Talk:History of the periodic table/Archive 1

Questions about history: From numbered sequence of elements to number of protons

 * (Moved questions from Talk:Helium)


 * When was helium identified as the element with atomic number 2 in the periodic table of elements?

This periodic table from 1891 (Image:Mendeleev Table 5th II.jpg) does not list helium, nor does it leave an empty slot for element number 2. The result is that all elements beyond hydrogen are given an "atomic number" one less than the number of protons. -- Petri Krohn 02:26, 29 November 2006 (UTC)

In fact the table is missing all noble gases, so there are other gaps in the table. Question number #2 is thus:


 * When were the noble gases added to the periodic table?

-- Petri Krohn 03:07, 29 November 2006 (UTC)

Helium was discovered about 30 years later, if I recall. I don't feel like looking it up, but it does mention it in Helium's article. It was discovered as part of the sun. Most of the other noble gases were found sometime later, as they are quite difficult to find, seeing as they are almost completely stable and do not react.

Importance
I'd like to set the importance of this article. I'll start it off at 'High' but feel free to discuss. -DjD- 13:08, 8 April 2007 (UTC)

Credit Revert War
Will you two knock it off? You're not getting anywhere. How about discussing here out in the open for others to comment on? -DjD- 01:25, 7 July 2007 (UTC)

WikiProject class rating
This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 09:54, 10 November 2007 (UTC)

Organizing / Cleanup
I'd like to see an effort to significantly cleanup this article. Currently the article doesn't really flow:
 * In Beginning
 * List a Couple People
 * 1st Table
 * List a Couple More People

I'm thinking of structuring it more like this:
 * Chronological Overview
 * Element Discoveries (elements that impacted the development of the table)
 * Important People

Anyone have an opinion on this? Do you think this would help? -DjD- 03:21, 9 April 2007 (UTC)

I agree this current article is in a bad state. The scientific history is poor too and sweeps past important chemists. I'm going to set up a Chronological Overview in the next few weeks so that I have something to work off when reforming the article. -- ScepticalChymist (talk) 13:11, 2 January 2008 (UTC)

Broken Link
refrence 9 about the larges table doesn't link correctly, i dont have the time but can someone fix please —Preceding unsigned comment added by 220.253.85.155 (talk) 07:51, 31 January 2008 (UTC)
 * Fixed. DMacks (talk) 18:58, 31 January 2008 (UTC)

Mendeleev or Mendeleyev
Can someone make this article consistent by deciding whether to spell Mendeleev as Mendeleev or Mendeleyev —Preceding unsigned comment added by Hubew (talk • contribs) 10:13, 4 August 2008 (UTC)

Cleanup done
I've done a major amount of cleanup on this article (changed from from this to this), but I do recognize that some small work remains within the sections. This would be best done by an expert, I think, I just wanted to give this article a half-way decent lead and some better structure. Un sch  ool  00:01, 29 December 2008 (UTC)

Atomic weight or atomic mass - in 1869?
Today's edits by 97.114.35.151 have systematically replaced atomic weight by atomic mass in the section on Mendeleev. I believe that this is historically incorrect, since Mendeleev like all 19th-century chemists referred to atomic weight which is related to weights determined with laboratory balances. References to atomic mass would probably have started with J.J. Thomson's mass spectrometry (from 1913), in which the forces are independent of gravity. Even then, I think most chemists continued to treat mass and weight as practical synonyms until the 1960s, when the space program made all scientists more aware that terrestrial gravity (g) is not a universal constant.

I propose therefore to reverse these edits and use atomic weight systematically in this historical article, except perhaps for a parenthetical mention after the first "atomic weight" to say "(now known as atomic mass)". Comments? Dirac66 (talk) 03:05, 20 February 2009 (UTC)
 * Sounds reasonable to me. Atomic weight makes it clear that this term refers to measured values of samples, which is what was being done at the time, whereas Atomic mass is about atoms as individual isotopes and collections of subatomic-particles. Mendeleev's own table is clearly bulk-sample natural-abundance-weighted averages (Cl is 35½ and Br is 80). DMacks (talk) 03:17, 20 February 2009 (UTC)
 * Yes, and this table also shows that Mendeleev was still using "atomic weight" in 1891, at least in the English translation. Also you are correct that "atomic mass" now refers to individual isotopes, so we should say that Mendeleev's "atomic weight" (quoted in grams in the 19th century) is now known as "molar mass".  Dirac66 (talk) 14:17, 20 February 2009 (UTC)

Bold
Regarding the partial revert by DMacks, "partial rv: MOS says to bold title-phrase in first sentence". I'm not about to make a fuss but my edit was justified. Here's what the MOS actually says:

"However, if the title of a page is descriptive it does not need to appear verbatim in the main text, and even if it does it should not be in boldface."

Descriptions like "History of the periodic table" should be unbold. J IM ptalk·cont 23:04, 7 May 2009 (UTC)
 * Interesting! Haven't read that section closely in a while:( Feel free to rv me if you like. DMacks (talk) 23:41, 7 May 2009 (UTC)

Sugestion: to add a TIME LINE ILLUSTRATION
SEE UP illustrations for history of the discoveries.

It is OK?? Please, comment here... Ok, was my sugestion, I do IT.

--Krauss (talk) 22:52, 2 April 2010 (UTC)

Transition Elements
When were the d-block transition elements first pulled out and placed in the center of the table rather than crammed in with the other elements in the Roman numeral columns? Who did this, or what publishing company first made a table such as this? I would think this was a rather important step in the history of the table. — Parsa (talk) 00:20, 7 October 2011 (UTC)
 * I would like to know this too!--feline1 (talk) 12:52, 4 April 2012 (UTC)
 * Would this website help? Double sharp (talk) 04:20, 6 April 2012 (UTC)

as cultural icon?
The whole section titled, "The periodic table as a cultural icon" is un-sourced, un-verified, un-encyclopedic, un-scholarly nonsense. For starters, if you want to claim that an object is a cultural icon then you might want to consider whose culture it is an icon of. Designed by a Russian but used by scientists and students all over the world it is not specific to any given culture or group of cultures. You might legitimately claim it is or could be viewed as a symbol of science, but you would need a source for that otherwise it's just POV. I am copying here (below) the claim about the biggest periodic table because if you can find a source for that claim it would be a useful addition to the article, but I have deleted the rest of the section for the reasons given above.
 * In 1998, a 35-by-65 foot (10x20 m) periodic table was constructed at the Science Museum of Virginia and is the largest Periodic Table in the world (by size).

 Cottonshirt  τ   05:41, 14 October 2012 (UTC)

New structure for the article

 * 1) Discovering elements: "dicoveries table" illustration (sugest centered jpg)
 * 2) In the beginning
 * (Before 1800)
 * 1) Antoine-Laurent de Lavoisier
 * 2) 1800-1849
 * 3) John Dalton, atomic weights, 1805
 * 4) Amedeo Avogadro, Avogadro's law, 1811
 * 5) Johann Wolfgang Döbereiner, triads of Döbereiner, 1817, 1829
 * 6) Leopold Gmelin, Table of the 55 elements of Leopold Gmelin, 1843
 * ... Not published discoveries...?
 * 1) 1850-1899
 * 2) Adolph Strecker, Table of 20 elements, 1859  — Preceding unsigned comment added by 128.69.77.224 (talk) 05:19, 13 October 2013 (UTC)
 * 3) Alexandre-Emile Béguyer de Chancourtois
 * 4) John Newlands
 * 5) The first periodic table: Julius Lothar Meyer, 1862, 1864, 1870
 * 6) 1900-1949
 * 7) Henry Moseley
 * 8) Glenn T. Seaborg
 * 9) Charles Janet, Adomah periodic table, 1928
 * 10) 1950-1999
 * 11) Vsevolod Klechkovsky  — Preceding unsigned comment added by 128.69.77.224 (talk) 05:23, 13 October 2013 (UTC)
 * 12) IUPAC, 1989
 * 13) 2000-nowadays
 * 14) IUPAC, 2012, 2013
 * 15) Makeyev A.K., The matrix of automatisms of matter (MAM), as for the Meyer-&-Janet’s periodic table of elements, was supplemented it and modified to the modern extended form to display the elements of vacuum and atomic levels of matter, 2000, 2010, 2013

--Krauss (talk) 19:20, 9 April 2008 (UTC)


 * Surely it would make sense to make a distinction between elements known and used by mankind from prehistoric times (e.g. gold, silver, copper, tin, carbon) and those discovered in the mediaeval/alchemical period (such as phosphorus)? --feline1 (talk) 12:38, 4 April 2012 (UTC)

Original table?
Could someone add Mendeleev's original table (or provide a link)? The image shown is (as noted) not the original one, since it contains the three predicted elements. Also, why would he have described scandium as "eka-boron"? The latter is aluminum which was discovered much earlier.--Roentgenium111 (talk) 15:41, 19 March 2008 (UTC)


 * Boron and scandium are both in group 3 in the old and nearly forgotten short form of the periodic table. You can see a depiction of if here: (Mendeleev placed boron in what would now be group 3A in this figure, in the same group as scandium, instead of 3B, which is the same group as aluminum). --Itub (talk) 18:50, 19 March 2008 (UTC)


 * Thanks for the answer. But the link doesn't work for me.--Roentgenium111 (talk) 21:03, 12 May 2008 (UTC)


 * Strange that the link doesn't work anymore. Anyway, here are a couple of links to short periodic tables on britannica.com:, . Plus, here's a version from a translation of Mendeleev's book that I found on Commons, so we could use it for this article: --Itub (talk) 09:12, 13 May 2008 (UTC)



So why don't we use this?
Since this is Mendeleev's original table in 1869 or 1871, why don't we use it in the article instead of the 1891 version which looks more like a list without any columns of elements? I propose to delete the 1891 version and use this instead. And also in the article on Mendeleev. Dirac66 (talk) 01:58, 27 April 2010 (UTC)

OK, I have inserted this 1869 table. There are some technical problems remaining: (1)the superscripts in the column headings are very hard to read, even at magnification to 800 px which is full column width. Presumably the oxide formulas are R2O, RO, R2O3 etc. (2) I wrote a caption Mendeleev's 1869 periodic table, but it does not show in the article. What did I forget?

Also I am not sure whether to delete the 1891 "table" as it is more a list of elements. I'll leave this decision to others. Dirac66 (talk) 20:39, 28 April 2010 (UTC)


 * The table I referred to as 1869 in the above comment was really the 1871 table with 8 columns, and I noticed today that it had been replaced (on 3 Jan 2014) by the 1869 table which is a list without columns. Given the importance of Mendeleev, I think we should show both the 1869 list which was his first published table, and also the 1871 table which introduced the columnar presentation which is the basis of the modern 18-column presentation. Therefore I have restored the 1871 table to the article, and kept the 1869 list as well. They are sufficiently different so that this is not really duplication. Dirac66 (talk) 21:40, 16 February 2014 (UTC)

Julius Lothar Meyer was first who built the periodic table of elements
German doctor, a chemist and physicist Julius Lothar von Meyer has the priority in the development of the Periodic Table. He has published articles on his classification table of the elements in a horizontal form (1862, 1864) and vertical form (1870), where the series of periods are properly terminated by an element of the earth metal group. A French scientist Charles Janet has published a detailed edition of the periodic table (Adomah periodic table) by Meyer (1928), which clearly displays the logical manifestation of all the elements of the substance of physical and chemical properties according to their location, to be counted up from the end to the beginning of their periods. As for the Meyer-&-Janet’s periodic table of elements, Russian doctor and freelance multidisciplinare researcher and inventor Makeyev Alexander Konstantsinovich to supplemented it and modified to the modern extended form to display the elements of vacuum and atomic levels of matter. This table may be supplemented by elements of molecular, biological, intellectual, information, technical and cosmic levels of matter. That is why Makeyev Alexander Konstantsinovich have named the table: The matrix of automatism of matter [1].

Facts about periodic table
While Dmitri Mendeleev is most often cited as the inventor of the modern periodic table, his table was just the first to gain scientific credibility ​and not the first table that organized the elements according to periodic properties. There are 90 elements on the periodic table that occur in nature. All of the other elements are strictly man-made. Technetium was the first element to be made artificially. The International Union of Pure Applied Chemistry, IUPAC, revises the periodic table as new data becomes available. At the time of this writing, the most recent version of the periodic table was approved 19 February 2010. The rows of the periodic table are called periods. An element's period number is the highest unexcited energy level for an electron of that element. Columns of elements help to distinguish groups in the periodic table. Elements within a group share several common properties and often have the same outer electron arrangement. Most of the elements on the periodic table are metals. The alkali metals, alkaline earths, basic metals, transition metals, lanthanides and actinides all are groups of metals. The present periodic table has room for 118 elements. Elements aren't discovered or created in order of atomic number. Scientists are working on creating and verifying element 120, which will change the appearance of the table.

Although you might expect atoms of an element to get larger as their atomic number increases, this does not always occur because the size of an atom is determined by the diameter of its electron shell. In fact, element atoms usually decrease in size as you move from left to right across a row or period. The main difference between the modern periodic table and Mendeleev's periodic table is that Mendeleev's table arranged the elements in order of increasing atomic weight while the modern table orders the elements by increasing atomic number. Durmstrang2002 (talk) 07:46, 5 November 2017 (UTC)

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Shouldn't there be a mention of Jöns_Jacob_Berzelius 1818?
See Jöns_Jacob_Berzelius, which mentions his 1818 publishing of atomic weights. This lacked the essential organization that makes the periodic table what it is today, but may have been one of the significant predecessors of the periodic table, given that it "provided evidence in favour of the atomic theory proposed by John Dalton" (quote from that wiki article). ToolmakerSteve (talk) 12:22, 12 November 2018 (UTC)
 * I'd say yes. Eric Scerri (PT story & significance) mentions him contributing:
 * Introducing the letter symbols instead of alchemical symbols like &#x263F; for mercury (1813)
 * Improve atomic weights, abandoning Prout's round-to-integer principle, still influential when Mendeleev started working with them (1850+)
 * Arriving at correct formulas for H2O, NH3, HCl, H2S, also heavily related to determining atomic weights (of course)
 * Using sub/superscripts in formula as we still do (albeit writing H2O not H2O)
 * -DePiep (talk) 16:17, 13 November 2018 (UTC)

Lede image
At the moment, the lede has this (single, composed) image. This image has some flaws. Too many (five) variants. The lines of development do not show (too complicated to show?). The iconic 1871 (or 1869 maybe) Mendeleevian version is missing. Note that this lede images are just an illustration, not a completeness or definition of the PT development.

I propose to use these images:
 * 1. An early image listing elements (away from earth-water-air-fire concept). File:Dalton, 1806
 * 2. Mendeleev's 1871 true PT version File:M 1871.
 * 3. A global modern version in black-and-white. File:PT in b/w (to be updated) done

That's a maximum of three, small-sized, well-captioned. All b/w to keep attention to structure. -DePiep (talk) 10:22, 11 December 2018 (UTC)
 * I will make a live proposal one of these days. -DePiep (talk) 09:35, 19 December 2018 (UTC)
 * Done. -DePiep (talk) 22:13, 29 December 2018 (UTC)
 * If a fourth image would be acceptable, I'd add the early spiral one (vis tellurique, 1862). Sure I'd like to reduce inter-image space (margins). -DePiep (talk) 00:09, 30 December 2018 (UTC)

Mendeleev - Meyer
The article seems to have a POV issue concerning Mendeleev's and Meyer's contribution.

"(Mendeleev) is nevertheless generally given sole credit for its development" (vs e.g. In 1882, both Meyer and Mendeleev received the Davy Medal from the Royal Society in recognition of their work on the Periodic Law.), any web search brings lots of results such as https://www.sciencehistory.org/historical-profile/julius-lothar-meyer-and-dmitri-ivanovich-mendeleev

"Meyer's table only included twenty-eight elements, which were not classified by atomic weight, but by valence, and he never reached the idea of predicting new elements and correcting atomic weights." (Meyer's table was classified by atomic weight, yet when this contradicted the periodicity of chemical properties he correctly gave priority to valence instead to minor differences in atomic weight. He predicted the element missing between Si and Sn, i.e. Ge), "Unknown to Mendeleev, a German chemist, Lothar Meyer, was also working on a periodic table." unlikely: they met at least here, Karlsruhe Congress, where the very topics leading to the modern PSE were discussed, according to the Meyer article Mendeleev sent Meyer a "preprint", implying he was aware of him working in this field, last not least Mendeleev would have been a very unusual scientist, ignoring the development in his field for years which itself is contradicted by him attending conferences.

"Meyer and Mendeleev are considered by some historians of science to be the co-creators of the periodic table, but Mendeleev's accurate prediction of the qualities of undiscovered elements enables him to have the larger share of the credit." certainly needs a citation. Contradicted at least by the Royal Society and the prediction of Ge, see above.

Meyer's table of 1864 is at first sight recognizable as a version of the PSE attributing correctly the main-group elements of group I,II,IV,V,VI and VII, the first version giving elements in the very same order we still use today. If you look at Mendeleev's 1st version of 1869, https://en.wikipedia.org/wiki/Periodic_table#/media/File:Mendeleev%27s_1869_periodic_table.svg it includes the transition metal elements and group III but does not resemble the modern arrangement and more seriously, the attribution of elements is wrong in many cases, most strikingly in case of the alkaline earth metals.

I changed the introduction, the Meyer section is essentially replaced by content from Julius Lothar Meyer. I think the article needs more revision than that. -Kawarayaki (talk) 17:33, 1 January 2019 (UTC)

Addendum: deleted "(Mendeleev) was the first scientist to make a periodic table similar to the one used today" marked with {citation needed|reason=There is reason to believe others have created periodic tables that predate Mendeleev's, please provide additional information|date=February 2016} -Kawarayaki (talk) 21:50, 1 January 2019 (UTC)

Period lengths
I notice that Mendeleev had the lengths of the periods wrong. Can someone tell us when it was realized that the period lengths were actually 8, 8, 18, 18, 32, 32? Eric Kvaalen (talk) 14:12, 19 March 2019 (UTC)


 * Well, Mendeleev had them right and most of the elements in PT 1871 are in the same group (column) ever since, including gap columns.


 * Point is, M. used "Reihe" (German, Row) not "Periods". With M., a Reihe had valence (oxidation state) columns I–VIII, column VIII having three elements.


 * Later (1930?), M.'s table was reordered: two Reihen made into one period; their Roman valence number kept and an "A" or "B" is added (See Group names, "old IUPAC, Europe" name form). The A and B still appear in the older Tables (&lt;2010?, see below on group numbering), and the VIII column has three elements *1. This new Periodic Table form was called the "long form". The translation, and number of elements with Mendeleev; no noble gases back then):


 * Reihe 1 = period 1 (1 E)*2


 * Reihe 2 = period 2 (7 E)


 * Reihe 3 = period 3 (7 E)


 * Reihe 4 = period 4 (10 E; group labels A)


 * Reihe 5 = period 4 (7 E; group labels B)


 * Reihe 6 = period 5 (10 E; group labels A)


 * Reihe 7 = period 5 (7 E; group labels B)
 * etc., (some detailing trouble enters here, with unknown element placeholders and where the lanthanides start entering)


 * Mendeleev had the numnbers right you mention, since he had these empty cells in the right place. (Reihe 1 only had H and the empty cells; Reihe 2, 3 each had no second "B-Reihe" set = today the empty cells in period 2, 3).


 * Later changes: disciovery of lanthanides and actinides as a separate block introduced the placeholder-symbol (like asterisk) and two rows below the basic table (into the "32" counting). Also, group numbers have been changed into 1–18 without A-B confusion. -DePiep (talk) 17:49, 19 March 2019 (UTC)
 * Actually, A-B is hardly a confusion. If you look at sulfur and chromium in a hexavalent state, you see that the properties of these elements are pretty close, which means even in the periods 3,4, and 5 we have smaller subperiods, where the properties are reproduced with a phase shift of 8. The old division to major and minor subgroups is very instrumental for understanding transition metals chemistry, and by no means it is confusing.--Paul Siebert (talk) 18:36, 19 March 2019 (UTC)


 * The only confusion I had in mind was the difference between European and US/CAS systems of A–B labeling. I.e., confusing not in chemistry but in communication. To the original question, this is quite irrelevant IMO. -DePiep (talk) 18:55, 19 March 2019 (UTC)


 * More details: I have addded the number of elements per Reihe.


 * * 1 group VIII: has three elements, or zero; there is one VIII-group per period not A and B. BTW in the 1871 image a fourth element is in VIII, that is repeated in group I: Cu, Ag, Au. Here I counted them as being in group I not VIII, as modern tables show them.


 * * 2 Noble gases (NG, in extra valence column "0"), were only added in the 1890's, in 1871 noble gases were not known as element.


 * Counting elements per modern period in Mendeleevs PT, and adding an NG (some time mixup then):


 * Period 1: 1 + NG = 2


 * Period 2: 7 + NG = 8


 * Period 3: 7 + NG = 8


 * Period 4: 17 + NG = 18


 * Period 5: 17 + NG = 18


 * Period 6: scattered elements known then, lanthanides not identified as such (Cs, Er, La, U (actn), Th)


 * So here are the numbers User:Eric Kvaalen mentions.


 * Opening with a periodicity of "2" (and only one so) is inconsistent this way, but only here. Janet in his Left Step periodic table has once more reordered the elements, or actually reordered the columns and rows not elements, showing two periods of "2" in top. -DePiep (talk) 07:30, 20 March 2019 (UTC)

Thanks for the reply. But I still say he had the periods wrong. Actually I was thinking of his 1869 table. There we see seven elements in the first column (what we now make a row). As you say, that's because he didn't know about neon or the other noble gases. Then he has a column with eight elements from Mg to Ca (skipping Ar), followed by an element with no name (scandium?) and three elements which don't belong. Then there's a column of 15 rows from Ti to Sr (putting Ni and Co on the same line, and skipping Kr), followed by four out of place elements. Then there's another column of 15 from Zr to Ba (skipping Tc and Xe, putting Rh where Tc should be, and putting "Ur" which I suppose is uranium in place of In). Then he has one more column of 15 from an element with no name (Hf?) to Pb, with several gaps.

His 1871 table seems to have only "periods" of eight, though he puts several elements of each row into group VIII.

I think the answer to my question is that the correct period lengths were understood when Moseley found the atomic numbers around 1914, using X-rays.

Eric Kvaalen (talk) 19:54, 23 March 2019 (UTC)
 * .. What I'd like to repeat is: even in 1869 (or 1871), there was no error in the concept. The number list you asked about,  ([2, 2] I added), can be pointed out in Mendeleev's earliest tables, systematically! Later discoveries (noble gases, lanthanides, actinides) did not break the concept. -DePiep (talk) 20:10, 23 March 2019 (UTC)
 * Fair enough. The 1869 periodic table does not show period lengths. Will have to take an other look at that one. And indeed they were understood only much later. Which, of course, is a feature of quality in the original 1871 design, not an omission! -DePiep (talk) 15:22, 24 March 2019 (UTC)

Structure of the article for the future rewriting
Back in December,, , and I agreed we would rewrite the article and bring it to the FA status. This section is to be dedicated to planning on how this will happen. I have made some planning back in December. I will now quickly draft out the general idea; the resulting draft will be a subject to discussion, questioning, amending, etc.

General outline

 * Antiquity to (roughly) Renaissance

At this point, people had very little understanding what elements were. Fire, earth, water, and air, this kind of stuff. Ancient Greece, China, India, the Arabs, Renaissance Europe are all worth mentioning. Maybe other regions of the world (such as Southeast Asia or the Swahili coast, maybe also the Americas) could be mentioned if (and that's quite an if) there's any written source on their concepts. This section will be relatively short.


 * Age of Enlightenment

An idea that is close to what we have today emerges at this point. A few other developments that have been instrumental for later researchers (such as that all element weights were equal to an integer multiplied by that of hydrogen or the concept of conservation of mass) also belong here


 * Attempts to find correlations (1817--1877)

We list here attempts of seeing any here and there, from Doebereiner to Meyer. Mendeleev should not be given any special treatment. It is, after all, only a few years later, when gallium was discovered that Mendeleev's work was all that widely recognized. See also History of aluminium for a prototype.


 * Pre-atomic theory developments (1871--1905?)

Some elements changed positions here and there and new ones kept emerging, the noble gases were discovered at this point, aether still was a thing that even Mendeleev wanted to put at the top of his table, I recall the lanthanides were expelled from the main body of the PT somewhere at this point, maybe something else.
 * The history of the lanthanides in the PT is a bit tricky to describe. I don't think Mendeleev's 1869 or 1871 table listed all the lanthanides known at the time, and they were quite tricky to place in a table as their chemical properties were extremely similar.


 * Atomic theory (1896--1940?)

Radioactivity was discovered and soon enough, it produced a gazillion of new elements which were too numerous to be put in the PT, which led to the concept of isotopes (Greek for "same place"). In general, the atomic theory re-defined the PT in the manner we know today (via protons) and became a major breakthrough in science in general. The history of that should be interesting. Bohr's 118 elements belong here, and the disruption on where the 5f series begins belongs here as well. We could also describe the emergence of the concept of relativity. Also, somewhere at this point the PT gets its most iconic 18-column form
 * Also include how the development of atomic theory led to precise identification of gaps (43, 61, 72, 75) in the PT once it took its well-known form
 * Thoennessen2016 has some useful information on "elements" that were later found to be isotopes.


 * Looking for expansions and the end of the PT (1940?--present)

Here, we look at 20th-century idea of how the extended PT would be structured as well as predictions of where it would end. Elements are now created synthetically, Seaborg suggests his actinide concept and his extension to element 218. Mention Fricke and Pyykko and here as well for PT ordering. For the end of PT bit, there was the simple 173 idea, then there was 137, then many others, none dominant yet. New elements were produced here from scratch, which revealed the island of stability which, in turn, shows just how wrong some theories can be (there was an expectation the PT would end after Z=103 or 104) and just see how far we are from there now.
 * There is some usable content in extended periodic table. We have to describe relativistic effects (breakdown of periodicity, first suggested in Fricke 1971?) and that no consensus exists on placement of undiscovered elements.


 * And most importantly

This is the part that could be easily overlooked but it is hugely important and belongs to this discussion as well. How did the PT become such an iconic symbol of science? When did chemistry classroom begin to have those on their walls? There was recently a very popular and very well-received American TV series which referred to the PT right in its logo; how did things lead to this? This is a story that I don't know too well but this is crucial and we'll need to find this out and from there figure how to spread this information across the article.

That is it. Comments are very welcome.--R8R (talk) 10:54, 12 June 2019 (UTC)

Comments re general outline

 * I'll drop a few comments here and there over the next few days and hopefully gather some information. I can't really start working until Tuesday, though. ComplexRational (talk) 18:12, 16 June 2019 (UTC) (comments added 18:21, 16 June 2019 (UTC))
 * That's fine. I will hardly be very active during this working week myself. However, while adding some information that we will use anyway is absolutely fine, let's not do anything rash before YBG has shared his ideas.--R8R (talk) 21:19, 16 June 2019 (UTC)
 * I'm a bit confused by the fact the mismatch between the date one era ends and the date the subsequent one begins. YBG (talk) 03:26, 18 June 2019 (UTC)
 * It's good you mentioned this because I certainly want to be clear on it. While the article is, in general, chronological, this division comes from the fact that different times in general display different periods which are based on different things, and it's these periods we are focused on. In particular, this helps avoid some mishmash when different concepts are developing at the same time, for instance, the story would be disorderly if it went, "in the 1870s, Mendeleev thought where to put his aether---in 1896, radioactivity was discovered---in 1905, Einstein rendered aether unnecessary (without looking it up, I'm not sure it was that, but for the sake of this argument, please play along)---in 1914, many elements of radioactivity were found to be just few ones."
 * Again, I do recommend checking out history of aluminium, specifically, the chronological overlap between Early industrial production and Electrolytic production and commercialization to see how this works. I'm sure you'll find that this storytelling is desirable. On a similar note, which period of time would you want to speak about if you were to discuss the American Civil War? Presumably it wouldn't be just 1861--1865 because you'd also want to discuss its pretext and consequences. This video, for instance, goes for 1845--1867.
 * I hope this clarifies things. Please let me know if it does.--R8R (talk) 06:43, 18 June 2019 (UTC)
 * Yes, that does clarify the situation. But it rather argues for naming the sections not by the era and year, but rather by the scientific concepts, as is done in history of aluminium. YBG (talk) 21:05, 18 June 2019 (UTC)
 * It certainly does clarify; I agree that the article would flow much better if it is organized by concept. Rereading history of aluminium, I also notice two other patterns (and I'm not sure to what extent we should follow them or if they are even relevant): every section starts with a quote, and there are no subsections. ComplexRational (talk) 21:46, 18 June 2019 (UTC)
 * Re : certainly I didn't mean the section headings to be final, but rather merely to help me explain the general concept to you. I will myself be strongly opposed to putting date ranges in the heading titles. And the actual titles will also be different. Actually, this problem seems very minor to me. It's best to understand what we want to tell. Under what title it will go is absolutely secondary. History of aluminium, which is finally in its final version (sorry for the repetition), only got two of its section titles in the last couple of days. So don't worry too much about it. It's not all that important and can always be improved.
 * So, can I call you in for the support of this original plan for now? As I mentioned, it is subject to further improvement along the way should a need for that arise. If I can, then we could proceed about thinking how who does what, how the article improvement proceeds, and all of that. Seems like ComplexRational is satisfied for the current structure for the time being.
 * Re : no section breaks are no coincidence and I would recommend we do that again. The reason for that is there is no real need to break anything; as you can see, each section in history of aluminium is a coherent wholesome story you read in one go. This seems to me to be great for this specific type of articles (history of X) because this history-related writing, in a certain sense, the most literature work you could possibly find in articles on chemical elements because you actually tell one long story here. (I describe writing an element article in a similar fashion but there, links between different aspects of elements are not obvious until you found them, whereas here you have the general chronology at the very least and the sense of how it really is one story and not many pieces collected together as with element articles.) I think it would be great to repeat that. In contrast, section breaks are needed when various parts of a section are too different, and it is desirable to look for specific subtopics. See, for instance, Hydrogen (basically, any Properties section of any element, with inevitably has atomic properties, macro-quantity properties, isotopes, maybe more). In theory, it could be that we run into the need to separate some specific aspect of a certain period of time. In practice, however, I think we will be able to avoid that and that we should try that as long as it's possible.
 * As for quotes: well, I don't think it's just as necessary. That being said, I do think they'd make a welcome addition. For the most part, history of aluminium had only one quote, the one in which Stalin asks Roosevelt for aluminum saying it will bring him victory. When I found that quote, I thought it was absolutely fantastic for the article because it shows how important aluminum is, and this is something you absolutely want in an article focused on history of aluminum. Quite some time later, I also found Hall's "I'm going for that metal," and I thought it was very catchy and interesting and I wanted to add it. However, I presumed that such a catchy quote could only be there if it were to stand out from a number of more ordinary quotes, and for that reason, I didn't add it for a while until I talked myself into looking for quotes for all sections (which I wasn't sure at the time was a good idea because it seemed like such a big change). In general, I think I found good quotes and everything seems fine to me now. I'm very satisfied with the result. Maybe we could try this again this time. Maybe not. Let's see, it's not the first thing on our to-do list anyway.
 * With all of that being said, I'd like to proceed to exact planning and scheming on how work will go. Can we; any objections?--R8R (talk) 21:35, 19 June 2019 (UTC)
 * Ready to go. ComplexRational (talk) 22:23, 19 June 2019 (UTC)
 * Yea, I'll accept the outline. But one caveat: as I look at it, the first thing that comes to mind is "what other outline could you possibly use?" Which probably means that either (a) it is a very good outline; or (more likely) that I've not thought enough about it (or don't know enough about it) to think of any alternatives. YBG (talk) 22:43, 19 June 2019 (UTC)

Current TOC
1 Antiquity to the 18th century 1.1 Hennig Brand 1.2 Antoine-Laurent de Lavoisier 2 19th century 2.1 William Prout 2.2 Johann Wolfgang Döbereiner 2.3 Alexandre-Emile Béguyer de Chancourtois 2.4 John Newlands 2.5 Julius Lothar Meyer 2.6 Dmitri Mendeleev 2.7 William Odling 2.8 Shortcomings of early versions of the periodic table 3 20th century 3.1 Frederick Soddy 3.2 Henry Moseley 3.3 Glenn T. Seaborg 4 See also 5 References 6 External links -DePiep (talk) 23:15, 12 June 2019 (UTC)

Complete rewrite?

 * I advise not to look at the present structure too expectantly. The article is in a bad shape and needs an ideal re-writing from scratch. Some bits may be taken here and there but that's it.
 * The present structure is also bad on itself: for instance, Lavoisier is for some reason in the same section as the ancient earth-water-fire-air myriad and not Pout while it clearly should be the other way around. The alternatives for what became the periodic law are discussed in too great detail. Focus is often on scientists rather than their concepts. 1800 and 1900 are very arbitrary borders between the time periods that only works because no continually of history is shown and it is (inevitably poorly) represented as a collection of individual events. Many things are omitted altogether, sometimes even conceptually (aether, noble gases). And that's just what comes to mind.--R8R (talk) 06:32, 13 June 2019 (UTC)
 * I fully agree. This is what we want to leave behind, no suggestion in there. -DePiep (talk) 07:04, 13 June 2019 (UTC)
 * I also agree that a near-total rewrite is needed (also to remove bulleted lists!), but how should we start? Slowly change section headers and fill them with new content, or draft first in userspace and then implement a whole new structure at once? ComplexRational (talk) 22:15, 13 June 2019 (UTC)
 * CR, as R8R proposes (and as I propose below with a different structure/TOC), we'd best rewrite from scratch. -DePiep (talk) 22:47, 13 June 2019 (UTC)
 * When I suggested the article should be rewritten from scratch, I meant that it should not be written with what we have today in mind at any degree and that there's nothing particularly good worth preserving rather than raw facts which (probably) all should be served differently. Those words were in no reference to how that result would be achieved. My point of view is that given the place we are in and the concept of openness that Wikipedia is so famous for, we should work in the main space. This basically means we cannot delete anything until we have written enough info to disregard it as superfluous or a too close detail unless we can independently conclude this information is totally not needed anyway. However, once we agree on what the final result should look like (some changes along the way are fine, so this is not the final decision; by the way, for that, input from yourself as well as YBG is certainly needed), we can create a new structure, including missing sections, even if empty for a while, and redistribute the existing information between what will be the final sections. Then we can fill the newly structure with information, then finalize it by removing details that do seem unnecessary after a hundredth read-through, etc.--R8R (talk) 19:56, 14 June 2019 (UTC)
 * I'm sorry, this section "Current TOC" should not have a discussion. It does not advocate anything. It is just an "as is today" notice. Please create new subsections below.-DePiep (talk) 00:43, 15 June 2019 (UTC)
 * ✅ Sections split. ComplexRational (talk) 01:44, 15 June 2019 (UTC)

Other comments
re the OP listing by R8R: maybe inverse the list? That is: list the concepts, not the periods. So the TOC (as a structuring base) may look like this:

Ancient Greece, China, India, the Arabs, Renaissance Europe are all worth mentioning. Maybe other regions of the world (such as Southeast Asia or the Swahili coast, maybe also the Americas) could be mentioned if there's any written source on their concepts. (Antiquity to (roughly) Renaissance).
 * Fire, earth, water, and air

Turning lead into gold.
 * Alchemistry

An "Element" has the properties of a material. An idea that is close to what we have today emerges at this point. (Age of Enlightenment)
 * Material elements

From Doebereiner to Meyer. Dalton's 1806 list. Pre-Mendeleev findings. (Attempts to find properties and correlations 1800--"1868")
 * Chemical elements, modern research

Claiming/finding structure in the list of elements. Periodicity, atomic weight, valence. Periodic tables as we know it.
 * Mendeleev et al, Periodic Tables

All the chemistry (not physics). Some elements changed positions here and there and new ones kept emerging, the noble gases were discovered at this point, aether still was a thing that even Mendeleev wanted to put at the top of his table, I recall the lanthanides were expelled from the main body of the PT somewhere at this point, maybe something else. (Pre-atomic theory developments (1871--1905?)
 * Filling the gaps

Looking inside the atom. Radioactivity, electrons/nuclei
 * Atomic physics


 * From Bohr's model to quantum physics


 * Isotopes & radioactivity


 * Astrophysics


 * Synthetic elements, f-block/rare metals (1940--)

Island of stability, 8th period,
 * The future

ADOMAH, Left step(?),
 * Other structural variants

Notes:
 * Up for grouping & fleshing out.
 * I'm having Scerri (2007) at hand of course.
 * This list better not be forced into a single timeling (as consequetive era), that doesn't fit well. Just let the topics speak for themselves, and overlap in time. Given the article title, the PT is a nice coat rack for all discoveries & theories. After all, they had to fit and did fit somehow (or are out of PT scope).
 * Hard to convey, but essential: when a concept does not fit well, both the concept & the PT still might be correct (eg Sandbh's recent group 3 setup, electron filling anomalies).
 * re R8R's last note on classroom popularity of the PT: could become speculative, but for me the ordering principle --proven right time & time again, albeit by sidenotes not PT-chemistry)-- is what invites scientists. The PT is what we would communicate to other intelligent forms in the universe (Emsley, Feinman).
 * I am having this plan for some time: create Graphic history of the periodic table. As you might know, my pet topic is separation of graphic presentation and scientific claims (editorial choices: 10-, 18-, 32 column form; habit of adding Ln's/An's below; add element data like atomic weight). I'd say graphic & editorial variants should not get too much attention in this History article (but needed are: change from "short" 10-column (Mendeleev) to 18-column ("long") to modern (Seeborg's An's/Ln's block).
 * (late sign) DePiep (talk) 22:47, 13 June 2019 (UTC)

Well, I think many are treated independently without any good reason for that. For one, I can't see why anyone would discuss the atomic theory and radioactivity separately. I generally think that more-or-less chronological timescale is a good idea, not simply because it recreates a straight time's arrow, but rather because roughly speaking, this was how the table unfolded. Separating interconnected aspects of a history seems like a bad idea because it will inevitably lead to some repetition or loss of context, or (likely) both. You can see that I have established my structure using not periods of time, but rather common topics. I certainly think some deviations from the straight chronological order is absolutely fine as long as it helps preserving this topical structure. (See, for instance, History of aluminium, which ends on 1936 and later, a period of time that is covered a few sections below.)

I feel very strongly about that Mendeleev's 1869--71 suggestion should not be given a section of its own. I feel it is important to describe a timeline in terms the contemporary people could use so the reader is more likely to follow the actual timeline and see how the events actually unfolded. It is important to remember science does not constitute the truth but only our way of conceiving the truth. History of science generally does not go with great men (it's usually men) coming up with a great idea and everybody quickly recognizing the genius and tipping the hat to the great man. It takes some effort to convince others; some worthy ideas are not eagerly recognized by the people of the time. Galileo is a famous example, although history is filled with many far more obscure ones. Even Mendeleev himself became so famous only after gallium was discovered and matched his predictions; before then, his idea was just one of a few, and not too many were really sure whether a really good one justifying the need for a chart in the first place was really there. That's what science is like. That's what I believe we should represent.

(Also: Mendeleev's table was 8-column, not ten. The point was that the group VIII was a single group still even if it included three elements. Took me a while and some reading on the subject to figure it out myself.)

Good one about alchemy, though. But again, this rather belongs in a catch-them-all section that includes all knowledge until the Renaissance.--R8R (talk) 20:26, 14 June 2019 (UTC)


 * I agree that the general structure should be chronological, but I think it would be helpful to name the sections by the key PT concepts. Thus we would avoid ===Name of era=== and instead use ===Name of PT concept=== or maybe ===Name of era: name of PT concept===.
 * Also, as this is the history of the PT, is there a graphic that could be used for PT of four "elements" air/earth/water/fire?
 * YBG (talk) 03:26, 18 June 2019 (UTC)
 * Maybe File:Fotothek_df_tg_0006472_Theosophie_^_Philosophie_^_Sonifikation_^_Musik.jpg (from classical element)? ComplexRational (talk) 17:37, 18 June 2019 (UTC)
 * (re Mewndeleev's being 8 or 10 column: a column is the tabular appearance. A group is the periodic (scientific) input. (Similar for row and period). So Mendeleev had eight groups (I-VIII), placed in 10 columns. Later noble gasses added one group and one column. When A/B groups were introduced, group VIIIA (c.q. VIIIB) was still presented in 3 columns (once, while I-VII were repeated as A and B; this counted up for 7A+7B+3+1NG = 18 columns; incidentally numbered group 1-18 much later in modern days). When came the Lns/Acs, without group numbers, and tuckerd away somewhere). -DePiep (talk) 17:51, 18 June 2019 (UTC)
 * Eh. It's no coincidence Mendeleev put the three (Fe-Co-Ni; it was, in fact, Fe-Co-Ni-Cu, and Cu would later reappear in the next row, with the primary position being with those three) together. So let's say that you are technically correct, but this holds little conceptual meaning. At least that's my current understanding of Mendeleev's 1870s thinking, of which I will not presently claim too much knowledge.--R8R (talk) 20:14, 18 June 2019 (UTC)
 * (Agree, Cu was there in Gruppe VIII too (in my 1871 print here), but Cu was repeated as "(Cu=63)", bracketed, in the next Reihe in Gruppe I. Anyway, the concept is the group, the presentation is by column.) -DePiep (talk) 21:00, 18 June 2019 (UTC)
 * I think about it as one column still having three symbols, something along the lines of this:
 * My presumption is that Mendeleev thought of it in a similar fashion.--R8R (talk) 21:09, 18 June 2019 (UTC)
 * (I don't think expanding on this sideissue is useful in this thread. I'll leave it here). -DePiep (talk) 10:04, 20 June 2019 (UTC)
 * My presumption is that Mendeleev thought of it in a similar fashion.--R8R (talk) 21:09, 18 June 2019 (UTC)
 * (I don't think expanding on this sideissue is useful in this thread. I'll leave it here). -DePiep (talk) 10:04, 20 June 2019 (UTC)
 * (I don't think expanding on this sideissue is useful in this thread. I'll leave it here). -DePiep (talk) 10:04, 20 June 2019 (UTC)

Planning
Sorry for leaving you waiting for so long.

So, let's get to planning. The first step will obviously be the implementiation of the agreed layout of the article. We will need to redistribute the existing content between the new sections. Some sections may have too little content, some may even have none (in which case we should add empty section). That's fine. An important thing to remember is that the article right now is in a rather poor shape. You can't break what's already broken. I'll get to it in a few days unless someone does this before me.

Then probably the best thing to do would be to read a few histories and compile what you can from them. Then look at the result critically and think what could be missing and try to find that. (I also provided some must-have points above.) If there are more questions after we've added that, that's great. More searching then. As the article becomes more and more complete, not only it becomes nicer and nicer, but also the more and more are you engaged with the story. This is what writing good articles is made of. My original assumption was that we would go section by section, although we may want to start with common writing and proceed to section-by-section writing once there's enough basic info. It is probably more easily comprehensible, so let's try that.

I don't think we need to plan far too long for now; it's better to just start and see from there after we've gotten a better impression of what kind of a story we're dealing with here (I have an idea of what we will be dealing with then but let's get there first). One important point I'd love to make one more time is that there should be no fear of being too wordy, feel free to write what you find worthy; if that is ever needed, we'll contract the length later. In the back of my mind I'll have the idea that we are likely to benefit from cool secondary stuff like pictures, or quotes, or interesting factoids, so it may be a good idea to stockpile it in the article or at least on this page for a while first; I suggest you have this in mind as well. There is, however, one important point I'd like to discuss. YBG, what do you think you will be capable of doing? It's absolutely fine if you have little time (this is the reason why I only started working on this in June rather than back in December). But what exactly do you think you will be able to do?--R8R (talk) 20:34, 24 June 2019 (UTC)

Also, on that note. Does everyone agree that this is what we do---read stories, think what's missing now and add that? I think it will indeed be easier to get some okay-to-good basic article and then perfect it later.--R8R (talk) 20:42, 24 June 2019 (UTC)


 * I have a feeling that I'll mostly end up reading short stories or papers marking significant developments in periodic table history - but I'll see if I can get anything longer online or from a library. Most likely I will concentrate on later history (specifically isotopes and the extended PT) as that is what I have been researching and writing for months, though I'll see what I can find that tells a more complete story and leads to these developments. Also, by common writing, are you referring to rearranging what we have or starting with a broader overview before diving into detail?
 * Overall, this seems like a prudent course of action. I'll try to get to this in the next few days, and I'll probably be making substantive edits on and off throughout July. ComplexRational (talk) 20:54, 24 June 2019 (UTC)
 * Well, what really matters here is that you get to the phase when you have a general understanding of the story and there are details that yourself would be interested to find out but still can't. Because then you set the questions before yourself and guide your research. This is when the writing part really opens before you in full: you decide what you want to write. Ideally, yes, I recommend trying to find a more-or-less lengthy story already completed before us. I'll try that myself but I'll note I don't know what the chances for success are yet. For instance, the stories of the periodic table in Russian that I saw invariably focus on Mendeleev and I think that we'll do best by avoiding as much flatter and awe before another great man in history (though I am certainly not proposing we take away his fame from him).
 * Yeah, it's a good question. I, too, wonder what I meant by "common writing" :) my point was, we may want to start off by treating the article as one big story and then as its individual parts are large enough, threat them separately as their own stories then. But restructuring should definitely come before anything else.--R8R (talk) 21:16, 24 June 2019 (UTC)
 * Your plan is a sound one, starting first with the general restructuring. I'm not sure how much help I'll be, but I will watch and work on copyediting as time allows. YBG (talk) 05:00, 25 June 2019 (UTC)
 * Thank you both for your kind words. I presume CR will be working on atomic theory-era developments and beyond, and YBG will share ideas and comments with us as well as improve prose, so I will start with the 19th century. When that will happen is rather unclear to me. I want to get over with the remaining subtleties with hassium, and then I'm up for this but I will need more free time to sit down and look up the topic in greater detail. Presumably this will happen soon but no promises.--R8R (talk) 19:21, 5 July 2019 (UTC)

Misc chat
hi, I think this source will be a good starting point for writing a story on the (roughly) first half of the 20th century, from Curie to Seaborg. It's already referenced in the article so you may have seen it, but in case you have not, feel free to take a look.--R8R (talk) 19:49, 12 July 2019 (UTC)
 * Thank you very much; I was looking for something like this to give a broader perspective than some of the specific discovery papers I found (and I haven't knowingly read it before). I'll take a closer look at some details tomorrow. ComplexRational (talk) 01:44, 13 July 2019 (UTC)
 * I added this to the article already, but you may be interested in this as it tells a concise story from start to finish. ComplexRational (talk) 14:23, 13 July 2019 (UTC)
 * Thank you. This article does indeed have some interesting details that I'd want to add. As I mentioned, I believe that the right way to tell a history of something is not to stand on the shoulders of giants and look back from there but rather to emulate the story as it unfolded. Especially in scientific contexts: you never know the right way until you're there, and looking for the right way even if you don't yet know where it is is absolutely crucial for science. For the purposes of the article, I especially appreciate the insights from the 19th century the paper provides. I am also delighted to see the recent detail about Ostrovsky because my presumption was the development pretty much stopped with the 1970s, and even Pyykko was providing a better version of the idea the was already there.
 * Even the context of article-writing aside, it is a nice read. Scerri is indeed good at crafting the language and storytelling, as always.--R8R (talk) 16:44, 13 July 2019 (UTC)


 * Note to self: need to add more info on initial skepticism toward everybody's tables. For Mendeleev, some quotes can be found in ru.wiki. It also mentions that the discoverers of Ga, Sc, and Ge all were in high appreciation of Mendeleev's accurate predictions and, although without a reference to back the claim, that the periodic law was recognized as an important theoretical foundation of chemistry since the late 1880s.--R8R (talk) 16:13, 14 July 2019 (UTC)

I just stumbled upon this very interesting article about Mendeleev's 1871 table: It seems that the eight-column form led him to (incorrectly) predict some elements, as he evidently believed that the lanthanides were another transition metal series. Additionally, it is one of the first uses of the 'dvi-' and 'tri-' prefixes in his predictions that I found.I can try to craft something from this in the next few days, though this is an especially tricky part to describe and it overlaps with both "comprehensive formalizations" and "pre-atomic theory developments". ComplexRational (talk) 17:45, 26 July 2019 (UTC)
 * Thank you very much. I do have some knowledge on this already, though your article clearly goes beyond it. Though I must add this is a preliminary commentary and I will read this more closely soon. Again, thank you very much indeed for sharing.
 * Trickiness is fine. This is your space to really play with the knowledge and categorize it properly. Such categorizations are indeed often useful in future understandings, as the history of the very concept of the periodic table shows.
 * (The spelling "altogæther" is rather amusing.)--R8R (talk) 20:28, 26 July 2019 (UTC)

Naming
"Periodic table history" sounded weird to me, so I moved to what seems a more natural title. If anyone disagrees, you may of course move it back. Isomorphic 14:18, 29 Apr 2004 (UTC) Destiny Day rocks she is the one to get in touch about the periodic table at pinkfroggy12@yahoo.com I suggest this article be expanded to indicate how people were able to tell the difference between elements and chemical compounds. That is, what was the criteria for inclusion of a given substance into the periodic table? Psychonaut 05:12, 6 Mar 2005 (UTC)
 * I chose Periodic table history because from Periodic table it brached from as Periodic_table_whatever. It's fine the way it is now, though. Goog 12:58, 30 Apr 2004 (UTC)
 * In general, it's a strong WP principle that articles don't have parents and must make sense of their main topics on their own, so try to avoid thinking "what is this a branch off of?" (I'm a wanton violator of the principle, for having made so many branches and levels of List of people by name, but IMO LoPbN is so far from being a real article (it's a navigational tool, like a dab or redirect) as to be an "exception that proves the rule" by showing what it takes to justify violating the rule.)  I mention that partly in the spirit of the discussion below of what else could go in this article.
 * --Jerzy·t 07:31, 8 Jun 2005 (UTC)
 * IMO that would involve the mistake of confusing the table with the modern concept of element, as if just bcz the table is our favorite way of listing the elements. Chemical element and Atomic weight are titles that should bear more directly on this (IMO) very article-worthy topic, and History of chemistry should include more about the law than is appropriate in this talk page's article. Modern history of element isolation or Atomic theory in chemistry may even be worthwhile.
 * --Jerzy·t 07:31, 8 Jun 2005 (UTC)

This article should expand more on the periodic law. --Jasonn 20:06, 6 Jun 2005 (UTC)
 * No, IMO. Periodic table could do so, and i'm not sure that it is excesssive to treat periodic law (which should not in any case redirect here), separately from the table. But history articles should focus on the dynamics of getting from one discovery to another, and not on laying out the logic of the final synthesis.
 * --Jerzy·t 07:31, 8 Jun 2005 (UTC)

The new TOC
My general comment on the new TOC and setup. While the article is titled History of the periodic table, the setup pivots about Atomic theory and isotopes (including a section titled Pre-atomic theory developments). I think this is the wrong choice. The PT is about chemical properties, and its discovery (discovering periodicity) should be central. Not the 20th century (physical) "Atomic theory". As it is, I was mislead by the "Pre" wording in the TOC.

Maybe a better setup would be like: "pre PT" (i.e., lists only, and possibly early categorisdations), "Periodicity" (1869), "Expansions" (addingf elements, adding group 0), "Atomic theory base" (QM, physics, etc). -DePiep (talk) 09:10, 2 November 2019 (UTC)

From 1871 to modern PT


This image caption is incomprehensible, also because the image uses Cyrillic. And: it is wrong.
 * 1. 1871 group VIII is today's groups 8-9-10 (three columns). This should be noted.
 * 2. "modern groups 1–7" is incorrect & incomplete: the 1871 PT also has modern groups 11-17 (Cu, Zn, B, C, N, O, F).
 * 3. "transition metals added": not the actual changes. TMs were there in 1871 (e.g. Ti, V, Cr, Mn, Fe, Co, Co, Ni, Cu, Zn). "addition of transition metals" is not what happened afterwards.

This is what changed in the PT after 1871, and what explains old/new groups & "rows" & periods.
 * Mendeleev's used Reihe (German: row) for period (File:Periodic_table_by_Mendeleev,_1871.svg).
 * A modern single period constitutes two Reihe (roughly). In such a period, Mendeleev's valences I-VII repeat; these were labeled "A" and "B" (so we see IIIA and IIIB). BTW this is European not US labeling style.
 * Reihe 1 and 2 are A/B mixed.
 * From Reihe 9 upwards it gets messy, because Mendeleev did not distinct a third cycle of "periodicity". Lanthanides and actinides; U and Th valences required a "C" row then.
 * Of course, after 1871 Group 0 was added.


 * So:
 * In 1871: groups I-VII (=7 columns), group VIII (=3 columns), makes 10-column PT.
 * ca. 1890: group "0" added, 11-column PT.
 * after 1900: From Reihe into period: Reihe 4+5 make period 4. Reihe 4 = IA-VIIA / modern 1-7; Reihe 5 = IB-VIIB/ modern 11-17; VIII = VIII /modern 8-9-10. This created the 7A+3(VIII)+7B+1(NG)=18-column PT, the labeled "long form".
 * ca. 1930(?): lanthanides and actinides discovered to be a separate block, pictured in the footnote as separate (not squeezed into any A/B group).

-DePiep (talk) 09:52, 2 November 2019 (UTC)

Uranide
I just learned that in the times of WWII, there was a concept of the uranides, since the newly discovered neptunium and plutonium behaved much like uranium, and it was expected elements 95 and 96 would follow suit. I found out about it in a 2007 German course by GSI and others. It will be great to add this here.--R8R (talk) 12:04, 27 January 2020 (UTC)
 * I wrote about this a while ago in actinide concept; it could definitely be reused here. ComplexRational (talk) 18:09, 27 January 2020 (UTC)

Reshuffling
I have changed the structure of the article somewhat. After seeing that the pre-atomic theory section did not look well because it was hard to have a coherent text of this length that would not fall into pieces (especially given that it tries to combine different things, like the rare earths and the noble gases), I broke the section into parts and it is much easier to comprehend (which is handy given that I want to write more). I have also considered the atomic theory section also hard to digest in one piece and broke it into parts, too; in doing so, I also found a couple of things that are currently missing. Finally, I broke the last section into pieces, too. Please take a look. We can discuss my breaks and what I find missing if you have any objections or ideas. Also, you can take on improving what I have highlighted while I am busy with the pre-atomic theory section.--R8R (talk) 19:32, 15 April 2020 (UTC)
 * I noticed, and I had been wondering about the lengthiness of some sections myself. The subheadings look much better and are more focused, which I now realize is even more important because each time period had several simultaneous developments – there are a few other things too in addition to those you marked with Empty section. I presume those are the ones you "highlighted"? In that case, I'll do some digging and write what I can in the next week or so. ComplexRational (talk) 22:38, 15 April 2020 (UTC)
 * Length alone is not too problematic; I think I handled history of aluminium and its sections fine. What you pointed out---"several simultaneous developments"---concerned me more. Originally it rather had to do with rare earths not really mixing with the noble gases well in the pre-atomic theory section, but what you said was definitely the bigger concern in the atomic theory section; the same, as I later realized, also goes for the topic of understanding how far we could go with the periodic table (in terms of Z) and the topic of how to describe what we expect to find there (Fricke and Pyykko, and maybe Seaborg as well).
 * My highlighting comes to all changes in the titles; not only Empty section templates, but also notice, for instance, that we don't mention (even though we absolutely should) the Rutherford model, or the Janet table, and I'd like to have some introductory words on quantum mechanics to explain many early 20th century discoveries (like the a short introduction for helium, though I'm not sure the latter will stand the test of time and live to see the FAC), related to how electrons in an atom behave. This is the context that I believe to be truly necessary for people to be able to learn from reading the article. I must have mentioned this before, but I am generally in great part motivated by feeling smart after understanding some concepts here on Wiki, and I want to replicate that for other people. It is cool to say Mendeleev invented the table, but what is missing is that he managed to gain recognition for it, something Meyer and Newlands didn't try all that hard in comparison, and that's a huge part of why we know his name better than Meyer's (and who is Newlands?). This sort of content is beyond what is usually written in popular sources, but it drastically improves the reading quality.--R8R (talk) 23:29, 15 April 2020 (UTC)

To be done

 * Another note to reflect: what we know now as periods 2 and 3 was not always known as that. They were often considered one before the atomic theory developed, including by Mendeleev (see the chart appended to his 1870 table to the right). I may also need to make a point about the uniqueness of the position of hydrogen is the table (and how Mendeleev did not believe it was the first element).--R8R (talk) 21:08, 15 April 2020 (UTC)
 * That sounds like a good idea, but it seems that instead periods 4–6 were each treated as ten and eight elements in adherence to the eight-column structure.
 * Also, we might have to note (albeit briefly): the emergence of alternate structures, maybe a historical summary and/or analysis of the group 3 issue (like a 10×TLDR), and the significance of the PT ranging across education, other scientific disciplines, and perhaps even 2019 as the international year of the PT. ComplexRational (talk) 22:43, 15 April 2020 (UTC)
 * Yes, that's a brilliant idea! I recall myself suggesting this back when we were first considering this idea (I think it was last year? my memory doesn't serve me very well on this) but it has slipped my mind since then. Thank you for bringing that up again.--R8R (talk) 08:03, 16 April 2020 (UTC)
 * Alright, so we'll incorporate it at some point (how exactly TBD). I think it was around last July you first mentioned it, but either of us could just scroll up or check the page history. ComplexRational (talk) 19:36, 17 April 2020 (UTC)
 * TBH: overall the article today is chaotic, deviating, lack structure and is not an improvement since many months ago at all. Its development status does not deserve article. For this, any such detailed proposals at this one is to be put on hold. -DePiep (talk) 19:55, 17 April 2020 (UTC)
 * Jawohl, Herr Oberst! Zu Befehl!
 * I cannot help but find this irritating. I disagree with the notion that the article is "chaotic", "deviating", and what else. ComplexRational has done a fine job improving the article. It would've passed GAN in the state it was before I started to make my edits last week. Now that I've come, I've messed with the article quite a bit, but this is clearly temporary and is set to highlight what is missing at the present moment. When filled, the article will be great. The structure will probably change a bit in the future, but the bulk of it is set already.
 * We are all here to enjoy ourselves. The bronze star is a good standard, and the sticker itself is good as an attainable goal, so that you can say to yourself at some point, "I really did it." I know how to write featured articles, my count is currently at seven---enough to understand how to do that. I've seen ComplexRational write island of stability (now an FA), and I am convinced he is a potent writer, too. We are committed to getting the bronze star here as well, so it can be taken for granted that we'll manage this eventually, and there's nothing for now left to do other than enjoying ourselves as we do it, research, write, and what else it takes.
 * Instead, we got a comment that says, "yeah, the article is in an ignominious state, hold your horses there and don't you do what you were going to do" without any argumentation or in oblivion to presented argumentation, and that's from a person who is not even involved in writing this article. (By the way, I think that this is the core of our previous quarrels, and that's what irritates me. That all other people at the aluminum/aluminium Hall argument expressed the same irritation hints that's probably not just me overdoing irritability.) This is not to be accepted. That is not to say that you should keep quiet---on the contrary, comments are welcome---but that is, if they are constructive and inviting to a dialogue. "Guys, I think the bigger problem with the article at the present moment is the structure: it misses this, this, and this. Perhaps it's more important to get to that first." Not vaguely disregarding others' work and telling them as if they were your minions what to do and what not.
 * We can try that again. What is chaotic about the article? What is wrong with its structure? What is "deviating" about it? Why do you believe the article has not improved? What do you suggest we do about all of these? Answers to these questions are a prerequisite for me to do anything (can't speak for CR, but I can speak for myself).--R8R (talk) 15:44, 18 April 2020 (UTC)
 * My thoughts exactly, I don't think I could've said it better. However, I wouldn't have GAN'd it back then because it focused more heavily on more recent developments (also since we weren't fully committed to it then) and wasn't polished or pruned yet. It's a work in progress now, and I'm confident we'll get it through to FA eventually. So,, if you have any specific constructive criticism, I'm all ears; otherwise, comments like this are unhelpful to say the least. ComplexRational (talk) 17:12, 18 April 2020 (UTC)
 * Of course my remark deserves a more elaborate foundation. For the sake of better arguing, I might reply to jabs &tc. elsewhere or otherwise.
 * For starters, see the TOC on April 2019 (1 y ago, pre-overhaul), October 2019 (6 months ago), and today.
 * Today's sections in the TOC look like many subtopics randomly grouped by an order hard to be discerned. Of course all related to the PT, but it is hard to see any historical line in there. Not chronologically, not by development of ideas incorporated. It also occurs to me that the history described is not the PT essentially, but the development of, say, chemistry understanding the elements and the atomic model (sure this is worth an article, but with a different title). Even the ideas from before 1869 that ultimately went into the PT (yes they deserve lots of space in here) are wrapped in two sections, about one paragraph each. Curious is that Mendeleev's PT, in the title and expressing a great achievement, is also just a paragraph (it does not show in the TOC then). From there (next section is titled 'Rare earth metals, ..'), I can not discern a general line. The sections are about Changes to the PT, Topic with sets (OK by itself, but aren't the Noble gases also a Change?), and a level-2 section about 'radioactivity and isotopes' is another angle of approach once more (there is no section 'protons, electrons and neurons', to poke a thought). Same for "Later expansions of the PT" -- if the section hasd that title, why aren't noble gases not in there? And the lanthanides? Another (future) issue might be that there is not good criterium to allow/remove certain topics. There are dozens of "Ether"-like topics that need a decision.
 * So this is why I used the word "chaos": the current setup is resulting in an inconsistent line of presenting the topic, a subdivision and grouping of subtopics by varying criteria, resulting in and showing by a TOC missing structure and consistency. And my overall impression is that sometimes the main topic seems to be the atomic model or element chemistry, over PT development itself. -DePiep (talk) 18:19, 18 April 2020 (UTC)
 * The ordering principle is a rough chronology of big themes: ancient history, first inconclusive categorizations, attempts to build a conclusive categorization, the period between then and the development of the atomic theory, the atomic theory, everything that follows it. It is generally understandable that some themes overlap. That's why the pre-atomic section ends in 1905 (or around then), and the next section will begin in 1896, with the discovery of radioactivity of uranium. None of the titles used now is final, the article is at the present time a sketch in work, they are there to serve as a motive of what is to be written there. What the titles themselves will be is a minor issue, and it will be dealt with after content has been written (my thinking is that titles are supposed to reflect content rather than vice versa, since I am more interested in a person who reads the article rather than who merely skims through the table of contents). The pre-atomic section is particularly in work. It's too early to pass judgments now.
 * That Mendeleev's work is not explicitly mentioned in the table of contents is intentional, and that is done to better reflect the nature of science. It is, of course, easy to look back now that we know the periodic table and hail Mendeleev. This is, however, not how real science works. Even an achievement as genial as Mendeleev's is often not recognized. You can be sure some great ideas have been overlooked by their contemporaries. That is common in science, and despite the romantic ideas that science knows everything or is set to know everything at some future date, it doesn't and it isn't. Science is what we the humanity see of the world. Scientific mainstream may easily overlook great ideas. That is why I mentioned, and I might need to make that more clear when I find a good source for that, that Mendeleev's achievement is in great part due to his persistence rather than his ingenuity alone.
 * As for what the article is about: the periodic table itself is a reflection of relationships between the elements. It is not the final truth of the cosmos. But it's our attempt to get as close to that as possible. Of course, we need to understand what we are going to reflect with the very idea of the periodic table. As our understanding of the world changed, so did the meaning of the periodic table. We need to explain the former to properly explain the latter.
 * As for quick questions:
 * The noble gases by themselves are not a change to the periodic table, they are a discovery. But a change to the actual table is needed to reflect that finding. These are two closely related but different matters.
 * There is a section named "Proton and neutron," actually, even if it's empty right now. I am pondering the question whether to include the electron in the section on quantum theory or elsewhere, but it will definitely be included somewhere. Most certainly, however, not with protons and neutrons: the topics of electron shells and nuclei are principally different.
 * As for title "Later expansions of the PT": it is subject to change. As I mentioned, all titles are. The point is to include the bulk of events that occurred after those that established the atomic theory.
 * Last but not least. In your original post, you mentioned these five things, in order of appearance:
 * The article is chaotic;
 * The article is deviating;
 * The article lacks structure;
 * The article has not improved in many months;
 * We are to put on hold the important question of popular usage of the periodic table.
 * (There was also this sentence: "Its development status does not deserve article," but I didn't discern its meaning.)
 * Now looking at this list, would you agree with me that these wordings create a very unpleasant impression for, first and foremost, CR and, secondarily, myself (because my input is smaller so far) as writers, without any real provocation that would justify this aggression? If we asked for a FAC right now, for instance, we would have to be prepared for harsh criticisms, that is clear and fine, but you came to judge a work that is clearly in making, making an offense that was in no way asked for. (And that notion that the article has not improved is plain wrong, and I think it would be fair for you to re-read the article and mitigate the impact of your words to CR; I'd be super pissed by such disregard of my work that is clear improvement over what was there before.) Not to mention that the order of how we do things is preferably left to us, the people who are actually going to do them, and will most certainly not be dictated (as opposed to suggested, which would've been fine). Would you retract that post and not be so aggressive in unasked for comments anymore? Your post I'm replying to right now, for instance, is an example of much better communication that does not include uncalled for offense. Things will keep going fine if we stick to this tone of communication.--R8R (talk) 20:25, 18 April 2020 (UTC)
 * I recall reading that Mendeleev complained about somebody moving the noble gas from group 0 to group VIII, which (if correct) means that somebody did this is his lifetime.--R8R (talk) 08:07, 16 April 2020 (UTC)
 * Henry D. Hubbard did this: in an 8+1-group PT, add group 0 left to group I (OK), and repeat noble gases in group VIII (?).
 * Hubbard (1870-1943) was a member of U.S. Bureau of Standards, and initiated this PT form in 1924; obviously too late for Mendeleev (died 1907). But maybe this form was going around somewhat longer. Hubbard's form was used well into the 1960's. I have not found a clarification for putting NGs in group VIII, by repetition even. -DePiep (talk) 11:47, 16 April 2020 (UTC)
 * Hubbard's table is from 1924, though, and Mendeleev died in 1907. There is no doubt to my mind that somebody drew the table with the noble gases to the right before Hubbard did that but after the atomic numbers were better understood. Hubbard's table is important too, but for a different reason (the 18-column form).--R8R (talk) 21:34, 16 April 2020 (UTC)
 * Is circa what I wrote. I mention Hubbard also because it seems to be a very widely & long-time used PT (in update versions).
 * Anyway, before putting such a form (NGs in group VIII) in here we need a clarification by the author at least, and even then it might be an irrelevant or undesired form. -DePiep (talk) 06:01, 17 April 2020 (UTC)
 * Hubbard's (1963); my former highschool had one from 1956 (not on show), and I recently saw this form as a backgrond with Seaborg ca. 1950 (in a YT video, not sure about rights). Must have been a common form. A crowded panel it is. -DePiep (talk) 11:56, 16 April 2020 (UTC)


 * Check if the Werner table has been given excessive relevance.
 * Mention how quantum chemists thought there was a 5f series, but they didn’t know where it starts.—R8R (talk) 08:36, 16 April 2020 (UTC)
 * Actinide concept and its sources a good place to start, I've thought about expanding that from time to time. ComplexRational (talk) 19:36, 17 April 2020 (UTC)
 * I am undecided on whether to include the story of how Mendeleev almost got a Nobel Prize.--R8R (talk) 11:43, 16 April 2020 (UTC)
 * Once a more cohesive structure is formed, the lead needs to be entirely (re)written to reflect everything. ComplexRational (talk) 19:38, 17 April 2020 (UTC)

English vs British
I'd like to ask for your guidance on this. We introduce some scientists in this article as English and some as British. Is there any good reason for not being consistent? My general inclination would be to call them all British, since we normally speak about whole countries and England and Scotland were united in the lifetimes of all these fine gentlemen, but I'd like to be sure on this.--R8R (talk) 19:32, 11 April 2020 (UTC)
 * For starters, both uses are correct and neither is strictly preferred as far as I know. Consistency is always better, yet the articles for said scientists are inconsistent with each other. To be safe, I'd agree to introduce them as British because some sources may not specify if they are English, Scottish, or Welsh (even if they did, it might detract); referring to the English as British is always okay, but the converse is not. One source I consulted draws an analogy to American vs. Texan, for instance, so the broader term is usually safer when in doubt. ComplexRational (talk) 16:20, 12 April 2020 (UTC)
 * Hm. That neither English nor British usage is strictly preferred, I believe, is rather different from the Texan/American example? My assumption would be that you always say American unless the context is clearly limited to the United States alone, or possibly a few other English-speaking countries too. But nonetheless, we'll use "British," then. Thank you.--R8R (talk) 18:41, 12 April 2020 (UTC)
 * I agree that it certainly is different, since England and Scotland are countries and pretty commonly used in place of British (e.g., we don't have a UK national football team), but it is the analogy that I read (I don't recall exactly where). For other countries, it's even less common I think than Texan/American; perhaps notwithstanding exceptions such as Cantonese/Fuzhounese, you'll probably not hear "Romagnolo" much outside Italy, for example. You're welcome, British it is then. ComplexRational (talk) 19:26, 12 April 2020 (UTC)

another question of a similar kind, I just want to be sure we're on the same page here. We've currently got "Austrian-Hungarian chemist Bohuslav Brauner" and "Prussian chemist Robert Bunsen"; I wrote these on the account they lived in the states of Austria-Hungary and Prussia at the times relevant to their respective mentions. However, they were ethnically Czech and German, respectively, and they spoke Czech and German. Nowadays, there are countries named Czechia and Germany, but then, they did not exist. I realize, of course, that one can argue that ethnicity and language together weight more than nationality, but preferring nationality seems to be consistent with the idea of calling every person from Britain British rather than English or Scottish. Do you agree with my logic here?--R8R (talk) 19:21, 19 April 2020 (UTC)

Mendeleev's failed predictions
could I ask you to assemble a list of Mendeleev's eighteen predictions? That fact that we mention them is asking for a visual clarification (a PT with locations of his predictions). I'll start making the graph in the weekend if I have the list at that moment. Or you can draw the graph if you feel like it. Anyway, I can't put my finger on the exact constitution of the list.

Here's what is easy to discern from 18, out of which only a half was successful:

(Sc), (Ge), (Tc), (Re), (At), (Fr), (Po?), two more successes (Hf and Ra if I had to guess? could it be a late prediction of Rn?)

nine failures (there is room for more between eka-Y and Ta, and this list probably includes coronium and newtonium)

By the way, I suspect that our Werner passage merits a closer check. Surely not everyone immediately accepted the idea, or was his genius indeed so quickly recognized?--R8R (talk) 19:55, 14 April 2020 (UTC)
 * Hmm. The article I read and linked here months ago says there were fourteen. Anyway, all the predictions I'm aware of are these:
 * the main, complete three – eka-B (Sc), eka-Al (Ga), eka-Si (Ge)
 * other successes – eka-Mn (Tc), tri-Mn (Re), dvi-Te (Po), dvi-Cs (Fr), eka-Ta (Pa) – (the uses of tri- and dvi- result from the dead zone, and eka-Ta is technically incorrect but was between Th and U)
 * dead zone (failed, now known in the lanthanide range) – eka-Mo, eka-Nb, eka-Cd, eka-I, eka-Cs
 * not sure about dvi-I (At), the gap was there but it's not elaborated in the article
 * dvi-Zr (Hf) is not mentioned at all in that article, but it was seen in 1869 and eventually realized
 * aether and coronium
 * These total 14 or 15, not including any other weak predictions lighter than H, in the dead zone, or heavier than U. If I discover any more I'll add them. And I'll look into the Werner passage probably tomorrow or Thursday, it's getting late here. ComplexRational (talk) 02:18, 15 April 2020 (UTC)
 * Some notes. (CR, can you indicate that article you added?)
 * Scerri (2007, Ch.5) notes that his extrapolations dit not mature; successes were in intrapolations.
 * See also Talk:History of the periodic table/Archive 1 esp. Periodic table (Reihen and periods) that shows both "1871" and "1871 in more modern structure".
 * Current sectiontitle "Mendeleev's inability to incorporate the rare earth metals" could be improved. Of the rare earth metals, he was right re Y (then symbol Yt) and Sc (predicted). Such problems only arose with the lanthanides, then. Interesting is that M. did note these placement problems by adding querstion mark before these four elements, & these only: ?Di [now La], ?Ce, ?Er, ?La.
 * Current accompanying image in article, File:Mendeleev 1904 Periodic Table.png, is not a good illustration for predictions
 * Maybe it's best next to or below the 1871 table, to show the filling of some gaps but persistence of others. ComplexRational (talk) 12:09, 15 April 2020 (UTC)
 * To be perfectly clear, the 1904 picture is not meant to be the illustration for this section. I imagined the illustration to be something like the 1871 table with the predictions, both right and wrong, highlighted/added. The 1904 table will be in a gallery in the end of the section, but for now I find writing content more important than compiling the said gallery.—R8R (talk) 12:59, 15 April 2020 (UTC)
 * I agree the content is the highest priority now. And I also forgot to mention, while content is still under construction, images may not display in their proper locations because the image "stack" is taller than the prose, which being unfinished is subject to restructuring before we make any judgements of this sort. ComplexRational (talk) 13:46, 15 April 2020 (UTC)
 * OK, image is not relevant. -DePiep (talk) 15:37, 15 April 2020 (UTC)
 * All in all, this article should make nuanced differences between the levels of predictions. IMO those predicted by Periodic Law are worth including, and only if he predicted them by addressing them (not just the &mdsash; in his PT).
 * -DePiep (talk) 07:35, 15 April 2020 (UTC)
 * Looks like Mendeleev's predicted elements needs an update. -DePiep (talk) 09:29, 15 April 2020 (UTC)
 * Yes, that article certainly does need an update. The article in question is, from one of my earlier posts. ComplexRational (talk) 12:09, 15 April 2020 (UTC)
 * For reference: the notion of eighteen elements comes from Scerri: "In all Mendeleev predicted a total of 18 elements, of which only nine were subsequently isolated."--R8R (talk) 21:03, 15 April 2020 (UTC)


 * The section now says "Compared to the rest of the work, Mendeleev's 1869 list misplaces seven then-known elements: ...". I find it odd to refer to his *1869* Table, while in 1871 he published a much-more elaborate PT. AFAIK, in the time between only he himself improved that PT, there was no outside correction (by other scientists) in play. For this article's scope, it seems needlessly detailed to zoiom min in the 1869-1871 difference. Also, replies and comments by other scientists should not refer to 1869 since the 1871 version is available. (1869 is important fir being the first publication of his periodic law ideas). -DePiep (talk) 08:19, 17 April 2020 (UTC)
 * The point is not in zooming in on the 1869--1871 difference. The point is that he knew full well about the problem, tried to resolve it, but failed. This will be complemented eventually by a mention of how the 1904 table still doesn't resolve the issue.--R8R (talk) 14:52, 17 April 2020 (UTC)
 * So at least we remove the '1869' referencing, OK. Next, I don't think the article should be focusing on Mendeleev's 1871-1904 line of thinking. After 1871, others got involved in the History. IOW, what M. said in 1904, is not that relevant here. -DePiep (talk) 19:04, 17 April 2020 (UTC)
 * That's a hunch I've had too. But how can you tell? If not Mendeleev, then who? It's not that he abandoned his work in 1871; he continued to push it for many years to come, and it was his persistence that had a huge role in getting the periodic table acknowledged (one famous episode is that he wrote to de Boisbaudran, the discoverer of gallium, that his density value might be wrong; imagine yourself discovering a part of something which evidently had no structure behind it and then getting a letter from far abroad saying that your result matches writer's predictions except for one, which needs to be rechecked, and then you recheck it and the letter is right).
 * "After 1871, others got involved in the History." -- like who? I only know about Brauner, and I mentioned him.--R8R (talk) 16:25, 18 April 2020 (UTC)

Here is the list I have found (Scerri 2019, pp. 142--143)

Scerri notes that this table "does not include elements such as astatine and actinium, which he predicted successfully but did not name. Neither does it include predictions that were represented just by dashes in Mendeleev’s periodic systems. Among some other failures, not included in the table, is an inert gas element between barium and tantalum, which would have been called ekaxenon, although Mendeleev did not refer to it as such."--R8R (talk) 20:22, 20 April 2020 (UTC)

Recognition of the periodic table and the scientific mainstream
I am strongly considering a subsection in the pre-atomic section that would follow us through the stages of recognition of the periodic table. I intend to move their the successes of Mendeleev's prediction of eka-aluminium, among other things. If my memory serves me right (which is, admittedly, quite an if), you posted some time ago something that mentioned how the periodic table became well circulated in American schools in the late 19th century; am I correct? If I am, would you post the link once again? I'm re-reading periodic table and it says that the 18-column form was popularized by Merck and Co. in the 1920s (the question why they did this in the first place is begging for an answer in the article). However, did they popularize the periodic table or only one form of constituting it? If you know this, please let me know as well.--R8R (talk) 14:08, 19 April 2020 (UTC) New signature because the corrected ping won't work otherwise--R8R (talk) 14:09, 19 April 2020 (UTC)
 * I don't recall posting that actually; if I did, it wasn't on this talk page. I'll have to research this some more. ComplexRational (talk) 18:45, 21 April 2020 (UTC)
 * Okay, thank you. I did think you had shown me that, but well, memory does serve me wrong from time to time. I'll also appreciate it if you look into the Merck and Co. story more closely: why did they do this? what was their motivation in this case? I really want to know the answer myself but I'm going to be busy with Mendeleev and his predecessors for a while.--R8R (talk) 19:09, 21 April 2020 (UTC)

Quotes
I mentioned that before, but I want to restate it to make sure you follow my logic and understand why I do this as well as possibly take part in it yourself. I add quotes when I do because they seem to be one-liners that characterize the section rather well. I did want to have something about nearing the end of periodicity in the last section, for instance, and I think that Oganessian quote is great for that. I also really like the first formulation of the periodic law by Mendeleev. As for the other Mendeleev quote, it's also cool and I want to have there something about the noble gases (which are important as they first challenged the periodic law and then strengthened it), but if you find anything better than that, we could discuss that. My initial desire for the atomic theory section is to have something about the electron shell; maybe there's a good quote from Bohr or Lewis, or something in the likes of that. The starting sections will also need quotes. If you find anything particularly cool, feel free to add that yourself.--R8R (talk) 11:46, 23 April 2020 (UTC)
 * That quote pretty nicely sums up one of the most important things about SHE research, and the Mendeleev one looks good as well. I remember you did this in history of aluminium and we had a short discussion on that, where you initially shared this idea; thank you for bringing it up again. If I find anything, I'll bring it here or add it directly. ComplexRational (talk) 01:16, 24 April 2020 (UTC)
 * Great! We're in no hurry with setting all quotes up. I'll add something else if I find that, too, I just thought it was important to let you know that you can add something you find particularly interesting. By the way, I've split the pre-atomic theory section into two, and I've got a Mendeleev quote for each of them. I like every one of the Mendeleev quotes, but I don't like having three of them. We will eventually need to replace one (or two) of them; the most obvious choice seems to be a noble gas quote from Ramsay if a cool one is available, though it depends on what exactly is available as a replacement. We're in no hurry to do this, either, but bear the need of getting a new quote in mind. I particularly want to keep the 1871 periodic law quote.--R8R (talk) 12:30, 24 April 2020 (UTC)

Breaking bad
The recent edit to add a lot of information about "Breaking bad" seems to me to trivial, but an excessive addition to this article. I think it should be deleted but would like opinion from others. --Bduke (talk) 10:19, 9 August 2020 (UTC)
 * The point of the planned section is to explain how the periodic table became so well known to the common people. It hasn't always been like that: as Poliakoff points out, its image was known only to chemists just fifty years ago, but nowadays, everyone knows it. The picture is meant to be an illustration of how the table is present in popular culture. As for the picture's caption, the first sentence explains how the logo is relevant to the periodic table and the second sentence explains why this logo is particularly notable for this article; if anything, only that second sentence is related to the actual series. I hope this explains why the picture is important although it could be the case that the first sentence could be contracted.--R8R (talk) 10:31, 9 August 2020 (UTC)
 * The picture is not part of the periodic table. Br and Ba are not next to each other in any periodic table I use. --Bduke (talk) 10:40, 9 August 2020 (UTC)
 * That's true, but the caption doesn't say anything like that, either. If you feel that the caption is wrong, please state specifically how so so that it could be helped.--R8R (talk) 10:55, 9 August 2020 (UTC)

Spam
In the section entitled "Priority of discovery", it says "Mendeleyev stood out" and seems to be belittling Meyer and Newlands. This seems to be spamming for Mendeleyev. Newlands was not under any obligation to seek recognition outside England. Citations were called for in the April of 2020. — Preceding unsigned comment added by 2a00:23c0:7980:3f00:21e6:55df:9391:4fdd (talk • contribs) 08:39, 11 September 2021 (UTC)

Lothar Meyer
I moved the placement of the footnote to Scerri's book and added a citation needed, since I couldn't find the story of the December 1869 paper in either the 2006 or the 2020 edition. It's possible that I overlooked it, or that another reference was meant. XOR&#39;easter (talk) 23:18, 18 September 2021 (UTC)