Foundations of Chemistry最新文献

The interrelation between two theories, theory of complexity and theory of systems, is analyzed by using the chemical graph-theoretical concept. The idea of complexity is systemized through three components: diachronic, synchronic, and combinatorial complexity. The relationships between entropy and complexity, as well as the problem of function are also discussed.

Robin Hendry has presented an account of two equally valid ways of understanding the nature of chemical bonding, consisting of what the terms the structural and the energetic views respectively. In response, Weisberg has issued a “challenge to the structural view”, thus implying that the energetic view is the more correct of the two conceptions. In doing so Weisberg identifies the delocalization of electrons as the one robust feature that underlies the increasingly accurate quantum mechanical calculations starting with the Heitler-London method and moving on to such approaches as the valence bond and molecular orbital theories of chemical bonding. The present article provides a critical evaluation of Weisberg’s article and concludes that he fails to characterize the nature of chemical bonding in several respects. I claim that Hendry’s structural and energetic views remain as equally viable ways of understanding chemical bonding. Whereas the structural view is more appropriate for chemists, the energetic view is preferable to physicists. Neither view is more correct unless one subscribes to the naively reductionist view of considering that the more physical energetic view is the more correct one.

The third article of the “Naming game…” series presents the issues of naming elements discovered and synthesized in the twentieth and twenty-first centuries. Based on the source data, the publication time of the names of the last 35 chemical elements was identified. In the case of discoveries from the end of the twentieth century and the beginning of the twenty-first century, the principle was adopted of the priority of information about the synthesis of a new chemical element in scientific journals or conference reports. However, when the same information was published earlier in the news sections of scientific journals, in articles in popular science journals, and (in modern times) on the websites of interested research institutes, such an info is presented as well. It turned out that in some cases this information is very complex as the names of some elements were changed several times and published in different media in the same period. Therefore, this article is an attempt to sort out the issue of first publishing of the names of the last known 35 chemical elements.

The aim of the series of the three articles entitled “Name game…” is to present the historical information about nomenclature history of every known chemical element. The process of naming each chemical element is analyzed, with particular emphasis on the first publication with a given name. It turned out that in many cases this information is not obvious and unambiguous, and the published data are even contradictory. In a few cases, the names of the elements were changed even several times. Moreover, even when the author of a given element name is known, it is sometimes not entirely clear in which publication he/she first used it. Therefore, the series of three articles are an attempt to sort out the issue of first publishing of the names of all 118 chemical elements known so far, based on original source texts, available thanks to the digitization of a number of collections of scientific literature. The articles are divided according to the time of discoveries: (1) research till the end of the 18th century, (2) discoveries in the 19th century, (3) discoveries and syntheses of elements in the 20th and 21st centuries. This particular article presents the history of naming of the first 37 elements: known from antiquity, discovered in nature and named in 17th and 18th century.

Formal charge and oxidation state are two means of estimating the charge of an atom in a molecule. Though these concepts have very different origins—formal charge is derived from the ball-and-hook model of bonding and oxidation state is based on the ionic approximation of molecules—they are used to predict reactivity and other molecular properties through their properties as charges. In this submission, it is shown that formal charge and oxidation state are two extreme descriptions of bonding: formal charge represents zero charge transfer between atoms while oxidation state represents complete charge transfer in each bond. These ‘localised electron approximations’ form an incomplete picture of atomic charge. Electronegativity measures the extent of polarity in real bonds; this concept can be introduced to polarise bonds relative to the ‘equal sharing model’. It is shown that the various electronegativity models are fundamentally related. We chose two models to demonstrate numerically that polar bonds yield charges intermediate between the localised electron approximations: Pauling and Mulliken. It is shown that probabilistic interpretation of the Pauling scale (‘scaled Pauling’ method) and use of asymmetric chemical potential (‘modified Mulliken’ method) lead to atomic charges that closely approximate experimental values using simple ‘back of the envelope’ calculations. It is seen that formal charge, oxidation state, and electronegativity-interpolated charge lie on a continuum and are mathematically related. It is therefore concluded that electronegativity introduces (quantum) delocalisation to the localised (classical) picture of electron bonding.

I challenge Gareth Eaton’s recent claim that Theodore Richards should be counted among the discoverers of isotopes. In evaluating Eaton’s claim, I draw on two influential theories of scientific discovery, one developed by Thomas Kuhn, and one developed by Augustine Brannigan. I argue that though Richards’ experimental work contributed to the discovery, his work does not warrant attributing the discovery to him. Richards’ reluctance to acknowledge isotopes is well document. Further, the fact that he made no claim to having made the discovery also undermines Eaton’s argument.