Mendeleev’s periodic system

But the periodic system is so fundamental, pervasive and familiar in the study of chemistry that it is often taken for granted. A century after the death of the leading discoverer of the periodic system, the Russian chemist Dimitri Mendeleev, it seems time to revisit the origins and modem status of this now-standard chemical classification. There were a number of historic precursors to Mendeleev s periodic system. But there are also current ongoing debates regarding the best way to display the periodic system, and whether there is really a "best way" of doing so. 

But what would become of Mendeleev s periodic system which now seemed to consist of 300 or so "elements" To some chemists, the discovery of isotopes implied the end of the periodic system as it was known.3 These chemists suggested that it would be necessary to consider the individual new isotopes as the new "elements." But the chemist Paneth adopted a less reductionist approach, arguing that the periodic table of the familiar chemical elements should be retained because it dealt with the "elements" that were of interest to chemists. A justification for this view was provided by the fact that, with a few exceptions, the chemical properties of isotopes of the same element are indistinguishable.4 Moreover, Paneth appealed to Mendeleev s distinction between the two senses of the concept of an "element" in order to provide a philosophical rationale for the retention of the chemist s periodic table. Paneth argued that the discovery of isotopes of the elements represents the discovery of new elements as simple substances, whereas periodic... 

Practical Inorganic Chemistry is aimed at assisting students to systematically study the basic properties of the chemical elements and their compounds from the standpoint of D. Mendeleev s Periodic System and also to gain skill in performing laboratory experiments. The textbook covers the most important sections of general and inorganic chemistry. 

Figure 1-17. (a) Soviet stamp block issued to the centenary of Mendeleev s Periodic System (b) The Periodic Table of the Elements as a fresco at what is today the Mendeleev Institute of Metrology in St. Petersburg and was the Board of Weights and Measures in Mendeleev s time (photograph by and courtesy of Alexander Belyakov, St. Petersburg) [65],... 

Mendeleev s Periodic System (p. 7) Volume 19, Number 61, March 1986... 

A. N. Nesmeyanov Usp. Khim. 28, 1164 D. I. Mendeleev s periodic system 37 Russ. Position of organometallic... 

As it is well known, metals of group VIII of Mendeleev s periodic system have found a widespread application as catalysts in a variety of chemical reactions. 

A few years ago, C. H. Evans noticed that historically the rare-earth elements [had] created theoretical, as well as practical, headaches for chemists , but he admitted that none [had been] greater than their proper position in the periodic table / According to Evans opinion, the interplay between Mendeleev s periodic system and the rare-earth elements is an interesting one, worfliy of deeper analysis by future scholars. Following this suggestion, the substance of this paper will focus on Mendeleev s attitude towards the problematic accommodation of the rare-earth elements in the periodic system during the period 1869-1871. Henceforth, the term rare-earth crisis will be used to denote this accommodation issue. 

According to the popular story, it was Mendeleev s many successfiil predictions that were directly responsible for the widespread acceptance of the periodic system, while his competitors either failed to make predictions or did so in a rather feeble manner. Several of his predictions were indeed widely celebrated, especially those of the elements germanium, gaUium, and scandium, and it has been argued by many historians that it was such spectacular feats that assured the acceptance of Mendeleev s periodic system by the scientific community. 

If we accept that it was his predictions that carried the most weight in the acceptance of Mendeleev s periodic system, then we are at a loss to answer this question. But perhaps, as some have argued, it is by no means established that prediction is the single most important factor in demonstrating the validity of a new scientific idea. In fact, rather than proving the value of prediction, the development and acceptance of the periodic table may provide us with a powerful illustration of the importance of accommodation, that is, the ability of a new scientific theory to explain already known facts. 

Table 5.5 lists all of Mendeleev s firm predictions. It contains only the elements to which he gave provisional names. Thus, it does not include elements such as astatine and actinium, which he predicted successfully but did not name. Neither does it include predictions that were represented just by dashes in Mendeleev s periodic systems. Among some other failures, not included in the table, is an inert gas element between barium and tantalum, which would have been called eka-xenon, although Mendeleev did not refer to it as such. 

Let us now examine the wider question of how scientists at large in this period of history reacted to the introduction of Mendeleev s periodic system, and whether they regarded predictions connected with the periodic table more favorably than the accommodation of already known elements. 

Cleve is clearly attaching some importance to this prediction, although there is no indication that he regards the overall case for Mendeleev s periodic system to be strengthened by this finding. 

A look at the historical record thus reveals that the acceptance of Mendeleev s system was not a simple matter, and certainly was not assured by either his accommodations or his successful predictions. Many of Mendeleev s contemporaries were impressed with the accommodations his system achieved others, like Bertholet, seemed to not be impressed by either the predictions nor the accommodations. Thus, the question remains regarding the manner in which Mendeleev s periodic system did indeed take hold fairly quickly in the decades following its introduction and how it came to occupy the central position in chemistry it still holds today. 

On the role of chemical textbooks for late eighteenth-century and nineteenth-century classification, see also Bertomeu-Sanchez et al. 12002] and Bensaude-Vincent et al. 12003]. The need to classify substances in chemical textbooks may also spur more exphcit reflection upon classiflcation. For example, Mendeleev s periodic system was constructed in the context of writing a chemical textbook see Bensaude-Vincent [2001a] and Gordin [2004]. 

The manipulations performed so far result in a 3D model for Mendeleev s periodic system, to which one may give the following interpretation. 

Fig. 8 - 3D Mendeleev s periodic system. Two monochromatic building blocks posed above one another in each layer correspond to an electron orbital...

Bensaude-Vincent B (1986) Mendeleev s periodic system of chemical elements. Br J Hist Sci 19 3-17... 

Bernadette Bensaude-Vincent has written extensively on how Mendeleev s crucial stage in the evolution of his periodic system was the recognition of the need to consider relationships between dissimilar elements (Bensaude-Vincent, Mendeleev s Periodic System ). In Mendeleev s case these were the alkali metals and the halogens. But, as she is no doubt aware, there were earlier attempts to make horizontal connections between the elements, although they were not as successful as those of Mendeleev. Such other attempts included those of the chemist Peter Kremers (Scerri, Evolution ). 

While on this subject, it should be remembered that Mendeleev rendered a great service which has not really been heeded. Although he considered various possible representations he also emphasized that the important aspect of the periodic system was the existence of the periodic law. The fact that Mendeleev attached so much importance to the periodic law, qua law, has been especially stressed by Bernadette Bensaude-Vincent in her many articles on the periodic table (Bensaude-Vincent, Mendeleev s Periodic System ). 1 believe that she is correct to do so and that the modem tendency to not even mention the periodic law, as such, is regrettable. The reason for this omission is presumably because of the prevalent notion that this law has now been explained away by the deeper laws of quantum mechanics (Scerri, Explanation ). This is just not true and 1 will return to the issue later in this article. 

Bensaude-Vincent, B. Mendeleev s Periodic System of the Elements. British Journal for the History of Science 19 (1986) 3-17. 

The order of phase equilibria description is determined by the Mendeleev s Periodic System only in a one case (ternary systems with two transition metals), an alphabetical order is used. 

The majority of experimental investigations deals with Al, Sn and metals of the fourth period in the Mendeleev s Periodic System. Therefore, our discussion will be based on the interaction peculiarities of rare earths with the above-mentioned elements. 

Part IV deals with the northern European periphery, including the three Scandinavian countries of Sweden, Denmark, and Norway. The chapters in this part describe indifference to the periodic system, much as in France, but for different reasons. Chapter 7 (by Anders Lundgren) explains that a long-standing practical and atheoretical tradition of Swedish chemistry was unaffected by the periodic system, with many new elements discovered by Swedish chemists independently of the system. Because Swedish chemists at the time had little interest in theory, they did not require any explanation of the periodicity of the elements. Nor was the periodic system used as a pedagogical tool for textbooks. Lundgren contends that Mendeleev s periodic system might not have been as important as historians of chemistry have traditionally believed. 

Chapter 11 (by Isabel Malaquias) explores traces of Mendeleev s periodic system in Portuguese higher education and secondary textbooks, some popular books, and several booklets published at the end of the nineteenth and early twentieth centuries. Although periodic classification was adopted officially as a topic to be taught... 

The Early Response to Mendeleev s Periodic System in Russia... 

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