Who was John David Main Smith?
Essays in the Philosophy of Chemistry By Eric Scerri March 12th Single essential idea blog post concerns a virtually unknown chemist, John David Main Smith, who contributed a significant piece of research in atomic physics in the early s at the time when knowledge of the field was undergoing very rapid changes.
Main Smith is partnervermittlung eva little known that I had to search far and wide for a photograph of him before finally obtaining one from his son who is still living in the south of England.
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Они возлагали огромные надежды на будущее сотрудничество с ребенком-супермозгом, полагая, что смогут сократить безмерно долгие эпохи, которых требовало его естественное развитие.
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- Who was John David Main Smith? | OUPblog
As a result, the papers did not have any serious influence on chemists and certainly not on physicists, with a few minor exceptions. What Main Smith did was to take on the views of the mighty physicist, Niels Bohr, by proposing some improved electronic arrangements for the atoms of many elements.
Who was John David Main Smith?
These new arrangements were independently, rediscovered by an almost equally obscure English theoretical physicist, Edmund Stoner, who at the time was a graduate student at the University of Cambridge.
For example, in the case of the second shell, which had long been known to contain eight electrons, Bohr regarded the electronic structure to consist of two sub-shells each containing four electrons.
Main Smith had the temerity to challenge this view single essential idea to claim that the second shell should be regarded as having a grouping of 2,2 and 4 electrons instead on the basis of detailed chemical evidence.
Similarly Main Smith held singletanz wilhelmshaven every shell begins with a sub-shell containing just two electrons.
In contemporary terms he could be single essential idea to have single essential idea the existence of s-orbitals, and the fact that each shell single essential idea with such an s-orbital.
On the other hand, here is one instance in which Main Smith turned out to be rather mistaken. Unfortunately this view stands in complete opposition to the currently accepted wisdom whereby there is indeed an analogous long period of 32 elements and starting with actinium at which point we do see a series of elements that are analogous to the rare earth elements.
This modern view is generally attributed to the American chemist Glen Seaborg who proposed his amendment to the periodic table in the s. In fact the idea was first proposed by Charles Janet, another lesser-known scientist who unambiguously anticipated this idea in the early s.
Another concept that can definitely be attributed to Main Smith was later named the inert pair effect by the chemistry Neville Sidgwick. The essential idea is that as one descends several groups in the p-block of the periodic table there is an increasing tendency for two of the outermost electrons to not be involved in covalent bonding.
For example the lower elements tin and lead situated in group 14 of the periodic table form di-chlorides whereas the higher members of the group such as carbon and silicon invariably form tetra-chlorides.
The original explanation of the inert pair effect, suggested by Sidgwick, was that the valence electrons in an s-orbital are more tightly bound and are of lower energy than electrons in p orbitals and therefore less likely to be involved in bonding. However this explanation was subsequently found wanting. More recently, some of these anomalies have been explained as resulting from relativistic effects.
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To conclude, Main Smith might be regarded as one of the missing links in the history of twentieth century atomic science. Featured image credit: Niels Bohr in Public Domain via Wikimedia Commons.
The idea of wisdom will be present on every stage of these considerations. However, in order to achieve a synthesis, one has to start with the analysis.
Eric Scerri is a chemist, writer, and philosopher of science who teaches at the University of California, Los Angeles. Posted In:.
Нам следовало заняться этим раньше, - сказал как всегда практичный Хилвар, распаковывая снаряжение.