Periodic Table left-step

In order to allow any multiple chlorination of the biphenyl skeleton, the user may define an atom list (eonsisting of hydrogen and chlorine atoms) and substitute all H-atoms by this list. One may click on the drop-down selection box behind the element icons, select the options Generics. .set the user-defined atom to A1 and quit by the OK button. As a result this atom selection is active for the subsequent drawing steps. After this atom list is drawn ten times as the ten substituents, its composition has to be defined by clicking the A, icon on the left-hand side of the structure editor and by selecting H and Cl in the periodic table (Figure 5-16). 

Paper eight first appeared in the Journal of Chemical Education in 2008. Whereas in my book on the periodic table, I recommended the left-step table as the best possible representation, I subsequently changed my mind and proposed a new table. First of all let me say why I initially supported the left-step table. My attention was first drawn to the left-step table by Henry Bent s unpublished booklets on the subject, although I felt that his... 

What actually converted me to the left-step table, at least for a period of a few years, was a rather concise paper by the periodic table designer Gary Katz, which appeared in The Chemical Educator.20 My own support for this form of the table centered on my interest in the dual sense of the term element and in particular the more fundamental sense, called element as a basic substance by Paneth. 

I wondered whether there might be some means of maximizing the number of atomic number triads that appear on the periodic table. One thing was immediately clear, namely that the relocation of helium, as proponents of the left-step favor, would lead to the loss rather than the gain of an atomic number triad. This was therefore one more argument against the relocation of helium. 

However, one aspect, having to do with triads of elements, is troubling in this otherwise elegant left-step periodic system. The use of the left-step table results in the loss of a triad involving helium, neon, and argon. 

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. 

Scerri, E. R. Educ. Chem. 2005, 42, 135-136. Scerri, E. R. Hyle 2005, l L 127-145. Scerri, E. R. Relative Virtues of the Pyramidal and Left-Step Periodic Tables. In The Periodic Table Into the 21 st Century Rouvray, D., King, B., Eds. Science Research Press Baldock, United Kingdom, 2004 pp 142-160. 

ABSTRACT This article concerns various foundational aspects of the periodic system of the elements. These issues include the dual nature of the concept of an "element" to include element as a "basic substance" and as a "simple substance." We will discuss the question of whether there is an optimal form of the periodic table, including whether the left-step table fulfils this role. We will also discuss the derivation or explanation of the [n + , n] or Madelung rule for electron-shell filling and whether indeed it is important to attempt to derive this rule from first principles. In particular, we examine the views of two chemists, Henry Bent and Eugen Schwarz, who have independently addressed many of these issues. 2008 Wiley Periodicals, Inc. Int J Quantum Chem 109 959-971, 2009... 

Key words elements periodic table Madelung rule left-step table... 

In the July 2007 issue of the Journal of Chemical Education Bent and Weinhold, an inorganic and a theoretical chemist, respectively, published an extensive paper on the left-step periodic table. One rather noticeable feature of their article is the overtly reductionist stance that the authors adopt. They wrote... 

It should also be said that the reason why Bent and Weinhold devote such attention to the n + ( rule is that, as mentioned earlier, the rule is clearly represented on the left-step table, the form of the periodic table that they favor. In addition, as was mentioned, the authors believe that the best representation of the periodic system should be based on the electronic structure of the neutral atoms of all the elements and not on their macroscopic properties. 

Similarly, the desire to maximize the number of atomic number triads would suggest that helium should not be moved away from its traditional place at the top of the noble gases as has been suggested by proponents of the left-step periodic table such as Bent and Weinhold. 

The problem is no longer the validity of Mendeleev s system, but the best way to represent it. Should it be the original short-form table with 8 columns, the familiar medium-long form with 18 columns, or perhaps even a long-form table with 32 columns, which more naturally accommodates the rare earth elements Into the main body of the table Altanahvely, some favor pyramidal tables, while others advocate the left-step form proposed by diaries Janet in the 1920s. Theodor Benfey and rhilip Stewart have proposed continuous spiral models. Hundreds, possibly even thousands, of periodic systems have been proposed, and each has its ardent supporters. 

The metallics are often called other metals and begin an arrangement on the periodic table in zigzag steps. (You may view this dark zigzag line that divides the metallics from metalloids on a copy of the Periodic table.) For the other metals or metallics, this zigzag line runs run from aluminum to gallium to indium to tin to thallium to lead and then ends with bismuth. Elements left of the zigzag are also called poor metals. ... 

The left-hand side boundary of the periodic table starts with one extremely high step (six formulas), followed by a four-formula step. When measured in the same way the following steps, as can be proved rigorously, always hold either three or two formulas. The first ( low ) two-formula step starts with C52H18 (h = 18) cf. Table 5. The last column in Table 5 (starting with C73H2i at the top) contains a three-formula ( high ) step, which is followed by a low step ... 

In 1926, Goldschmidt demonstrated the analogies between the elements Th, Pa, U and the lanthanides on the basis of the observation that the volumes of Th and U showed the same contractions as the ions of the lanthanide series. Striking early examples of periodic tables in which actinium, thorium, protactinium, and uranium are considered as homologues of the rare earths lanthanum, cerium, praseodymium, and neodymium are the circular system and left-step table of Charles Janet (Janet, 1929). 

It should be noted that although for decennia lanthanum and actinium could be found below yttrium in most periodic tables, some authors have placed lutetium below yttrium in the past. For instance, in the periodic table of Werner (1905a,b), there is an open place below yttrium at the position where lutetium is expected, but it should be realized that at that time lutetium had not yet been discovered (this was in 1907). However, Werner did not consider lanthanum as a homologue of yttrium, because of the differences in chemical properties between these two elements. Also in the circular system of Janet (Figure 28), the left-step table of Janet (Figure 32) and in the periodic table of Bohr (Figure 21), lutetium was placed below yttrium. 

FIGURE 32 The left-step periodic table. In this representation, the f-block consists of 14 groups of f-elements with lanthanum (La) and actinium (Ac) as the first representatives of each row and ytterbium (Yb) and nobelium (No) as the last ones. Lutetium (Lu) and lawrencium (Lr) are accommodated as d-block elements in the periodic table, below scandium (Sc) and yttrium (Y). The left-step periodic table is in perfect agreement with the Madelung rule. 

T1.2 Your coverage of early proposals for the periodic table should at least include DObereiner s triads, Newlands Law of Octaves, and Meyer s and Mendeleev s tables. From the modem designs (post-Mendeleev) you should consider Hinrichs spiral periodic table, Benfey s oval table. Janet s left-step periodic table, and Dufour s Periodic Tree. 

The portion of the periodic table that contains the metallic elements is shown here in gray, and the portion that contains the nonmetallic elements is shown in light blue. The stair-step line that starts between B and Al on the periodic table and descends between Al and Si, Si and Ge, and so on separates the metallic elements from the nonmetallic elements. The metals are below and to the left of this line, and the nonmetals are above and to the right of it. Most of the elements that have two sides of their box forming part of the stair-step line are metalloids. Aluminum is usually considered a metal. 

Copper is a typical metal. It is lustrous (although it tarnishes readily) it is an excellent conductor of electricity (it is widely used in electrical wires) and it is readily formed into various shapes, such as pipes for water systems. Copper is one of the transition metals—the metals shown in the center of the periodic table. Iron, aluminum, and gold are other familiar elements that have metallic properties. All of the elements shown below and to the left of the heavy "stair-step" black line in Figure 3.7 are classified as metals, except for hydrogen (see Figure 3.9). 

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