Philosophy of Chemistry

This paper reframes anomalous melting point drift in crystalline compounds as a manifestation of recursive phase alignment, challenging both conventional purification-based thermodynamics and morphic resonance speculation. Using the CODES framework, it proposes that melting point is not a fixed trait but a coherence plateau reflecting structured resonance evolution across synthesis cycles.

The article sets out to clarify a number of confusions that exist in connection with the Born–Oppenheimer approximation (BOA) (Born-Oppenheimer, 1927). It is generally claimed that chemistry cannot be reduced to quantum mechanics because of the nature of this commonly used approximation in quantum chemistry, that is popularly believed to require a ‘clamping’ of the nuclei. It is also claimed that the notion of molecular structure, which is so central to chemistry, cannot be recovered from the quantum mechanical description of (...) molecules and that it must be imposed by hand through the BOA. Such an alleged failure of reduction is then taken to open the door to concepts such as emergence and downward causation. Another mistaken view is that chemists have no choice but to use the BOA whereas there is an entire sub-discipline which involves non-Born Oppenheimer calculations, and which regularly and successfully calculates many chemical and biochemical properties of molecules. Yet another misconception, according to the present author, is the view that the application of the BOA represents a violation of the Heisenberg Uncertainty Principle. Many of the claims made in the philosophy of chemistry community are based on the highly technical papers of authors such as Sutcliffe and Wooley, many of which date from about 50 years ago. While these authors remained skeptical of the possibility of recovering molecular structure from quantum mechanics, others maintained that it would eventually possible to do so. Significant progress has now been made in this direction. For example, whereas it is claimed that the full, or Coulombic Hamiltonian, for a molecule precludes the existence of molecular dipoles, some recent calculations have succeeded in obtaining the exact value of dipole moment of the LiH molecule. Even more significantly, a group in Norway has now succeeded in recovering the structure of the D3 + molecule in a completely ab initio manner without applying the BOA, but through the use of a Monte Carlo approach. (shrink)

It is generally accepted that the exact solution to the Schrödinger equation cannot be expressed as a single determinant of orbitals. This assertion is the result of the traditional approach taken to solve the N-electron problem in 3N dimensions, namely, integration over coordinates. Integration over coordinates averages the various interactions leading to approximations to the exact solution; this loss of local information is sought to be recovered through multi-determinant formalisms. We introduce the local Schrödinger equation (in $${\mathbb{R}}^{6}$$ ) from the (...) energy density representation of the Schrödinger equation (in $${\mathbb{R}}^{3N}$$ ). A proof is presented that shows that there exists a single determinant representation (of one-electron orbitals) for the exact wavefunction that satisfies the Schrödinger equation. We also show that the exact orbitals that describe the system have the same orbital energy, thereby equalising the chemical potential within the system. (shrink)

In this brief article I respond to Seifert’s recent views on the periodic law and the periodic table in connection with the views of philosophers regarding laws of nature. I argue that the author makes some factual as well as conceptual errors which are in conflict with some generally held views regarding the periodic law and the periodic table.

Knowledge about atomic structure has been developed over the years, and through the Philosophy of Science, including Epistemology, it may be approached in Science Teaching. Considering the existence of many explanations for the structure of matter, a review of this concept and the atomic models was carried out to explore what is discussed in the literature from scientific articles in English, Spanish, and Portuguese. It was possible to highlight the importance of developing this research in the languages mentioned above, yielding (...) diverse results, contributing to the discussion of the structure of matter and Science Education. More than 40 explanations for the structure of matter were found, revealing distinct perspectives, many in philosophical approaches and others in models developed by physicists and chemists. The models found were cited, defined, or discussed by the articles. The ideas presented in models were classified as indivisibles, divisibles condensed, divisibles with nucleus and quantization of energy. The Nature of Science was a theoretical base in which cognitive and epistemic aspects were addressed as well as social and institutional to present and analyze the results. (shrink)

Abstract -/- This paper proposes that intelligence is not stochastic adaptation but resonant recall—a structured response to stored asymmetry in molecular, cognitive, and civilizational substrates. Using aromatic rings as canonical coherence structures, we explore how phase-locked memory fields guide emergence across biology, chemistry, cognition, and culture. Intelligence is reframed as a compression field, released not through computation but through resonance alignment. By decoding patterns from floral chemistry to polymer invention and phase-aligned cognition, we outline a substrate theory of emergent intelligence: (...) one that remembers before it thinks, and aligns before it acts. (shrink)

Why do chemists think that the bond is real in spite of objections raised from the quantum mechanical studies of molecules? (Parr and Yang in Density-functional theory of atoms and molecules Clarendon Press, Oxford, 1994) Focusing on the cognitive aspect of investigative practices in chemistry, we reveal the meaning of the chemical bond for chemists and why they take it as real. Our argument is based on the historical studies of the bond and an understanding of the epistemological technique of (...) transdiction as well. The latter is a way of reasoning developed since the days of Newton. The rationalist reconstruction of forces of nature is an illustration of transdiction as a tool of building theories. In the history of chemistry, a comparison between the notions of a directed valence proposed by van’t Hoff and an asymmetrical molecule by Le Bel shows transdiction has some methodological differences in application. In relation to transdiction we argue the meaning of the word ‘hypotheses non fingo,’ which serves as a key to understanding cognitive grounds for reality in experimental sciences. Our approach adopted in this study is characterized by functional realism we advocate in the context of organic chemistry. (Ochiai in Found Chem 26: 399–411, 2024) This approach reveals that the bond is a kind of function of the molecule that becomes actualized on occasions of solving problems in organic chemistry. Provided that reality is the epistemological concept, bonds are real for chemists in terms of function expected from chemical substances. It should be noted that the confusion between chemical ‘bond’ and quantum mechanical ‘bonding’ causes a lot of problems in understanding the concept of bond. The bond is a coded representation and not a visualization of quantum mechanical facts. Such is also the case with molecular structure, which is a functional map, as it were, to show what part of the molecule is susceptible to chemical transformations. (Ochiai in Hyle Int J Philos Chem 19: 139–160, 2013) It should be distinguished from the images of molecules obtained by using Scanning Tunneling Microscopy, for instance. This analysis shows that chemistry cannot be reduced to so-called more fundamental sciences like quantum mechanics, for the latter is not concerned with the functional aspects of chemical substances. (shrink)

Scerri (2024) has argued that the metaphysical question of what natural lawhood consists in is irrelevant to science and science education. This paper identifies how Scerri’s arguments fail and suggests that contrary to Scerri, there is no gulf between the philosophers’ and scientists’ conceptions of lawhood. The distinctions drawn by philosophers would be useful in science education.

In this study, we present a didactic analysis of the impact of epistemological obstacles -identified by various studies over the past 30 years- may have on the learning of biochemical models of cellular respiration. Epistemological obstacles refer to general reasoning patterns that shape people’s conceptions on different topics, such as teleology, essentialism, and linear causal reasoning, among others. Our analysis aims to characterize these epistemological obstacles as they underlie the conceptions that emerge in the teaching and learning of cellular respiration (...) within the context of biochemistry education. This topic has been relatively unexplored from this perspective in biochemistry education research, particularly at the interface of biology and chemistry, where various alternative conceptions have been identified. Similarly, the specific process of cellular respiration -central to cellular metabolism and energy production in living organisms- has received limited attention from this viewpoint. Furthermore, in this article, we propose strategies to address these epistemological obstacles in educational settings, with a specific focus on cellular respiration. We argue that surveying and characterizing these epistemological obstacles in biochemistry education can support the development of teaching strategies that effectively address them in science classes, fostering metacognitive vigilance and conceptual understanding. (shrink)

This paper performs a historical study of the attempts made by Thomson and Bohr to explain the Periodic Table in terms of the electronic configurations of chemical elements. Specifically, Thomson’s early theoretical ideas about the electronic arrangements of atoms are initially outlined. This system gave way to the first quantum constrains introduced by Bohr in 1913. It is discussed how Bohr eventually revised this initial work on this topic ten years later. Then, it is presented a concise historical account of (...) the progressive incorporation of quantum numbers in the different theories of the electronic structure of elements. In this regard, the contributions made by Sommerfeld, Stoner and Pauli are examined. Finally, the Madelung rule is analyzed, focusing on both how it has normally been used to teach students the atomic electronic configurations and its limitations. These shortcomings are usually not considered in chemistry textbooks. It is reported how this neglect generates several incorrect teaching assumptions. (shrink)

Although the two-letter symbol pH is extremely common in chemistry and elsewhere, its origin and early dissemination has only received scant attention among chemists and historians of science. Introduced as a convenient symbol for ‘hydrogen ion exponent’ by the Danish biochemist S.P.L. Sørensen in 1909, after a decade or two pH won broad acceptance in the fields of physiology, biochemistry, medical research, and industrial chemistry in particular. Apart from detailing how pH and related concepts were initially received, this paper examines (...) the language and nomenclature associated with the pH scale until about 1930. What is today written as pH was in the past symbolized in a variety of other ways. Although Sørensen never became a Nobel laureate, he was nominated many times and the evaluations of the Nobel committees throw further light on how his innovation was conceived by contemporary chemists and physiologists. The paper also discusses, if in less detail, how the original definition $${\text{pH}} = - {\text{log}}\left[ {{\text{H}}^{ + } } \right]$$ pH = - log H + was revised in the early 1920s into the currently accepted form involving hydrogen ion activities rather than concentrations. The paper is essentially but not strictly limited to the period from about 1905 to the mid-1930s. (shrink)

Scientific metaphysics asserts that the findings of our best and most mature science can reveal metaphysical principles. In this paper, the findings of contemporary chemical investigation, specifically the chemical transformation of molecules, serves as a starting point for metaphysical reflection and allows us to identify metaphysical principles that ground characteristic features of chemical change. The causal nature of chemical change is described in terms of molecules that possess powers-based dispositional properties, with quantitative features fixed by governing laws of nature. Finally, (...) the proposal is made that both laws of nature and metaphysical principles are primitive, fundamental principles of reality. (shrink)

Being aware of the scarcity of research in the fields of History and Philosophy of Science and the Philosophy of Chemistry for Chemistry Education, this endeavor aimed to discuss conceptions about the relevance of the dialectical unity between theoryand practicefor the development of Chemistry in the fields of Philosophy of Science and Philosophy of Chemistry, from a Marxist perspective. To support this work, we focused on the understanding of practice in Vázquez's Philosophy and in the Philosophy of Chemistry, in summary: (...) the understanding of this category as the concretization of human teleological activity in the material world, while in science it manifests in an interdependent way with theory, in a dialectical movement. In this way, a discussion was held based on the literature in Philosophy of Science that relates to this dialectical unity, criticizing discourses that prioritize theory in order to rethink the Philosophy of Science Curriculum for Chemistry Teaching Degrees and include the philosophical specificities of Chemistry in these courses. Finally, it is noted that the characteristics of Chemistry as a utilitarian science, its pragmatism, and its relational epistemology place it in a position as an ideal technoscientific knowledge to embody this dialectical unity between theory and practice in scientific practice. (shrink)

The concept of a “chemical speciation”, as defined by in the year 2000, is grounded in an empiricist semantics. It is a static concept, as it is associated with the ontological category of the chemical state of the distribution of chemical species in a system and is further restricted to chemical species of a single element as it excludes chemical species with more complex chemical systemic subunits, such as molecular species, crystals, or nanoparticles. In this work, we propose a new (...) definition of “chemical speciation” based on a semantics of meaning, applying Mario Bunge’s philosophical system. Chemical speciation is the distribution of chemical systemic subunits amongst defined chemical species in a system. Additionally, we propose two dynamic concepts associated with chemical speciation: chemical species transformation and chemical species evolution. These concepts aim to account for the chemical changes that explain both the diversity of chemical species sharing common systemic subunits and the historical emergence of new modes of chemical speciation. These modes, in turn, explain the appearance of new systemic chemical subunits and novel substantial properties. Our definitions have the advantage of being consistent with general theories of the evolution of matter, such Assembly Theory. Additionally, at the chemical level, this approach encompasses broader systemic chemical subunits beyond elemental particles, allowing for the chemical speciation of families of molecules, crystals, nanoparticles, etc. Finally, our proposal offers the advantage of overcoming the issue of arbitrariness in choosing the reference systemic chemical subunit by linking this choice to the concepts of substantial property, and function. (shrink)

Molecular structure is one of the dispositional attributes of the molecule and counted as an example of affordances. This attribute has been systematically exploited through the development of theories and practice of organic chemistry. (Ochiai 2023, pp. 141–149) The question to be addressed in this study is whether we can legitimately claim that this type of attribute is real. To answer the question, we first clarify what is worthy of the word ‘reality’ in scientific arguments. Whitehead claims that a physical (...) substance like electron is a bundle of spatial-temporal experience. (Mesle 2008, p. 36) The contention is that we cognize the causal relationships of the physical world through the experience of events. What we cognize as real is not unchanging matter but various kinds of events we experience. Based on this recognition we examine the nature of affordances. Affordances are the context-relative dispositional attributes of {agent-world} complexes. (Harré 2014, pp. 77–91; Harré and Llored 2018, pp. 167–186) The affordance of a knife becomes actualized through our experience of cutting. In this way affordances are concerned with work or the function of something useful. They are materialized as tools. This suggests that affordances are real, and so is molecular structure. Molecular structure is characterized by a certain function which molecules show in organic synthesis. Other dispositional attributes of molecules that become actualized in the context of organic chemistry are also examined. We refer to the physical significance of wavefunctions as well, which we discussed in the previous study. (Ochiai 2023, pp. 359–367) Creating function, we expand a world we cognize as real. This view of the world we name ‘functional realism.’ Our conceptual scheme is supported by Quine’s holism. (shrink)

In philosophy, the empirical success of a science is often explained by the fact that it has managed to discover some law(s) of nature. This line of thought has not been thoroughly explored with respect to chemistry. The aim of this paper is to fill this gap by showing how we could think about laws in chemistry. Specifically, it briefly presents how laws of nature are understood in philosophy of science. It then discusses two case studies from chemistry—the periodic table (...) and chemical reactions—and explains how general ideas about law-hood can be applied to these cases. Lastly, it presents research questions and philosophical problems that arise by considering chemistry from the perspective of laws. This analysis illustrates that there is value in thinking about laws in chemistry. (shrink)

The article contrasts the way that laws are regarded by some philosophers of science with the way that they are regarded by scientists and science educators. After a brief review of the Humean and necessitarian views of scienfic laws, I highlight difference between scientists who regard laws as being merely descriptive and philosophers who generally regard them as being explanatory and, in some cases, as being necessary. I also discuss the views of two prominent philosophers of science who deny any (...) role for scienfic laws. I conclude that science educators should be wary of adopng the necessitarian view of scienfic laws. (shrink)

In this paper we will argue that the identity of the entities that inhabit the nanoworld is a contextual identity. To defend that, we will analyse the so-called “biological” identity and the “synthetic” identity of nanomaterials. From this analysis, we will claim that nano-individuals (entities that show an intermediate nature between individuals and stuff), can be adequately understood from the perspective of a processual ontology. With that, we intend to contribute to the philosophical understanding of the ontology of the nano-domain.

In recent years, the definition of mole, the unit of the amount of substance, has changed to have the base units of the International System defined by “explicit-constant” formulations. The old definition, by referring explicitly to both mass and elementary units, suggests that the mole is a bridge between the macroscopic and microscopic registers. Conversely, the new definition emphasizes the aspect of counting, referred to any kind of elementary unit. Paradoxically, this results in the disappearance of the notion of substance (...) from the very unit of the quantity amount of substance. This change of definition elicited both positive and negative remarks from various authors, in relation to its epistemological, disciplinary, lexical and educational implications. In the present paper, we analyze some of these issues, highlighting the (conflicting) motivations of metrologists and chemists. We argue that the new definition of mole reflects a view of chemistry according to which the microscopic perspective prevails, possibly entailing the loss of reference to the macroscopic register; this could be related with the profound change undergone by the cognitive practices of chemistry along this last century. (shrink)

Although the electron density can be calculated with the formal resources of quantum mechanics, in physics it does not play the leading role that the quantum state does. In contrast, the concept of electron density is central in quantum chemistry. There is no doubt about how the electron density is computed in terms of the wave function of an atom or molecule. However, when the interpretation of the concept is at stake, there is no general agreement. In this article we (...) will analyze the two main interpretations of the concept of electron density: the Born-style probability density interpretation and the Schrödinger-style charge density interpretation. In particular, we will examine their differences, their relations with quantum mechanics and the consequences that each of them entails from a strictly quantum point of view. (shrink)

In this paper, we will address a recurring problem in the field of the general philosophy of science but one that takes on particular relevance in the context of chemistry: the problem surrounding scientific laws. The main challenge is that the laws of chemistry are not universal; moreover, in practice, they are stated alongside numerous exceptions. Given that there are exceptions, we could argue that what the laws assert is neither universally true nor necessary. But if that's the case, are (...) they genuine scientific laws? And if so, what is the reason for such lawfulness? (shrink)

Franklin and Seifert (2021) argue that solving the measurement problem of quantum mechanics (QM) also answers a question central to the philosophy of chemistry: that of how to reconcile QM with the existence of definite molecular structures. This conclusion may appear premature, however, because interactions play a crucial role in shaping molecules, but we generally lack detailed models of how this is accomplished. Given this explanatory gap, simply choosing an interpretation of QM is insufficient, unless the interpretation also has relevant (...) conceptual resources that address how spatially organized molecules are composed. This article seeks to close the gap, using the interpretation provided by relational quantum mechanics (RQM), along with a posited causal ontology. This framework, which entails the co-existence of multiple perspectives on systems within a single world, offers a path toward reconciling the quantum mechanical view of molecules with another conception more congenial to chemistry: that of molecules shaped by patterns of localizing interactions. (shrink)

The theme surrounding scientific discoveries is quite neglected in and about the sciences, especially in terms of historical and epistemological understanding. Discoveries are often treated as simple information about dates, places, and people. This work presents discussions centered on historical episodes related to chemical elements and the Periodic Law, based on reflections by Thomas Kuhn and Norwood Hanson, aiming to highlight and contextualize specific scientific discoveries' conceptual and epistemological structure. With that in mind, issues related to the inseparability of the (...) contexts of discovery and justification are recovered, along with the complex intrinsic structures of the genesis of scientific knowledge and distinct types and categories of scientific discoveries. (shrink)

Prelog’s model was one of the first empirical models to explain the stereoselectivity of the Grignard reactions of 2-oxocarboxylic acid esters bearing a chiral alcohol. Prelog constructed his model based on some assumptions regarding the conformation of chiral 2-oxocarboxylic acid esters to explain the relationship in configuration between the chiral alcohol starting materials and the 2-hydroxycarboxylic acid products. Construction of the model involves four steps: (1) mentally analyzing the reactants to identify the basic stereochemical structures, (2) assuming the conformations of (...) the chiral alcohol moiety as the main reasons for stereoselectivity, (3) modeling the transition states to explain the relationship in configuration between the chiral alcohols and 2-hydroxycarboxylic acids, and (4) validating the evidence to revise the model. The process of constructing this historically pivotal model may have implications for science education, especially for developing theories from extensive data. The four steps from the Prelog’s model were compared with the models for boiling points of hydrocarbons and solubility of amino acids. (shrink)

There are 2 main problems with the current periodic table: artificial breaks from a given noble gas to the next alkali metal (along with the common protrusion of the “f” block) and hydrogen placed in the alkali group, although this gas also exhibits halogen properties. This paper proposes arranging chemical elements in a square spiral with hydrogen at the centre. This element is also above lithium but passes above fluorine to connect with helium, representing its dual alkali and halogen nature (...) effectively. Then the spiral moves outwards in a counter-clockwise direction, avoiding artificial breaks and following the natural direction of reading for the “s” and “p” blocks elements placed at the bottom of the spiral. Furthermore, this proposed square spiral improves upon previous Janet´s and Benfey´s representations with a more regular shape to draw, an effective depiction of the dual nature of hydrogen, and easily identifiable orbital blocks without the need for protrusions. (shrink)

In this paper, we present a bibliometric analysis of the Periodic Table. We have conducted a comprehensive analysis of Scopus based database using the keyword “Mendeleev Periodic Table". Our findings suggest that the Periodic Table is an influential topic in the field of Inorganic as well as Organic Chemistry. Areas for future research could include on expanding our analysis to include other bibliometric indicators to gain a more comprehensive understanding of the impact of the Periodic Table in the chemistry-based scientific (...) investigations and even in the field of astrochemistry, which explores chemical processes in space, is intricately linked to fundamental chemistry. In this context, the quote of Carl Sagan is relevant where he eloquently expressed an inherent connection between chemistry and astrophysics: “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars.” In the ongoing study we have presented a ground level investigation of the conjecture of Sagan via Periodic Table based on bibliometric analysis whereas in the next level our aim is to present the stellar connection of it through Hertzsprung-Russel diagram as well as cluster of stars. The Periodic Table holistically serves as a foundational platform for understanding chemical elements both on the Earth and in celestial bodies. The present investigation fundamentally identifies the main working field of research and lays the groundwork for potential connections to astrochemical studies. (shrink)

In this contribution, the role of epistemology in understanding quantum chemistry is discussed. Quantum chemistry is the study of the behavior of atoms and molecules using the principles of quantum mechanics. Epistemology helps us evaluate claims to knowledge, distinguish between justified and unjustified beliefs, and assess the reliability of scientific methods. In quantum chemistry, the epistemology of knowledge is heavily influenced by the mathematical nature of quantum mechanics, and models can be tested, proven, and validated through experimentation. This paper also (...) discusses key concepts used in quantum chemistry, such as the wave-particle duality of matter and the uncertainty principle. This work utilizes Kant’s philosophy of science to frame debates and discussions in quantum chemistry, particularly with regard to the interplay between empirical observation and theory. Additionally, the text explores how Kant’s ideas about the role of the mind in constructing our understanding of the world can help us comprehend the counterintuitive phenomena of quantum mechanics and its applications in quantum chemistry theory. (shrink)

The new mathematical connection of De Donder’s differential entropy production with the differential changes of thermodynamic potentials (Helmholtz free energy, enthalpy, and Gibbs free energy) was obtained through the linear sequence of equations (direct, straightforward path), in which we use rigorous thermodynamic definitions of the partial molar thermodynamic properties. This new connection uses a global approach to the problem of reversibility and irreversibility, which is vital to global learners’ view and standardizes the linking procedure for thermodynamic potentials (Helmholtz free energy, (...) enthalpy, and and Gibbs free energy)—preferably to the sensing learners. It is shown that De Donder’s differential entropy production in an isolated composite system is equal to the differential change in total entropy and that De Donder’s equation agrees with Clausius’ inequality. The useful work of the irreversible process is discussed, which with the decrease of irreversibility tends towards the hypothetical maximum useful work of the reversible process. (shrink)

This paper proposes a theoretical approach to discuss the relations among reality, chemists’ interactions with it, and the resulting interpretation and representation of the acquired scientific knowledge. Taking into account that such relations are of semiotic nature, this paper aims at discussing in the light of Peirce’s theory of signs different descriptions of chemical activity and chemical education proposed by Alex Johnstone and elaborated by other science educators. In order to discuss the contributions and limitations of the proposed theoretical framework, (...) and considering its potential interest for chemical education, an example on the communication strategies for the content ‘vapour pressure’ found in twentieth-century general chemistry university textbooks is also presented. (shrink)

Are acids natural kinds? Or are they merely relevant kinds? Although acidity has been one of the oldest and most important concepts in chemistry, surprisingly little ink has been spilled on the natural kind question. I approach the question from the perspective of microstructural essentialism. After explaining why both Brønsted acids and Lewis acids are considered functional kinds, I address the challenges of multiple realization and multiple determination. Contra Manafu and Hendry, I argue that the stereotypical properties of acids are (...) not multiply realized. Instead, given the equivalence between the proton-donating and electron-accepting mechanisms of Brønsted and Lewis, respectively, I show that acidity as a property type can be identified with a unique microstructural property, namely the presence of a LUMO or other low energy empty orbital. In doing so, I defend the view that the Lewis theory encompasses Brønsted–Lowry, and that all Brønsted acids are also Lewis acids. Contra Hacking and Chang, I thus maintain that the different concepts of acidity do not crosscut, and that the hierarchy requirement is met. Finally, by characterizing natural kinds as powerful objects and by adopting a dispositional view of functions, I illustrate how the microessentialist can make sense of the latent and relational character of most acids. In sum, I contend that acids are genuine natural kinds, even for the microstructural essentialist. (shrink)

In this short essay I address the central topic of the Centenary Workshop on Acidity, that is the relations of the classical protonist acid–base theory by Brønsted and the electronist approach by Lewis. Emphasis is laid on the empirical background of both approaches and the over-theoretization of chemical phenomena (essentialism) is criticized.

Among the many acid-base concepts, the theory of Usanovich is one of the least known despite the most general scope including almost all chemical reaction types and even redox chemistry. Published 1939 in a Soviet journal in Russian language, it gained little immediate attention, and was later criticized mainly as being too broad in scope. Although several articles recently remembered Usanovich and his acid–base theory, one major inconsistency again was overseen: the electron is put in a row along with anions. (...) Chemical history probably correctly puts this concept aside, also because it added little explanation capabilities beyond the elaborated considerations of the simultaneously published acid–base theory of Gilbert N. Lewis which was later refined by Pearson (hard and soft acids and bases, “HSAB”). A modified version of the core of Usanovich' concept is finally discussed. It combines the classic protic and aprotic acid–base concepts on the foundations of Lewis’ and Pearsons ideas. (shrink)

Acidic substances were known for thousands of years, and their macroscopic-sensory characteristics were reflected by words in most ancient languages. In the Western canon, the history of the concept of acidity goes back to Ancient Greece. In Greek, the word associated with acidity from its early literary references was ὀξύς (“sharp”), and still in contemporary Greek the words “sour” and “acidic” have the same root. This paper makes a short presentation of the appearance of the abstract concept in the works (...) of Plato and Aristotle and relates it, on one side to the already existing theological-philosophical tradition, starting with Hesiod´s Theogony and on the other, to the then available to the Greeks organoleptic experiences of sourness-vinegar and sour milk. (shrink)

Language is an important part of the human culture. It serves for the expression and communication of thoughts. In is article, the problem of chemical jargon as a tool for communication between scientists is discussed.

The meaning of the once widely used term the Gibbs Free Energy in terms of available work energy is perfectly illustrated for chemical reactions by the Van’t Hoff Equilibrium Box. Combining this with DeDonder’s extent of reaction variable and using the reaction of $$\hbox {NH}_3$$ to $$\hbox {H}_2$$ and $$\hbox {N}_2$$ at $$200^{\circ }\hbox {C}$$ as an example shows the difference between total work energy and available work energy, and in addition allows calculation of the equilibrium composition, demonstration of the (...) minimum in the Gibbs energy curve, and the standard relationship between $$\Delta _\textrm{r}G^{\circ }$$ and $$\ln {K}$$. (shrink)

In this transdisciplinary investigation, we focus on the invention and development of gunpowder. We aim to answer the questions regarding (1) the inspiration behind the invention, including historical, mythological, and intellectual backgrounds, (2) how it came about in concreto, and (3) its impact on the history of science in China. We argue that the invention has to be viewed in a broader context and that various factors come into play with regard to the above questions. The discussion starts by examining (...) the preconditions of the invention of gunpowder in ancient Chinese mythology, natural philosophy, and the idea of life extension. After that, the invention, its direct contexts, and historical developments during the first millennium CE are investigated. To complement the former analysis of historical worldviews, the modern perspective of chemistry is applied in this context. From the angle of the additional question of “open individuals,” namely as agents of progress, this is also taken into consideration from the perspective of personality analysis. Finally, we investigate how the development of scientific understanding was embedded in the innovative philosophical developments of Song dynasty Neo-Confucianism. In our view, the early Chinese gunpowder research exemplifies the preceding and contemporary development of the scientific stratum that is part of the concept of the “investigation of things” (gewu) in the sense of the teachings of Zhu Xi (1130–1200). (shrink)

J. Willard Gibbs derived the following equation to quantify the maximum work possible for a chemical reaction$${\text{Maximum work }} = \, - \Delta {\text{G}}_{{{\text{rxn}}}} = \, - \left( {\Delta {\text{H}}_{{{\text{rxn}}}} {-}{\text{ T}}\Delta {\text{S}}_{{{\text{rxn}}}} } \right) {\text{ constant T}},{\text{P}}$$ Maximum work = - Δ G rxn = - Δ H rxn - T Δ S rxn constant T, P ∆Hrxn is the enthalpy change of reaction as measured in a reaction calorimeter and ∆Grxn the change in Gibbs energy as measured, if (...) feasible, in an electrochemical cell by the voltage across the two half-cells. To Gibbs, reaction spontaneity corresponds to negative values of ∆Grxn. But what is T∆Srxn, absolute temperature times the change in entropy? Gibbs stated that this term quantifies the heating/cooling required to maintain constant temperature in an electrochemical cell. Seeking a deeper explanation than this, one involving the behaviors of atoms and molecules that cause these thermodynamic phenomena, I employed an “atoms first” approach to decipher the physical underpinning of T∆Srxn and, in so doing, developed the hypothesis that this term quantifies the change in “structural energy” of the system during a chemical reaction. This hypothesis now challenges me to similarly explain the physical underpinning of the Gibbs–Helmholtz equation$${\text{d}}\left( {\Delta {\text{G}}_{{{\text{rxn}}}} } \right)/{\text{dT}} = - \Delta {\text{S}}_{{{\text{rxn}}}} \left( {\text{constant P}} \right)$$ d Δ G rxn / dT = - Δ S rxn constant P While this equation illustrates a relationship between ∆Grxn and ∆Srxn, I don’t understand how this is so, especially since orbital electron energies that I hypothesize are responsible for ∆Grxn are not directly involved in the entropy determination of atoms and molecules that are responsible for ∆Srxn. I write this paper to both share my progress and also to seek help from any who can clarify this for me. (shrink)

Hydrogen is troublesome in any periodic table classification. This being so it may as well be placed in a position that confers desirable attributes to the arrangement of the elements, while notionally recognising its lineage to the group 1 alkali metals and the group 17 halogens. Since the noble gases bridge the halogens and the alkali metals, and hydrogen encompasses the transition from the alkali metals to the halogens, there is more to the idea of hydrogen over helium. (Meyer 1870, (...) p. 357) (Proust 1927, p. 559). (shrink)

Spectroscopy is a scientific topic at the interface between Chemistry and Physics, which is taught at high school level in relation with its fundamental applications in Analytical Chemistry. In the first part of the paper, the topic of spectroscopy is analyzed having in mind the well-known Johnstone’s triangle of chemistry education, putting in evidence the way spectroscopy is usually taught at the three levels of chemical knowledge: macroscopic/phenomenological, sub-microscopic/molecular and symbolic ones. Among these three levels, following Johnstone’s recommendations the macroscopic (...) one is the most useful for high school students who learn spectroscopy for the first time. Starting from these premises, in the second part of the paper, we propose a didactic sequence which is inspired by the historical evolution of spectroscopic instruments from the first spectroscopes invented by Gustav Kirchhoff and Robert Bunsen in 1860 to the UV–vis spectrophotometers which became common since the 1960s. The idea behind our research is to analyze the conceptual advancements through the history of spectroscopy and to identify the key episodes/experiments and spectroscopic instruments. For each of them, a didactic activity, typically an experiment, is then proposed underlining the relevant aspects from the chemistry education point of view. The present paper is the occasion to reflect on the potentialities of an historical approach combined with a laboratorial one, and to discuss the role of historical instruments and related technological improvements to teach spectroscopy. (shrink)

The way of thinking of mathematicians and chemists in their respective disciplines seems to have very different levels of abstractions. While the firsts are involved in the most abstract of all sciences, the seconds are engaged in a practical, mainly experimental discipline. Therefore, it is surprising that many luminaries of the mathematics universe have studied chemistry as their main subject. Others have started studying chemistry before swapping to mathematics or have declared some admiration and even love for this discipline. Here (...) I reveal some of these mathematicians who were involved in chemistry from a biographical perspective. Then, I analyze what these remarkable mathematicians and statisticians could have learned while studying chemical subjects. I found analogies between code-breaking and molecular structure elucidation, inspiration for statistics in quantitative analytical chemistry, and on the role of topology in the study of some organic molecules. I also analyze some parallelisms between the way of thinking of organic chemists and mathematicians in terms of the use of backward analysis, search for patterns, and use of pictures in their respective researches. (shrink)

Slater’s method is an integral part of the undergraduate experience. In actuality, Slater’s method is part of an atomic model and not simply a set of rules. Slater’s rules are a simple means for computing the effective nuclear charge experienced by an orbital. These rules are based on the shell-like structure of the Slater atom in which outer shell electrons are incapable of shielding inner electrons. Slater’s model provides a qualitative description of the valence electrons in multi-electron atoms with tremendous (...) ease. The model is useful for explaining atomic properties such as ionisation energy, electron affinity and atomic radius qualitatively. Slater’s rules also correctly reproduce the Madelung rule of filling and the ionisation sequence (4s before 3d); however, these rules are not able to reproduce the anomalous configurations of atoms such as Cr and Cu. It is found that the atomic properties that Slater’s model reproduces are all related to the exponential decay factor of the Slater orbital. We find—from estimating the polarity of a diatomic molecule using a simple model—that molecular polarity is related to the difference in the exponential decay factors of the valence orbitals of the two atoms, implying that the decay factor acts as the electronegativity of the atom. (shrink)

Compelling evidence is presented that Glauber worked as a laborator (laboratory assistant) for Landgrave Georg of Hesse-Darmstadt from 1632/33 till he was appointed apothecary in Giessen in 1635. During this time, he was also used as laborator by the landgrave’s personal physician, Helwig Dieterich. Glauber became a famous chemist, whose alchemical secrets were keenly solicited by King Frederik III of Denmark, Queen Christina of Sweden, and, according to the 1662 diary of Ole Borch, King Charles II of England. A 1689 (...) letter to Queen Christina contains detailed descriptions of Glauber’s alkahest, his decomposition and redintegration of saltpeter, and his ‘most secret sal armoniacum’, which is interpreted here for the first time. (shrink)

Théophile De Donder, a Belgian mathematician born in Brussels, elaborated two important ideas that created a bridge between thermodynamics and chemical kinetics. He invented the concept of the degree of advancement of a reaction, and, in 1922, he provided a precise mathematical form to the already known chemical affinity by translating Clausius’s uncompensated heat into formal language. These concepts merge in an important inequality that was the starting point for the formalization of non-equilibrium thermodynamics. The present article aims to reconstruct (...) how De Donder elaborated his ideas and developed them by exploring his teaching activity and its connection with his scientific production. Furthermore, it emphasizes the role played by the discussions with his disciples who became his collaborators. The paper analyzes De Donder’s efforts in participating in the second Solvay Chemistry Council in 1925 to call the attention of chemists to his mathematical approach. We explain why his work did not receive much attention at the time, and how, despite this, his formalization of chemical affinity became the basis for the birth of the so-called Brussels school of thermodynamics. (shrink)

This work describes the concept of bond order. It shows that covalent bond energy is correlated to bond order. Simple expressions which included bond order are introduced to calculate bond energies of homo-nuclear and hetero-nuclear bonds. Calculated values of bond energies are compared with literature values and show there is very good agreement between and calculated and experimental values in the vast majority of cases. Bond order reveals the strength of a bond and shows the number of bonds in both (...) homo-nuclear and hetero-nuclear covalent bonds. (shrink)

The 2016 Royal Society of Chemistry’s report Future of the Chemical Sciences presents four different scenarios for the future of chemistry: chemistry saves the world; push-button chemistry; a world without chemists; and free market chemistry. In this paper we ethically assess them. If chemistry is to solve many of the greatest challenges facing the contemporary world, prioritization of research topics will need to be done explicitly on the basis of moral values, ​​such as solidarity and equity, but also environmental justice, (...) which will have to be central in determining a research agenda for chemistry. The decentralization of chemistry will also present ethical challenges to the research standards established by the scientific community. Ethical education in chemistry may help counteract these risks. We also argue that if chemistry and its subdisciplines are to fulfil their goal of generating knowledge and helping us solve the great challenges of the contemporary world, then it is ethically imperative that scientists from different disciplines be more open to interdisciplinary work. Finally, if the future of chemistry is in free market forms, then it is necessary that we pay more attention to the possible risks that this model has. We call attention to two: first, it is likely that problems that affect the lowest income countries or the most disadvantaged sectors of society, who do not have the means to pay for some of the goods and services, will not be addressed; second, the free market tends to foster unsustainable forms of development. (shrink)