Featured articlePeriodic table is a featured article; it (or a previous version of it) has been identified as one of the best articles produced by the Wikipedia community. Even so, if you can update or improve it, please do so.
Main Page trophyThis article appeared on Wikipedia's Main Page as Today's featured article on February 28, 2004, and on January 8, 2018.
Article milestones
DateProcessResult
January 19, 2004Refreshing brilliant proseKept
February 9, 2005Featured article reviewDemoted
January 11, 2012Peer reviewReviewed
June 12, 2012Good article nomineeListed
July 11, 2012Peer reviewReviewed
November 7, 2012Featured article candidatePromoted
Current status: Featured article

Template:Vital article

Ambiguity regarding the positioning of Lanthanum (La) and Actinum (Ac) in the Periodic Table.

Hello! I believe that though we study La and Ac along with the F-block elements, they should be placed in the D-block as they have none and full 4f orbitals respectively. This makes them unfit for being in the F-block. Please do help me with this. Thanks, SSG123 (talk) 17:02, 6 November 2021 (UTC)Reply[reply]

That is the so-called "Group 3" problem, discussed at Periodic table#Group 3 and endlessly on these Talk Pages and archives. It will be very difficult to undo the present consensus unless and until IUPAC make a ruling (and many will continue to disagree even then). Mike Turnbull (talk) 21:03, 6 November 2021 (UTC)Reply[reply]
Thank You! SSG123 (talk) 06:36, 8 November 2021 (UTC)Reply[reply]

There are a couple of things to consider.

1. In 1960, Sanderson (p. 8) wrote:

“If a d electron, for example, can easily behave like an f electron, or vice versa, the argument as to the exact ground state configuration becomes relatively unimportant.”

That is to say, given La is the progenitor of the lanthanides it seems to be the case that it can relatively easily behave as if it were an f element (as is the case with Lu) never mind its electron configuration of 5d16s2 rather than the expected 4f16s2.

2. In any event, if the 4f row is shown as La to Yb, the number of f electrons in each atom corresponds to its position in the row, in all bar three cases (La, Ce and Gd). Whereas if the 4f row is instead shown as Ce to Lu, the number of f electrons in each atom corresponds to its position in the row in only three of 14 cases (Ce, Gd, Yb).

The situation in the 5f row, for Ac to No, is a little more complex, bearing in mind the earlier members show a decreasing resemblance to their transition metal congeners until the group 3 resemblance sets in.

If the actinide series is shown as Ac-No, it can be divided into three relatively cohesive sets:

The position number and either d or f electron count matches in 10 of 14 cases.

If the actinide series is instead shown as Th–Lr, the three sets become discombobulated:

The position number and either d or f electron count matches in 5 of 14 cases.

Conclusion: With Lu-Lr in group 3, the electron configuration “filling pattern” becomes easier to explain, and more consistent with quantum mechanics (QM) acknowledging electron configurations do not explain everything and that chemistry is not fully reducible to QM. Sandbh (talk) 10:40, 8 November 2021 (UTC)Reply[reply]

Above notes updated. Sandbh (talk) 21:00, 13 December 2021 (UTC)Reply[reply]

Error in ionization energy

I spotted a mistake in the section about ionization energy. Ionization energy increases “left to right and down to up”, and not “left to right and up to down” as in the current text 71.232.97.135 (talk) 02:33, 13 December 2021 (UTC)Reply[reply]

 Done Yes indeed. I've made the change. Mike Turnbull (talk) 15:28, 22 December 2021 (UTC)Reply[reply]

Periodic table of the elements

I’d like to be able to come to this site and be able to see a color coordinated list of the names of them. 135.134.173.151 (talk) 14:52, 22 December 2021 (UTC)Reply[reply]

There are many way to color-coordinate the elements and one commonly-used way is shown at Periodic table#Classification of elements. Was there something else you had in mind? Many of the other tables in the article either explicitly name the elements or have links to them which show full names if you hover over them with the cursor. Mike Turnbull (talk) 15:18, 22 December 2021 (UTC)Reply[reply]
A black-and-white periodic table image shows its main features best: columns=groups, rows=periods, rectangular units=blocks. Immediately recognisable! Any color coding would distract from this main setup. And after all, this is the introductionary image, no details have to be explained. However, when going into details and analysis, coloring can be very helpful. So there is: 1, 2, 3. -DePiep (talk) 08:32, 9 January 2022 (UTC)Reply[reply]

18-column form needed as the lede table

Consistent with what DePiep noted above about a black and white v. coloured table, I suggest the periodic table in the lede should be an 18-column form rather than a 32-column form. The 18-column form is by far and away the iconic form widely recognisable around the world. In comparison, the 32-column form is obscure, non-representative of the literature, and in this context, undue. It should not be featured in the lede although it certainly warrants a mention later on in the article. An 18-column form would also be more legible. Sandbh (talk) 23:01, 9 January 2022 (UTC)Reply[reply]

  • @Sandbh: no, this is not "Consistent with what DePiep noted above". For starters, I invoke "... would distract from this main setup", "introductionary image, no details have to be explained", "shows its main features best" and "immediately recognisable!". And concluding, I say "[for] details and analysis, coloring can be very helpful" (italics added). -DePiep (talk) 06:49, 10 January 2022 (UTC)Reply[reply]
  • No. The 18-column format is a deformation, by non-scientific grounds even. We don't need an "iconic" form, we need the informative form. 18-column has a needeless complication: it is deconstructed, a deviation from the proper scientific periodic table. The icon is only helpful for initiated people like scholars (who immediately, intuitively and by excecise, understand and overlook the complications). But tallying published forms is not a sound base to reach a good encyclopedic result: you are polling the in-crowd. Those people are used to it. It started with Seaborg no less 80 years ago, when he needed to fork out the new discoveries as a block (and again, writing for high-end scolars). Scholars more easily could accept the books page-ratio limits (at the cost of extra studies, for example the exact border cases wrt group 3). By the way, since say 2000, webpages are available, overcoming such hard limits.
We are creating a general encyclopedia, and we do not require such proir knowledge, training or intuition. It's easy: After you've seen/grasped/recognised/learned the single-graph version, one can quite easily recognise & understand the forked graph. The opposite route, start by learning the scattered blocks, then reconstruct the full form in mind, is not obvious and requires extra mental steps to get the essence.
As an encyclopedia: there is no advantage in presenting a deconstructed form. -DePiep (talk) 11:00, 10 January 2022 (UTC)Reply[reply]
@DePiep: Oh, what I meant by being consistent with you was where you wrote, “And after all, this is the introductionary image.”
Thus, the 18-column form is universally the introductory form in the literature. It matters not at all what your personal views are about how “bad” the 18-column form is. Not only that, the 18-column form has achieved the status of an icon in the Western world. As an encylopedia we are obliged to reflect the literature. Hence the periodic table in the lede should by an 18-column form, as adopted by the International Union of Pure and Applied Chemistry[1], the American Chemical Society[2], the Royal Society of Chemistry[3], PubChem[4], and ptable.com[5]. Sandbh (talk) 09:44, 11 January 2022 (UTC)Reply[reply]
I wrote about being an introductionary image in relation to the coloring of details (ie, not useful in this introduction). As one can read. I did not write that being an introduction means there are no encyclopedic requirements. Agree with you that personal opinions don't matter, so it fits that I wrote that for encyclopedic reasons we should use the most helpful one. (Sandbh, next time please leave out the personal jab and the out-of-context misreading—esp when orig quote is nearby so easily to point out. iow: speak for yourself). -DePiep (talk) 15:05, 12 January 2022 (UTC)Reply[reply]
I’m not a regular on this article but do have an interest. The main reason the 18 column version is published in so many locations is it’s easier to publish on 8.5x11” or A4 dimensions. It’s a matter of convenience, not preference, in other words. (Let’s just hope we don’t have to make room for the next row, which would likely be 50 columns, anytime soon!) Jtrevor99 (talk) 20:13, 12 January 2022 (UTC)Reply[reply]

Mental states with the periodic table

Mendeleev, 1871

1871–

Wikipedia reader trying to understand an 18-column periodic table

Early XXI century

Showroom Wikipedia: Featured Article

Periodic Table, 10k visitors per day
DePiep (talk) 20:02, 10 January 2022 (UTC)Reply[reply]

Rfc about the periodic table in the lede

18 COLUMNS
Consensus to have an 18-column version which has an indication of where the f block goes, as it is the most recognisable (aligning with MOS:LEADIMAGE, although no one mentioned it) and easy to interpret, both in terms of reading it and being able to view it on mobile.
Colour was touched on by four people, although not discussed enough to establish consensus (!votes were 2 for, 1 against, 1 unstated).

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Should the periodic table in the lede be an 18-column table or a 32-column table? Sandbh (talk) 04:15, 20 January 2022 (UTC)Reply[reply]

!Votes

One editor's unhelpful insertion of his own comments into the middle of another editor's unhelpfully long comment
@Sandbh: "most common appearing in books" - by editorial choice and limits such as print page ratio, not by scientific or educational base. No one should have(!) to discover the Periodic table from a crippled form. Today, this being a website we are not limited/forced by bookpage ratio any more, and of course tallying books is no substitute for sound educational approach.
My reason (1) now says "by far and away the most common form appearing in the literature, including books as their lede table." Sandbh (talk) 22:31, 22 January 2022 (UTC)Reply[reply]
"status of an icon": this is not a museum for old icons. Nor are we tallying preferences (made in another time and context). This is an encyclopedia, aimed to inform. To convey the essence of the Periodic table, for example eh periodicity, the deconstructed 18-column form breaks good encyclopedic presentation. Nice for those in the know, needlessly complicating for those who are here to learn.
"Icon" means, "a person or thing regarded as a representative symbol" which is the case for the 18-column form.
You like citing Eric Scerri, a world authority on the periodic table. Here is what he says at the very start of the introduction to the 2nd edition of his book, The Periodic Table: Its Story and Its Significance:

The periodic table of the elements is one of the most powerful icons in science: a single document that captures the essence of chemistry in an elegant pattern. Indeed, nothing quite like it exists in biology or physics, or any other branch of science, for that matter. One sees periodic tables everywhere: in industrial labs, workshops, academic labs, and of course, lecture halls.

And he wasn't referring to the 32-column form. Sandbh (talk) 22:31, 22 January 2022 (UTC) Reply[reply]
"obliged to reflect literature"—but not by copying their editorial choices. Not their page size, not their font type. 18- or 32 column is not a scientific distinction. To be clear: by definition both forms do and should present exactly the same scientific claims.[1]
Please see the Discussion subsection, below, for the scientific difference between the 18-column form and the 32-column form. Sandbh (talk) 22:31, 22 January 2022 (UTC) Reply[reply]
"IUPAC uses ..."—As we know, IUPAC/Scerri have published recently[1] that IUPAC has not and does not declare preference for any of those two forms.
IUPAC uses the 18-column form on their web site, and in their Red Book on the Nomenclature of Inorganic Chemistry (p. 2). That said, they do not recommend any particular form of periodic table. Sandbh (talk) 22:31, 22 January 2022 (UTC)Reply[reply]
All in all: we should choose the image that is best for the encyclopedia, in presenting & conveying & education the Periodic table. Tallying old books and non-context situations are not a proper base for this. See also my # !vote for 32 below. -DePiep (talk) 10:31, 22 January 2022 (UTC)Reply[reply]
There are no "non-context" situations. IUPAC recently surveyed 192 university text books (1970s to 2010s) and found six examples of a 32-column table, which represents a 3% hit rate. For the scientific difference between the 18-column form and the 32-column form, please see the Discussion section, below. Sandbh (talk) 22:31, 22 January 2022 (UTC)Reply[reply]
Lengthy comment by DiPiep
TL;DR: being an encyclopedia, we must convey the information as accessible as possible. Nicely, the 32-column graph shows the essence right away from its introduction, both in detail and in glance. And immediately recognisable both as structure and as icon. Then, later on, a Reader more easily recognises or remembers the main structure, further down the road or outside of WP, when a graph shows details/non-primary properties/colors/deformations including 18-columns: all superimposed on the one basic structure, and recognised as such in the mind's background. On the other hand: for readers not familiar with the basic Periodic table structure, the 18-column graph requires mental excercise to replace the cellar-stored elements into their right place, before grasping, understanding and appreciating the Peridic table, while we cannot assume that every reader can do or even understands this requirement. Even worse: the cellar storage distracts from the essence (so gently present in the Right Table: periodicity-with-holes first and foremost). Of course, those already(!) familiar with the Periodic Table like scolars, scientists and editors like us, have studied and internalised the structure beforehand and outside of Wikipedia. Good for them, but not a guide for our encyclopedic presentation. Anyway, 32-column form does no encyclopedic harm to these people: the form serves both groups of readers.
- Longer: We are supposed to clarify matter, and make it understandable. As for the Periodic table, the task of the top image is to convey its principles. All other is distraction, confusion, mis-aiming. That core is: the plain flat 2-dimensional Table. Principal features: rows/periods, columns/groups, blanks/blocks full stop. Not by accident, these are present and immediately recognisable in a b/w 32-column form. Even better: this without distractions.
- Shifting parts to the cellar makes the table's essences hard if not impossible to grasp. It would require(!) a mental excercise to reposition the cellar-stored parts back in their right place. It is as if an uninitiated reader has to apply an IKEA montage manual each time(!) one meets a deconstructed 18-column Periodic table. That is: each and every time before being able to get to whatever aspect the reader is looking for.
Seaborg in his lab
Hubbard Periodic table (1924–..)
- For the initiated reader, those who already have internalised the main structure, there is no loss or harm (unless one counts "I am not used to it", but allow me to discharge this as not an argument). Like scolars, scientists, interested readers. There is no reason to cater only just for those (with a complicated graph) while the broader all-reader inclusive approach is available. Even worse: it would be counterproductive to take those readers as leading for the encyclopedic presentation. Our encyclopedia job is to write for people who do not (yet) know.
- Now once the basic, 2-dimensional straight Table is introduced and recognised (that is, in 32-column graph), a reader can dive into detail graphs such as those presenting electron configuration, classifications, a metalloid staircase, physics, without loosing the big picture = structure. Which is the perfect way to present complicated information: unfold, zoom in, invite to details; all from the Big Picture. This fits with how the human mind works in learning.
- Coming from a straight Periodic table, other graphs are more easily understood (again, for not having to bother with the mental mis-image): presentation forms (like earlier Mendeleevian tables, spirals) and different structure by science (Janet's Left Step, ADOMAH's quantum based)
- Illustration. Seaborg was scientist who, in the period 1930–1960, made huge contributions to the science of elements & the Periodic table. He was the one who discovered the f-block elements structure, and they were conveniently put below the then-known Periodic table (introducing placeholder notation like * asterisks). While doing so, Seaborg did not need an introduction to the Periodic table: he rewrote the Table himself, and from an already internalisation into intuition. On his laboratory wall was Hubbard's Periodic table wallplate. Hubbard's Table was complete, but not an invitation to study the topic. For the initiated Seaborg this was no issue. For readers of an encyclopedia, looking for an inviting introduction, this would be prohibitive in appreciating the Periodic table.
-DePiep (talk) 08:01, 22 January 2022 (UTC)Reply[reply]
The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Talk, notes, questions, suggestions

@NadVolum: The location of the lanthanides and actinides could be be made obvious by adding a column for them, as seem in the image. I feel that colors is something that should be the topic of a separate RFC, after this one. Sandbh (talk) 22:58, 20 January 2022 (UTC)Reply[reply]

Conventional periodic table showing where the Ln and An fit in
I certainly much prefer that! Thanks. NadVolum (talk) 16:52, 21 January 2022 (UTC)Reply[reply]
Incidentally, this is pretty much how the WebElements periodic table looks. Double sharp (talk) 20:17, 22 January 2022 (UTC)Reply[reply]

Graphic design

I feel that 18 or 32 is not primarily a graphic design question. Rather, it has more to do with the fact that there are only 18 numbered groups, not 32.

Another consideration is that the early actinides show some similarities to their transition metal congeners: 

Lu +3, Hf +4, Ta +5, W +6, Re +7, Os +8
Ac +3, Th +4, Pa +5, U +6, Np +7, Pu +8

This secondary alignment is not apparent in the 32-column form.

Further, there is a corollary between the lanthanides and d block metals extending to the similarities of La with Lu; Ce with Zr/Th [13]; and the recent preparation of Pr(V) cf. Ta(V).[14][15] Sandbh (talk) 03:46, 22 January 2022 (UTC)Reply[reply]

Prerequisite for this RfC question is, that there is no scientific difference between those two graphical (editorial, presentational) forms. And I don't see how one could wiggle in these scientific differences (in an RfC you wrote yourself btw). So no, this is *not* part of the discussion or proposals.
Already Eric Scerri et al. (2020) for IUPAC have declared that the presentation form between these 18/32 is a free choice, i.e., has no scientific meaning.[1]
Preceding unsigned comment was posted by DePiep.[16] Sandbh (talk) 11:31, 22 January 2022 (UTC)Reply[reply]
Just a small thing, but the font used in that 19 column form above could be made a bit larger to fit the cells more like they are in the current 32 bit form. Then the actual contents would be quite easily readable on a mobile without enlarging I think. NadVolum (talk) 09:58, 22 January 2022 (UTC)Reply[reply]

For consistency with the 89-102 cell below it, I think the 57-70 cell should have "La-Yb" instead of "La to Yb". Double sharp (talk) 11:52, 22 January 2022 (UTC)Reply[reply]

Done and Done, I believe! Sandbh (talk) 12:21, 22 January 2022 (UTC)Reply[reply]

Does anyone here know how to make animations? This would be a really great way to show the relationship between the 32 and 18/19 column forms. Not sure it would be a good idea for the led graphic, but somewhere in the article. YBG (talk) 17:59, 26 January 2022 (UTC)Reply[reply]

References

  1. ^ a b c Scerri, Eric (18 January 2021). "Provisional Report on Discussions on Group 3 of the Periodic Table" (PDF). Chemistry International. 43 (1): 31–34. doi:10.1515/ci-2021-0115. S2CID 231694898. Retrieved 9 April 2021.

Scientific meaning?

DePiep, above, suggests the choice between 18 or 32 columns has no scientific meaning, citing a Provisional Report.

A careful reading of the report shows that it makes no such statement. It is well known that when the switch occurred from the old short 8-column form to the 18-column, from the late 1920s onwards, many of the similarities between the old main group elements in columns I to VIII and their transitional metal counterparts became forgotten.[1] While nobody is advocating for a return to the 8-column form it is a fact that lining up the f-block under the d-block, as occurs in the 18-column form, is profitable in terms of bringing out and maintaining the secondary relationships between e.g. the early actinides and their transition metal congeners, as I explained earlier. These secondary relationships become disconnected in the 32 column form. Sandbh (talk) 13:01, 22 January 2022 (UTC)Reply[reply]

The report doesn't make such a statement, but the project's page does: The task group does not intend to recommend the use of a 32-column periodic table or an 18-column. This choice which is a matter of convention, rather than a scientific one, should be left to individual authors and educators. Double sharp (talk) 09:20, 24 January 2022 (UTC)Reply[reply]
I wonder why they felt the need to say what they were not going to recommend, given the scope of their work was to deliver a recommendation on the composition of group 3 as either Sc, Y, La and Ac; or Sc, Y, Lu and Lr? Sandbh (talk) 00:55, 26 January 2022 (UTC)Reply[reply]

g-block layout

Extended PT layout, with g block

Should we ever reach it.

For those who prefer footnote markers, that would be an opportunity to break out:

An swagger of asterisks IOW. Sandbh (talk) 01:17, 24 January 2022 (UTC)Reply[reply]

My objection to this is that the column between groups 2 and 3 makes it look like 121-138 go directly under Ac-No. Quite how 18 elements are supposed to fit under 14 is not quite explained.
That said, I think a layout like this would be clearer (taking the Aufbau extrapolation for now):
K   Ca                  Sc  Ti  V
Rb  Sr                  Y   Zr  Nb
Cs  Ba          La-Yb   Lu  Hf  Ta
Fr  Ra          Ac-No   Lr  Rf  Db
119 120 121-138 139-152 153 154 155 ...
Of course this is just theoretical at the moment. Also, it's not too clear to me how a hypothetical 50-column form of the table ought to look if some but not all of the g-block row is actually discovered. If 121 is discovered, but 122-138 aren't, then how do you connect the left and right sides? Ah well, this will presumably only be a problem in a decade or so... Double sharp (talk) 09:15, 24 January 2022 (UTC)Reply[reply]
Thanks. I hope the image is OK now. Sandbh (talk) 12:53, 24 January 2022 (UTC)Reply[reply]
Yes, except that 139 should be Ute rather than Utn. :) But that's hardly important.
The Madelung rule probably doesn't work this well up in the 130s and 140s, but still, Scerri has suggested that perhaps the table could follow it anyway: Now even if elements with atomic numbers as high as 139 and 140 were ever to materialize, one can still ask whether such unexpected orderings or violations of the Madelung rule should be reflected in any modified periodic table. After all, there are many violations of the Madelung rule such as the 20 well-known anomalous configurations beginning with chromium and copper which do not lead us to modify the periodic table. So it seems at least possible that this is what we'd end up with, especially since I doubt anyone would care about species that wouldn't even survive a microsecond. Double sharp (talk) 13:33, 24 January 2022 (UTC)Reply[reply]

Instead of asterisks, I wonder if "4f", "5f", "5g", "6f" would make better footnote markers, marking the exact subshell being filled in the respective footnotes. Double sharp (talk) 19:55, 24 January 2022 (UTC)Reply[reply]

I fixed Utn, err…Ute.
4f, 5f, 5g etc are potentially contentious since 4f―in a semi-formal sense―does not start filling until Ce; 5f does not do so until Pa; and 5g is not expected to make an appearance until perhaps 125. Sandbh (talk) 00:43, 26 January 2022 (UTC)Reply[reply]
Okay, fair enough. Being explicit is probably better for the lede, then. Double sharp (talk) 11:06, 26 January 2022 (UTC)Reply[reply]

References

  1. ^ Scerri, Eric (2020). The Periodic Table: Its Story and Its Significane. New York: Oxford University Press. p. 409. ISBN 9780190914370.

Semi-protected edit request on 23 January 2022

change "this its only valence electron" to "this is its only valence electron" Jesbus (talk) 23:20, 23 January 2022 (UTC)Reply[reply]

 Done, good catch. Thanks,  BelowTheSun  (T•C) 00:14, 24 January 2022 (UTC)Reply[reply]
Categories