The Dual Sense of the Term "Element," Attempts to Derive the Madelung Rule, and the Optimal Form of the Periodic Table, If Any

Author(s):  
ERIC R. SCERRI
Author(s):  
Eric Scerri

The article concerns various proposals that have been made with the aim of improving the currently standard 18-column periodic table. We begin with a review of 8-, 18- and 32-column formats of the periodic table. This is followed by an examination of a possible, although rather impractical, 50-column table and how it could be used to consider the changes to the periodic table that have been predicted by Pyykkö in the domain of superheavy elements. Other topics reviewed include attempts to derive the Madelung rule as well as an analysis of what this rule actually provides. Finally, the notion of an ‘optimal’ periodic table is discussed in the context of recent work by philosophers of science who have examined the nature of classifications in general, as well as the notion of natural kinds. The article takes an unapologetically philosophical approach rather than focusing on specific data concerning the elements. Nevertheless, some pragmatic issues and educational aspects of the periodic table are also examined. This article is part of the theme issue ‘Mendeleev and the periodic table’.


Author(s):  
Ali Bayri ◽  
fatih bulut ◽  
Serdar Altin

In this study, we have looked the periodic table from the Barut’s point of view and discussed the deviations from the Madelung rule. Expected, observed and computed total energies (Hartree-Fock and Gaussian) are given for two different (one for expected and the other one is observed) configurations of the Cr atom. The data shows that preferred electronic configuration for the Cr is 4s13d5 not 4s23d4 as dictated by the Madelung rule. This event may be due to the spin correlation effect which is closely related to the Hund’s rule.


Author(s):  
R. Herrera ◽  
A. Gómez

Computer simulations of electron diffraction patterns and images are an essential step in the process of structure and/or defect elucidation. So far most programs are designed to deal specifically with crystals, requiring frequently the space group as imput parameter. In such programs the deviations from perfect periodicity are dealt with by means of “periodic continuation”.However, for many applications involving amorphous materials, quasiperiodic materials or simply crystals with defects (including finite shape effects) it is convenient to have an algorithm capable of handling non-periodicity. Our program “HeGo” is an implementation of the well known multislice equations in which no periodicity assumption is made whatsoever. The salient features of our implementation are: 1) We made Gaussian fits to the atomic scattering factors for electrons covering the whole periodic table and the ranges [0-2]Å−1 and [2-6]Å−1.


2015 ◽  
Vol 20 (3) ◽  
pp. 190-203 ◽  
Author(s):  
Ernesto Panadero ◽  
Sanna Järvelä

Abstract. Socially shared regulation of learning (SSRL) has been recognized as a new and growing field in the framework of self-regulated learning theory in the past decade. In the present review, we examine the empirical evidence to support such a phenomenon. A total of 17 articles addressing SSRL were identified, 13 of which presented empirical evidence. Through a narrative review it could be concluded that there is enough data to maintain the existence of SSRL in comparison to other social regulation (e.g., co-regulation). It was found that most of the SSRL research has focused on characterizing phenomena through the use of mixed methods through qualitative data, mostly video-recorded observation data. Also, SSRL seems to contribute to students’ performance. Finally, the article discusses the need for the field to move forward, exploring the best conditions to promote SSRL, clarifying whether SSRL is always the optimal form of collaboration, and identifying more aspects of groups’ characteristics.


Author(s):  
Michael D. Gordin

Dmitrii Mendeleev (1834–1907) is a name we recognize, but perhaps only as the creator of the periodic table of elements. Generally, little else has been known about him. This book is an authoritative biography of Mendeleev that draws a multifaceted portrait of his life for the first time. As the book reveals, Mendeleev was not only a luminary in the history of science, he was also an astonishingly wide-ranging political and cultural figure. From his attack on Spiritualism to his failed voyage to the Arctic and his near-mythical hot-air balloon trip, this is the story of an extraordinary maverick. The ideals that shaped his work outside science also led Mendeleev to order the elements and, eventually, to engineer one of the most fascinating scientific developments of the nineteenth century. This book is a classic work that tells the story of one of the world's most important minds.


2018 ◽  
Author(s):  
Alexander Bolano
Keyword(s):  

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