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  Web Book Home Page | Chemogenesis Main Index Foreword:  Chemogenesis & Chemical Education Part I   Atoms | Elements | Periodic Tables 1.1  Introduction to Chemogenesis 1.2  Nucleosynthesis of The Elements 1.3  The Segrè Chart 1.4  Quantum Numbers to Periodic Tables 1.5  The Periodic Table: What Is It Showing? 1.6  The INTERNET Database of Periodic Tables 1.7  Periodicity Part II   Structure | Bonding | Material Type 2.1  Mono-Bond Typed Binary Compounds 2.2  Binary Compound Synthlet 2.3  Electronegativity 2.4  van Arkel-Ketelaar Triangles of Bonding 2.5  Tetrahedra of Structure, Bonding & Material Type 2.6  Structure, Bonding & Material Synthlet 2.7  The Classification of Matter: Chemical Stuff Part III   Interactions | Reactions | Mechanisms 3.1  The Chemogenesis Analysis: An Overview 3.2  Lewis and Brønsted Models of Acidity 3.3  The Hard Soft [Lewis] Acid Base Principle 3.4  Main Group Elemental Hydrides 3.5  Five Hydrogen Probe Experiments 3.6  Congeneric Dots, Series & Planars 3.7  Quantifying Congeneric Behaviour 3.8  Ligand Replacement Congeneric Series 3.9  Congeneric Array Interactions 3.10  Emergence of Organic Chemistry 3.11  Congeneric Array Database 3.12  The Five Reaction Chemistries 3.13  Lewis Acids & Lewis Bases: A New Analysis 3.14  The Lewis Acid/Base Interaction Matrix 3.15  Patterns in Reaction Chemistry Poster 3.16  Lewis Acid/Base Interaction Matrix Database 3.17  Nucleophiles, Bases & The Fluoride Ion 3.18  Redox Chemistry 3.19  Redox Chemistry Synthlet 3.20  Radical Chemistry 3.21  Diradical Chemistry 3.22  Photochemistry 3.23  Species/Species Interactions 3.24  The Simplest Mechanistic Step: STAD 3.25  Unit & Compound Mechanistic Steps 3.26  The Mechanism Matrix 3.27  Addition To A Double Bond Synthlet 3.28  Pericyclic Reaction Chemistry Part IV   Chemical Theory 4.1  Why Do Chemical Reactions Occur? 4.2a  Thermochemistry: List Reactions Synthlet 4.2b  Thermochemistry: Play With Reaction Synthlet 4.2c  Thermochemistry: Bulid A Reaction Synthlet 4.3  Timeline of Structural Theory 4.4  Modern Lewis Theory 4.5  Valence Shell Electron Pair Repulsion: VSEPR 4.6  Diatomic Species by Molecular Orbital Theory 4.7  Polyatomic Species: Molecular Orbitals 4.8  Organic π-Systems 4.9  Functional Group Database Part V   Complexity & Emergence 5.1  Chemistry & Complexity: Systems 5.2  Linear Chemistry Systems 5.3  Chemical Systems Prone to Complexity Part VI   Extras 6.1  Chemogenesis Videos 6.2  Chemical Thesaurus Reaction Chemistry Database 6.3  Paper: Chemogenesis 6.4  Paper: Electronegativity as a Basic Elemental Property (FoC) 6.5  Workshop: What is Chemistry? 6.6  Paper: Scientific laws, Dalton’s postulates, chemical reactions
          and Wolfram’s NKS (FoC) 6.7  Literature References & Further Reading

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The INTERNET Database of Periodic Tables

There are thousands of periodic tables in web space, but this is the only comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Mark R. Leach Ph.D. The database holds information on periodic tables, the discovery of the elements, the elucidation of atomic weights and the discovery of atomic structure (and much, much more).

Periodic Tables from the year 2026:

The Approximate Chemical Formula of the (Observable) Universe

From xkcd, The Approximate Chemical Formula of the (Observable) Universe:

Thanks to Marcus for the tip!

Pairs and Squares Periodic Table

"Pairs and Squares" Periodic Table by Leonid A. Levin of Boston University

Leonid writes:

"All the tables [in the PT Database] share a common problem: their irregularity exceeds by far their periodicity.

"In my youth I was greatly bothered by this. Yet, taking advantage of a few patterns in atomic orbitals allows a complete elimination of all irregularities, putting all periods in a perfect pattern.This perfectly regular rendition would be much more comfortable, especially at one's first high school exposure to this Science symbol.I am attaching such "Pairs and Squares" rendition with a brief explanation."

Read more in the full 'Pairs and Squares' paper, here.

Tableau_Périodique des Elements

La Corrésale writes:

"I have been developing an alternative geometric representation of the periodic table, and I would greatly appreciate your perspective on it.

"The model is a radial (hexagonal) construction with hydrogen and helium positioned at the center, and successive concentric layers corresponding to principal quantum numbers (n = 1-7). The layout follows the Madelung (Klechkowski) filling order, so that the s, p, d, and f blocks arise naturally from the geometric structure.

"Lanthanides and actinides are fully integrated into the continuous sequence rather than separated.

"My intention is not to replace the conventional rectangular table, but to offer a complementary representation that makes the electronic layering and energetic hierarchy more visually explicit. The structure effectively behaves like a “macro-atom,” with shells accumulating outward in a way that mirrors electronic shell construction. Certain periodic trends, such as radial progression and diagonal relationships, appear to become more intuitive in this configuration.

"I am aware that many alternative periodic tables exist, and I have tried to avoid unnecessary aesthetic distortion while preserving structural coherence and regular tiling. I would be very interested to know whether you see any pedagogical or conceptual merit in such a representation, or any structural issues I may have overlooked."

View the .PDF version here.

6 Times Scientists Were Wrong About the Periodic Table

A video from SciShow discussing six times scientists made incorrect predictions about chemical elements: Coronium; Nebulium (Nebulium, Nephium, Nephelium); Masurium (Davium, Leucium, Neponium... actually Technecium); Florencium/Illinium (actually Promethium); Ausenium; and Hesperium.

What is an element, and how is it defined in the IUPAC Gold Book?

A recent publication by Eric Scerri: What is an element, and how is it defined in the IUPAC Gold Book?

Read the paper or download the PDF here, or go to page 36 of the Chemistry International journal here.

Quest To Understand Where Atoms End

By Philip Ball in Chemistry World, who writes:

"There is no consensus. 'We have some models and theories [of atomic size] but none have been really amenable to experimental verification,' says Amin Alibakhshi at the Technical University of Dortmund in Germany. 'That’s why we have many different definitions, like van der Waals radii, covalent radii, and so on.' But is each of these definitions in the end a rather arbitrary attempt to carve up the smooth and continuous electron density so that it seems to have hard edges? Or might there be, after all, some deeper and more objective meaning to the size of an atom?"

Spin and The Forth Dimension

A paper (click to view pdf) by V.V. Varlamov of Siberian State Industrial University, Novokuznetsk, Russia who writes:

"A group-theoretic interpretation of the periodic system of elements is given within the framework of the weight diagram of the Lie algebra SO(4,4) of the fourth rank, where the four quantum numbers n, l, m, scorrespond to the eigenvalues (weights) of the Cartan generators of the maximal Abelian subalgebra (the maximal torus of the group SO(4,4)). Etc."

The paper generates a Janet Left-Step formulation:

Thanks to Eric Scerri for the tip!

Aperiodic Table

(Exploiting a quirk of the English language) Aperiodic Table by XKCD:

Thanks to Marcus for the tip!

Johnson’s Quaternionic Periodic Chart of the Elements

Johnson’s Quaternionic Periodic Chart of the Elements: An Amendment to Janet’s Left Step Periodic Chart by Willie Johnson Jr.

What sets the formulation apart is:

1. The chart is structured such that helium legitimately assumes it rightful place as the 1st noble gas.
2. The chart accounts for the disparate chemical properties of Hydrogen.
3. The chart is based upon a five quaternion set: 0, s, i, j, k.
4. The entire chart is mapped to a Clifford Torus. This ensure all interactions are orthogonal.
5. It is found that by interacting moving electrons orthogonally we engender a new chemical bond called the Tovacian Bond thus obviating any undo electrostatic repulsion.

Read the full paper.pdf.

Personality Elements, Periodic Table of

A Periodic Table of Personality Elements by Frans Maan.

Click here (or click on the images below) to see the full size version.

Frans gives this web link.

Marks: Step-Pyramid Mendeleyev

A periodic table highlighting Mendeleyev´s periodic law by John Marks.

It further follows Bohuslav Brauner (1855-1935), a keen disciple of Mendeleyev, in searching for internal periodicity, well demonstrated in the A-subgroups (d-elements), but his attempts to show this in the B-subgroups (f-elements) met with frustration. Ironically, had many of the actinides been available for his examination, he would have had more success than with the lanthanides. The periods comprise two initial sets of octets, followed by two of 18 and then two of 32, the last being incomplete because of spontaneous fission.

Within the periods, Brauner´s internal periodicity is clear to see. After the octets, new elements are added in the middle, between groups VIII (0) and I, yet follow the rhythm of the octets. K and Ca (groups I and II) are followed by Sc, group IIIA. This continues with the additional elements added at groups 9 and 10 (IXA and XA) and then recapitulated with Cu and Zn as groups IA and IIA before continuing the rhythm with Ga (group III). The same phenomenon occurs with the rare-earth and radioactive series. Brauner´s hypothesis would be corroborated by discovery of hexavalent Ty or monovalent θu.

Notes on Nomenclature:

A standard text saw fit to write: "Lanthanum has only one important oxidation state in aqueous solution, the +3 state. With few exceptions, this tells the whole boring story about the other lanthanides." [Pimentel, G., Spratley, R.: "Understanding chemistry", Holden-Day, San Francisco (1971), p. 862]. Others wrote similarly, explaining it as a consequence of the current convention of removing the f-block elements from the body of the periodic table.

However, undoubtedly ugly names like dysprosium and neodymium and confusing ones like terbium, ytterbium and erbium, aggravate this. The problem is not confined to the lanthanoids, with unimaginative examples like technetium, protoactinium and astatine.

The set of chemical canasta cards renames many of the worst offenders. Since the village of Ytterby has four elements named after it (five, if one includes holmium), I have reduced this to yttrium (cf. strontium, after Strontian) plus erbium and terbium to reflect the historical confusion: between 1843 and 1878 erbium and terbium even swapped names! I have replaced neodymium and praseodymium with names both more euphonious and relevant, often pairing a lanthanoid with its corresponding actinoid.

I have left the initiator of the series, lanthanum (Gk. for ‘hidden’) as appropriate and familiar.

Among the actinoids, since the same laboratory in America is represented in three elements, this has been replaced by Am (americum), Il (illinium, after the Argonne national laboratory, Illinois) and Cf (californium). Other alternatives are offered with names that are equivalent contemporary (at the time and place of discovery) metaphors, both more euphonious and more memorable:

Danubium, Da, Z=43 cf Rhenium, Z=75, the other northern boundary of the Roman empire, but the Danube is divided by many cataracts and rapids, reflecting danubium's radioactivity.

Berzelium, Bz, Z=59 and Meitnerum, Mt, Z=91 After Berzelius, the discoverer of a lanthanoid and the difficult properties (especially separation) of the lanthanoids and after Meitner, the discoverer of an actinoid and of many peculiar properties (especially nuclear fission) of the actinoids.

Tyrium, Ty, Z=60 After Tyr (cf uranium, Z=92 after the Greek god, Uranus) and for its tyrian (purple) coloured salts and the Norse god, Tyr.

Spectrium, Sp, Z=70 and Cyclonium, Cy, Z=102 Spectrium after the spectroscope which identified many lanthanoid elements and cyclonium after the cyclotron which identified many actinoid elements. (Cy is not included in the chemical canasta set, which covers only the first hundred elements)

Therine, θe, Z=85 After Thera, the unstable volcanic isle of classical mythology, a metaphor for instability. Niton, Nt, Z=86 From the Latin 'nitens' = shining, the name given it by Ramsay on account of its spontaneous luminescence. 'Radon' is short for 'radium emanation', Nt-222, and is thus merely an isotope of niton. Similarly thoron is Nt-220 and actinon is Nt-219. Lavoisium, Lv, Z=66 is named for Lavoisier, the founder of modern chemistry, replacing the ugly “dysprosium”.

I have also named Mendeleyev´s groups: VII (or -1) Cavendish's; VIII (or 0) Ramsay's; I Davy's; II Döbereiner's; III Mendeleyev's; IV Dalton's; V Boyle's; VI Lavoisier's.

Many recently named elements have had "-ium" added unthinkingly without realizing that "-um" is equally valid and more appropriate for the prosody of many names. Aluminum seems to be the etymologically correct derivative of alumina. Reasons of prosody have chosen "-um" in meitnerum, americum and platinum.

The symbol J for iodine reflects the consonantal nature of the initial. Since science is familiar with the Greek alphabet, θu, θa, θe and θ are suggested for Z = 69, 81, 85 and 90. This would also ease the pressure on finding suitable Berzelian symbols for new superheavy elements.

Periodicity of Protons in Atoms

The Periodicity of Protons in Atoms by James C. Decandole.

Osman's Developed Models of Periodic Table of Elements

Developed Models of Periodic Table of Elements Dr. Khalid Abdel Fattah M. Osman, Associate Professor at Merowe Institute of Technology Merowe University of Technology, Sudan.

My latest 2026 research in periodic table of elements, titled "Developed Models of Periodic Table of Elements", introduces an innovative mathematical simulation that addresses some of the long-standing structural challenges in the modern periodic law [1.3.1، 1.3.4].

Unlike traditional models, the model leverages parabolic properties to map atomic shells and subshells, simulating an electronic configuration based on symmetrical circular orbits with a two-electron capacity each. This mathematical symmetry results in a highly coherent Extended Periodic Table, which elegantly accommodates predicted super heavy elements (beyond element 118) and offers a potential resolution to the debate surrounding the end of the periodic table.

© Mark R. Leach Ph.D. 1999 –

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