Chemical and Physical Hardness, Ralph G. Pearson, J. Chem. Ed., 76, 267, (1999).

Electr5onic Properties of Some Inorganic Solids, Ralph G. Pearson, Inorg. Chim. Acta, 270, 252, (1998).