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The first attempt to represent the Periodic system graphically was the Telluric Helix (Vis Tellurique) presented in 1862 by Alexandre-Emile Béguyer de Chancourtois, in which the sequence of elements was wound round a cylinder. This has hardly been attempted since, because the intervals between periodic returns vary in length from 2 to 32 elements,...
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... Though the (n + ℓ, n) rule is in line with s-p-d-f blocks of the Periodic Table of Janet as discussed by Stewart (2020), indeed, the order of orbital energies (aufbau) is different from orbital filling rules of (n + ℓ, n), and it has been discussed in details for example by Pilar (1978), Vanquickenborne et al. (1994), Schwarz (2006), Wang et al. (2006), and Schwarz (2010). ...
This article describes a descriptive-qualitative method for analyzing and reviewing several textbooks for high school as samples commonly used by teachers and students in their teaching–learning to reveal possible misconceptions. This study focused on the subjects of quantum numbers and electronic configuration. From the advanced literature review to analyze the samples the occurrence of various misconceptions was noted. All textbooks described correctly the four symbols of quantum numbers, but none correlates correctly the magnetic-angular quantum number to the Cartesian labeled orbitals. All textbooks consider mistakenly the meaning of aufbau as the building-up energy of orbitals by following (n + ℓ, n) rules on describing the electronic configuration for all atoms. Only one textbook states that the electronic configuration of transition metal atoms (3d series) can be described in the following order of shell (n), thus giving rise to two types of electronic configurations, [Ar] 3d 4s (Type I) beside [Ar] 4s 3d (Type II), leading further misconception. All textbooks described favorably an unpaired electron of ms = + ½ due to the specific agreement, which is a potential misconception in applying Hund’s rule. In drawing the diagram boxes of orbitals, they are arranged in increasing or decreasing the numeric mℓ, due to the specific agreement, and again leading to a potential misconception on describing the quantum number of electrons issued. Three textbooks introduced the terms of the last and the xth electron associated with the quantum numbers, leading to serious further misconceptions. No books stated that the ordering energy of the (n + ℓ, n) rule is true only for the first twenty atoms.
... Combined with an oversimplified Aufbau rule (i.e., neglecting the two-electron repulsion energies), the energetic order of AOs is often assumed as independent of the element number Z, the atomic charge q and the bonding state, following always the so-called (n+ℓ,n) rule, see e.g., refs. [24][25][26][27][28]. A section of the (n+ℓ,n) AO energy pattern (namely the one relevant for the 3d elements in period n = 4) is displayed as rule (1). ...
The electron configurations of Ca, Zn and the nine transition elements M in between (and their heavier homologs) are reviewed on the basis of density functional theory and experimental facts. The d - s orbital energy and population patterns are systematically diverse. (i) The dominant valence electron configuration of most free neutral atoms M ⁰ of groups g = 2–12 is 3 d g −2 4 s 2 (textbook rule), or 3 d g −1 4 s ¹ . (ii) Formal M q+ cations in chemical compounds have the dominant configuration 3 d g − q 4 s 0 (basic concept of transition metal chemistry). (iii) M ⁰ atoms in metallic phases [M ∞ ] of hcp, ccp(fcc) and bcc structures have intermediate populations near 3 d g −1 4 s 1 (lower d populations for Ca (ca. ½) and Zn (ca. 10)). Including the 4 p valence orbitals, the dominant metallic configuration is 3 d g − δ 4( sp ) δ with δ ≈ 1.4 (±0.2) throughout (except for Zn). (iv) The 3 d ,4 s population of atomic clusters M m varies for increasing m smoothly from single-atomic 3 d g −2 4 s ² toward metallic 3 d g −1 4 s ¹ . – The textbook rule for the one-electron energies, i.e., n s < ( n −1) d , holds ‘in a broader sense’ for the s block, but in general not for the d block, and never for the p block. It is more important to teach realistic atomic orbital (AO) populations such as the ones given above.
... Relation (5) maps onto the periodic table design of Figure 6, with 8 periods up to Z = 120, being called the Janet Left Step Periodic Table (LSPT; Janet, 1930;Scerri, 2007Scerri, , 2020Stewart, 2010Stewart, , 2020. The LSPT looks particularly 'elegant' and 'symmetric' with regularly arranged s, p, d, f blocks. ...
The chemical elements are the “conserved principles” or “kernels” of chemistry that are retained when substances are altered. Comprehensive overviews of the chemistry of the elements and their compounds are needed in chemical science. To this end, a graphical display of the chemical properties of the elements, in the form of a Periodic Table, is the helpful tool. Such tables have been designed with the aim of either classifying real chemical substances or emphasizing formal and aesthetic concepts. Simplified, artistic, or economic tables are relevant to educational and cultural fields, while practicing chemists profit more from “chemical tables of chemical elements.” Such tables should incorporate four aspects: (i) typical valence electron configurations of bonded atoms in chemical compounds (instead of the common but chemically atypical ground states of free atoms in physical vacuum); (ii) at least three basic chemical properties (valence number, size, and energy of the valence shells), their joint variation across the elements showing principal and secondary periodicity; (iii) elements in which the (sp)⁸, (d)¹⁰, and (f)¹⁴ valence shells become closed and inert under ambient chemical conditions, thereby determining the “fix-points” of chemical periodicity; (iv) peculiar elements at the top and at the bottom of the Periodic Table. While it is essential that Periodic Tables display important trends in element chemistry we need to keep our eyes open for unexpected chemical behavior in ambient, near ambient, or unusual conditions. The combination of experimental data and theoretical insight supports a more nuanced understanding of complex periodic trends and non-periodic phenomena.
Hydrogen is troublesome in any periodic table classification. This being so it may as well be placed in a position that confers desirable attributes to the arrangement of the elements, while notionally recognising its lineage to the group 1 alkali metals and the group 17 halogens. Since the noble gases bridge the halogens and the alkali metals, and hydrogen encompasses the transition from the alkali metals to the halogens, there is more to the idea of hydrogen over helium.Hydrogen…seems to claim an exceptional position (Meyer 1870, p. 357)
The real voyage of discovery consists not in seeking new lands but in seeing with new eyes (Proust 1927, p. 559)
Hydrogen is troublesome in any periodic table classification. This being so it may as well be placed in a position that confers desirable attributes to the arrangement of the elements, while notionally recognising its lineage to the group 1 alkali metals and the group 17 halogens. Since the noble gases bridge the halogens and the alkali metals, and hydrogen encompasses the transition from the alkali metals to the halogens, there is more to the idea of hydrogen over helium.
