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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.

Use the drop menus below to search & select from the more than 1100 Period Tables in the database:

Text search:       


Periodic Table formulations referencing René, by date:

1874   von Richter's Periodic System of the Elements
1875   Gibbes' Synoptical Periodic Table
1875   Concentric Ring Arrangement of Wiik
1878   Waechter's Numerical Regularities
1882   Bayley's Attempt
1885   Carnelley & The Periodic Law
1891   Wendt's Generation-Tree of the Elements
1893   Rang's Periodic Arrangement of The Elements
1896   Ramsay's Elements Arranged in the Periodic System
1896   Venable's The Development of The Periodic Law
1907   Grouping of The Elements to Illustrate Refractivity
1909   Garrett's The Periodic Law
1920   Black & Conant's Periodic Classification Of The Elements
1920   Stewart's Arrangement of The Elements
1927   Le Roy's Periodic Table
1931   LeRoy's Updated Periodic Table
1932   Bacher & Goudsmith's Periodic System and Index
1935   Rysselberghe's Periodic Table
1939   Foster's Periodic Arrangement
1945   Talpain's Gnomonic Classification of the Elements
1946   Achimof's System
1946   Yost & Russell's Periodic System
1946   Harrington's Crystal Chemistry of the Periodic System
1947   Stedman's Design
1949   Scherer's Student Model of Spiral Periodic Chart
1949   Catalan's Periodic System/Sistema Periodico Ampliado
1950   McCutchon's Simplified Periodic Classification of the Elements
1950   Sidgwick's Periodic Classification (Mendeleeff)
1952   Hakala's Periodic Law in Mathematical Form
1952   Coryell's Periodic Table in Long Form
1956   Remy's Long Period Form Periodic Table
1956   Walker & Curthoys' New periodic Table Based of Stability of Atomic Orbitals
1957   Laubengayer's Long Periodic Table
1960   International Rectifier Corporation Periodic Table
1963   Bedreag's Système Physique Des Éléments
1964   Haward's Periodic Table
1969   Dash's Quantum Table of the Periodic System of Elements
1969   Mendeleevian Conference, Periodicity and Symmetries in the Elementary Structure of Matter
1970   Pauling's "General Chemistry" Periodic Table
1971   Clark, John O. E. Periodic Table
1974   Mazurs' Redrawing of Stedman's Formulation
1987   Step-Pyramid Form of the Periodic Chart
1987   Variation of Orbital Radii with Atomic Number
1987   Mineralogical-Crystallochemical Classification of Elements
1992   Magarshak & Malinsky's Three Dimensional Periodic Table
1995   Klein's Periodic Table of The Elements
2003   Two-Amphitheater Pyramid Periodic Table
2004   Classroom Kids Periodic Table
2007   Mechanical Engineer's Periodic Table
2007   Bent & Weinhold's 2D/3D Periodic Tables
2011   Tresvyatskii's Periodic Table
2017   Restrepo's Similarity Landscape
2019   Chemical Bonds, Periodic Table of
2019   Slightly Different Periodic Table
2019   Group 3 of The Periodic Table
2019   Vernon's Oxidation Number Periodic Table
2020   Annotated Periodic Table
2020   Vernon's Periodic Table showing the Idealized Solid-State Electron Configurations of the Elements
2020   Correlation of Electron Affinity (F) with Elemental Orbital Radii (rorb)
2020   Vernon's Constellation of Electronegativity


1874

von Richter's Periodic System of the Elements

From page 244 of A Text-book of Inorganic Chemistry by Victor von Richter, Published by Blakiston (US ed. in English, 1885). The full text (scanned) is available from archive.org. The first edition was published in 1874 in German. von Richter was was from the Baltic region, in the the Russian empire at the time.

von Richter's work is almost certainly the first chemistry textbook based on the periodic system. Many (indeed most) modern Inorganic Chemistry texts follow this format.

von Richter, writes:





Thanks to René for the tip!

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1875

Gibbes' Synoptical Periodic Table

From page 127 of The Development of the Periodic Law by Venable, Francis Preston (1856-1934), Easton, Pa. Chemical Pub. Co (1896). The full text (scanned) is available from archive.org.

Venable writes:


Thanks to René for the tip!

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1875

Concentric Ring Arrangement of Wiik

From page 133 of The Development of the Periodic Law by Venable, Francis Preston (1856-1934), Easton, Pa. Chemical Pub. Co (1896). The full text (scanned) is available from archive.org.

Venable writes:


Thanks to René for the tip!

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1878

Waechter's Numerical Regularities

From page 136 of The Development of the Periodic Law by Venable, Francis Preston (1856-1934), Easton, Pa. Chemical Pub. Co (1896). The full text (scanned) is available from archive.org.

Venable writes:


Thanks to René for the tip!

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1882

Bayley's Attempt

From page 158 of The Development of the Periodic Law by Venable, Francis Preston (1856-1934), Easton, Pa. Chemical Pub. Co (1896). The full text (scanned) is available from archive.org.

Venable writes about Bayley:


Thanks to René for the tip!

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1885

Carnelley & The Periodic Law

From page 172 of The Development of the Periodic Law by Venable, Francis Preston (1856-1934), Easton, Pa. Chemical Pub. Co (1896). The full text (scanned) is available from archive.org.

Venable writes:



Thanks to René for the tip!

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1891

Wendt's Generation-Tree of the Elements

From page 244 of The Development of the Periodic Law by Venable, Francis Preston (1856-1934), Easton, Pa. Chemical Pub. Co (1896). The full text (scanned) is available from archive.org.

Venable writes:


Thanks to René for the tip!

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1893

Rang's Periodic Arrangement of The Elements

P.J.F. Rang's The Periodic Arrangement of the Elements, Chemical News, vol. 67, p. 178 (1893)

Observing that that Rang's table has four 'groups': A, B, C & D, René Vernon writes:

    1. Group A contains the strongest positive elements; group D the strongest negative elements. At such an early date, it's odd to see groups 1 to 3 categorised together.
    2. Group B are the elements with high melting points; "they are all remarkable for their molecular combinations" (presuamably, a reference to multiple oxidation states). At one side of group B are the "anhydro-combinations", probably referring to the simple chemistry of Ti, Zr, [Hf] Nb and Ta being dominated by insoluble oxides. At the other side are the "amin, carbonyl, and cyanogen combination", probably a reference to the group VIII carbonyls, as metal carbonyls had only just been discovered. Ni is shown after Fe, rather than Co.
    3. Group C includes the "heavy metals that have low melting points"; an early reference to frontier or post-transition metals, as a category.
    4. Rang says: ...if groups A and D be split up vertically in respectively three and two parts, the table presents seven vertical groups, and horizontally seven more or less complete series. Each group in each of the series 2 and 3 are represent by one element... The octave appears both horizontally and vertically in the table.
    5. Rang's reference to Di as representing all the triads between Ba and Ta kind of works since Hf would go under Zr, and that would leave 15 Ln or five sets of three. Thus, something like this:

      Gd occupies the central position among the Ln. This arrangement won't fit however unless Rang envisaged all 15 Ln occupying the position under Y.
    6. The location of H over | Ga | In | Tl, appears strange... but the electronegativity of H (2.2) is closer to B (2.04) than it is to C (2.55).

From Quam & Quam's 1934 review paper.pdf

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1896

Ramsay's Elements Arranged in the Periodic System

From The Gases of the Atmosphere, The History of Their Discovery by William Ramsay (and from the Gutenberg Project.)

The author writes pp 220-221:

"In 1863 Mr. John Newlands pointed out in a letter to the Chemical News that if the elements be arranged in the order of their atomic weights in a tabular form, they fall naturally into such groups that elements similar to each other in chemical behaviour occur in the same columns. This idea was elaborated farther in 1869 by Professor Mendeléeff of St. Petersburg and by the late Professor Lothar Meyer, and the table may be made to assume the subjoined form (the atomic weights are given with only approximate accuracy):—"

Thanks to René for the tip!

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1896

Venable's The Development of The Periodic Law

The Development of the Periodic Law by Venable, Francis Preston (1856-1934), Easton, Pa. Chemical Pub. Co (1896).

The full text (scanned) is available from archive.org.


Thanks to René for the tip!

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1907

Grouping of The Elements to Illustrate Refractivity

From C. Cuthbertson & E. Parr Metcalfe, Part III On The Refractive Indices of Gaseous Potassium, Zinc, Mercury, Arsenic Selenium and Tellurium, Phil. Trans. A: Mathematical & Physical Sciences, vol 207, pp135–148, 1907.

René Vernon writes:

"A curious periodic table which runs from group 12 on the left to group 13 on the right (see below). It seems to have done that way to bring out the pattern in multiples of refractivities i.e. x½ x 4 x 6 x10. The border around the elements in groups 15 to K-Rb-Cs in group 1 denotes this relatively strong regularity among the refractivity values. The L for iodine is a printer's error."

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1909

Garrett's The Periodic Law

A book reviewing The Periodic Law by A.E. Garrett, pub. D. Appelton & Co (1909). This work shows the state of knowledge in the first decade of the 20th century.

René Vernon writes:

"On page 43 Garrett notes that, '[Thomas] Carnelley was the first English chemist to work out in detail the manner in which the properties of the elements are periodic functions of their atomic weights. His papers on this subject appeared in the Philosophical Magazine between the years 1879 and 1885.' "

Read more one Carnelley here.

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1920

Black & Conant's Periodic Classification Of The Elements

From N.H. Black NH & J.B. Conant's Practical Chemistry: Fundamental Facts and Applications to Modern Life, MacMillan, New York (1920)

Eric Scerri, who provided this formulation writes (personal communication):

"Notice conspicuous absence of H. And, Conant was the person who gave Kuhn his first start in the history of science at Harvard."

René Vernon tells us that Conant and his coauthor write:

"The position of H in the system has been a matter of some discussion, but it is not of much consequence. It seems to be rather an odd element. Perhaps the best place for it is in group IA as it forms a positive ion." (p. 350)

Thanks to Eric Scerri for the tip! 
See the website EricScerri.com and Eric's Twitter Feed.

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1920

Stewart's Arrangement of The Elements

From A.W. Stewart, Recent Advances in Physical and Inorganic Chemistry, 3rd ed., Longmans, Green and Co., London (1920) 

René Vernon writes:

"Stewart discusses the 'forced symmetry' of Mendeleev's table, and the distinction between 'facetious symmetry' (as he calls it) and the actual correlation of facts (as he saw them at that time)."

Extracts:

237. Mendeleev... objected strongly to the employment of graphic methods of expressing the Periodic Law, on the ground that such methods did not indicate the existence of a limited and definite number of elements in each period.

239. The Periodic Table, as laid down by Mendeleeff in his writings, exhibits a symmetry which was one of its greatest assets. For some psychological reason, symmetry has an attraction for the human mind; and we are always apt to prefer a regular arrangement to one in which irregularities pre- dominate. Psychological peculiarities are, however, undesirable guides in the search for truth; and a careful examination of the Table in the light of our present knowledge will suffice to show that it can boast of no such symmetry as we are led to expect from the text-books of our student days.

For example, owing to the omission of some of the rare earth elements and by the insertion of blanks, the Table in its original form attained a very high degree of regularity; but since there are, as we know from the X-ray spectra results, only sixteen elements to fill the eighteen vacant spaces in the Table, it is evident that the symmetry of Mendeleeff s system is purely factitious.

Further, in order to produce the appearance of symmetry, Mendeleeff was forced to place copper, silver, and gold in the first group, although there is no known oxide Au2O and the stable chloride of gold is AuCl3.

These examples are well-known, and are mentioned here only for the purpose of enforcing the statement that the symmetry of Mendeleef's system cannot be sustained at the present day. Fascinating though its cut-and-dried regularity may be, we cannot afford to let symmetry dominate our minds when in actual fact there is no symmetry to be found.

240. The most superficial examination shows that, instead of being a symmetrical whole, the Table is really pieced together from a series of discrete sections.

250. The first attempt to arrange all the elements in a periodic grouping took the form of a three-dimensional model the Telluric Helix of de Chancourtois and it is not surprising that from time to time attempts have been made to utilize the third dimension as an aid to classification. It cannot be said that much light has been thrown on the matter by these essays; but some account of them must be given here for the sake of completeness.

251. The main drawback to the spiral representation appears to be that in it no new facts are brought to light, and there is no fresh collocation of the allied elements which might give it an advantage over the ordinary forms of classification. Also, in most cases it is more difficult to grasp as a whole.

253 ...if we have to choose between factitious symmetry and actual correlation of facts, we must decide in favour of the latter, discomforting though the choice may be.

255. The following new grouping seems worth considering. Although it has many good points, it is not to be regarded as a final solution, but is put forward mainly in the hope that an examination of it may suggest some more perfect system.

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1927

LeRoy's Periodic Table

R.H. LeRoy, Teaching the Periodic Classification of Elements, School Science and Mathematics 1927, 27: 793-799. This formulation thulium in group IC and has the actinides in the C groups, analogous to the lanthanides, two decades before Seaborg.

René adds:

"This 1927 formulation has several remarkable features.

"The lighter and heavier lanthanides and actinides are shown in numbered C groups i.e. C4, C5, C6, C7 and C1, C2, and C3. The 14 remaining elements between C7 and C1 are labelled as transition elements, analogous to the old chemistry notion of the ferromagnetic and platinum metals in IUPAC groups 9 to 11 being labelled as transition elements. There is no known Tm(I) although this would not be inconceivable. Nd is in group C6, which doesn't quite work since there is no Nd(VI) although such an oxidation state is not inconceivable given the existence of Pr(V). in group C7, Pm(VII) is not known. For the actinides, Md(I) has been reported but not confirmed.

"B-Al-Sc-Y-La-Ac are shown as main group metals; that would be consistent with their chemistry. While Sc-Y-La-Ac are routinely classified as transition metals their chemistry is largely that which would be expected of main group metals following the alkaline earths in IUPAC group 2.

"The author refers to the noble gases as 'transitional'. The noble gases bridge the most reactive groups of elements in the periodic table – the alkali metals in group I and the halogens in group VII. That's a concept that's rarely referred to these days even though it's still quite valid.

"Ga-In-Tl are shown as B3 metals, falling just after Zn-Cd-Hg in group B2, and Cu-Ag-Au in group B1. That doesn't work for Ga etc, which are nowadays regarded as main group metals.

"H is shown floating above the A elements, and in the transitional zone, with links to F and to Li."

Thanks to John Marks for the tip, and to René for the comments/analysis!

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1931

LeRoy's Periodic Table

R.H. LeRoy, Teaching the Periodic Classification of Elements, School Science and Mathematics 1927, 27: 793-799. This formulation thulium in group IC and has the actinides in the C groups, analogous to the lanthanides, two decades before Seaborg.

René adds:

"This 1927 formulation has several remarkable features.

"The lighter and heavier lanthanides and actinides are shown in numbered C groups i.e. C4, C5, C6, C7 and C1, C2, and C3. The 14 remaining elements between C7 and C1 are labelled as transition elements, analogous to the old chemistry notion of the ferromagnetic and platinum metals in IUPAC groups 9 to 11 being labelled as transition elements. There is no known Tm(I) although this would not be inconceivable. Nd is in group C6, which doesn't quite work since there is no Nd(VI) although such an oxidation state is not inconceivable given the existence of Pr(V). in group C7, Pm(VII) is not known. For the actinides, Md(I) has been reported but not confirmed.

"B-Al-Sc-Y-La-Ac are shown as main group metals; that would be consistent with their chemistry. While Sc-Y-La-Ac are routinely classified as transition metals their chemistry is largely that which would be expected of main group metals following the alkaline earths in IUPAC group 2.

"The author refers to the noble gases as 'transitional'. The noble gases bridge the most reactive groups of elements in the periodic table the alkali metals in group I and the halogens in group VII. That's a concept that's rarely referred to these days even though it's still quite valid.

Ga-In-Tl are shown as B3 metals, falling just after Zn-Cd-Hg in group B2, and Cu-Ag-Au in group B1. That doesn't work for Ga etc, which are nowadays regarded as main group metals.

"H is shown floating above the A elements, and in the transitional zone, with links to F and to Li."

Thanks to John Marks for the tip, and to René for the comments/analysis!

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1932

Bacher & Goudsmith's Periodic System and Index

R.F. Bacher RF and S.A. Goudsmith, Atomic Energy States, McGraw-Hill, New York, p. xiii. 1932:

Thanks to René for the tip!

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1935

Rysselberghe's Periodic Table

Pierre Van Rysselberghe J. Chem. Educ. vol. 12, no. 10, pp. 474—475 1935.

The author writes:

"The usual relationships between analogous elements are preserved and are in fact emphasized by this new arrangement. The only missing regularity is the natural succession of atomic, numbers, but all periodic classifications have to sacrifice it on account of the rare earths. Moreover, it can easily be restored by reading the horizontal lines n the order indicated by the numbers written on the left of the heavy frame line. Each horizontal line is limited by the frame of the table. For instance, K and Ca on the one hand, Cu and Zn on the other hand, form two distinct horizontal lines, as shown by the different numbers given to these groups. They are at the same level because the valence electrons have the same quantum numbers."

Thanks to René for the tip!

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1939

Foster's Periodic Arrangement

L.S. Foster, "Why not modernise the textbooks also? I. The periodic table", Journal of Chemical Education, vol. 16, no. 9, pp. 409–412, https://pubs.acs.org/doi/10.1021/ed016p409

Foster writes:

"The [above] modern periodic table is simply an orderly array of the elements with all unnecessary ornamentation omitted, has been found highly satisfactory for instructional purposes.

"The transitional elements, with two unfilled electron shells, are separated from the non-metallic elements.

"The rare-earth elements, defined as those with three incomplete electron shells, are shown to be those of atomic numbers 58 to 70, while La and Lu, which have only two incomplete electron shells are classified as transitional elements.

"Copper, silver, and gold act as transitional elements except when the state of oxidation is one."

René Vernon writes:

Foster couldn't show the coinage metals – with their full d10 complements – as transitional elements, but by adding a broken line around them he was showing they had the capacity to act as if they were.

I tried to work out how he distinguished La & Lu from Ce to Yb. Foster seems to be saying that La 5d1 6s2, has incomplete 5th and 6th (ie. 6p) shells.

Same for Lu 4f14 5d1 6s2 having incomplete 5th and 6th shells. Whereas, for example, Ce 4f1 5d1 6s2 has incomplete 4th, 5th and 6th shells. Presumably this was in the years before the fact that the 4f shell became full at Yb was widely appreciated. So, strictly speaking, group 3a should have read:

On the other hand, Yb3+ has an f13 configuration, so it does meet his three unfilled shells criterion. Had he known, he probably would've put a broken line around Yb to indicate its full f14 complement but that it normally acted as a rare earth, with an incomplete 4f shell; whereas neither La nor Lu have this capacity.

Good to see Foster put so much thought into organising his table, and his experience with using it for instructional purposes.

Van Spronsen does not mention Forster's table. Mazurs has a reference to Foster's table but lumps it in with the other medium-long tables, not appreciating its subtlety.

Mark Leach writes:

This formulation is very much like the XBL 769-10601, Periodic Table Before World War II used by Seaborg and the Manhattan project and is a precursor to the modern periodic table.

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1945

Talpain's Gnomonic Classification of the Elements

Talpain PL 1945, Gnomonic classification of elements, J.Phys. Radium 6, 176-181 (in French), https://doi.org/10.1051/jphysrad:0194500606017600

Talpain writes:

"To overcome the drawbacks presented by the various tables in rows and columns into which the classification of chemical elements is usually inserted, the author proposes a diagram in space, having the form of a double pyramid constructed according to a simple arithmetic law, inspired by Greek surveyors. Under these conditions, all the bodies belonging to the same chemical family are placed on the same column, and all those which have similar physical properties (magnetic, electrical, radioactive, crystallographic, rare earths, etc.) are grouped together. This same diagram also makes it possible to represent the electronic structure of the atoms, the quantified states of the electrons, the energy levels and the spectral lines of hydrogen. Perhaps spectroscopists will be able to use it to also represent the lines of other bodies."

Lindsay's Periodic Table

Thanks to René for the tip!

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1946

Achimof's System

Van Spronsen, on p. 157, says:

"Achimov's system took the form of a cross-section of a pyramid. He based his system on the principle that the lengths of the periods and the analogies in properties between the elements of these periods must be clearly demonstrated."

Achimov EI 1946 Zhur. Obshchei Khim., vol. 16, p. 961

Thanks to René for the tip!

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1946

Yost & Russell's Periodic System

From D.M. Yost & H. Russell, Systematic Inorganic Chemistry of the Fifth-and-Sixth-group Nonmetallic Elements, Prentice-Hall, 1946, New York, p. 406.

René Vernon writes:

"Features of this peculiar periodic system:

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1946

Harrington's Crystal Chemistry of the Periodic System

R.H. Harrington, The Modern Metallurgy of Alloys, John Wiley & Sons, New York, p. 143 (1946)

René Vernon writes:

    "The numbers below each element symbol refer to the crystal: 1 = FCC, 9 = graphite structure, 11 = orthorhombic, etc. Extra numbers are for structures at higher temperatures.

    "The wriggly lines between groups 3 and 4, and 11 and 12 refer to a gradation between the classes involved. Wikipedia calls these linking or bridging groups

    "Harrington's class names are novel. [Who would have thought of the elements of groups 1 to 3 as being called the "salts of electrons"?] Then again, "in view of the extensive role that electrons play as anions" Dye (2015) asked: "where should electrons be placed in the periodic table?" (Note: In 1946 Achimof tried answering this, with an electron as element -1 above H and a neutron as element 0 above He.)

    "Aluminium appears in group 3 and group 13 since, according to Harrington, it has the crystalline structure of a true metal. This is not quite true since its crystalline structure shows some evidence of directional bonding.

    "For the transition metals as "wandering bonds", Harrington writes that the metallic bond is spatially undirected and that it may operate between any given atom and an indefinite number of neighbours" (p. 145). Since A-metals are better called, in his mind, "salts of electrons" [and B-metals show signs of significant directional bonding] the transition metals are therefore called by him as wandering bonds. This becomes confusing, however, given d electrons in partially filed d-orbitals of transition metals form covalent bonds with one another.

    "Counting boron as a pseudo metals looks strange.

    "Germanium is counted as a metal: "...the electrical conductivit[y]... [is] sufficiently high to show that the outer electrons are very loosely held and the linkage must be partly metallic in character." (p. 148). In fact the electrical conductivity of high purity germanium, which is a semiconductor, is around 10–2S.cm–1. Compare this with antimony, at 3.1 x 104S.cm–1

    "Tin has brackets around it to show its "renegade" status, "with its white form behaving largely as would a True Metal, whereas its grey form is more non-metallic than metallic." White tin actually has an irregularly coordinated structure associated with incompletely ionised atoms.

    "Thallium and lead have brackets around them since their crystalline structures are supposedly like those of true metals. This is not quite right. While both metals have close-packed structures they each have abnormally large inter-atomic distances that have been attributed to partial ionisation of their atoms.

    "The B-subgroup metals are divided into pseudo metals and hybrid metals. The pseudo metals (groups 11 and 12) behave more like true metals than non-metals. The hybrid metals As, Sb, Bi, Te, Po, At – which other authors would call metalloids – partake about equally the properties of both. According to Harrington, the pseudo metals can be considered related to the hybrid metals through the carbon column.

    "The location of the dividing line between metals and nonmetals, running as it does through carbon to radon is peculiar. The line is usually shown running through boron to astatine."

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    1947

    Stedman's Design

    In his article Stedman says:

    Thanks to René for the tip!

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    1949

    Scherer's Student Model of Spiral Periodic Chart

    George A. Scherer, New Aids for Teaching the Periodic Law, School Science and Mathematics, vol. 49, no. 2 (1949).

    René Vernon writes:

    "This is a Left-Step periodic table with a split d-block, that can be rearranged into a cylinder. Students were expected to keep a copy of the two halves of the table in their note books, for reassembly as required. It was a clever way of introducing the 32-column form, and the transition from 2D to 3D (that faded into obscurity)":

    Thanks to René for the tip!

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    1949

    Catalan's Periodic System/Sistema Periodico Ampliado

    Two versions of Catalan's Periodic System/Sistema Periodico Ampliado. The first from C.E. Moore 1949, Atomic Energy Levels, National Bureau of Standards, Circular no. 467, Washington DC, vol. 1, table 25 (1949) and the second as referenced here: http://www.miguelcatalan.net/pdfs/bibliografia/biblio09.pdf.

    Click on either image to enlarge:

    Thanks to René for the tip!

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    1950

    McCutchon's Simplified Periodic Classification of the Elements

    McCutchon KB, A simplified periodic classification of the elements, Journal of Chemical Education, vol. 27, no. 1, pp. 17–19 (1950)

    This 3-dimensional table has two double-sided flaps attached. The top flap is the f bock. Under that is the d block.

    The superscripts denote the number of d electrons an element has. Thus, La1 is shown as being an f1 element. But it has a 1 superscript, meaning that the f electron count is reduced by 1 and the d electron count is 1.

    René Vernon writes:

    "On group 3, McCutchon cryptically says: The proposed arrangement brings out certain known facts about the tertiary elements which are rarely shown by other arrangements. For example, it suggests, correctly, that the resemblance between yttrium and lutecium is greater than that between yttrium and lanthanum. It classifies lanthanum but not lutecium as a rare earth, in accordance with their chemical properties (which also contradict spectrographic evidence at this point). It also demonstrates the tetravalence of both cerium and thorium, and that thorium and protactinium show a resemblance in chemical properties to zirconium and niobium, as well as to hafnium and tantalum."

    I say "cryptically" because McCutchon presents no further evidence in support of his assertion that the resemblance between Y and Lu is greater than between Y and La. He may have had in mind the fact that Lu is more often found in ores of Y than is the case for La... and I don't understand his reference to spectrographic evidence.





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    1950

    Sidgwick's Periodic Classification (Mendeleeff)

    From N.V. Sidgwick, Chemical Elements and Their Compounds, vol. 1, Oxford University, London, p. xxviii (1950).

    René Vernon writes:

    "In this curious table the Lanthanides are located in group IIIA while the Actinides have been fragmented.

    Instead:

    • Ac, Th, and Pa are located in groups IIIA, IVA and VA under Lu, Hf, and Ta, respectively
    • The uranides, U, Np, Pu, Am, and Cm, are located in group VIA, under W."

    Sidgwick writes:

    "This subgroup (VIA) consists of Cr, Mo, W, and U, to which the 'uranide' elements, Np, Pu, Am, and Cm (which might be assigned to any Group from III to VI) must now be added." (p. 998)

    "...the trans-uranium elements 93–6... for the first time give clear evidence of the opening of the 'second rare earth series', the 'uranides', through the expansion of the fifth quantum group from 18 towards 32." (p. 1069)

    "The question whether the fifth quantum group of electrons which is completed up to 18 in gold begins to expand towards 32, as the fourth does in cerium, has now been settled by the chemical properties of these newly discovered elements. In the Ln the beginning of the expansion is marked by the main valency becoming and remaining 3. With these later elements of the seventh period there is scarcely any sign of valencies other than those of the group until we come to uranium... Up to and including uranium, the group valency is always the stablest, but beyond this no further rise of valency occurs, such as we find in rhenium and osmium. Hence the point of departure of the new series of structures (corresponding to lanthanum in the first series) is obviously uranium, and the series should be called the uranides. (p. 1092):

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    1952

    Hakala's Periodic Law in Mathematical Form

    Reino Hakala published a paper, The Periodic Law in Mathematical Form, J.Phys.Chem., 1952, 56(2) 178-181. It is argued that: "Janet's [left-step] best meets these requirements".

    Thanks to René for the tip!

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    1952

    Coryell's Periodic Table in Long Form

    Charles D. Coryell The periodic table: The 6d-5f mixed transition group, J. Chem. Educ., vol. 29, no. 2, pp. 62–64 1952.

    Coryell (1912–1971), was an American chemist involved in the discovery of promethium.

    René Vernon writes:

    "In Coryell's table, just two elements are shown as having two solid 'tie lines':

    Yttrium: to La-Ac and to Lu-Ac

    Silicon: to Ti-Zr-Hf and to Ge-Sn-Pb.

    "These days Ti-Zr-Hf-Rf is deemed to make-up group 4 (rightly so given group 4 is the first to exhibit characteristic transition metal properties) whereas C-Si-Ge-Sn-Pb-Fl is deemed to make-up group 14.

    The solid tie lines Coryell shows between Hf-Th, Ta-Pa, and W-U would now be rendered in broken form.

    If Coryell's table was mapped to a 32- or 18-column form, group 3 would presumably be shown as bifurcating after Y.

    The circle around indium is possibly a typo(?): indium has two stable isotopes, In-113 (4.29%) & In-115 (95.71%)... actually, In-155 has a half-life of 4.4x1014 years."

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    1956

    Remy's Long Period Form Periodic Table

    From H. Remy's 1956, Treatise on Inorganic Chemistry, Vol. 1, (Introduction and main groups of the periodic table), Elsevier, Amsterdam, p. 4, is what Remy calls a "Long-Period Form of the Natural System of the Elements".

    This is a semi-lanthanide/actinide formulation, with Th-Pa-U shown as 6d metals, and the remaining actinides (Np, etc.) shown as transuranic counterparts to Pm, etc. The layout of Remy's table was based on ideas by Haissinsky in competition with Seaborg's formulation of 1945.

    Thanks to René for the tip!

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    1956

    Walker & Curthoys' New periodic Table Based of Stability of Atomic Orbitals

    By W. R. Walker and G. C. Curthoys, A new periodic table based on the energy sequence of atomic orbitals, J. Chem. Educ., 1956, 33 (2), p 69.

    The abstract states:

    "Since the theory of atomic and molecular orbitals has proven to be of such value in interpreting the data of inorganic chemistry, it is hoped that a new periodic table based on the energy sequence of atomic orbitals will be an aid to the further systematizing of chemical knowledge."

    Thanks to René for the tip!

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    1957

    Laubengayer's Long Periodic Table

    From A.W. Laubengayer, General Chemistry, revised ed., Holt, Reinhart and Winston, New York (1957).

    René Vernon writes:

    "In this busy table the author appears to show three of each of groups I to VII (e.g group I; group IA; group IB) and one group VIII, and one group 0, for a total of 23 groups and subgroups."

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    1960

    International Rectifier Corporation Periodic Table

    International Rectifier Corporation was an American power management technology company manufacturing analog and mixed-signal ICs, advanced circuit devices, integrated power systems, and high-performance integrated components for computing. It is now part of Infineon Technologies.

    The periodic table below was produced in the late 1950s to early 1960s. The earliest version we can find on the web dates from 1960.

    Click to enlarge.

    Thanks to René for the tip!

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    1963

    Bedreag's Système Physique Des Éléments

    From Le Journal De Physique Et Le Radium, 24, pp27 (1963).

    After a short historical account of the evolution of the periodic system Bedreag analyses some properties of various groups of elements: density, spectra, ionic radii, ionization potentials and so on, arguments are given in favour of the division of the transuranic elements into "uranides" and "curides".

    Thanks to René for the tip!

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    1964

    Haward's Periodic Table

    Roger Hayward created this periodic table for the book: Pauling & Hayward, p4, The Architecture of Molecules, W H Freeman and Company, San Francisco (1964).

    From The Pauling Blog:

    "By the end of the 1950s, Roger Hayward had retired from his professional work as an architect at the same time that his career as an illustrator was reaching its peak. Hayward signed a contract in the early 1960s that helped to solidify his position as a technical artist. The contract that Hayward signed was with W.H. Freeman & Company, a San Francisco-based publishing house that rose out of relative obscurity primarily by publishing Linus Pauling's hugely popular textbook, General Chemistry."

    Thanks to René for the tip!

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    1969

    Dash's Quantum Table of the Periodic System of Elements

    Harriman H. Dash, A quantum table of the periodic system of elementsInternational Journal of Quantum Chemistry, vol. 3, no. S3A, supplement: Proceedings of the International Symposium on Atomic, Molecular, and Solid?state Theory and Quantum Biology, 13/18 January 1969, pp. 335–340.

    The abstract reads:

    "The shortcomings of the long form of the periodic table of the chemical elements and the evident need for updating this format are briefly reviewed. To the question 'what format?' quantum physics provides an unequivocal answer. The foundations for the design of a quantum table are outlined. These are based on the principal quantum number as derived from the Schroedinger wave equation, the law of second order constant energy differences, and the coulomb–momentum interaction. These concepts are all combined into a single format which optimally and explicitly relates periodicity to atomic structure and the physical, chemical, and biological properties of the elements. This relationship emphasizes the unity and universality of all sciences."

    Thanks to René for the tip!

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    1969

    Mendeleevian Conference, Periodicity and Symmetries in the Elementary Structure of Matter

    Atti del Convegno mendeleeviano : periodicità e simmetrie nella struttura elementare della materia : Torino-Roma, 15-21 settembre 1969 / [editor M. Verde] Torino : Accademia delle Scienze di Torino ; Roma : Accademia Nazionale dei Lincei, 1971 VIII, 460 p.

    Google Translate: Proceedings of the Mendeleevian Conference: periodicity and symmetries in the elementary structure of matter: Turin-Rome, 15-21 September 1969 / [editor M. Verde] Turin: Turin Academy of Sciences; Rome: National Academy of the Lincei, 1971 VIII, 460 p.

    From the Internet Archive, the scanned book. Papers are in Italian & English.

    For the 100th Anniversary of Mendeleev's iconic periodic table, a conference was held to look at (review) the elementary structure of matter. The 1960s saw huge developments in particle physics, including the theory of quarks. Papers were presented by many notable scientists including John Archibald Wheeler and the Nobel laureates: Emilio Segrè & Murray Gell-Mann.




    Thanks to René for the tip!

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    1970

    Pauling's "General Chemistry" Periodic Table

    From Linus Pauling's General Chemistry (3rd Ed.). Notice that the noble gases apear twice, at the beginning and the end of each period.

    Thanks to René for the tip!

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    1971

    Clark, John O. E. Periodic Table

    Thanks to René Vernon who found this formulation, and writes:

    "Here's a strange table I found in the following book: Clark Jonh O.E. 1982, Chemistry (The Hamlyn Publishing Group, Feltham, Middlesex) ISBN 0600001245. The colour coding is exasperating. The way the table is laid out is bizarre. The copy I have is a reprint of the original 1971 edition so I have to wonder if the graphic designer was drawing inspiration from the trippy 60s."

    Clock PT

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    1974

    Mazurs' Redrawing of Stedman's Formulation

    An spiral formulation by Mazurs, cited as being after Janet (1928). However, it is actually, it is after Stedman (1947).

    In an article Bull. Hist. Chem., VOLUME 34, Number 2 (2009) O.T. Benfey writes:

    "After we had developed our own [Periodic Snail] spiral design, we found that E. G. Mazurs had published a spiral with a separate protrusion for the lanthanides which, under the image, he misleadingly ascribed to Charles Janet in 1928, the same year that Janet had published a simple circular form also shown by Mazurs. The Mazurs diagram with the lanthanide protrusion was reprinted in [the journal] Chemistry. However, [Philip] Stewart informed me that the Mazurs figure bears no resemblance to the Janet diagram he indicated nor to any other of his designs. Detailed references given a few pages later by Mazurs suggested correctly that the spiral derives from Stedman and is so identified and depicted by van Spronsen. The Mazurs diagram is a mirror image of the Stedman spiral, updated to include elements discovered since 1947." [For references, see the article.]"

    Mazurs (p. 77) writes:

    "Subtype IIIA3–1a Helix on a modified cone. The transition and inner transition elements have special revolutions in the form of loops. This table, originated by Stedman in 1947 is not a successful one."

    Thanks to René for the tip and information!

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    1987

    Step-Pyramid Form of the Periodic Chart

    By Bill (William) Jensen, a Step-Pyramid form of the periodic chart.

    This formulation is an updated version of the charts by Thomsen (1895) and Bohr (1922) with more elements, including placeholders up to 118, electronic configuration lables, etc. Read more on the Science History Institute website.

    Thanks to René for the tip!

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    1987

    Variation of Orbital Radii with Atomic Number

    From Jour. Fac. Sci., Hokkaido Univ., Ser. IV. vol. 22, no. 2, Aug., 1987, pp. 357-385, The Connection Between the Properties of Elements and Compounds; Mineralogical-Crystallochemical Classification of Elements by Alexander A. Godovikov & Yu Hariya.

    The analyses of the variations of the orbital atomic radii values (rorb) with the increase of the atomic number (Z) allow establishment of the following recurring regularities of their change:

    Click image below to enlarge:

    Thanks to René for the tip!

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    1987

    Mineralogical-Crystallochemical Classification of Elements

    From Jour. Fac. Sci., Hokkaido Univ., Ser. IV. vol. 22, no. 2, Aug., 1987, pp. 357-385, The Connection Between the Properties of Elements and Compounds; Mineralogical-Crystallochemical Classification of Elements by Alexander A. Godovikov & Yu Hariya.

    Any mineralogical-crystallochemical classification of elements must provide answers to the following queries:

    1. Which type of compounds certain elements will prefer to form under given conditions of mineral genesis (elementary substance, chalcogenide, oxide, oxysalt, etc.,)
    2. Whether the element will play a role of a cation or anion of a certain valency
    3. Which type of chemical bond the resulting mineral compound will have

    Click images below to enlarge:



    Thanks to René for the tip!

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    1992

    Magarshak & Malinsky's Three Dimensional Periodic Table

    Y. Magarshak & J. Malinsky's Three Dimensional Periodic Table from Nature, 360, 114-115 (1992).

    M&M say:

    "We believe that our three dimensional representation is a useful tool for visualizing properties of chemical elements and is in complete accord with quantum mechanics."

    Thanks to René for the tip!

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    1995

    Klein's Periodic Table of The Elements

    Klein DJ, Similarity and Dissimilarity in Posets, Journal of Mathematical Chemistry, 18(2), 321–348 (342) (1995)

    The relevance of partially ordered sets (or posets) in a wide diversity of contexts in chemistry is emphasized, and the utility of distance functions (or metrics) on such posets is noted. First a notion of "scale similarity" is introduced to make comparisons within certain so-called "scaled" posets, for which there is formulated natural "comparators", which in turn lead to associated distance functions. Beyond taking note of several chemically relevant examples of these "scaled" posets and their consequent associated similarity measures, a second chemically relevant class of so-called "shifted" posets is similarly developed, with examples. Even further extension of some aspects of the current approach is indicated, and finally the multi-posetic character of chemical periodic law is suggested.

    Thanks to René for the tip!

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    2003

    Two-Amphitheater Pyramid Periodic Table

    From Chemical Education Journal (CEJ), Vol. 7, No. 2

    A Novel Way of Visualization of the Periodic Table of the Elements by Alaa El-Deen Ali Mohamed, Alexandria University, Egypt.

    The author writes:

    "New form of the periodic table of the elements is given in this paper. This form can be seen as two amphitheater pyramids facing each other. The cubes that meet are s-elements (interior) then the p-elements then d-elements and the f-elements at last (exterior). The table can be represented by X-, Y- and Z-axes, where the Z-axis gives the number of the period that the element occupies. The table can be modeled by colored cubes helping in introducing the periodic table to the pupils early in the primary education."

    Thanks to René for the tip!

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    2004

    Classroom Kids Periodic Table

    From a paper by René Vernon, a drawing of the elements as classroom personality kids, drawing by Richard Thompson 1957-2016.

    From a National Geographic coffee table book: Curt Suplee, The New Everyday Science Explained, National Geographic Society, Washington DC, p. 130 (2004). The undated credit is given to Richard Thompson.

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    2007

    Mechanical Engineer's Periodic Table

    Avallone EA, Baumeister T & Sadegh AM (eds) 2007, Marks' Standard Handbook for Mechanical Engineers, 11th ed., McGraw-Hill, New York, p. 6-6. Click here for a larger version.

    This mech eng PT has a couple of odd features: hydrogen is in Group 17 above fluorine and the lanthanides are split:

    Thanks to René for the tip!

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    2007

    Bent & Weinhold's 2D/3D Periodic Tables

    From a paper by Henry Bent & Frank Weinhold, J. Chem. Educ., 2007, 84, 7, 1145 and here. The authors write in the abstract:

    "The periodic table epitomizes chemistry, and evolving representations of chemical periodicity should reflect the ongoing advances in chemical understanding. In this respect, the traditional Mendeleev-style table appears sub-optimal for describing a variety of important higher-order periodicity patterns that have become apparent in the post-Mendeleevian quantal era. In this paper we analyze the rigorous mathematical origins of chemical periodicity in terms of the quantal nodal features of atomic valence orbitals, and we propose a variety of alternative 2D/3D display symbols, tables, and models.":

    Thanks to René for the tip!

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    2011

    Tresvyatskii's Periodic Table

    Powder Metallurgy and Metal Ceramics, Vol. 49, Nos. 9-10, 2011:

    The paper published below represents Tresvyatskii's fundamental study. It establishes the interrelation between the ionization potential and place of an element in the periodic table. Oxides with a certain composition may form only when an element is ionized to the needed degree. Hence, the ionization potential of elements is an important parameter that governs the formation of an oxide. In this regard, the dependence of the ionization potential on the place of an element in the periodic table is of paramount importance. The role of the ionization potential in the hightemperature chemistry of oxide compounds, which underlies modern oxide materials science, is especially significant. The paper is published in Tresvyatskii's original version.

    René Vernon adds:

    A depiction of the short-form table, showing some clever thinking:

    • The reversal in atomic number order of Np to Am
    • The return of the curides
    • The placement of the Ln and the curides alongside the main table
    • The assignment of the Ln and An to groups
    • Triple periodicity among the Ln and heavy An

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    2017

    Restrepo's Similarity Landscape

    Building Classes of Similar Chemical Elements from Binary Compounds and Their Stoichiometries by Guillermo Restrepo, Chapter 5 from: Elements Old and New: Discoveries, Developments, Challenges, and Environmental Implications p 95-110.

    From the abstract:

    Similarity is one of the key concepts of the periodic table, which was historically addressed by assessing the resemblance of chemical elements through that of their compounds. A contemporary approach to the similarity among elements is through quantum chemistry, based on the resemblance of the electronic properties of the atoms involved. In spite of having two approaches, the historical one has been almost abandoned and the quantum chemical oversimplified to free atoms, which are of little interest for chemistry. Here we show that a mathematical and computational historical approach yields well-known chemical similarities of chemical elements when studied through binary compounds and their stoichiometries; these similarities are also in agreement with quantum chemistry results for bound atoms. The results come from the analysis of 4,700 binary compounds of 94 chemical elements through the definition of neighbourhoods for every element that were contrasted producing similarity classes. The method detected classes of elements with different patterns on the periodic table, e.g. vertical similarities as in the alkali metals, horizontal ones as in the 4th-row platinum metals and mixed similarities as in the actinoids with some transition metals. We anticipate the methodology here presented to be a starting point for more temporal and even more detailed studies of the periodic table.

    Lindsay's Periodic Table

    Thanks to René for the tip!

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    2019

    Chemical Bonds, Periodic Table of

    The Max Planck Society (M-P-G, Max-Planck-Gesellschaft) has an article about the hidden structure of the periodic system.

    Guillermo Restrepo, MPI for Mathematics in the Sciences:

    "A periodic table of chemical bonds: Each of the 94 circles with chemical element symbols represents the bond that the respective element forms with an organic residue. The bonds are ordered according to how strongly they are polarized. Where there is a direct arrow connection, the order is clear: Bonds of hydrogen, for example, are more polarized than bonds of boron, phosphorus, and palladium. The same applies to rubidium in comparison to caesium, which has particularly low polarized bonds and is therefore at the bottom of the new periodic table. If there is no direct arrow between two elements, they may still be comparable – if there is a chain of arrows between them. For example, the bonds of oxygen are more polarized than the bonds of bromine. Bonds represented by the same colour have the same binding behaviour and belong to one of the 44 classes.":

    Thanks to René for the tip!

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    2019

    Slightly Different Periodic Table

    The Max Planck Society (M-P-G, Max-Planck-Gesellschaft) has an article about the hidden structure of the periodic system.

    Guillermo Restrepo, MPI for Mathematics in the Sciences:

    "A slightly different periodic table: The table of chemical elements, which goes back to Dmitri Mendeleev and Lothar Meyer, is just one example of how objects – in this case the chemical elements – can be organized in such a system. The researchers from Leipzig illustrate the general structure of a periodic table with this example: The black dots represent the objects ordered by the green arrows. Using a suitable criterion, the objects can be classified into groups (dashed lines) in which the red arrows create a sub-order":

    Thanks to René for the tip!

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    2019

    Group 3 of The Periodic Table

    There are several ways in which the 'common/modern medium form' periodic table are shown with respect to the Group 3 elements and how the f-block is shown. Indeed, there is even some dispute about which elements constitute Group 3.

    There are three general approaches (also see Scerri's take and Thyssen's view):

    Which one is 'better'?

    The general feeling amongst the knowledgeable is that leaving a gap is not an option, so it comes down to:

    Sc, Y, La, Ac     vs.     Sc, Y, Lu, Lr

    René Vernon has looked as the properties of the potential Group 3 elements, including: 1st ionisation energies, densities, ionic radii, electron affinity, melting points & 3rd ionisation energies:

    Upon reviewing the data, René's comment is that: "The net result is that the two options seem inseparable" and he proposes that IUPAC adopt the following periodic table numbering system:

    Professor Sir Martyn Poliakoff's [of the Periodic Videos YouTube channel & Nottiningham University] take on this matter:

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    2019

    Vernon's Oxidation Number Periodic Table

    René Vernon's periodic table showing oxidation number trends.

    René writes:

    Click image to enlarge

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    2020

    Annotated Periodic Table

    From René Vernon's paper, Vernon, R.E. Organising the metals and nonmetals. Found Chem (2020). https://doi.org/10.1007/s10698-020-09356-6 (in the supplementary material).

    Click image to enlarge.

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    2020

    Vernon's Periodic Table showing the Idealized Solid-State Electron Configurations of the Elements

    René Vernon writes:

    "I've attached a periodic table showing the solid-state electron configurations of the elements. Among other things, it provides a first order explanation as to why elements such as Ln (etc.) like the +3 oxidation state.

    "The table includes two versions of the f-block, the first starting with La-Ac; the second with Ce-Th. The table with the first f-block version has 24 anomalies [with respect to Madelung's rule]; the table with the second f-block version has 10 anomalies.

    "In the case of the Sc-Y-La-Ac form, I wonder if such a solid-state table is more relevant these days than a table based on gas phase configurations, which has about 20 anomalous configurations.

    "Partly we use gas phase configurations since, as Eric Scerri mentioned to me elsewhere, configurations were first obtained (~100 years ago?) from spectroscopy, and this field primarily deals with gas phase atoms. That said, are gas phase configurations still so relevant these days – for this purpose – given the importance of solid-state physics?

    "I've never been able to find a periodic table of solid-state electron configurations. Perhaps that has something to do with it? Then again, surely I'm not the first person to have drawn one of these?"

    Click image below to enlarge:

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    2020

    Correlation of Electron Affinity (F) with Elemental Orbital Radii (rorb)

    From Jour. Fac. Sci., Hokkaido Univ., Ser. IV. vol. 22, no. 2, Aug., 1987, pp. 357-385, The Connection Between the Properties of Elements and Compounds; Mineralogical-Crystallochemical Classification of Elements by Alexander A. Godovikov & Yu Hariya and expanded by René Vernon who writes.

    René Vernon writes:

    I was delighted to read about two properties that account for nearly everything seen in the periodic table.

    Two properties
    While researching double periodicity, I happened upon an obscure article, which simply correlates electron affinity with orbital radius, and in so doing reproduces the broad contours of the periodic table. Having never thought much about the value or significance of EA, and its absence of easily discernible trends, I was suitably astonished. The authors left out the Ln and An and stopped at Bi. They were sitting on a gold mine but provided no further analysis.

    Development
    I added the data up to Lr, updated the EA values, and have redrawn their graph. It is a thing of beauty and wonderment in its simplest sufficient complexity and its return on investment. I've appended 39 observations, covering all 103 elements.

    Observations

    Conclusion
    So there it is, just two properties account for nearly everything.

    Click images below to enlarge:


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    2020

    Vernon's Constellation of Electronegativity

    René Vernon has created a "Constellation of Electronegativity" by plotting Electronegativity against Elemental Orbital Radii (rorb)

    Observations on the EN plot:

      1. The results are similar to the orbital radii x EA plot, although not quite as clear, including being more crowded
      2. Very good correspondence with natural categories
      3. Largely linear trends seen along groups 1-2, 17 and 15-18 (Ne-Rn)
      4. First row anomaly seen for He (or maybe not since it lines up with the rest of group 2)
      5. For group 13, the whole group is anomalous
      6. For group 14 , the whole group is anomalous no doubt due to the scandide contraction impacting Ge and the double whammy of the lanthanide and 5d contraction impacting Pb
      7. F and O are the most corrosive of the corrosive nonmetals
      8. The rest of the corrosive nonmetals (Cl, Br and I) are nicely aligned with F
      9. The intermediate nonmetals (IM) occupy a trapezium
      10. Iodine almost falls into the IM trapezium
      11. The metalloids occupy a diamond, along with Hg; Po is just inside; At a little outside
      12. Rn is metallic enough to show cationic behaviour and falls into the metalloid diamond
      13. Pd is located among the nonmetals
      14. The proximity of H to Pd is again (coincidentally?) curious given the latter's capacity to adsorb the former
      15. The post-transition metals occupy a narrow strip overlapping the base of the refractory metal parallelogram
      16. Curiously, Zn, Cd, and Hg (a bit stand-off-ish) are collocated with Be, and relatively distant from the PTM and the TM proper
      17. The ostensibly noble metals occupy an oval; curiously, W is found here; Ag is anomalous given its greater reactivity; Cu, as a coinage metal, is a little further away
      18. Au and Pt are nearest to the halogen line
      19. The ferromagnetic metals (Fe-Co-Ni) are colocated
      20. The refractory metals, Nb, Ta, Mo, W and Re are in a parallelogram, along with Cr and V; Tc is included here too
      21. Indium is the central element of the periodic table in terms of mean orbital radius and EN; Tc is next as per the EA chart
      22. The reversal of He compared to the rest of the NG reflects #24
      23. All of the Ln and An fall into an oval of basicity, bar Lr
      24. The reversal of the positions of Fr and Cs is consistent with Cs being the most electronegative metal
      25. A similar, weaker pattern is seen with Ba and Ra. 

    Click to enlarge:

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    What is the Periodic Table Showing? Periodicity

    © Mark R. Leach Ph.D. 1999 –


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