The Periodic Table

The heated debates and severe conflicts between the atomists and the anti-atomists of the latter half of the nineteenth century are well known to the historian of science. The position of Dmitrii Ivanovich Mendeleev towards these nineteenth century debates on atomism will be studied in this paper. A first attempt will thus be offered to reconcile Mendeleev’s seemingly contradictory comments and ambiguous standpoints into one coherent view.

The philosophical vision of the world and the consequent methodology behind the book are clarified. The perspective used is the systemic one, but since today this term has assumed a wide and diversified meaning in the literature, this introduction will clarify the specific meaning of our approach, starting from the meaning of the term "system". Our idea of system is based on three key assertions that may seem contradictory, but are necessary and complementary to its definition. In particular, we considered (...) the usual idea that the system is more and less than the sum of its juxtaposed parts, highlighting the role of emergencies and constraints. In our idea of a system, however, we must consider a third fundamental characteristic: its dynamism, the dual nature of the system as an entity and as a process, its role as a "dynamic entity". Afterwards, the holistic and reductionist approaches were analysed in detail, and both the specific merits and the fact that these two opposing worldviews, considered individually, cannot give a complete and balanced description of reality, were taken into account. For us, only the systemic approach provides a balanced description of both the parts and the whole and must, therefore, be preferred. Finally, the differences between our approach and the approaches mentioned above have been considered in detail in this introduction. (shrink)

We provide a detailed history of the concepts of atomic number and isotopy before the discovery of protons and neutrons that draws attention to the role of evolving interplays of multiple aims and criteria in chemical and physical research. Focusing on research by Frederick Soddy and Ernest Rutherford, we show that, in the context of differentiating disciplinary projects, the adoption of a complex and shifting concept of elemental identity and the ordering role of the periodic table led to a relatively (...) coherent notion of atomic number. Subsequent attention to valency, still neglected in the secondary literature, and to nuclear charge led to a decoupling of the concepts of elemental identity and weight and allowed for a coherent concept of isotopy. This concept received motivation from empirical investigations on the decomposition series of radioelements and their unstable chemical identity. A new model of chemical order was the result of an ongoing collaboration between chemical and physical research projects with evolving aims and standards. After key concepts were considered resolved and their territories were clarified, chemistry and physics resumed autonomous projects, yet remained bound by newly accepted explanatory relations. It is an episode of scientific collaboration and partial integration without simple, wholesale gestalt switches or chemical revolutions. (shrink)

The Periodic Table of Elements is one of the greatest achievements of the human intellect but is far from a finished work. Generations of chemists and physicists have improved on it, in light of the discovery of new elements and advancements in the domain of Quantum Mechanics. Specially, the role of the four quantum numbers that dictates the distribution of the elements throughout the Table has been clarified. However, as the Table grew older and venerable, a tradition developed that froze (...) its overall shape, obfuscating somewhat the comprehension of its underlying principles. Proposals of reforming it has been made but face the opposition of scientists, professionals and educators who are comfortable with the Table as it has been for several decades. Here, the author advocates for possible alternatives, discuss potential advantages and answer to some criticisms on them. (shrink)

Physical science solved an age-old problem in the 19th century: what makes elements similar or dissimilar? Mendeleev generally is given credit for the discovery of the underlying structure of chemical elements, known as the periodic table. Like chemicals, qualia seem to share different relationships within a modality and between modalities. Wundt’s structuralism represents an early effort to build the structure of mind through data obtained by introspection. Unfortunately, as have many other subjects, structuralism has been victimized by behaviorism’s domination. And (...) the cognitive revolution did not completely eliminate the unfavorable status of consciousness, thus hampering the revival of structuralism unlike many other topics in psychology. With the subject of consciousness having been just about fully sanctioned by science beginning in the early 1990s, the time has come to build the periodic table of mental science by uncovering the hidden patterns of qualia. This paper proposes four different scales of intrinsic patterns: the notion of bipolar dimension, the three complementaries, the principle of square of opposition, and the double-cone system. They are able to accommodate 15 different modalities in a systematic and unified way: chromatic, acoustic, tactile, olfactory, gustatory, exteroceptive motion, exteroceptive orientative, exteroceptive locus, proprioceptive motion, proprioceptive orientative, proprioceptive locus, magnitude, emotive, hedonistic, and predicative. (shrink)

This manuscript aims to systematically consider the main periodicity and additional (secondary, internal, and tetrad) periodicities using a uniform approach. The main features are summarized in table form. The history of the origin and development of these concepts is discussed. It is described how these periodicities manifest themselves and how they are determined at the experimental and theoretical levels. Areas of manifestation of these periodicities are outlined. As the general approach to explaining internal periodicity, attention is drawn to the symmetry (...) of the quantum number S of atoms and the principle of equivalence of electrons and holes. Arguments are presented in favor of a more correct classification of the tetrad effect as tetrad periodicity, and an overview of this regularity is provided. A small modification of the conventional Periodic table is proposed, which reflects all the mentioned periodicities. (shrink)

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 documented. Further, the fact that he made no claim to having made (...) the discovery also undermines Eaton’s argument. (shrink)

I respond to Scerri’s recent reply to my claim that there was a scientific revolution in chemistry in the early twentieth Century. I grant, as Scerri insists, that there are significant continuities through the change about which we are arguing. That is so in all scientific revolutions. But I argue that the changes were such that they constitute a Kuhnian revolution, not in the classic sense of The Structure of Scientific Revolutions, but in the sense of Kuhn’s mature theory, developed (...) in the 1980s and early 1990s. (shrink)

The thesis is: the “periodic table” of “dark matter” is equivalent to the standard periodic table of the visible matter being entangled. Thus, it is to consist of all possible entangled states of the atoms of chemical elements as quantum systems. In other words, an atom of any chemical element and as a quantum system, i.e. as a wave function, should be represented as a non-orthogonal in general (i.e. entangled) subspace of the separable complex Hilbert space relevant to the system (...) to which the atom at issue is related as a true part of it. The paper follows previous publications of mine stating that “dark matter” and “dark energy” are projections of arbitrarily entangled states on the cognitive “screen” of Einstein’s “Mach’s principle” in general relativity postulating that gravitational field can be generated only by mass or energy. (shrink)

To this day, a hundred and fifty years after Mendeleev's discovery, the overal structure of the periodic system remains unaccounted for in quantum-mechanical terms. Given this dire situation, a handful of scientists in the 1970s embarked on a quest for the symmetries that lie hidden in the periodic table. Their goal was to explain the table's structure in group-theoretical terms. We argue that this symmetry program required an important paradigm shift in the understanding of the nature of chemical elements. The (...) idea, in essence, consisted of treating the chemical elements, not as particles, but as states of a superparticle. We show that the inspiration for this came from elementary particle physics, and in particular from Heisenberg's suggestion to treat the proton and neutron as different states of the nucleon. We provide a careful study of Heisenberg's last paper on the nature of elementary particles, and explain why the Democritean picture of matter no longer applied in modern physics and a Platonic symmetry-based picture was called for instead. We show how Heisenberg's Platonic philosophy came to dominate the field of elementary particle physics, and how it found its culmination point in Gell-Mann's classification of the hadrons in the eightfold way. We argue that it was the success of Heisenberg's approach in elementary particle physics that sparked the group-theoretical approach to the periodic table. We explain how it was applied to the set of chemical elements via a critical examination of the work of the Russian mathematician Abram Ilyich Fet the Turkish-American physicist Asim Orhan Barut, before giving some final reflections. (shrink)

In this essay, we aim to provide an overview of the periodic table’s origins and history, and of the elements which conspired to make it chemistry’s most recognisable icon. We pay attention to Mendeleev’s role in the development of a system for organising the elements and chemical knowledge while facilitating the teaching of chemistry. We look at how the reception of the table in different chemical communities was dependent on the local scientific, cultural and political context, but argue that its (...) eventual universal acceptance is due to its unique ability to accommodate possessed knowledge while enabling novel predictions. Furthermore, we argue that its capacity to unify apparently disconnected phenomena under a simple framework facilitates our understanding of periodicity, making the table an icon of aesthetic value, and an object of philosophical inquiry. Finally, we briefly explore the table’s iconicity throughout its representations in pop art and science fiction. (shrink)

In his account of scientific revolutions, Thomas Kuhn suggests that after a revolutionary change of theory, it is as if scientists are working in a different world. In this paper, we aim to show that the notion of world change is insightful. We contrast the reporting of the discovery of neon in 1898 with the discovery of hafnium in 1923. The one discovery was made when elements were identified by their atomic weight; the other discovery was made after scientists came (...) to classify elements by their atomic number. By considering two instances of the reporting of the discovery of a new chemical element 25 years apart, we argue that it becomes clear how chemists can be said to have been responding to different worlds as a result of the change in the concept of a chemical element. They saw, did, and reported different things as they conducted their research on the new chemical elements. (shrink)

The periodic table represents and organizes all known chemical elements on the basis of their properties. While the importance of this table in chemistry is uncontroversial, the role that it plays in scientific reasoning remains heavily disputed. Many philosophers deny the explanatory role of the table and insist that it is “merely” classificatory (Shapere, in F. Suppe (Ed.) The structure of scientific theories, University of Illinois Press, Illinois, 1977; Scerri in Erkenntnis 47:229–243, 1997). In particular, it has been claimed that (...) the table does not figure in causal explanation because it “does not reveal causal structure” (Woody in Science after the practice turn in the philosophy, history, and social studies of science, Routledge Taylor & Francis Group, New York, 2014). This paper provides an analysis of what it means to say that a scientific figure reveals causal structure and it argues that the modern periodic table does just this. It also clarifies why these “merely” classificatory claims have seemed so compelling–this is because these claims often focus on the earliest periodic tables, which lack the causal structure present in modern versions. (shrink)

This paper argues that the field of chemistry underwent a significant change of theory in the early twentieth century, when atomic number replaced atomic weight as the principle for ordering and identifying the chemical elements. It is a classic case of a Kuhnian revolution. In the process of addressing anomalies, chemists who were trained to see elements as defined by their atomic weight discovered that their theoretical assumptions were impediments to understanding the chemical world. The only way to normalize the (...) anomalies was to introduce new concepts, and a new conceptual understanding of what it is to be an element. In the process of making these changes, a new scientific lexicon emerged, one that took atomic number to be the defining feature of a chemical element. (shrink)

From Mendeleev’s time on, the Periodic Table has been an attempt to exhaust all the chemical possibilities of the elements and their interactions, whether these elements are known as actual or are not known yet as such. These latter elements are called “eka-elements” and there are still some of them in the current state of the Table. There is no guarantee that they will be eventually discovered, synthesized, or isolated as actual. As long as the actual existence of eka-elements is (...) predicted, they cannot be considered as actual but only as purely possible. Given that eka-elements are chemical pure possibilities, a possibilist approach, entitled “panenmentalism,” can gain support as well as an important implication. (shrink)

In this paper, first we discuss an old problem in teaching electron configuration of transition metals and the order in which the orbitals are filled. Then we propose two simple computational experiments, in order to show that in the case of first row transition metals and the main group elements after them, the electrons occupy the 3d subshell before the 4s. It is shown that if we begin with the bare nucleus of above elements in the vacuum and then continue (...) with adding the electrons the 19th electron firstly occupies the 3d subshell and not the 4s. Indeed, the 4s subshell in the third row of periodic table only fills first in the case of K and Ca atoms. However, the 3d subshell in transition metals and the main group elements after them is more stable than 4s and so fills first. Thus there is no scientific reason to write the electron configuration of transition elements as [Ar] 4s 3d and the correct form is [Ar] 3d 4s.Graphical. (shrink)

The periodic table may be seen as the most successful example of inquiry in the history of science, both in terms of practical application and theoretic understanding. As such, it serves as a model for truth as it emerges from inquiry. This paper offers a sketch of a central moment in the history of chemistry that illustrates an intuitive metamathematical construction, a model of emerging truth. The MET, reflecting the structure the surrounds the periodic table, attempts to capture the salient (...) epistemological elements that warrant truth claims based on sets of models that are progressive in light of both empirical and theoretical advance seen over time. (shrink)

The spiral form of the Periodic Law is proposed as its fundamental graphic representation. This idea is based on the fact that the spiral is the most appropriate form in description transitions from simple to complicated. The spiral is easily obtained from the linear succession of the elements when they are ranged by growing nuclear charge. The spiral can be simply transformed into many other graphic representations, including tables. This paper suggests the conception of the autonomy of blocks. This autonomy (...) is clearly seen in the variation of the outer electronic shells, in the width and the height of the blocks, as well as the number and properties of elements included therein. The regularities in the changes of element properties are pronounced in certain blocks but actually absent in others. The blocks can be permuted to obtain full-fledged versions of Periodic Table. The new stage of the verification of the blocks autonomy is the use of the total number of the differentiating electrons as an independent variable in describing the properties of the elements and their compounds. Consideration of individual blocks made it possible to deduce the periodic equations valid for all the elements within each block. Formulation of the Periodic Law is advanced: while describing characteristic determining the properties of the elements, the nuclear charge is replaced by the total number of differentiating electrons. Two modifications of the conventional Periodic Table are obtained by minimal changes. The first one shows the secondary and the additional periodicites. Another table shows the total number of differentiating electrons for each element. (shrink)

This work utilizes examples from chemical sciences to present fundamentals of dialectics and synergetics. The laws of dialectics remain appropriate at the level of atoms, at the level of molecules, at the level of the reactions, and at the level of ideas. The law of the unity and conflict of opposites is seen, for instance, in the relationships between the ionization energy and electron affinity of atoms, between the forward and back reactions, as well as in the differentiation and integration (...) between the various areas of chemistry. The law of the passage of quantitative changes into qualitative changes describes the transformation properties of the compounds when the number and arrangement of atoms in the molecule undergoes changes. According to this law, the development is accompanied by breaks and jumps. This paper suggests equations for the description of these relationships. The law of the negation of the negation is manifested in the Periodic Law, in the evolution of ideas about the mutual transformation of chemical elements, in the development the concept of triads of elements, etc. Small changes in the conventional Periodic Table on the basis of previously rejected versions allow reflecting secondary and additional periodicity. Synergetics, similarly to dialectics, is dedicated to the studies of general laws of evolution. Synergetics includes highly advanced and specified ideas of dialectics. The cornerstone of synergetics is the principles of self-organization and nonlinearity. Mathematical development of these concepts was substantially facilitated by considering oscillating chemical reactions as an example. These reactions are quite complex and therefore provide adequate models for self-organization. Oscillations may exist only upon execution of specific thermodynamic, mathematical, and chemical conditions. Mechanisms of several oscillatory reactions are briefly reviewed. The construction of novel biomimetic or smart materials based on oscillating reactions is described. (shrink)

This article updates the author’s 1982 argument that lutetium and lawrencium, rather than lanthanum and actinium, should be assigned to the d-block as the heavier analogs of scandium and yttrium, whereas lanthanum and actinium should be considered as the first members of the f-block with irregular configurations. This update is embedded within a detailed analysis of Lavelle’s abortive 2008 attempt to discredit this suggestion.

This paper presents the contributions of Alcindo Flores Cabral, professor of Chemistry at the Faculdade de Agronomia Eliseu Maciel, nowadays part of the Universidade Federal de Pelotas, to chemistry teaching. It is a contribution almost unknown to the Brazilian chemical community, although recognized as valuable by several renowned chemists abroad, like W. Hückel, G. Charlot, F. Strong, E. Fessenden and others. Cabral’s innovative helical representation is presented in connection not only with contemporary representations, but also an incursion is made into (...) the first helical systems proposed, those of Hinrichs and of Baumhauer. Some comments are made not only on Cabral’s Classificação Natural dos Elementos, published in 1946, but also about other texts he wrote for an efficient chemistry teaching. (shrink)

Since its inception in 1869, the periodic system — icon of modern chemistry — has suffered from the problematic accommodation of the rare-earth elements. The substance of this paper intends to retrace Mendeleev’s shifting attitudes with regard to the rare-earth crisis during the period 1869–1871. Based on a detailed examination of Mendeleev's research papers from that period, it will be argued that the rare-earth crisis played a key role in inducing a number of important changes in Mendeleev’s philosophical viewpoints with (...) regard to the epistemological concept of a chemical element and the nature of elementary groups. Many of Mendeleev's most cherished beliefs got endangered by the nature of these elements. Their mystifying properties forced him to revise his ideas about primary and secondary groups, the elements as basic and simple substances, and the use of short and long form tables. They made him question the validity and universality of the periodic law, and led him into hypothesizing about the internal structure of matter and constitution of atoms. (shrink)

In this commentary to Leal (2013), we argue that the memorization of the names and symbols of the chemical elements is necessary in the study of that topic because this task is the key for the later understanding of the Periodic Table. We can make the memorization task in an enjoyable, but effective way, using some educational games in chemistry class. Some recent puzzles, card games, mnemonics rules or games based on drawings to learn the chemical elements are addressed in (...) this paper. (shrink)

In the Periodic Tables the transition from atoms to double-charged cations is accompanied by alterations in the composition of s and p blocks and reciprocal location of blocks, as well as by changes in the composition and length of periods. We have previously described the relationship between the atom properties and the total number of differentiating electrons. This paper demonstrates that, despite the above transition-related alterations, this relationship is also valid for the description of the properties of double-charged cations. This (...) can be exemplified by the dependence of the ionization energy on the total number of p electrons in p block, d electrons in d block, and f electrons in f block. Furthermore, a single periodic equation is sufficient for the description of properties of all of double-charged cations from each block. (shrink)

The iconic status of the periodic table of the elements has been recognized by a variety of prominent chemists and historians of science. For example, John Emsley proclaimed: “As long as chemistry is studied there will be a periodic table. And even if someday we communicate with another part of the universe, we can be sure that one thing that both cultures will have in common is an ordered system of the elements that will be instantly recognizable by both intelligent (...) life forms” .Furthermore, its paramount significance is universally recognized even far beyond the field of chemistry. According to the late American astronomer Harlow Shapley , “[The periodic table] is probably the most compact and meaningful compilation of knowledge that man has yet devised. The periodic table does for matter what the geological age table does for cosmic time. Its history is the story of man’s great conquests in the microcosmos” .Of course, philosopher of science Eri .. (shrink)

Besides the book under review here, the “30-Second” series of books includes numerous titles such as those on anatomy, architecture, astronomy, the Bible, brain, economics, maths, mythology, philosophies, politics, psychology, religion, and theories.Together with eight contributors, each a leading authority with a proven track record for successfully explaining science to a general audience, Eric Scerri, Lecturer in Chemistry at the University of California, Los Angeles; founder and editor of this journal; and the undisputed world authority on the history and philosophy (...) of the periodic table, has edited this most attractive addition to the series.The chemical elements, the separate building blocks of our physical universe, lend themselves ideally to this 30-second approach. In his introduction to the volume Scerri briefly sketches the plan of the book and discusses the evolution of the periodic table from Dmitri Ivanovich Mendeleev’s original proposal to the latest developments in the .. (shrink)

The “story behind the story” of the genesis of this book is an involved and fascinating one. In May the Sven and Dagmar Salén Foundation decided to give a grant to Ulf Lagerqvist to permit publication of his manuscript titled The Bewildered Nobel Committee by the World Scientific Publishing Company . This decision was based on a thorough review by Torbjörn Norin, Professor of Organic Chemistry at the Royal School of Technology in Stockholm and a member of the board of (...) the foundation. Unfortunately, Lagerqvist, a Professor of Biochemistry and Chairman of Medical and Physiological Chemistry at Gothenburg University, Sweden , member of the Royal Swedish Academy of Sciences, influential researcher on the metabolism of the components of the nucleic acids in the rapidly developing field of molecular biology, and an outstanding writer popularizing the history of science since his retirement , di .. (shrink)

A quick question! Who’s the first name that comes to mind when the periodic table is mentioned? Dmitrii Ivanovich Mendeleev is the obvious and universal answer. And the second name? Most of you would probably agree with my answer: Eric R. Scerri, Lecturer in Chemistry and History and Philosophy of Science at the University of California, Los Angeles, and founding editor of this journal, devoted to the philosophy of chemistry, another of his specialties.Through the years I have followed Scerri’s work (...) on the periodic table, reading his numerous articles and reviewing his two previous books (Scerri 2007; Laing and Kauffman 2007; Scerri 2009; Kauffman 2011). In his latest book he comprehensively but succinctly examines this true cultural iconic symbol of science that is used by artists, advertisers, and of course, scientists in all fields. It is almost as familiar to the general public as the chemical formula for water, and an understanding and appreciation for it is essential to the physi. (shrink)

Chemical elements are the bricks with which Chemistry is build. Their names had a history, but part of it is forgotten or barely known. In this article the forgotten, no more used, never used, and alternatively used names and symbols of the elements are reviewed, bringing to us some surprises and deeper knowledge about the richness of Chemistry. It should be stressed that chemical elements are important not only for chemists but for all people dealing with science. As in any (...) other aspect of our lives, we tend to better understand something by knowing his history. By knowing them we can have a deeply understanding of how science evolves and how it is influenced by our human aspects. (shrink)

Predictivism is the view that successful predictions of “novel” evidence carry more confirmational weight than accommodations of already known evidence. Novelty, in this context, has traditionally been conceived of as temporal novelty. However temporal predictivism has been criticized for lacking a rationale: why should the time order of theory and evidence matter? Instead, it has been proposed, novelty should be construed in terms of use-novelty, according to which evidence is novel if it was not used in the construction of a (...) theory. Only if evidence is use-novel can it fully support the theory entailing it. As I point out in this paper, the writings of the most influential proponent of use-novelty contain a weaker and a stronger version of use-novelty. However both versions, I argue, are problematic. With regard to the appraisal of Mendeleev’ periodic table, the most contentious historical case in the predictivism debate, I argue that temporal predictivism is indeed supported, although in ways not previously appreciated. On the basis of this case, I argue for a form of so-called symptomatic predictivism according to which temporally novel predictions carry more confirmational weight only insofar as they reveal the theory’s presumed coherence of facts as real. (shrink)

Every so often an experiment trying to give reliable evidence for a metallic hydrogen solid is reported. Such evidence is, however, not too convincing. As Eric Scerri has recently reiterated, “the jury is still out on that issue” . This search stems from the common spectroscopy shared by the hydrogen atom and all the alkali metal atoms, and perhaps is guided by a desire to place hydrogen atop the alkali metals, in Mendeleiev’s Table, reinforced by the fact pointed out by (...) Scerri that there is no other obvious place for hydrogen in said Table. But H2 is a light gas at room temperature, while Li, Na, K and the other alkali elements form solid metal crystals. At very low temperatures, of course, hydrogen solidifies, but it is formed by H2 molecules . Our purpose here is to use a new argument to break this impasse: “should H be grouped with the alkali metals with which it shares a common spectroscopy, but which solidifies in a completely different fashion?” This argument has been proposed before in a couple of papers in this journal to establish a similar question for He and the alkaline earths , as is discussed in “Precedents” section. (shrink)

Among the subjects that attract historians of chemistry and philosophers of chemistry alike are the chemical elements and their classification within the periodic system. In 2007, Eric Scerri, a distinguished philosopher of the chemical sciences, published The Periodic Table (Oxford University Press), a comprehensive and critical account of the subject. He describes the present work as “a follow-up book,” and a few of the chapters are indeed condensed versions of chapters appearing in the 2007 book. Nonetheless, A Tale of 7 (...) Elements has a different scope and also a different intended audience. It is a story of seven little-known elements, some of which—such as promethium, francium and astatine—are extremely rare and with almost no applications. While Scerri’s 2007 book was in the more traditional academic genre, this one appeals to an audience much wider than the limited community of historians and philosophers of science. It is a brave and largely successful attempt to bridge the infa .. (shrink)

At the heart of chemistry lies the periodic system of chemical elements. Despite being the cornerstone of modern chemistry, the overall structure of the periodic system has never been fully understood from an atomic physics point of view. Group-theoretical models have been proposed instead, but they suffer from several limitations. Among others, the identification of the correct symmetry group and its decomposition into subgroups has remained a problem to this day. In an effort to deepen our limited understanding of the (...) periodic law, we have extended the traditional Lie algebraic framework to account for the peculiar degeneracy structure of the periodic system. Starting from the four-dimensional hidden symmetry and accidental degeneracy of the hydrogen atom, as first revealed by Fock in 1935, our research has mainly focussed on the way this SO(4) symmetry of the Coulomb potential gets broken in the periodic system as a consequence of the transformation of the hydrogenic (n, l) filling order to the Madelung (n+l, n) order due to electronic repulsions, relativistic effects and spin-orbit couplings. In this PhD dissertation, a new left-step format of the periodic table is first proposed on the basis of the Madelung rule. Following the particle physics tradition, the chemical elements are then considered as various states of some 'atomic matter', which is described by a non-compact spectrum-generating dynamical Lie group. The chemical elements are shown to form a basis for a single infinite-dimensional degeneracy space of the SO(4,2) ⊗ SU(2) group. An explanation for the period doubling is then proposed in terms of a particular symmetry breaking of the SO(4,2) group to the anti de Sitter SO(3,2) group. The Madelung rule is rationalised on the basis of nonlinear Lie algebras which reflect the screening of the Coulomb hole. This opens new perspectives for a symmetry-based understanding of how the periodic law emerges from its quantum mechanical foundations, and holds the future promise of complementing our current phenomenological approach by a direct atomic physics approach. (shrink)

Chemistry and physics are two sciences that are hard to connect. Yet there is significant overlap in their aims, methods, and theoretical approaches. In this book, the reduction of chemistry to physics is defended from the viewpoint of a naturalised Nagelian reduction, which is based on a close reading of Nagel's original text. This naturalised notion of reduction is capable of characterising the inter-theory relationships between theories of chemistry and theories of physics. The reconsideration of reduction also leads to a (...) new characterisation of chemical theories. This book is primarily aimed at philosophers of chemistry and chemists with an interest in philosophy, but is also of interest to the general philosopher of science. (shrink)

Electronegativity, described by Linus Pauling described as “The power of an atom in a molecule to attract electrons to itself” (Pauling in The nature of the chemical bond, 3rd edn, Cornell University Press, Ithaca, p 88, 1960), is used to predict bond polarity. There are dozens of methods for empirically quantifying electronegativity including: the original thermochemical technique (Pauling in J Am Chem Soc 54:3570–3582, 1932), numerical averaging of the ionisation potential and electron affinity (Mulliken in J Chem Phys 2:782–784, 1934), (...) effective nuclear charge and covalent radius analysis (Sanderson in J Chem Phys 23:2467, 1955) and the averaged successive ionisation energies of an element’s valence electrons (Martynov and Batsanov in Zhurnal Neorganicheskoi Khimii 5:3171–3175, 1980), etc. Indeed, there are such strong correlations between numerous atomic parameters—physical and chemical—that the term “electronegativity” integrates them into a single dimensionless number between 0.78 and 4.00 that can be used to predict/describe/model much of an element’s physical character and chemical behaviour. The design of the common and popular medium form of the periodic table is in large part determined by four quantum numbers and four associated rules. However, adding electronegativity completes the construction so that it displays the multi-parameter periodic law operating in two dimensions, down the groups and across the periods, with minimal ambiguity. (shrink)

Este artigo apresenta a contribuição de Alcindo Flores Cabral (1907-1982) - professor de química da Faculdade de Agronomia Eliseu Maciel, hoje incorporada à Universidade Federal de Pelotas - ao ensino de química, uma contribuição quase desconhecida pela própria comunidade química brasileira, embora reconhecida como relevante por diversos químicos estrangeiros importantes, como W. Hückel, G. Charlot, F. Strong, E. Fessenden e outros. A inovadora representação helicoidal de Cabral é apresentada não só em conexão com representações contemporâneas, mas também inclui-se uma incursão (...) pelos primeiros sistemas helicoidais propostos, os de Hinrichs e de Baumhauer. Apresentam-se alguns comentários não somente sobre a Classificação natural dos elementos, publicada em 1946, mas também sobre outros textos escritos para tornar mais eficaz o ensino de química. (shrink)

This paper explores the development of the chemical table as a tool designed for chemical information visualization. It uses a historical context to investigate the purpose of chemical tables and charts, analyzing them from the perspective of theory of tables, cartography, and design. It suggests reasons why the two-dimensional periodic table remains the de facto standard for chemical information display.

The basis of the Periodic Table is discussed. Electronic configuration recurs in only 21 out of the 32 groups. A better basis is derived by considering the highest classical valency (v) exhibited by an element and a new measure, the highest valency in carbonyl compounds (v*). This leads to a table based on the number of outer electrons possessed by an atom (N) and the number of electrons required for it to achieve an inert (noble) gas configuration (N*). Periodicity of (...) these is nearly complete. The new basis helps to settle the question of the best form of table and related issues. (shrink)

In a recent paper in this Journal, one of us argued against placing He above Be in Mendeleiev’s system of the elements. In it the goal was to dispute the notion that in Mendeleiev’s system of the elements the location of He should in fact lie above Be, which has a very similar electronic configuration, rather than above the noble gas column. That paper was based on rather old, Hartree–Fock limit studies on the strikingly limited non-additive contributions in the He3 (...) and He4 systems in contrast with the much larger non-additivity obtained for the Be3, Be4 and Be5 oligomers. In a recent benchmark multireference Averaged Quadratic Coupled Cluster results on Be2 and Be3 we showed that the delocalized non-additive contribution comprises 94 % of the binding energy of Be3. Here we use this and other pertinent information (drawn from the same paper) to conclude that He may not be associated with Be in Mendeleiev’s Table, despite their quite similar spectroscopic ground states. Furthermore, we use the new results to show that the large non-additivity implies that less than 2 % of the Be3 binding is located in each Be pair contained within the Be trimer. The rest of the interaction energy is necessarily delocalized over all three Be atoms. This might actually announce the bulk properties (i.e. “the electron gas”) that in solid-state physics explain the large electric and heat conduction for the solid Be metal. Thus, in the case of beryllium the metallic characteristics are already evident in Be3, a far cry from the monoatomic helium gas. (shrink)

The early Periodic Tables displayed an 8-Group system. Though we now use an 18-Group array, the old versions were based on evidence of similarities between what we now label as Group (n) and the corresponding Group (n + 10). As part of a series on patterns in the Periodic Table, in this contribution, these similarities are explored for the first time in a systematic manner. Pourbaix (Eh–pH) diagrams have been found particularly useful in this context.