Lewis’s cubical atom

Lewis s cubical atom [3-72] deserves special mention. It was instrumental in shaping the concept of the shared electron pair. It also permitted a resolution of the apparent contradiction between the two distinctly different bonding types, viz., the shared electron pair and the ionic electron-transfer bond. In terms of Lewis s theory, the two bonding types could be looked at as mere limiting cases. Lewis s cubical atoms are illustrated in Figure 3-51. They are also noteworthy as an example of a certainly useful though not necessarily correct application of a polyhedral model. 

Figure 3-51. (a) Lewis s cubical atoms and some molecules built from such atoms (cf. Ref. 

Fig. 1.3 (a) Young Gilbert N. Lewis (Courtesy of the Lawrence Berkeley National Laboratory) (b) G. N. Lewis s cubical atoms and some molecules built from such atoms, first proposed in 1916 his original sketches are at the lower part of the Figure (Ref. [10])... 

Lewis s interest in chemical bonding and structure dated from 1902. In attempting to explain "valence" to a class at Harvard, he devised an atomic model to rationalize the octet rule. His model was deficient in many respects for one thing, Lewis visualized cubic atoms with electrons located at the corners. Perhaps this explains why his ideas of atomic structure were not published until 1916. In that year, Lewis conceived of the... 

In 1920, Bom wrote to G. N. Lewis about the reprint he had received of Lewis s 1916 paper on the "atom and the molecule." The "cubic" distribution of electrons, Born cautioned, had no general usefulness, and Lewis should look at how Born treated the problem in his new work, which he had sent Lewis. 3 Born expressed some humility about his knowledge of chemistry, confessing to Lewis a few years later, with respect to the new Lewis and Randall textbook on chemical thermodynamics, that he could not speak as well to the chemical side as to the physical side.4... 

Lewis established a theory of cubical atoms consisting of a kernel and a shell, referring to Richard Abegg s extension of the coordination number to valency [4]. For his part this goes back to Alfred Werner s observation that only carbon is the lucky case where the maximum coordmatirm number is identical to the valency. 

These ideas on the cubic atom and pairs of electrons were to lead Lewis to formulate one of the most influential ideas in the whole of modern chemistry the notion of a covalent bond as a shared pair of electrons. Until this time, chemical bonds had been regarded exclusively as involving the transfer of electrons and the formation of ionic bonds. It is interesting to realize that the concept of a covalent bond thus began, like so many important developments in modern science, with research connected to the periodic system of the elements. Moreover, Lewis s 1916 article, titled The Atom and the Molecule, has turned out to be one of the most influ-... 

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