Scerri

Eric Scerri is the author of The Periodic Table Its Story and Its Significance, Oxford University Press, New York, 2007. 

E. R. Scerri, Collected Papers on Philosophy of Chemistry, Imperial College Press, London, 2008. 

E. R. Scerri, Normative and Descriptive Philosophy of Science and the Role of Chemistry, in Philosophy of Chemistry, the Synthesis of a New Discipline, D. Baird, E. R. Scerri, L. McIntyre (eds.), Boston Studies in the Philosophy of Science, Vol. 242, pp. 119-128, 2005 E. R. Scerri, Philosophy of Chemistry — A New Interdisciplinary Field Journal of Chemical Education 77 522-526, 2000. 

F. L. Pilar, 4s Is Always Above 3d Or, How to Tell the Orbitals From the Wavefunctions, Journal of Chemical Education, 55 2—6, 1978 E. R. Scerri, M. Melrose, Why the 4s Orbital Is Occupied Before the 3d, Journal of Chemical Education, 73(6) 498—503, 1996 L. G. Vanquickenborne, K. Pier loot, D. Devoghel, Transition Metals and the Aufbau Principle, Journal of Chemical Education, 71 469-471, 1994. 

E. Barnes, On Mendeleev s Predictions Comment on Scerri and Worrall, Studies in History and Philosophy of Science, Part A, 36 801-812, 2005 S. Schindler, Use-novel predictions and Mendeleev s Periodic Table Response to Scerri and Worrall, Studies in History and Philosophy of Science, Part A, 39 265-269, 2008 D. Harker, On the Predilections for Predictions, British Journal for the Philosophy of Science, 59 429—453, 2008 E. R. Scerri, Response to Barnes Critique of Scerri and Worrall, Studies in History and Philosophy of Science, 36 813-816, 2005. 

The problems which the orbital approximation raises in chemical education have been discussed elsewhere by the author (Scerri [1989], [1991]). Briefly, chemistry textbooks often fail to stress the approximate nature of atomic orbitals and imply that the solution to all difficult chemical problems ultimately lies in quantum mechanics. There has been an increassing tendency for chemical education to be biased towards theories, particularly quantum mechanics. Textbooks show a growing tendency to begin with the establishment of theoretical concepts such as atomic orbitals. Only recently has a reaction begun to take place, with a call for more qualitatively based courses and texts (Zuckermann [1986]). A careful consideration of the orbital model would therefore have consequences for chemical education and would clarify the status of various approximate theories purporting to be based on quantum mechanics. 

Scerri, E. R. [1989] Transition Metal Configurations and Limitations of the Orbital Approximation , Journal of Chemical Education, 66(6), p. 481. 

Eric Scerri studied chemistry at the Universities of London, Cambridge and Southampton, and obtained a Ph.D. in the history and philosophy of science from King s College, London on the question of "The Reduction of Chemistry to Quantum Mechanics," He has been a research felloiu in the history and philosophy of science at the London School of Economics and at the California Institute of Technology. He is currently an assistant professor of chemistry at Bradley University, where he also teaches histoiy and philosophy of chemistry, which are also his main research interests. He is editor of the new journal Foundations of Chemistry. Address Department of Chemistry, Bradley University, Peoria, IL 61625. Internet scerri bradley.edu. 

Scerri, E. R. 1991. Electronic configurations, quantum mechanics and reduction. British Journal for the Philosophy of Science 42 309-325. 

Eric Scerri teaches in the Department of Chemistry, Purdue University West Lafayette, IN 47907... 

Prediction and the Periodic Table Eric R. Scerri and John Worrall ... 

See Scerri (1998), where it is argued that, while still no one has succeeded in giving a mathematically precise version of the periodic law, and while the law has not exactly been reduced to quantum mechanics, sufficient progress has been made to suggest that a precise version of the law may eventually be possible (if only in the limit ). (See also Scerri, 1999, where further clarification is provided.)... 

And other heuristic guides could kick in to give plausible, but never deductively derived, predictions . (So, for example, Paneth in the 1920s used simple reasoning based on the Periodic Table to predict that then undiscovered hafnium would occur in the same ores as zirconium. This is nonetheless a considerably looser notion of prediction than applies to standard cases from physics. See Scerri, 1994). 

Scerri, E, (1994) Prediction of the Nature of Hafnium from Chemistry, Bohr s Theory and Quantum Theory , Annals of Science 51, 131-150. 

Scerri, E, (1998) How Good is the Quantum Mechanical Explanation of the Periodic Table , Journal of Chemical Education 75, 1384-1385. 

In the case of the second excerpt I think I can safely say that Lowdin is wrong. The simple energy rule regarding the order of filling of orbitals in neutral atoms has now entered every textbook of chemistry, although his statement may have been partly true in 1969 when he wrote his article.1 Although Lowdin can be excused for not knowing what was in chemistry textbooks I think it is also safe to assume that he is correct in his main claim that this important rule has not been derived. Nor as I have claimed in a number of brief articles has the rule been derived to this day (Scerri, 1998). 

The full explanation of why the 4s 3d configuration is adopted in scandium, even though the 3d level has a lower energy, emerges from the peculiarities of the way in which orbital energies are defined in the Hartree-Fock procedure. The details are tedious but have been worked out and I refer anyone who is interested in pursuing this aspect to the literature (Melrose, Scerri, 1996).6,7... 

But let me return to the question of whether the periodic table is fully and deductively explained by quantum mechanics. In the usually encountered explanation one assumes that at certain places in the periodic table unexpected orbital begins to fill as in the case of potassium and calcium where the 4s orbital begins to fill before the 3d shell has been completely filled. This information itself is not derived from first principles. It is justified post facto and by some tricky calculations (Melrose, Scerri, 1996 Vanquickenbome, Pierloot, Devoghel, 1994). 

Meanwhile orbitals cannot be observed either directly, indirectly since they have no physical reality contrary to the recent claims in Nature magazine and other journals to the effect that some d orbitals in copper oxide had been directly imaged (Scerri, 2000). Orbitals as used in ab initio calculations are mathematical figments that exist, if anything, in a multi-dimensional Hilbert space.19 Electron density is altogether different since it is a well-defined observable and exists in real three-dimensional space, a feature which some theorists point to as a virtue of density functional methods. 

Very briefly, the issue is resolved by recognizing that the energies of the 4s and 3d orbitals vary depending on the configuration in question (Melrose, Scerri, 1996). 

This is why I and some others have been agitating about the recent reports, starting in Nature magazine in September 1999, that atomic orbitals had been directly observed. This is simply impossible unless one is using the word "orbital" rather perversely to mean charge density (Scerri, 2000). 

I have tried to stress the educational implications of the claims for the observation of orbitals in other articles and will not dwell on the issue here (Scerri, 2000 in Science and Education). 

---