The Dual Conception of the Chemical ElementEpistemic Aspects and Implications for Chemical Education

In the present work, the notion of chemical element is analyzed from the perspective of chemical education. Chemists refer to elements either as the final term of chemical analysis (i.e., simple substances) or as what persists in a chemical change. This duality has deep historical roots and it is sanctioned by IUPAC’s definition of chemical element. Nevertheless, it is inherently contradictory and it may result in deep misunderstandings in the educational context. After discussing the problems raised by the identification of the element with any material body—either macroscopic or microscopic—we analyze a number of definitions of elements, proposed by chemists, epistemologists, and educators. After pointing out the strengths and weaknesses of such definitions, we argue that the chemical element is a unifying chemical concept that designates an abstract category, identified by the atomic number.

Substance and Function

This paper aims to analyze the two aspects of elements, material and conceptual, in order to further understand the functional role played by elements in chemistry. First, we will refer to how Mendeleev gradually built his periodic table. Second, we will both highlight and reflect upon the functional role of elements in chemistry. In doing so, we will refer in particular to Cassirer’s philosophy of science. In conclusion, we propose that a functional approach is important for understanding current chemical practice, especially in nanochemistry and quantum chemistry. This approach also contributes to the analysis of different types of mereology that coexist in chemistry today.

The Changing Relation between Atomicity and Elementarity

Early modern efforts to reconceptualize atomicity as a chymical notion fell by the wayside during the chemical revolution, as Antoine Lavoisier’s desire to transform chemistry into a strictly empirical and quantitative science led him to reject all metaphysical speculation about the fundamental nature of matter. Instead, Lavoisier focused on identifying elementary substances, which he defined operationally as the final products of chemical analysis. Our current understanding of the relation between atoms and elements, however, owes a great deal to the work of nineteenth-century chemist John Dalton. Dalton’s chemical atomic theory reconciled the concepts of “atomicity” and “elementarity” and rendered both as empirical and chemical notions, amenable to measurement and quantitative analysis. One of the central goals of Dalton’s theory was understanding how relative weights of chemical atoms determine the properties of elements and how the chemical atoms of different elements combine to form compound substances. Thus, Dalton’s theory provided a way of studying and measuring the properties of atoms and elements in a way that allowed chemists to finally understand the chemical relations between them.

Referring to Chemical Elements and Compounds

How do we refer to chemical substances, and in particular to chemical elements? This question relates to many philosophical questions, including whether or not theories are incommensurable, the extent to which past theories are later discarded, and issues about scientific realism. This chapter considers the first explicit reference to types of colorless air in late-eighteenth-century chemical practice. Reference to a gas by one chemist was generally intended to give others epistemological, methodological, and practical access to the gas. This chapter proposes a causal-descriptive theory of reference for chemical substances. Implications for debates about incommensurability and realism are also briefly noted.

From Simple Substance to Chemical Element

The introduction of the modern concept of chemical element has often been credited to Lavoisier. I will argue that despite the significant impact of the definition of elements as non-decompound bodies in Lavoisier’s “Elements of Chemistry,” this claim is misleading for at least three reasons. First, elements were already defined as residues of analysis prior to Lavoisier. Second, Lavoisier did not totally give up the traditional view of elements as constituents of all bodies. Third, the modern definition of chemical element implies a clear distinction between simple bodies and elements that was later introduced by Dmitri Mendeleev. I will outline the role of this conceptual distinction in Mendeleev’s process of classification of elements and symmetrically emphasize how the periodic system contributed to stabilize his notion of element as an individual defined by its position in the system. Thus the concept of element appears as both a precondition and a product of the construction of the periodic system.

Chemical Elements and Chemical SubstancesRethinking Paneth’s Distinction

In 1931, Paneth identified a dual meaning of the term “chemical element,” translated as “basic substance” and “simple substance.” Since then multiple philosophers of chemistry have also identified ambiguities surrounding this concept, and the IUPAC still holds a double definition today. This paper aims to help resolve this ambiguity through an analysis and reinterpretation of the two meanings of the term “element” proposed by Paneth. It is important to distinguish between elements as substances and elements as constituents, because the elementary substances disappear when elements enter into compounds, whereas the constituent subsists. The notion of simple substance fails to capture the stability of the element as a constituent of matter, and Paneth’s metaphysical idea of basic substance is contradictory with a concept of element that evolved thanks to scientific practice, not independent of it. Since these meanings are mutually exclusive, their combination within one term is problematic; yet, this paper will show that neither of them individually suffice to qualify the element. Therefore, based on a brief analysis of the history of chemistry, I will propose a way of rethinking Paneth’s distinction in order to understand the different aspects of this complex chemical concept. Though there is a certain duality to the notion of element in the sense that it can be characterized both as an abstract constituent and as a chemical substance, the term “element” does not have two distinct meanings; it refers to the element in all forms of chemical combination.

Making Elements

In the present chapter I explore the historical and systematic aspects of the dictum “All chemical substances are preparations,” and particularly address the empirical background of the elements of the science of substance behavior in different time periods. This exploration is intended as an examination of metachemical conventions, rather than another hackneyed and whiggish criticism of apparently wrong old theories.

A Formal Approach to the Conceptual Development of Chemical Element

A chemical element, treated as a concept, entails objects and attributes. From the eighteenth century to date, objects include substances up to quasi-molecular species and nuclides. Attributes range from non-decomposability up to lifetimes of 10-14 seconds. By analyzing the historical changes of the concept, we found the central role “chemical reaction” has played. However, historical changes of objects and attributes of the concept of chemical element lead to expand chemical reactions to the more general “chemical relations,” which contain traditional chemical reactions and any kind of relation between chemical species. In such a setting, a general structure for the concept of chemical element is presented that entails chemical species as objects and detected chemical relations and experimental measurement of atomic number as attributes.

Dmitri Mendeleev’s Concept of the Chemical Elements Prior to the Periodic Law

This article examines the scientific work of Dmitri Mendeleev in the years prior to his discovery of the periodic law in 1869, paying special attention to how he addressed the issues of the concept of elements and their atomic weights. Mendeleev’s early work for his undergraduate and master’s theses on isomorphism and specific volumes was almost exclusively based on the existing literature on these topics with little original research. The knowledge that Mendeleev gained through this work, however, proved to be useful when he was elaborating his periodic law. Mendeleev attended the International Congress of Chemistry in Karlsruhe in 11860 and wrote that he was greatly impressed by Cannizzaro’s work and presentations at the congress. Mendeleev did not consistently adopt Cannizzaro’s atomic weights and continued to rely mainly on Gerhardt’s and Laurent’s values, with slight modifications. Mendeleev devoted much of his attention during his early scientific career to organic chemistry, including publishing a textbook in which he elaborated his “Theory of Limits” as an organizing principle. While this theory was quickly eclipsed by the Structural Theory of Organic Chemistry, it was influential to Mendeleev in his thinking about the organization of the elements. In the years immediately prior to the formulation of the periodic law, Mendeleev began to develop an abstract definition of an element, which proved important for his thinking about the periodic law.

The Existence of Elements, and the Elements of Existence

Philosophers sometimes discuss the “ontological status” of this or that kind of entity. They should be addressing one of the following questions, or the word ontological is being misused: 1. Does X exist? 2. Under what conditions can X exist? 3. Do we have good reasons to think that X exists? All three questions can be asked about elements, and have been asked. Aristotle criticized the atomist account of chemical combination, according to which elements survive in their compounds. Eighteenth-century chemists rejected the Aristotelian view, although tacitly; they simply assumed that an element lives on in its compounds. Nineteenth-century chemists gradually adopted (an adapted form of) atomism, according to which an element can exist wherever its characteristic atoms do. The periodic table also allowed them to ask, of its empty spaces, whether they correspond to real but unknown elements. Priority disputes forced them to consider when there is sufficient evidence for the discovery of new elements. In the 1920s, IUPAC proposed a very thin definition of an element, according to which an element exists wherever its characteristic nuclear charge does. But according to some scientists, it is now challenged by the fleeting existence of some superheavy elements; if a nucleus cannot survive long enough to acquire a stable electronic structure, then it cannot be said to have any chemical properties. How then can it be called a chemical element? In this paper I explore this latest ontological question, in the light of a sufficiently nuanced understanding of earlier ones. I then relate this discussion to a more general question about existence: the Special Composition Question.