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HSAB is an acronym for "hard and soft (Lewis) acids and bases".HSAB is widely used in chemistry for explaining the stability of compounds, reaction mechanisms and pathways. It assigns the terms 'hard' or 'soft', and 'acid' or 'base' to chemical species.
In the theory of chemical reactivity, the Klopman–Salem equation describes the energetic change that occurs when two species approach each other in the course of a reaction and begin to interact, as their associated molecular orbitals begin to overlap with each other and atoms bearing partial charges begin to experience attractive or repulsive electrostatic forces.
Ralph Gottfrid Pearson (January 12, 1919 – October 12, 2022) was an American physical inorganic chemist best known for the development of the concept of hard and soft acids and bases (HSAB). He received his Ph.D. in physical chemistry in 1943 from Northwestern University , and taught chemistry at Northwestern faculty from 1946 until 1976 ...
Quantum chemistry computer programs are used in computational chemistry to implement the methods of quantum chemistry.Most include the Hartree–Fock (HF) and some post-Hartree–Fock methods.
Hard acids form stronger complexes with hard bases than with soft bases. In general terms hard–hard interactions are predominantly electrostatic in nature whereas soft–soft interactions are predominantly covalent in nature. The HSAB theory, though useful, is only semi-quantitative. [28] The hardness of a metal ion increases with oxidation ...
Gaussian / ˈ ɡ aʊ s i ə n / is a general purpose computational chemistry software package initially released in 1970 by John Pople [1] [2] and his research group at Carnegie Mellon University as Gaussian 70. [3]
Reed, James L. Electronegativity: Chemical Hardness II. Journal of Physical Chemistry A (1997), 101(40), 7401-7407. ACS abstract extract: "It has been suggested that the abs. hardness of d. functional theory be identified with the chem. hardness of Pearson's principle of hard and soft acids and bases. It is unclear whether these two hardnesses ...
A variety of hardness-testing methods are available, including the Vickers, Brinell, Rockwell, Meyer and Leeb tests. Although it is impossible in many cases to give an exact conversion, it is possible to give an approximate material-specific comparison table for steels .