Two different models for chemical bond were developed almost simultaneously after the Schrödinger formulation of quantum theory. These are known as the valence bond (VB) and molecular orbital (MO) theories. Initially chemists preferred the VB theory and ignored the MO theory. Now the VB theory is almost dropped out of currency. The context of discovery and Linus Pauling’s overpowering influence gave the VB theory its initial advantage. The current universal acceptance of the MO theory is due to its ability to (...) provide direct interpretation of many different types of experiments now being pursued. In current research both localized bonds and delocalized charge distributions play important roles and the MO theory has been successful in giving a good account of both. (shrink)

Astbury's role in the X-ray study of DNA; his failure to continue his pioneering appraisal; surprising details of his MRC grant application; and his disinterest in Beighton's DNA photographs demand attention. Rosie Franklin's later involvement and behaviour receive comments, which, as with Astbury, are based on personal knowledge.

The selective synthesis and manipulation of chiral molecules is a major part of stereochemistry. Interactions involving components with “handedness” also occur in nuclear and particle physics. Both fields employ phenomenologies based on group theoretical classifications and symmetry constraints such as the conservation or violation of parity. Smale's discovery of a sphere eversion—homotopic to a central inversion—evades the parity dichotomy by allowing states of opposite chirality to be connected by smooth maps. This transformation demonstrates that parity changes can, in principle, result (...) from the action of sufficiently complex processes, and do not necessarily have to be interpreted as violations of a symmetry. (shrink)

The question of the ontological status of social wholes has been formative to the development of key positions and debates within modern social theory. Intrinsic to this is the contested meaning of the concept of emergence and the idea that the collective whole is in some way more than the sum of its parts. This claim, in its contemporary form, gives exaggerated importance to a simple truism of re-description that concerns all wholes. In this paper I argue that a better (...) way to test the ontological status of wholes is to ask whether their causal properties can be reduced to the qualities of their parts. If reduction is possible the ontological status of emergent wholes is diminished. A close analysis of William Wimsatt's definition, conceptualisation, and characterisation of emergent phenomena provides an understanding of the relationship between wholes and their parts and suggests, also, that the properties of collective phenomena of a social kind reduce to the activities of people. Social wholes and their parts reside in the same mode of organisation. This paper concludes by employing Jaegwon Kim's method of ‘functional reduction’ to demonstrate how to reduce the qualities of wholes to those of their parts. (shrink)

Summary Linus Pauling played a key role in creating valence-bond theory, one of two competing theories of the chemical bond that appeared in the first half of the 20th century. While the chemical community preferred his theory over molecular-orbital theory for a number of years, valence-bond theory began to fall into disuse during the 1950s. This shift in the chemical community's perception of Pauling's theory motivated Pauling to defend the theory, and he did so in a peculiar way. Rather than (...) publishing a defence of the full theory in leading journals of the day, Pauling published a defence of a particular model of the double bond predicted by the theory in a revised edition of his famous textbook, The Nature of the Chemical Bond. This paper explores that peculiar choice by considering both the circumstances that brought about the defence and the mathematical apparatus Pauling employed, using new discoveries from the Ava Helen and Linus Pauling Papers archive. (shrink)

The concepts of atoms and bonds in molecules which appeared in chemistry during the nineteenth century are unavoidable to explain the structure and the reactivity of the matter at a chemical level of understanding. Although they can be criticized from a strict reductionist point of view, because neither atoms nor bonds are observable in the sense of quantum mechanics, the topological and statistical interpretative approaches of quantum chemistry (quantum theory of atoms in molecules, electron localization function and maximum probability domain) (...) provide consistent definitions which accommodate chemistry and quantum mechanics. (shrink)

This paper widens the scope of our previous paper (Harré and Llored in Found Chem 13:63–76, 2011) by scrutinizing how whole/parts relations are involved in the study of molecules. In doing so, we point out two mereological fallacies which endanger both philosophical and chemical inferences. We also further explore how the concept of affordance is related to our mereological investigation. We then refer to quantum chemistry in order to pave the way for a new mereological approach for chemistry.

The question of the ontological status of social wholes has been formative to the development of key positions and debates within modern social theory. Intrinsic to this is the contested meaning of the concept of emergence and the idea that the collective whole is in some way more than the sum of its parts. This claim, in its contemporary form, gives exaggerated importance to a simple truism of re-description that concerns all wholes. In this paper I argue that a better (...) way to test the ontological status of wholes is to ask whether their causal properties can be reduced to the qualities of their parts. If reduction is possible the ontological status of emergent wholes is diminished. A close analysis of William Wimsatt's definition, conceptualisation, and characterisation of emergent phenomena provides an understanding of the relationship between wholes and their parts and suggests, also, that the properties of collective phenomena of a social kind reduce to the activities of people. Social wholes and their parts reside in the same mode (or level) of organisation. This paper concludes by employing Jaegwon Kim's method of ‘functional reduction’ to demonstrate how to reduce the qualities of wholes to those of their parts. (shrink)

In his classic work The Mind and its Place in Nature published in 1925 at the height of the development of quantum mechanics but several years after the chemists Lewis and Langmuir had already laid the foundations of the modern theory of valence with the introduction of the covalent bond, the analytic philosopher C. D. Broad argued for the emancipation of chemistry from the crass physicalism that led physicists then and later—with support from a rabblement of philosophers who knew as (...) much about chemistry as etymologists—to believe that chemistry reduced to physics. Here Broad’s thesis is recast in terms more familiar to chemists. In the hard sell of particle physics, several prominent figures in chemistry—Hoffmann, Primas, and Pauling—have had their views interpreted to imply that they were sympathetic to greedy reductionism when in fact they were not. Indeed, being chemists without physicists as alter egos, they could not but side with Broad’s contention that chemistry, as a science that deals primarily in emergent phenomena which are beyond the purview of physicalism, owes no acquiescence to particle physics and its ethereal wares. Historically, among the most widely used expediencies in chemistry and materials science are additivity or mixture rules and their cohort transferability, all of which are devised and used under the mantle of naive reductionism. Here it is argued that while the transfer of functional groups between molecules works empirically to an extent, it is strictly outlawed by the no-cloning theorem of quantum mechanics. Several illustrative examples related to chemistry’s irreducibility to physics are presented and discussed. The failure of naive reductionism exhibited by the deep-inelastic scattering of leptons by A > 2 nuclei is traced to the same flawed reasoning that was the original basis of Moffitt’s ‘atoms in molecules’ hypothesis, the neglect of context, nuclei in the case of high-energy physics and molecules in the case of chemistry. A non-exhaustive list of other contexts from physics, chemistry, and molecular biology evidencing similar departures from the ideal of additivity or reductionism is provided for the perusal of philosophers. Had the call by the mathematician J. T. Schwartz for developments in mathematical linguistics possessed of a less single, less literal, and less simple-minded nature been met, perhaps it might have persuaded scientists to abandon their regressive fixation with unphysical reductionism and to adapt to new methodologies that engender a more nuanced handling of ubiquitous emergent phenomena as they arise in Nature than is the case today. (shrink)

Interpretation of experiments involving use of vacuum ultraviolet radiation to effect ionization of N 2 in terms of measurements of a molecular orbital is erroneous.

Chemistry is the study of the structure and transformation of matter. When Aristotle founded the field in the 4th century BCE, his conceptual grasp of the nature of matter was tailored to accommodate a relatively simple range of observable phenomena. In the 21st century, chemistry has become the largest scientific discipline, producing over half a million publications a year ranging from direct empirical investigations to substantial theoretical work. However, the specialized interest in the conceptual issues arising in chemistry, hereafter Philosophy (...) of Chemistry, is a relatively recent addition to philosophy of science. Philosophy of chemistry has two major parts. In the first, conceptual issues arising within chemistry are carefully articulated and analyzed. Such questions which are internal to chemistry include the nature of substance, atomism, the chemical bond, and synthesis. In the second, traditional topics in philosophy of science such as realism, reduction, explanation, confirmation, and modeling are taken up within the context of chemistry. (shrink)

We defend the fundamental ontological-pragmatic principle that where there are continua in reality science is often forced to make partly fiat terminological delimitations. In particular, this principle applies when it comes to describing biological organisms, their parts, properties, and relations. Human-made fiat delimitations are indispensable at the level of both individuals and the natural kinds which they instantiate. The kinds of pragmatically based ‘fiatness’ that we describe can create incompatibilities and lack of interoperability even between properly designed ontologies, if not (...) appropriately handled. (shrink)

In this article I sketch G. N. Lewis’s views on chemical bonding and Linus Pauling’s attempt to preserve Lewis’s insights within a quantum‐mechanical theory of the bond. I then set out two broad conceptions of the chemical bond, the structural and the energetic views, which differ on the extent in which they preserve anything like the classical chemical bond in the modern quantum‐mechanical understanding of molecular structure. †To contact the author, please write to: Department of Philosophy, Durham University, 50 Old (...) Elvet, Durham DH1 3HN, UK; e‐mail: [email protected]. (shrink)

Controversies, i.e., multiple theory confrontations, may have a strong impact on the development of science. By an analysis of the so-called resonance controversy in chemistry the view that controversies and their resolution differ considerably from the process of theory succession is defended. It is argued that controversies are symptomatic of foundational problems, produce theory-scattering or domain-splitting, and induce ontological shifts. An explication is given of the role of existence claims and the applicability of Ockham's Razor in the resolution of controversies. (...) The requirement of a realistic interpretation of theories at all times, as defended by some philosophers, is criticised. (shrink)

In this paper I aim to show that a certain law of nature, namely that common salt (sodium chloride) dissolves in water, is metaphysically necessary. The importance of this result is that it conflicts with a widely shared intuition that the laws of nature (most if not all) are contingent. There have been debates over whether some laws, such as Newton’s second law, might be definitional of their key terms and hence necessary. But the law that salt dissolves in water (...) is not that kind of law. The law statement ‘salt dissolves in water’ is clearly synthetic. It appears a classic case of a contingent law. We like to believe that there are possible worlds in which the laws of nature are different and in which salt does not dissolve in water. (shrink)

A numerical classification was performed on 69 elements with 54 chemicaland physicochemical properties. The elements fell into clusters in closeaccord with the electron shell s-, p- andd-blocks. The f-block elements were not included forlack of sufficiently complete data. The successive periods ofs- and p-block elements appeared in an ovalconfiguration, with d-block elements lying to one side. Morethan three axes were required to give good representation of thevariation, although the interpretation of the higher axes is difficult.Only 15 properties were scorable for (...) the noble gases, but despite thepaucity of properties reflecting chemical reactivity, analysis of the 69elements on these properties still showed the major features seen fromthe full set. (shrink)

A modification of the regular medium-form periodic table is presented in which certain elements are placed in more than one position. H is included at the top of both the alkali metals and the halogens; He is above Be and above Ne. The column of noble gases is duplicated as Groups O and 18. The elements of the second and third periods are duplicated above the transition metals. This arrangement displays more patterns and connections between the elements than are seen (...) in the regular format. It fits more facts and so gives better guidance to useful predictions. (shrink)

The use of a concept called "explicativity", for (provisionally) accepting a theory or Hypothesis H, has previously been discussed. That previous discussion took into account the prior probability of H, and hence implicitly its theoretical simplicity. We here suggest that a modification of explicativity is required to allow for what may be called the pragmatic simplicity of H, that is, the simplicity of using H in applications as distinct from the simplicity of the description of H.

The potential reducibility of chemical entities to their physical bases is a matter of dispute between ontological reductionists on one hand, and emergentists on the other. However, relevant debates typically revolve around the reducibility of so-called ‘higher-level’ chemical entities, such as molecules. Perhaps surprisingly, even committed proponents of emergence for these higher-level chemical entities appear to accept that the ‘lowest-level’ chemical entities – atomic species – are reducible to their physical bases. In particular, the microstructural view of chemical elements, actively (...) developed and defended by emergentists, appears to hold that the explanatory power of nuclear charge justifies being reductionist about atomic species. My first task in this paper is to establish that nuclear charge cannot ultimately provide explanations sufficient to justify a reductionist approach to atomic species, unless we abandon the persuasive intuition that the presence of an element in a substance ought to explain the properties of that substance. The ‘missing piece’ for explaining the properties of substances by way of their elemental constituents is the electronegativity values of participant atoms. But electronegativity is a strikingly disunified concept that appears distinctly unamenable to analysis by way of fundamental physical principles. Through evaluating the uncertain physical identity of electronegativity, as well as its widespread and indispensable epistemic utility in chemical practice, I argue that electronegativity provides compelling grounds to seriously consider emergence for atomic species. (shrink)

According to Woodward’s influential account of explanation, explanations have a counterfactual structure, and explanatory counterfactuals are analysed in terms of causal relations and interventions. In this paper, we provide a formal semantics of explanatory counterfactuals based on a Ramsey Test semantics of conditionals. Like Woodward’s account, our account is guided by causal considerations. Unlike Woodward’s account, it makes no reference to causal graphs and it also covers cases of explanation where interventions are impossible.

Electronegativity is an important physico-chemical concept to study the chemical structure and reactivity. Although, the conundrum related to measurement of electronegativity still persists. In view of this fact, a simple yet rigorous scale of electronegativity, invoking an inverse relationship with atomic nucleophilicity index, has been proposed for 103 elements of the periodic table. The computed data follows periodicity distinctly satisfying all the sine qua non of a standard scale of electronegativity. Further, electronegativity values display a sound similarity with the standard (...) electronegativity scales validating the suitability of the proposed model. Molecular electronegativities of some polyatomic molecules have also been calculated using the proposed scale of electronegativity.Graphic. (shrink)

There is a persisting debate about what chemical bonds are and whether they exist. I argue that chemical bonds are real patterns of interactions between subatomic particles. This proposal resolves the problems raised in the context of existing understandings of the chemical bond and provides a novel way to defend the reality of chemical bonds.

Long since, people tried to solve the mystery of the way that led to the appearance and propagation of living entities. However, no harmonious understanding of this mystery existed, because neither the scientifically grounded source minerals nor the ambient conditions were proposed and because it was groundlessly taken that the process of living matter origination is endothermal. The Life Origination Hydrate Theory (LOH-Theory) first suggests the chemical way capable of leading from the specified abundant natural minerals to origination of multitudes (...) of multitudes of simplest living entities and gives an original explanation for the phenomena of chirality and racemization delay. The LOH-Theory covers the period up to origination of the genetic code. The LOH-Theory is grounded on the following three discoveries based on the available information and on the results of our experimental works performed using original instrumentation and computer simulations. (1) There is the only one triad of natural minerals applicable for exothermal thermodynamically possible chemical syntheses of simplest living-matter components. (2) N-base, ribose, and phosphdiester radicals and nucleic acids as whole are size-compatible with structural gas-hydrate cavities. (3) The gas-hydrate structure arises around amido-groups in cooled undisturbed systems consisting of water and highly-concentrated functional polymers with amido-groups.The natural conditions and historic periods favorable for simplest living matter origination are revealed. The LOH-Theory is supported by results of observations, biophysical and biochemical experiments, and wide application of original three-dimensional and two-dimensional computer simulations of biochemical structures within gas-hydrate matrix. The instrumentation and procedures for experimental verification of the LOH-Theory are suggested. If future experiments are successful, they, possibly, could be the first step on the way to industrial synthesis of food from minerals, i.e., to execution of the work that is performed by plants. (shrink)

New definitions are proposed for communication and language. Communication is defined as the evolution of physical, biochemical, cellular, community, and technological information exchange. Language is defined as community communication whereby the information exchanged comprises evolving individual and group-constructed knowledge and beliefs, that are enacted, narrated, or otherwise conveyed by evolving rule-governed and meaningful symbol systems, that are grounded, interpreted, and used from within evolving embodied, cognitive, ecological, sociocultural, and technological niches. These definitions place emphasis on the evolutionary aspects of communication (...) and language, and they are here differentiated from four older paradigms that instead focus either on the referential or social aspects of language, or the informational or semantic aspects of communication. In contrast with these paradigms, the definitions proposed here for communication and language are in line with a pluralistic evolutionary worldview, one that necessitates the recognition that a multitude of units, levels, mechanisms and processes are involved in bringing forth communication and language. (shrink)

Quantum physics is the foundation for chemistry, but the concept of chemical bonding is not easily reconciled with quantum mechanical models of molecular systems. The quantum theory of atoms in molecules, developed by Richard F.W. Bader and colleagues, seeks to define bonding using a topological analysis of the electron density distribution. The “bond paths” identified by the analysis are posited as indicators of a special pairwise physical relationship between atoms. While elements of the theory remain subject to debate, I argue (...) that QTAIM embodies a distinctive interactive conception of bonding that is an attractive alternative to others previously discussed. (shrink)

Examples are given of applications by Pauling, Mulliken, Marcus and G.E.Kimball of the three Pythagorian means to formulate the scales of electronegativity of the elements, to the calculations of rate constants of electron transfer cross-reactions, to the calculation of the observed rate constant as function of activation and diffusion rate constants in the case of mixed reaction-diffusion rates and to the calculation of the effective diffusion coefficient in solution of a salt AB as a whole from the diffusion coefficients of (...) the ions in which it dissociates. (shrink)

A selective history of the benzene problem is presented, starting with August Kekulé's proposal of a hexagonal structure in 1865 and his hypothesis of 1872 that the carbon–carbon bonds oscillate between single and double. Only those theories are included that were accepted or at least discussed by a significant number of chemists. Special attention is given to predictions, their empirical tests, and the effect of the outcomes of those tests on the reception of the theories. At the end of the (...) period covered by this article, chemists generally accepted the valence bond theory proposed by Linus Pauling; some of them considered this a more sophisticated version of Kekulé's oscillation hypothesis. The sequel describes the replacement of the valence bond theory by the molecular orbital theory in the period ending around 1980. (shrink)