Element as basic substance

What I hope to have added to the discussion has been a philosophical reflection on the nature of the concept of element and in particular an emphasis on elements in the sense of basic substances rather than just simple substances. The view of elements as basic substances, is one with a long history. The term is due to Fritz Paneth, the prominent twentieth century radio-chemist. This sense of the term element refers to the underlying reality that supports element-hood or is prior to the more familiar sense of an element as a simple substance. Elements as basic substances are said to have no properties as such although they act as the bearers of properties. I suppose one can think of it as a substratum for the elements. Moreover, as Paneth and before him Mendeleev among others stressed, it is elements as basic substances rather than as simple substances that are summarized by the periodic table of the elements. This notion can easily be appreciated when it is realized that carbon, for example, occurs in three main allotropes of diamond, graphite and buckminsterfullenes. But the element carbon, which takes its place in the periodic system, is none of these three simple substances but the more abstract concept of carbon as a basic substance. 

Schwarz also makes the interesting identification between neutral atoms and elements as simple substances on one hand, and between bonded atoms and elements as basic substances on the other hand. As a frequent participant at conferences on the philosophy of chemistry, Schwarz seems to have fully grasped the importance of this distinction between the two senses of the macroscopic element. Whether or not his one-to-one identification of the dual sense of an element with microscopic atoms is meaningful remains to be seen, but here I argue that he is mistaken. 

Instead I propose a more radical solution, namely that of not identifying bonded atoms with elements as basic substances, a view for which I claim support from the work of Mendeleev and Paneth. This does not solve the problem of redesigning a periodic table to reflect the behavior of bonded atoms. But if we are to retain the traditional periodic table of neutral atoms, we may still forge a connection with elements as basic substances by arranging the elements so as to maximize atomic number triads, where atomic number may now be interpreted to also mean element number . 

The aim of the present article is to elevate the role of triads to an even greater extent. Since triads are now expressed in terms of atomic numbers they coincidentally characterize the elements as basic substances. In other words they characterize the true basis for periodic classification compared with the elements as simple substances, as argued by Mendeleev and more recently by Paneth and other authors. 

As suggested in the title of the present article, we believe that the periodic table, which initially arose from the discovery of atomic weight triads, can now be further enhanced by recognizing the fundamental importance of atomic number triads. In addition one should recognize the more fundamental nature of the elements as basic substances rather than as simple substances, and that the periodic system is primarily a classification of the former. Whereas we previously suggested that these aims were best served by the left-step table we now favor the revised left-step table shown in Figure 3. 

The new proposed version does not alleviate the concern that some authors voice in wanting to maintain the metals on the left and non-metals on the right of the table. We suggest that such a desideratum does not necessarily reflect the most fundamental aspects of the elements as basic substances whereas the left-step and its new variant do. The latter two forms aim to represent elements as basic substances as well as establishing a closer connection with fundamental aspects of electron-shell filling, and consequently with quantum mechanics, than the medium-long form table does. Finally, we have recently published another new table that differs only in shape from the one proposed here (10). 

Indeed, the terminology of element as basic substance as opposed to as simple substance, which has been used throughout this article, originates with this work of Paneth. 

However, I believe that Bent s understanding of elements as basic substances is incorrect because he insists on identifying them with neutral atoms of the elements. 

Bent claims that the periodic system should be primarily based on the structure of neutral atoms rather than on macroscopic properties of the elements. In doing so he claims support from none other than Mendeleev. Bent also claims to garner support from the writings of Mendeleev in steering clear of the properties of the elements as simple substances in crucial matters of classification of the elements. In fact, the identification of elements as basic substances with the atoms of the elements is... 

To remedy this mistaken identification I propose a return to discussing elements as basic substances, without recourse to any microscopic account. 

It immediately becomes clear from this list that Schwarz is not falling into the error of identifying elements as basic substances with the neutral atoms of the elements, given that he includes the neutral atoms as a third sense of element in addition to basic substances and simple substances. 

Elements as basic substances Elements as simple substances Bonded atoms Neutral atoms... 

It was suggested earlier that Schwarz s identification of bonded atoms with elements as basic substances represents a step in the right direction. This notion will now be examined more carefully, since it too will be found lacking in a rather fundamental way, which was hinted at in some earlier quotations from Paneth. The concern voiced by Paneth regarding associating elements as basic substances with neutral atoms was due to the fact that these concepts inhabit different epistemological levels. This is equally true of the identification of elements as basic substances with bonded atoms, which is the identification that Schwarz supports. 

Instead of identifying elements as basic substances with neutral atoms (Bent and Weinhold and almost everybody else) or elements as basic substances with bonded atoms (Schwarz), I would like to propose just focusing on elements as basic substances in Paneth s macroscopic sense. The one ma-... 

Summary of How the Elements as Basic Substances are Regarded by Various Authors. 

What is being suggested is that given the fundamental importance of concentrating on elements as basic substances, and given the fact that such elements are characterized by their atomic numbers, one should aim to maximize the number of perfect triads in displaying the periodic table. This proposal has an immediate consequence on the question of where the element helium, as well as other troublesome elements such as hydrogen, should be placed.13... 

Processes of this type can be discussed in the same way as chemical reactions. The constituents of the mixture assume the role of elements as basic substances whose amounts are conserved during transformation (see Sect. 1.2). The homogeneous and heterogeneous mixtures themselves, however, correspond to chemical compounds. Therefore, the composition of these mixtures can be given by a content formula but with the peculiarity that the content numbers are not necessarily integer... 

Thus, his view of the elements allowed Mendeleev to maintain the vahd-ity of the periodic law even in instances where observational evidence seemed to point against it. Such boldness may have resulted from a deeply held beliefs that the periodic law applied to the abstract elements as basic substances and that this law was as fundamental and equal in status to Newtons laws of mechanics. Had he been more of a positivist, Mendeleev might easily have lost sight of the importance of the periodic law and might have harbored doubts about some of his predictions. 

It would be a pity to conclude a book on the periodic table without broaching the subject of the variety of tables and systems currently on offer. In addition, this final section serves to revisit some philosophical strands that may have been left hanging in preceding chapters, such as the question of elements as basic substances. 

In some preceding chapters, the subject of elements as basic substances compared with elements as simple substances is discussed. As described in chapter 4, Mendeleev placed greater emphasis on the elements as basic substances than on elements as simple substances when he produced his periodic classification. The main criterion of basic substances was their atomic weight. When atomic number took... 

Moreover, in the 1920s, Paneth drew on the metaphysical essence of elements as basic substances in order to save the periodic system firom a major crisis. Over a short period of time, many new isotopes of the elements had been discovered, such that the number of atoms or most fundamental units suddenly seemed to have multiplied. The question was whether the periodic system should continue to accommodate the traditionally regarded atoms of each element or whether it would be restructured to accommodate the more elementary isotopes that might now be taken to constitute the true atoms. Paneth s response was that the periodic system should continue as it had before, in that it should accommodate the traditional chemical atoms and not the individual isotopes of the elements.Paneth regarded isotopes as simple substances in that they are characterized by their atomic weights, while elements as basic substances are characterized in his scheme by atomic number alone. ... 

It is worth noting that, in the case of this isotope controversy, Paneth s recommendation for the retention of the chemist s periodic table depended on the notion of elements as basic substances and not as simple substances. If the chemists had focused on simple substances, they would have been forced to recognize the new elements in the form of isotopes that were being discovered in rapid succession. By choosing to ignore these elements in favor of the elements as basic substances, chemists could continue to uphold that the fundamental units of chemistry, or its natural kinds, remained as the entities that occupied a single place in the periodic system. 

Rather than considering the relative virtues of these placements in chemical terms, the argument for the removal of hydrogen and hehum from the main body of the table can be examined from the perspective of the elements as basic substances. The widely held behef among chemists is that the periodic system is a classification of the elements as simple substances that can be isolated and whose properties can be examined experimentally. However, as emphasized in the present book, there is a long-standing metaphysical tradition of ako regarding the elements as unobservable basic substances. 

But once again, rather than relying on specific properties of the elements as simple substances, I suggest that we should concentrate on elements as basic substances. Perhaps one should seek some form of underlying regularity in order to settle the question of the placement of any element. Such a possibility is discussed below, along with the question of the best possible form for the periodic system. 

However, as I argued in the preceding section, such worries are alleviated once one acknowledges that the periodic system is primarily intended to classify the elements as basic substances and not simple substances. Although one can partly agree with the view that different representations can help to convey different forms of information, I believe that one may still maintain that one particular representation reflects chemical periodicity, regarded as an objective fact, in the best possible manner. 

The metaphysical notion of the elements as basic substances and as the bearers of properties has been historically important in the case of Mendeleev s establishment of the periodic system and Paneth s resolution of the fate of the periodic system in... 

There is a certain irony here in that Mendeleev is really breaking away from Lavoisier in upholding the importance of the elements as basic substances, something that Lavoisier considered a sterile concept. 

Of course, it may be that future chemistry might reveal that helium does indeed belong in the alkahne earths.The notions of elements as basic substances and as simple substances are complementary, not contradictory. 

As in the use of atomic number, the use of the n + /rule appeals to elements as basic substances and not as simple substances.This rule represents a generalization concerning all the elements, although it is violated in some instances and is not concerned with any directly observable properties of the elements. 

It appears that the notion of elements as basic substances made its comeback in the writing of Mendeleev who insisted that his periodic classification was primarily concerned with this sense of the term element and not as observable simple substances. However, Mendeleev did not merely return to the ancient view whereby the elements as basic substances were completely devoid of properties or characteristics. For Mendeleev a basic substance possessed at least one attribute, namely its atomic weight which served to distinguish it from other elements and which was used to order the elements in a unique sequence. 

The distinction between elements as basic substances and as simple substances was held to be of crucial importance by Mendeleev. There are many passages in his classic textbook. The Principles of Chemistry, in which he goes to great lengths to explain it. 

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