→On the "supposed" consistency of the literature: Last try at being reasonable |
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== RFC: Should the default form of the periodic table be changed to put Lu and Lr in group 3, rather than La and Ac? == |
== RFC: Should the default form of the periodic table be changed to put Lu and Lr in group 3, rather than La and Ac? == |
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{{rfc|sci|rfcid=C4F78FE}} |
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Should the default appearance of the periodic table on Wikipedia be changed to what it was in 2016, i.e. to have lutetium (<sub>71</sub>Lu) and lawrencium (<sub>103</sub>Lr) in group 3 rather than lanthanum (<sub>57</sub>La) and actinium (<sub>89</sub>Ac)? Or should it simply have markers below yttrium where all the lanthanides and actinides are supposed to go in? [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 10:08, 20 July 2020 (UTC) |
Should the default appearance of the periodic table on Wikipedia be changed to what it was in 2016, i.e. to have lutetium (<sub>71</sub>Lu) and lawrencium (<sub>103</sub>Lr) in group 3 rather than lanthanum (<sub>57</sub>La) and actinium (<sub>89</sub>Ac)? Or should it simply have markers below yttrium where all the lanthanides and actinides are supposed to go in? [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 10:08, 20 July 2020 (UTC) |
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:Note for further clarification: ''this does not propose to treat any form as the only one'', because that would contradict [[WP:NPOV]]. On this article we must of course discuss both forms and treat them neutrally but briefly, that goes without saying. I simply mean to discuss the appearance of our templates like {{tlx|Periodic table}}, {{tlx|Compact periodic table}}, the one in the infoboxes like {{tlx|infobox helium}}, etc. These normally appear as navigation aids in articles where the group 3 dispute is simply irrelevant, therefore unless someone has a better solution we seem to need to pick a default form for those. [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 12:44, 20 July 2020 (UTC) |
:Note for further clarification: ''this does not propose to treat any form as the only one'', because that would contradict [[WP:NPOV]]. On this article we must of course discuss both forms and treat them neutrally but briefly, that goes without saying. I simply mean to discuss the appearance of our templates like {{tlx|Periodic table}}, {{tlx|Compact periodic table}}, the one in the infoboxes like {{tlx|infobox helium}}, etc. These normally appear as navigation aids in articles where the group 3 dispute is simply irrelevant, therefore unless someone has a better solution we seem to need to pick a default form for those. [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 12:44, 20 July 2020 (UTC) |
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::Current RFC withdrawn for a last try at drafting something both Sandbh and I will find acceptable. [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 08:51, 21 July 2020 (UTC) |
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===The three forms=== |
===The three forms=== |
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=====Last try at being reasonable===== |
=====Last try at being reasonable===== |
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{{ping|Double sharp}} So, are we going to cancel this RFC and come up with an NPOV version, suitable for another RFC post online publication of my article, or are you going to waste everyone's time and some poor [[WP:ADMIN]]'s? [[User:Sandbh|Sandbh]] ([[User talk:Sandbh|talk]]) 08:19, 21 July 2020 (UTC) |
{{ping|Double sharp}} So, are we going to cancel this RFC and come up with an NPOV version, suitable for another RFC post online publication of my article, or are you going to waste everyone's time and some poor [[WP:ADMIN]]'s? [[User:Sandbh|Sandbh]] ([[User talk:Sandbh|talk]]) 08:19, 21 July 2020 (UTC) |
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:{{ping|Sandbh}} RFC tag removed (I understand this withdraws the RFC). |
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:Now I have stepped back and thought about it. I have gone overboard, and I apologise for it. I am still not at all convinced by your arguments and believe the Lu form is significantly better. However, since I also believe helium over beryllium is significantly better, yet recognise that that approach has no chance to become the default on WP, I am willing to let this one go provided we add notes to the relevant articles like what I did on [[helium]] explaining that there is a dispute. So, I have decided not to start a new RFC even after your article is published. |
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:I do not wish to discuss the issue further on WP at present. Everything relevant has already been said far too many times, and it seems unlikely that either of us are going to change our minds if it is said more times. It is also true that the fact that most textbooks discuss Sc, Y, La, and Ac together is, for Wikipedia, probably definitive at this moment. So, let's drop the issue until and unless IUPAC decides eventually on Lu under Y. In that circumstance, I think no one will argue that an RFC will be justified, but we do not have it at the moment. |
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:Respectfully, [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 08:51, 21 July 2020 (UTC) |
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===Discussion=== |
===Discussion=== |
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*<big>'''Extremely strong oppose'''</big> (I have to make this prominent to balance and counteract the supports above) Just about all the arguments are irelevant and we should just use the traditional form eith La and Ac under Y. If needed we can use the place holder * or **. [[User:Graeme Bartlett|Graeme Bartlett]] ([[User talk:Graeme Bartlett|talk]]) 07:52, 21 July 2020 (UTC) |
*<big>'''Extremely strong oppose'''</big> (I have to make this prominent to balance and counteract the supports above) Just about all the arguments are irelevant and we should just use the traditional form eith La and Ac under Y. If needed we can use the place holder * or **. [[User:Graeme Bartlett|Graeme Bartlett]] ([[User talk:Graeme Bartlett|talk]]) 07:52, 21 July 2020 (UTC) |
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*'''Illegitimate RFC''' due to breaching [[Wikipedia:Neutral point of view|'''Neutral point of view''']], [[Wikipedia:Verifiability|'''Verifiability''']], [[Wikipedia:No original research|'''No original research''']], and [[Wikipedia: Civility|'''Lack of civility''']]. [[User:Sandbh|Sandbh]] ([[User talk:Sandbh|talk]]) 08:15, 21 July 2020 (UTC) |
*'''Illegitimate RFC''' due to breaching [[Wikipedia:Neutral point of view|'''Neutral point of view''']], [[Wikipedia:Verifiability|'''Verifiability''']], [[Wikipedia:No original research|'''No original research''']], and [[Wikipedia: Civility|'''Lack of civility''']]. [[User:Sandbh|Sandbh]] ([[User talk:Sandbh|talk]]) 08:15, 21 July 2020 (UTC) |
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*:{{ping|Sandbh}} RFC tag removed (I understand this withdraws the RFC). |
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*:Now I have stepped back and thought about it. I have gone overboard, and I apologise for it. I am still not at all convinced by your arguments and believe the Lu form is significantly better. However, since I also believe helium over beryllium is significantly better, yet recognise that that approach has no chance to become the default on WP, I am willing to let this one go provided we add notes to the relevant articles like what I did on [[helium]] explaining that there is a dispute. So, I have decided not to start a new RFC even after your article is published. |
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*:I do not wish to discuss the issue further on WP at present. Everything relevant has already been said far too many times, and it seems unlikely that either of us are going to change our minds if it is said more times. So, let's drop the issue until and unless IUPAC decides eventually on Lu under Y. In that circumstance, I think no one will argue that an RFC will be justified, but we do not have it at the moment. |
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*:Respectfully, [[User:Double sharp|Double sharp]] ([[User talk:Double sharp|talk]]) 08:51, 21 July 2020 (UTC) |
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Mendeleev Tabli first edition
According to the final chronology of the first publications of the Mendeleev’s Periodic Table (Druzhinin, 2020[1]), the first Medneleev ‘s Table published March 26-27 [O.S. March 14-15] 1869 in the Mendeleev’s The Principles of Chemistry 1st Edition, and around March 17 [O.S. March 29] 1869 Mendeleev printed separate broadsheets with Periodic table - Attempt - to be sent to overseas scientists; April 17/19 for the first time the Mendeleev’ Periodic table was published in Europe in Journal für Praktische Chemie (in German)[2]
References
- ^ Druzhinin, Petr (2020). "The First Publication of Mendeleev's Periodic System of Elements: A New Chronology". Historical Studies in the Natural Sciences. 50: 129–182.
- ^ Mendeleev, Dmitri (1869). "Versuche eines Systems der Elemente nach ihren Atomgewichten und chemischen Functionen" [System of Elements according to their Atomic Weights and Chemical Functions]. Journal für Praktische Chemie. 106: 251.
A relevant argument, unfortunately incomplete in sources
I wrote this paragraph, but then deleted it:
“ | Because of the almost completely regular variation of lattice and solvation energies across the lanthanide series, the most important factor determining redox stability of lanthanide compounds is the third ionisation energy. This almost always involves the loss of one f electron, for which ligand field stabilisation energies are negligible as the f shells are deeply buried; that is distinct from the behaviour of the d transition elements. In almost all cases this ionisation is M2+ (4fn) → M3+ (4fn−1); although lanthanum (La2+ [Xe]5d1) and gadolinium (Gd2+ [Xe]4f75d1) are exceptions, the regular configurations [Xe]4f1 and [Xe]4f8 are very low-lying excited states (energies 0.8881 eV and 0.295 eV) respectively that negligibly affect the ionisation energy trend on being subtracted (the third ionisation energies of La and Gd respectively are 19.1773 eV and 20.63 eV). Similar processes are observed for example in the condensation of the lanthanides, which generally involves the transition 4fn6s2 → 4fn−15d16s2 and so varies in energy similarly to the above 4fn → 4fn−1 ionisations. In condensed phases the configurations of the Ln2+ may also change due to smaller destabilisation of the 5d orbitals compared to the 4f by ligand field effects. Energy variation of a process across the lanthanide series can be predicted from how the number of 4f electrons changes during its reactions. However, lutetium cannot be considered to be of this type as an f shell cannot hold the 15 electrons that would be required. Similarly, if we consider the processes where it is the relative stability of M3+ and M4+ that is at stake, then lanthanum cannot be considered as getting it to the +4 state would require breaking open the xenon core. (cite Johnson from the article) | ” |
The problem is that this argument, so far as it is taken in the source, does not clearly support either La-Yb or Ce-Lu as the 4f row. (Of course, there are lots of arguments about why La-Yb is the right answer and why the arguments for Ce-Lu are focusing on chemical irrelevancies in the literature. I know it probably doesn't look like the periodic table in your textbook, but (1) that textbook is probably not focusing on group 3 and (2) if you can cite Seaborg, as well as Landau and Lifshitz, on your side, like I have, it's definitely not a fringe view. XD) In order to make it complete, you would have to note that physical properties universally support the +2 to +3 process' double periodicity, but so far I haven't seen that being noted. Which is admittedly a bit puzzling, because it is absolutely obvious from the cited values of melting and boiling points: minima occur at Eu and Yb, just as they do at Mn and Zn. Double sharp (talk) 04:44, 18 May 2020 (UTC)
- Deleting it was a good move.
- Johnson: The relevance of his reference to the third ionisation energy involving the loss of one f electron in the free atom, is puzzling.
- The Ln metals, as opposed to the free atoms, are mostly f1-14d1s2. In their most stable trivalent cationic forms they are f1-14. Here, Ce3+ is f1, Pr3+ is f2, ending with Yb3+ f13 and Lu3+ f14. Thus, the f-block metals and their cations run from Ce-Lu. La is not include in the particular set, since La3+ is [Xe] i.e. it has no f electron.
- As Seaborg wrote, "it is the electronic structure of the ions and compounds that we are chiefly concerned with in chemistry".
- Seaborg again: An examination of Seaborg's article on the development of the actinide hypothesis shows he consistently distinguished between La-Ac, and Ce-Lu, Th-Lr. See figures 2, and 4-6 (pp. 52, 54-56).
- The right answer: There are no arguments about why La-Yb is the "right" answer. Rather, there are some arguments in the literature suggesting La-Yb looks better in some cases. Many of these are one-shots based on a single property. Jensen had a red-hot go at corralling these arguments in 1982, in support of La-Yb, but his effort failed to gain traction. He was criticized by Scerri, (chair of the IUPAC Group 3 project group) and Parsons (2018, p. 143), for being too selective in his arguments. There was Holden (1985) who looked at seven properties but estimated the argument of Landau & Ligshitz (1958) to be the strongest. For a discussion as to the unreliability of Landau and Lifshitz, see here.
- A survey by the IUPAC Group 3 project team found that the majority of textbook and other periodic tables in the 18-column format show the elements of group 3 as scandium, yttrium, lanthanum and actinium. The survey did not include a Google image search, since such results are plagued by bias arising from the false impression that the IUPAC *-** table is “official”, and unreliable sources.
- Mathias (1969) grumbled about La in group 3 being the most popular form. Myers, Oldham and Tocci (2004, p. 130) found La and Ac to be the most popular form of periodic table, a sentiment echoed by Clarke and White (2008); and Lavelle (2008; 2009).
- Clark RW & White GD 2008, "The flyleaf periodic table", Journal of Chemical Education, vol. 85, no. 4, p. 497
- Holden NE 1985, Status of the lanthanides and actinides in the periodic table, accessed 24 November 2016
- Jensen WB 1982, The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table, Journal of Chemical Education vol. 59, pp. 634−636
- Lavelle L 2008, "Lanthanum (La) and actinium (Ac) should remain in the d-block", Journal of Chemical Education, vol. 85, no. 11, pp. 1482–1483, doi: 10.1021/ed085p1482
- —— 2009, "Response to misapplying the periodic law", Journal of Chemical Education, vol. 86, no. 10, p. 1187, doi: 10.1021/ed086p1187
- Mathias BT 1969, "Systematics of superconductivity", in PR Wallace (ed.), "Superconductivity: Proceedings of the Advanced Summer Study Institute on Superconductivity", McGill University, Montreal, vol. 1, Gordon and Breach, New York, pp. 225−294
- Myers RT, Oldham KB & Tocci S 2004, Holt chemistry, Holt, Rinehart and Winston, Orlando
- Scerri ER & Parsons W 2018, "What elements belong in Group 3 of the periodic table?". In E Scerri & G Restrepo (eds), Mendeleev to Oganesson: A multidisciplinary perspective on the periodic table, Oxford University Press, New York, pp. 140–151
- Chemical irrelevancies: There are no arguments in the literature, to my knowledge, saying Ce-Lu is focusing on "chemical irrelevancies".
- Double periodicity: As to Eu and Yb, and Mn and Zn, it is more relevant, from a chemistry based view, rather than a physical property-based view, to note double periodicity for the 4f and 3d metals pivots around Gd and Lu, and Mn and Zn.
- Shchukarev (1974, p. 118), a well-regarded Russian chemist, supported -La-Ac on the grounds that the 4f shell does not start filling until cerium and that (effectively) the filling sequence—which runs from cerium to lutetium—is periodic, with two periods. Thus, after the occurrence of a half-full 4f shell at europium and gadolinium, the filling sequence repeats with the occurrence of a full shell at ytterbium and lutetium (Rokhlin 2003, pp. 4–5). A similar, but weaker, periodicity (Wiberg 2001, p. 1643–1645) is seen in the actinoids, with a half full 5f shell at americium and curium, and a full shell at nobelium and lawrencium.
- Placing lutetium and lawrencium under yttrium obscures the start of the filling of the f-block (it would appear to start at lanthanum) and visually truncates its double periodicity (it would be cut off at ytterbium whereas it would actually end in the d-block). In Shchukarev’s words, the "correctness of placing of imitators before gadolinium and curium as well as lutetium and lawrencium, would be lost. The exceptional uniqueness of Gd and Cm, akin to that of Mn and Zn, would also be unclear."
- Here is what a lanthanum table looks like:
+4 +2 | +4 +2 Ce Pr Nd Pm Sm Eu Gd | Tb Dy Ho Er Tm Yb Lu ½f ½f | f f | +4 +2 | +4 +2 Th Pa U Np Pu Am Cm | Bk Cf Es Fm Md No Lr ½f ½f f f
- Shchukarev’s imitators are Eu2+ and Yb2+ which like to attain the Gd3+ and Lu3+ cores. Then there is Ce4+, which likes to attain the core of its lanthanoid progenitor namely La3+; and Tb4+ attaining the same configuration as Gd3+.
- Europium, the most reactive of the lanthanoids, is associated with the place of a halogen, and gadolinium is associated with place of a noble gas, although to a much lesser degree. See the Rare-earth metal long term air exposure test (Hamric 2007). Terbium to lutetium are much less reactive, and the Group 17/18 analogy is not seen here.
- The f-block contraction starts with Ce3+ and culminates in Lu3+.
- The lutetium option is less regular:
+4 +2 | +4 +2 La Ce Pr Nd Pm Sm Eu | Gd Tb Dy Ho Er Tm Yb ½f | ½f f | +4 +2 | +4 +2 Ac Th Pa U Np Pu Am | Cm Bk Cf Es Fm Md No ½f ½f f
- The ½-filled and filled f- sub-shell regularity is lost; the correspondence of europium and gadolinium to Group 17 and 18 metals is lost; the f-block contraction starts with Ce3+ and awkwardly finishes in the d-block.
- Shchukarev’s approach is consistent with the observation of a progressively delayed start of filling of the f-shell as one goes down the periodic table i.e. at cerium for 4f; at protactinium for 5f although some 5f involvement may be possible for thorium (Edelstein & Kot 1993, p. 86); and at E123−125(?) for 5g (Eugen Schwarz, pers. comm. 8 Dec 2019).
- This double periodicity had been noted by Klemm (1929; 1930) on the basis of atomic structure (Remy 1956, p. 492); and by Sobolev (2000, pp. 44–45).
- Edelstein NM and Kot WK 1993, "Spectroscopic and magnetic studies of tetravalent Pa and trivalent Th compounds", Journal of Alloys and Compounds, vol. 193. pp. 82–87
- Hamric D 2007, "Rare-earth metal long term air exposure test", Metallium, Inc., viewed 7 March 2020
- Horovitz O & Sârbu C 2005, "Characterisation and classification of lanthanides by multivariate-analysis methods", Journal of Chemical Education, vol. 82 no. 3, pp. 473–483, doi: 10.1021/ed082p473
- Klemm W 1929, "Measurements on divalent and quadrivalent rare earth compounds. II. A system of rare earths based on periodic property changes of their ions", Zeitschrift für anorganische und allgemeine Chemie, vol. 184, p. 345
- —— 1930, "Measurements on divalent and quadrivalent rare earth compounds. IV. Supplement to the communication: A system of rare earths", Zeitschrift für anorganische und allgemeine Chemie, vol. 184, p. 29
- Remy H 1956, Treatise on inorganic chemistry, vol 2, Elsevier, Amsterdam
- Rokhlin LL 2003, Magnesium alloys containing rare earth metals: Structure and properties, Taylor & Francis, London
- Sobolev BP 2000, The rare earth trifluorides: The high temperature chemistry of the rare earth trifluorides, vol. 1, Institut d'Estudis Catalans, Barcelona, pp. 44–45
- Ternström T 1976, "Subclassification of lanthanides and actinides", Journal of Chemical Education, vol. 53, no. 10, pp. 629–631
- Wiberg N 2001, Inorganic Chemistry, Academic Press, San Diego
- Physical properties: Concluding with these, lutetium resembles the 5d transition metals more than is the case for lanthanum. That said, lutetium resembles closely erbium and holmium, and while it melts at a slightly higher temperature and is essentially non-magnetic, the details of producing, purifying and fabricating it are almost identical to that for holmium (Spedding et al. 1968).
- Spedding FH & Beadry BJ 1968, "Lutetium", in CA Hampel (ed.), The encyclopedia of the chemical elements, Reinhold Book Corporation, New York, pp. 374–378
Recent attempts to change the periodic table (Scerri 2020)
Here's a link to the latest article by Eric Scerri, a world authority on the periodic table.
Here are some extracts from, and my commentary on, this interesting piece:
Philosophy v pragmatism?
The focus of the paper is philosophy rather than pragmatism. (p.2)
I suggest a need to focus on philosophy and pragmatism.
Focusing on just one results in needless arguments, including of the kind I used to make.
Insisting on one PT
Scerri writes:
- "There is no need to insist on the periodic table having a format that is suited mainly for the purposes of the chemical community and for chemical educators." (p. 6)
As far as I know, no one has made such an insistence. It is rather a case of people insisting on such a table within a particular sub-context or interest dependence, and usually not making this clear enough.
Who owns the PT?
Scerri writes:
- "The periodic table has now become as much the property of physicists, geologists, astronomers and others as it is of its chemical originators." (p. 7)
This is a contentious generalisation.
I suggest the periodic table, in the first instance, remains the organising icon of chemistry. Thus, here is what Scerri said in the 2nd (2020) edition of his Red Book:
- "…it helps to remember that, when all is said and done, the periodic table remains primarily in the domain of chemistry, although the relationship between chemistry and the underlying explanation from physics remains as the underlying theme… (p. ix)"
Rather than becoming a shared commodity, the periodic table concept has been borrowed, adapted, tailored and presented in various different guises—including the 15-element wide f-block version—by the physicists, geologists, astronomers and others.
As Scerri rightly says:
- "It becomes increasingly clear that there may not be any such thing as one optimal table in a purely objective sense. The question seems to depend on what criteria are considered and, most importantly perhaps, on whether one favours chemical or physical criteria or general didactic considerations." (p. 12)
To this commendable end, he goes on:
- "We should accept that a degree of convention must be used in selecting a periodic table that can be presented as perhaps the best possible table that combines objective factors as well as interest dependence." (p. 14)
Quite so, having regard to the priorities of each interest group.
The Madelung Rule
- "In any case, it is interesting to see that Pyykkö admits that it is surprising, in view of the relativistic effects, that the Madelung rule survives so well all the way up to atomic number 172." [!] (p. 8)
As far as the MR anomalies/symmetry breaking we observe in real life are concerned, the analogy is to an aeroplane experiencing turbulence. The flight path always returns to normal, after each turbulence episode.
The MR can also be regarded as the "spine" underlying the pattern of free atom electron configurations. The spine has bumps, dips, and knobbly bits on it, but still runs "true", so to speak.
Group 3
- "While the majority of textbook and other periodic tables in the 18-column format show the elements of this group as scandium, yttrium, lanthanum and actinium, a significant number of more recent tables feature the last two elements as lutetium and lawrencium instead." (p. 10)
Serving the largest audience
Scerri seems to go off-message in his conclusion, with references to:
- "…the format of the periodic table that serves the greatest number of periodic table users including students, instructors and practising chemists alike"; and
- "…how the periodic table is presented to the widest possible audience of users." (p. 15)
Surely the result of these notions will be a periodic table that attempts to cater to everyone but pleases no one?
Going off-message at this point is peculiar, since he earlier wrote:
- "It becomes increasingly clear that there may not be any such thing as one optimal table in a purely objective sense. The question seems to depend on what criteria are considered and, most importantly perhaps, on whether one favours chemical or physical criteria or general didactic considerations." (p. 12)
Accordingly, give me a tailor-made PT anytime, whether that is 14CeTh, 15LaAc, or 14LaAc, Adomah, AAE, Janet or some other variation, as long as the applicable context is set out.
The bugaboo of the split s-block
Scerri notes the periodic table is generally depicted with helium in group 18, and this splits the s-block (p. 11).
This is one of those things—the split s-block—that effectively all chemists (to a first approximation) do not lose any sleep over.
Same goes for the split d-block, which is less visible.
That said, better chemists keep both of these interesting aspects of the PT in mind.
It is like what Jones says:
- "Scientists should not lose sleep over the hard cases. As long as a classification system is beneficial to economy of description, to structuring knowledge and to our understanding, and hard cases constitute a small minority, then keep it. If the system becomes less than useful, then scrap it and replace it with a system based on different shared characteristics." Jones 2010, Pluto: Sentinel of the outer solar system, Oxford University Press, p. 171).
The anomalous first period
- "Another attractive feature of the left-step table is that it restores regularity and perhaps even balance to the otherwise awkwardly shaped traditional periodic table representation. More significantly than such aesthetic considerations, this table provides greater regularity in depicting every single-period length as repeating once as, 2,2,8,8,18,18,32,32. Meanwhile, the traditional table features an anomalous first period that, unlike all subsequent ones, does not repeat in length to give a sequence of 2,8,8,18,18,32,32. (p. 13)
I don't understand why the lack of repetition of the length of the first period is regarded as anomalous. There is no first principles derivation being breached here, as far as I know. It only means that, from a chemistry perspective, it is more meaningful to break the periods after the end of the noble gases. At the same time, the left step table is still good for its particular uses.
Thorium
- "Needless to say, the characterization of these blocks of the periodic table is only approximate, just as the assignment of electronic configurations to atoms represents an approximation. Moreover, one may readily concede that an element such as thorium does not actually possess any f-orbital electrons and yet it is classified as being among the f-block elements even in all four of the periodic table representations shown in figures 10 to 13.
--- Sandbh (talk) 00:44, 19 July 2020 (UTC)
RFC: Should the default form of the periodic table be changed to put Lu and Lr in group 3, rather than La and Ac?
Should the default appearance of the periodic table on Wikipedia be changed to what it was in 2016, i.e. to have lutetium (71Lu) and lawrencium (103Lr) in group 3 rather than lanthanum (57La) and actinium (89Ac)? Or should it simply have markers below yttrium where all the lanthanides and actinides are supposed to go in? Double sharp (talk) 10:08, 20 July 2020 (UTC)
- Note for further clarification: this does not propose to treat any form as the only one, because that would contradict WP:NPOV. On this article we must of course discuss both forms and treat them neutrally but briefly, that goes without saying. I simply mean to discuss the appearance of our templates like
{{Periodic table}}
,{{Compact periodic table}}
, the one in the infoboxes like{{infobox helium}}
, etc. These normally appear as navigation aids in articles where the group 3 dispute is simply irrelevant, therefore unless someone has a better solution we seem to need to pick a default form for those. Double sharp (talk) 12:44, 20 July 2020 (UTC)
- Current RFC withdrawn for a last try at drafting something both Sandbh and I will find acceptable. Double sharp (talk) 08:51, 21 July 2020 (UTC)
The three forms
Lu and Lr below Y. The form I propose, and which we had before 2016.
18-column:
H | He | |||||||||||||||||
Li | Be | B | C | N | O | F | Ne | |||||||||||
Na | Mg | Al | Si | P | S | Cl | Ar | |||||||||||
K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr | |
Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe | |
Cs | Ba | * | Lu | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
Fr | Ra | ** | Lr | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |
* | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | ||||
** | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No |
32-column:
H | He | ||||||||||||||||||||||||||||||
Li | Be | B | C | N | O | F | Ne | ||||||||||||||||||||||||
Na | Mg | Al | Si | P | S | Cl | Ar | ||||||||||||||||||||||||
K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr | ||||||||||||||
Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe | ||||||||||||||
Cs | Ba | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
Fr | Ra | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |
La and Ac below Y. The current form.
18-column:
H | He | |||||||||||||||||
Li | Be | B | C | N | O | F | Ne | |||||||||||
Na | Mg | Al | Si | P | S | Cl | Ar | |||||||||||
K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr | |
Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe | |
Cs | Ba | La | * | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
Fr | Ra | Ac | ** | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |
* | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | ||||
** | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |
32-column:
H | He | ||||||||||||||||||||||||||||||
Li | Be | B | C | N | O | F | Ne | ||||||||||||||||||||||||
Na | Mg | Al | Si | P | S | Cl | Ar | ||||||||||||||||||||||||
K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr | ||||||||||||||
Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe | ||||||||||||||
Cs | Ba | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
Fr | Ra | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |
Markers below Y. The compromise form. IUPAC shows it on its periodic table, but they also plan to change it to one of the other forms. Which one has not been decided.
18-column:
H | He | ||||||||||||||||
Li | Be | B | C | N | O | F | Ne | ||||||||||
Na | Mg | Al | Si | P | S | Cl | Ar | ||||||||||
K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr |
Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe |
Cs | Ba | * | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
Fr | Ra | ** | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |
* | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | ||
** | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |
32-column (note the stretching of scandium and yttrium necessary):
H | He | ||||||||||||||||||||||||||||||
Li | Be | B | C | N | O | F | Ne | ||||||||||||||||||||||||
Na | Mg | Al | Si | P | S | Cl | Ar | ||||||||||||||||||||||||
K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr | ||||||||||||||
Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe | ||||||||||||||
Cs | Ba | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
Fr | Ra | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn | Nh | Fl | Mc | Lv | Ts | Og |
Background information by Double sharp
I spent some time making this issue understandable for any bystanders who may want to join in, helped by feedback from User:Dreigorich. As such, here is an explanation in the form of a dialogue. I have tried to keep answers very short. (The first version was a huge wall of text. Now it is not.)
The issue had its most recent reignition on Wikipedia in December 2019 and raged on through Wikipedia talk:WikiProject Elements/Archive 42, Wikipedia talk:WikiProject Elements/Archive 44, Wikipedia talk:WikiProject Elements/Archive 46, and until a few days ago Wikipedia talk:WikiProject Elements. I say "until a few days ago" because that's when I gave up the endeavour as fruitless: nobody seems about to have a change in opinion, and the arguments are raging in circles, and civility has been thrown out the window (and I realise now that I'm partly responsible for that, which I'm sorry for).
At that point we had exactly, among eight participants:
- one (1) editor in favour of La (Sandbh);
- five (5) in favour of Lu (myself, Droog Andrey, Officer781, Dreigorich, ComplexRational);
- and two (2) who at least found the arguments being made in favour of La questionably convincing (DePiep, R8R).
Since the issue was previously decided in an RFC back at Template talk:Periodic table, discussion between me and R8R concluded that going to another RFC would be the best way to propose it be changed back to how it was before the first RFC. Given that that RFC was over three years ago, and one of the main La proponents in it was me, and I've learnt enough new information since then that makes me think that the arguments I was propounding were wrong-headed, I think starting a new RFC is also most reasonable.
In theory one should get a neutral editor to write the background information. However, the problem is that this issue has something in common with many of the disputes at Wikipedia:Lamest edit wars. It is impossible to find a neutral editor to write background information because as soon as she looks at the issue enough to understand the background information, she takes a side herself and is no longer neutral. That is quite unusual given that Wikipedia:Lamest edit wars does not have a category for natural science, much less chemistry. Indeed, the main positive difference between the issue here and the ones over there is that so far there has not been any actual edit warring. Some uncivil remarks when people on either side get fed up, yes, and I am sorry that I have made some of them. But, thankfully, no edit warring.
So I wrote it. Even if I obviously have an opinion and am obviously supporting it with arguments here, I'm at least referring to reliable sources focusing on the issue to do it. If that is still not suitable, then this may at least be considered as a long explanation of my !vote rather than background information.
Questions 1 to 5
Q1: What are you arguing about?
Well, it turns out that somewhere near the bottom-left of the periodic table there's a bit of a dispute about which elements should go where.
Q2: Really? But I thought the periodic table was ancient history chemically speaking.
Yes, Mendeleev's first table dates from 1869. We still haven't sorted everything out, though. There are a bunch of elements that are rather difficult to place.
Q3: That sounds interesting. Tell me more.
In the words of Eric Scerri, "there's trouble at the beginning, middle and end of the periodic table". This RFC is about the middle: the rare earth elements.
Q4: So are you going to tell us what it is already?
It comes down to whether lutetium (Lu) or lanthanum (La) is a better fit for the position under yttrium (Y) in the periodic table. There's also a third form which has all fifteen lanthanides under yttrium, which we did have on WP a while ago, but not anymore.
Q5: Why is this so terribly important? If an element fits well in two places, why not duplicate it in both positions?
This is not generally done by reliable sources, except maybe when making a point. Therefore on Wikipedia we should not start doing it.
Questions 6 to 10
Q6: What about the "markers below yttrium" form? Isn't it a reasonable compromise?
It looks like one, but it is also a side in itself.
I do not support it for two reasons. One is technical. We sometimes use 32 column templates because they fit better as footers, e.g. {{compact periodic table}}
, and then this approach becomes really problematic: scandium and yttrium have to stretch to cover 15 columns.
The other is chemical. This form claims that the f-block is a degenerate branch of the d-block and thus by extension that the f orbitals are a part of the valence core, which is simply false for almost all the elements involved (all but Lu and Lr, in fact). Every redox-capable f element (which is almost all of them) is obviously using its f electrons, and even those which are not seem to have some f contribution anyway (see Q22). See Jensen for a discussion. Maybe all the lanthanides are similar enough to fit below yttrium, but can anyone really claim that for the actinides?
Q7: Well, shouldn't we follow NPOV and show all three options all the time then?
That makes sense, and is what I support, when the group 3 controversy is the topic at hand. But usually it is not. Then you have to pick one to avoid going off on a tangent which is not relevant. Below I argue for Lu under Y.
For reasons of brevity, I will hence forth shorten the options' names to:
- Lu table: Lu and Lr below Y.
- La table: La and Ac below Y.
- * table: Markers * and ** below Y.
Q8: The things are called lanthanides and actinides. Shouldn't lanthanum and actinium continue to be used as the placeholders?
They're not placeholders. The * table and La table are different. Moreover, the whole point of the categories "lanthanide" and "actinide" is that those elements are similar to La and Ac. It seems quite weird to put La and Ac away from the rest of them. It is less weird for Lu (whose properties among the lanthanides are furthest from those of La) and not weird at all for Lr (which is quite unlike the other late actinides Es-No in properties).
Q9: IUPAC is the relevant source here, surely? What do they have to say?
They show their table as a * table, but they also state:
“ | While IUPAC has no recommendation for a specific form of the periodic table, i.e. 18-column or 32-column format, the version here presented is in the conventional long form and is yours to use. | ” |
— IUPAC Periodic Table website |
So it is not clear if that is an actual IUPAC recommendation for the * form or not.
IUPAC also organised a project to resolve precisely this issue, as can be seen from number 7 on their periodic table page. That project considers the La and Lu alternatives, but not the * one that they currently show. It started in 2015 and still has not concluded anything. Since it has both strong La and Lu proponents on it I also doubt it will conclude anything soon.
All we can conclude for now is that they seem to intend to deprecate the * form they currently show, thus leaving us without a firm guide in the meantime.
Q10: Why aren't we waiting for them then?
Because (1) I doubt that their work will be finished anytime soon, (2) we don't always follow IUPAC (we follow it for spelling aluminium but not for phosphane), and (3) any way you look at it, we have to show something in the meantime, see Q7.
I argue that we should look at the consensus of reliable sources that focus on the matter. Because an article focusing on group 3 and explaining why the authors think La or Lu should be there, I argue, outweighs in terms of reliability somebody who just draws a periodic table and gives no clue as to why he or she has drawn it that way. I claim that's in favour of Lu.
Questions 11 to 15
Q11: What do most reliable sources say?
Depends really. If you do a Google Image survey on "periodic table", * below Y dominates with proportions La:Lu:* of 1:1:4. The IUPAC project organised a survey that seems to show that La below Y dominates in textbooks (with La:Lu:* proportions of 4:1:1). However usually those textbooks have * in the same cell as La with a group 3 header above, therefore also implicitly claiming that the other lanthanides go there. So there is, at least, an ambiguity. Also, all these dominances are just 2/3 majorities, it's not a rare thing at all to find a textbook or periodic table poster giving Lu below Y.
I claim it's more relevant to look at what articles specifically focusing on this issue tell us, because it's common for textbooks to repeat standard errors on issues like this (e.g. claims that d orbitals are involved for phosphorus in PCl5, which are false but ubiquitous in textbooks), and most of these textbooks are hardly focusing on these heavy 4f and 5d elements that the dispute is all about. Those have a majority supporting the Lu form. I tallied them with Sandbh in an old submission to IUPAC we made on this matter in 2016; I've updated the list to 2020 below. Back then we agreed that La is better; then I changed my mind in response to new evidence from Droog Andrey that Lu is better, so we started arguing.
Advocates Lu | Advocates La | Advocates * |
---|---|---|
Bury (1921) Shemyakin (1932) Landau and Lifshitz (1958) Hamilton (1965) Merz and Ulmer (1967) Chistyakov (1968) Mathias (1971) Wittig (1973) Jensen (1982 and again 2015) Holden (1985) Fang et al. (2000) Horovitz and Sârbu (2005) Wulfsberg (2006) Ouyang et al. (2008) Scerri (2012) Nelson (2013) Settouti and Aouragi (2014) Alvarez (2020) |
Smith (1927) Trifonov (1970) Shchukarev (1974) Atkins (2006) Lavelle (2008) Restrepo (2017) Cao et al. (2020) |
Xu and Pyykkö (2016) |
Q12: Aren't you essentially claiming that a whole lot of eminent scientists are wrong?
It's a controversy. No matter which side you pick you're going to be claiming that a whole lot of eminent scientists are wrong. La advocates like Sandbh have Sergey Shchukarev on their side, Lu advocates like me have Landau and Lifshitz, so we can see that both options have had respected adherents. That's why I claim we have to look at the articles focusing on this issue and also consider the chemistry involved.
Q13: Many chemists have never heard that there was such a debate. Are you sure you're not just another fringe theory peddler?
Landau and Lifshitz are hardly "fringe". Neither is Clayden et al.'s Organic Chemistry, which has a Lu table. And Jensen, before his 1982 article, had not heard of this debate either.
Q14: What is the status of that interminable thread at Wikipedia talk:WikiProject Elements, stretching from last December to this July?
We have 5-1 for Lu and an extra two who at least think the La arguments proffered are problematic.
- Well, I guess it goes without saying that I support the Lu form, yes?
- "La arguments are totally local, while Lu arguments are pretty regular. That exactly matches Ptolemy vs. Copernicus. The history just repeats itself. Nothing more to say." - Droog Andrey
- "Cool, thanks. This makes perfect sense. Well said. Team Lu for me!" - Dreigorich
- "I'd really just want to get rid of the Scandium/Yttrium overhang in the long periodic table. It is ugly and very artificial IMO." - Officer781
- "I am more convinced by the Lu arguments I've read, and given the support of the scientific community and lack of consensus against it here (no "battleship" as you describe), I'll join the RfC once it's underway." - ComplexRational
- "Even worse, a publication may be biased towards a preference for more simple or elegant or 'by authority' (IUPAC) form, which is a beauty contest not science. I understand Sandbh does argue for such criteria seriously, but that still does not convince me—FWIW." - DePiep
- "I have noted in the very beginning of this discussion, which started with an article you [Sandbh] wrote, that it did not appear to me that pro-La-Ac and pro-Lu-Lr arguments were given the same weight, and I said, perhaps not as explicitly but to the same meaning, that it looked like this was done so deliberately so that one option is favored over the other. I am afraid that what I've read so far reinforces this thinking within me." - R8R
versus a single one:
- "Ahead of the recommendation of the IUPAC project I see no case for change." - Sandbh
However since we carried out the last change in an RFC, I feel (after discussion with R8R) that a proposed reversal should also go through an RFC. It seems only fair.
Q15: Have you addressed Sandbh's arguments there?
Yes, I responded to everything new he raised. Though not always in the most polite way after a few months of arguing, for which I am sorry.
Questions 16 to 20
Q16: Exactly why were you arguing this fiercely with Sandbh?
Well, he was writing an article, to be published in Foundations of Chemistry, that supports La under Y, and brought it to WT:ELEM for peer review last December. I and Droog Andrey disagreed with his arguments on what seemed to me to be logical grounds. Eventually it got to this:
“ | When you get as old as me, you'll learn there is much more to the world than logic. ...
You keep asking for a falsifiable theory. There isn't one! |
” |
— Sandbh, 07:49, 12 May 2020 (UTC) |
I found this quite surprising and responded in a rather too harsh manner, which I'm sorry for. Nevertheless I still cannot agree with this approach. Unless we use logic as a base, I don't see how we can judge the strength of arguments.
Q17: So why did it last so long?
Arguing with him was very helpful to sharpen my own understanding. But let's be honest: "someone is wrong on the Internet" also had something to do with it on my part, and I should really wean myself off of that.
Q18: But you've not been a complete angel yourself dealing with him.
That is true. I'm sorry. I will undertake to be more civil in future.
Q19: What's the history of this neverending argument anyway?
Mendeleev more or less gave up on placing the lanthanides, mostly leaving it to his Czech colleague Bohuslav Brauner. After some other attempts, eventually a form with all lanthanides under yttrium (basically the * form) was settled on. However even during this time tables that quite clearly don't put La under Y had already appeared (Henry Bassett 1892, Alfred Werner 1905). Actually Werner's form (yes, that's the father of coordination chemistry we're talking about) is incredibly close to the modern 32-column Lu form (with the exception that Be and Mg go over Zn instead of Ca). The only reason I do not call it a Lu table is because Lu had not yet been discovered(!).
In the 1920s and 1930s some chemists assigned Lu under Y because the chemistry of Y is more similar to Lu than La (Sc, Y, and Lu separate in the yttrium group of rare earths, but La and Ac in the cerium group).
The current dominance of the La form seems to stem, according to Jensen, from wrong electron configurations from the 1940s in which the lanthanides were assumed to be fn-1ds2 instead of fns2. These were later corrected, but by that time it seems the La form had stuck. We should not forget that these electron configurations are for the gas-phase ground state and are not really relevant for chemistry anyway (in chemical environments they change).
Meanwhile articles supporting Lu have appeared since 1921 and have been going on until the present; there have not been as many articles supporting La. Some authors have changed their periodic tables, others have not, there is still no consensus. IUPAC started a project in 2015 to look into it, they still have not made a decision.
It is possible that things will change. Be-Mg-Zn was present in Werner's periodic table of 1905, B-Al-Sc was once shown by Pauling(!), and prior to Seaborg it was generally accepted that the actinides known (Ac, Th, Pa, U) form a fourth d block row with uranium being eka-tungsten. Now you don't see any of these.
Q20: Should tradition count for something here?
There's not much of a tradition when chemists still argue about it. I prefer that we take the option that most of them who really analyse the issue support when we're not discussing the issue.
Questions 21 to 25
Q21: Would it not simply work if we just added footnotes like for helium where we explain that the other option is also common?
For the infobox, for the footer, you do not want to emphasise the issue where it is irrelevant, e.g. for the article on helium where group 3 matters not at all. The "overhang" the La table has in the 32 column form draws the eye's attention. The "stretchy scandium and yttrium" of the * table draws even more of the eye's attention. In order to make them look good, you have to use an 18 column instead of a 32 column form, which strikes me as not terribly good considering that those are supposed to be the same thing (just with the footnote glued in or not). So for these purposes I claim the Lu table is better: it preserves the symmetry. Moreover there is even scientific basis for preserving that symmetry, as the periodic table is explained by the valence orbitals and thus quantum mechanics, the Madelung rule having derived in the 1950s by Klechkovsky already.
Of course, whenever it is relevant (i.e. article of lanthanum, article of lutetium, and the period 7 congeners), we will add a note like there is for helium (about helium over beryllium being supported by some chemists). That goes without saying, for WP:NPOV reasons. But I think the reader would be better served with a Lu under Y default for when the situation does not matter.
Q22: OK, so are you going to get on to the scientific basis of this change or not?
Here are eight short arguments and the evidence behind them.
- Per Jensen (1982) Lu under Y matches the trends in the d block better.
- Per Gschneidner (2016) La has 4f involvement in the metal that impacts its melting point, making it 450 °C lower than expected. The figure to the right from his paper shows "pseudo-La" for the expected melting point of La if it didn't have this 4f hybridisation. Such 4f involvement also ties together lots of properties of lanthanum: it explains melting point, heat of sublimation, high coordination numbers around 12 (difficult to explain without f orbitals), cubic molecular geometries of lanthanum complexes (difficult to explain without f orbitals giving the symmetry), superconductivity (it is superconductive, but Sc, Y, Lu are not), quite possibly also its crystal structure (which matches the early f elements but is different from Sc, Y, and Lu). Putting La under Y misses the point that the first element for which the 4f orbitals are non-hydrogenic and can participate chemically is lanthanum, not cerium.
- Lutetium has no involvement of the f electrons in chemistry. All they do is contribute incomplete shielding effects which is exactly like the effect of the lanthanide contraction on hafnium through mercury. On those grounds it is surely a d element.
- Properties of yttrium are closer to those of lutetium than lanthanum.
- The only precedent for taking an element out of its block is helium, which is obviously much closer in properties to neon than beryllium. Why do that for lanthanum when yttrium is already closer to lutetium in all ways?
- Taking La out of the f block on the grounds of its ground-state gas-phase electron configuration lacking a 4f electron is irrelevant (these configurations change in chemical environments) and inconsistent with thorium. Thorium is in the f block, yet its ground-state gas-phase configuration lacks a 5f electron. Besides the periodic table is not even based on ground-state gas-phase electron configurations in the first place, as evidenced by the fact that no one rips nickel [Ar]3d84s2, palladium [Kr]4d105s0, and platinum [Xe]4f145d96s1 apart from each other. Rather it is based on the number of valence electrons and which orbitals they may enter across all chemical environments.
- Examining properties reveals that La fits well with f elements, but is an outlier in the d elements. Same is true for Ac. Lu is OK either way (mostly), but Lr seems to fit well in the d elements but is an outlier in the f elements (we mostly only have predictions for that one of course).
- When examining properties, Eu and Yb show the properties expected and known from Mn and Zn (half-filled and filled subshell); Gd and Lu do not. That supports La-Yb as the f block. In fact a lot of analogies with the d block strongly support La-Yb as the f block for exactly this reason (standard electrode potentials, electronegativity, ionisation energies, melting and boiling points).
Everything said of the lanthanides above is also true or suspected of the corresponding actinides.
Evidence
For the 7th period elements no one has ever made more than a few atoms of, calculated properties have been used.
In general properties of Sc-Y-Lu match the d block trend better. Sc-Y-La matches the s block trend, but remember that group 3 is a d block group, and the s block groups are in fact anomalous: they break the trend of having no even-odd periodicity. (Even-period elements usually are more electronegative and more oxidising in higher oxidation states; odd-period elements act the opposite way. From 5d onwards relativistic effects make it not quite right, as 5d is electronegative but prefers higher oxidation states, and 7p is electropositive but prefers lower oxidation states. But mostly it is still correct as a generalisation.) That's because there's no contraction:
1s period I 2s 2p period II 3s 3p period III 4s 3d 4p period IV 5s 4d 5p period V 6s 4f 5d 6p period VI 7s 5f 6d 7p period VII
From the build-up of the periodic table we see that for non-s blocks, even periods either have the first orbital of a given angular momentum (which is smaller than expected), or they have suffered a new contraction that wipes out the expected increase of radius and basicity (3p-4p increase wiped out by 3d, 4d-5d increase wiped out by 4f, 5p-6p increase wiped out both by 4f, 5d, and relativistic contraction of 6s). The s block is an exception: it always sits right above the noble gas core and never has any incomplete shielding effects (except a tiny bit for 2s vs 3s, and the obvious massive exception of 1s). There's no reason why any other group should follow them.
1st ionisation energies of the elements. Lu and especially Lr fall off the trends of the lanthanides and actinides respectively, and fit better with the trends of the succeeding 5d and 6d transition metals.
3rd ionisation energies of the transition elements (makes sense, having ionised the s electrons away already, and now probing the energies to remove a d or an f electron). This is not perfect, but when the configuration is "wrong", the "right" one is usually so close that it doesn't matter. La2+ is [Xe]5d1, but the expected [Xe]4f1 is about 0.89 eV up in energy; Gd2+ is [Xe]4f75d1, but the expected [Xe]4f8 is about 0.30 eV up in energy. I hope we agree that this is small potatoes compared to the differences between neighbouring elements.
Natural families La-Eu and Gd-Yb are supported, following Sc-Mn and Fe-Zn; the half-full and full subshell gives a local maximum in energy, because the next electron going in is either paired (after half-full) or in a higher-energy subshell (after full) and is then easier to remove. The effect weakens for higher rows (as you can see from the 1st IE chart as well; N-O is an obvious blip downward, P-S is not so obvious, by Sb-Te it doesn't go down anymore), but you can still see it.
property | La | Lu | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg |
---|---|---|---|---|---|---|---|---|---|---|---|
m.p. (K) | 1193 | 1925 | 2506 | 3290 | 3695 | 3459 | 3306 | 2719 | 2041.4 | 1337.33 | 234.43 |
b.p. (K) | 3737 | 3675 | 4876 | 5731 | 5828 | 5869 | 5285 | 4701 | 4098 | 3129 | 629.88 |
specific heat capacity (J/(g*K)) | .195 | .154 | .144 | .14 | .132 | .137 | .13 | .131 | .133 | .129 | .14 |
EN (Pauling) | 1.1 | 1.27 | 1.3 | 1.5 | 2.36 | 1.9 | 2.2 | 2.2 | 2.28 | 2.54 | 2.0 |
EN (Kulsha-Kolevich) | 1.11 | 1.31 | 1.38 | 1.46 | 1.54 | 1.55 | 1.67 | 1.75 | 1.84 | 1.93 | 1.81 |
Density | 6.145 | 9.84 | 13.31 | 16.654 | 19.25 | 21.02 | 22.61 | 22.56 | 21.46 | 19.282 | 13.5336 |
Young's modulus | 36.6 | 68.6 | 78 | 186 | 411 | 463 | ??? | 528 | 168 | 78 | ??? |
Bulk modulus | 27.9 | 47.6 | 110 | 200 | 310 | 370 | 462 | 320 | 230 | 180 | 25 |
Resistivity (nΩm, close to r.t.) | 615 | 582 | 331 | 131 | 52.8 | 193 | 81 | 47.1 | 105 | 22.14 | 960 |
Brinell hardness (MPa) | 350-400 | 893-1300 | 1450-2100 | 441-3430 | 2000-4000 | 1320-2500 | 3920-4000 | 1670 | 310-500 | 188-245 | ??? |
Heat of fusion (kJ/mol) | 6.20 | 22 | 27.2 | 36.57 | 52.31 | 60.43 | 57.85 | 41.12 | 22.17 | 12.55 | 2.29 |
In most properties Lu matches the properties of the 5d elements better than La. That is also true for chemical properties (Lu is less basic and less big as a cation, matching 5d elements better), but those are harder to show as data. ^_^
property | Ac | Lr | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | Cn |
---|---|---|---|---|---|---|---|---|---|---|---|
m.p. (K) | 1323 | 1900 | 2400 | ??? | ??? | ??? | ??? | ??? | ??? | ??? | 283 |
EN (Kulsha-Kolevich) | 0.97 | 1.29 | 1.34 | 1.41 | 1.49 | 1.59 | 1.72 | 1.83 | 1.92 | 1.99 | 1.91 |
Density (g/cm3) | 10.07 | 15.6 | 23.2 | 29.3 | 35.0 | 37.1 | 40.7 | 37.4 | 34.8 | 28.7 | 14.0 |
1st IE (kJ/mol) | 499 | 470 | 580 | 665 | 757 | 740 | 730 | 800 | 960 | 1020 | 1155 |
3rd IE (kJ/mol) | 1900 | 2228 | 2300 | 2378 | 2484 | 2570 | 2830 | 2900 | 3030 | 3080 | 3160 |
The little known and predicted about Ac vs Lr-Cn seems to show the effect is even stronger. All bulk properties of Lr-Cn are of course predictions as nobody has ever made enough. Kulsha-Kolevich electronegativity was used because no other scale actually seems to have values for elements as heavy as copernicium.
property | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1st IE (kJ/mol) | 499 | 587 | 568 | 598 | 605 | 585 | 578 | 581 | 601 | 608 | 619 | 627 | 635 | 642 | 470 |
3rd IE (kJ/mol) | 1900 | 1978 | 1814 | 1900 | 1997 | 2084 | 2132 | 2026 | 2152 | 2267 | 2334 | 2363 | 2470 | 2643 | 2228 |
m.p. (K) | 1323 | 2115 | 1841 | 1405 | 917 | 913 | 1449 | 1613 | 1259 | 1173 | 1133 | 1125 | 1100 | 1100 | 1900 |
EN (Kulsha-Kolevich) | 0.97 | 1.01 | 1.04 | 1.06 | 1.08 | 1.12 | 1.07 | 1.18 | 1.22 | 1.27 | 1.32 | 1.36 | 1.39 | 1.37 | 1.29 |
Density (g/cm3) | 10.07 | 11.72 | 15.37 | 18.95 | 20.45 | 19.84 | 13.69 | 13.51 | 14.79 | 15.1 | 8.84 | 9.7 | 10.3 | 9.9 | 15.6 |
Lawrencium's properties, as far as they are predicted, seem to be a quite bad match for the late actinides. (Data for Fm through Lr bulk properties is predicted, no one has ever made enough.)
M | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
mp (°C) | 842 | 1541 | 1668 | 1910 | 1907 | 1246 | 1538 | 1495 | 1455 | 1085 | 420 | 30 | 938 |
bp (°C) | 1484 | 2836 | 3287 | 3407 | 2482 | 2061 | 2861 | 2927 | 2730 | 2562 | 907 | 2400 | 2833 |
M | Ba | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | Hf |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
mp (°C) | 727 | 920 | 795 | 935 | 1024 | 1042 | 1072 | 826 | 1312 | 1356 | 1407 | 1461 | 1529 | 1545 | 824 | 1652 | 2233 |
bp (°C) | 1633 | 3464 | 3443 | 3130 | 3074 | 3000 | 1900 | 1529 | 3000 | 3123 | 2567 | 2600 | 2868 | 1950 | 1430 | 3402 | 4603 |
Double periodicity in melting and boiling points likewise supports La-Eu and Gd-Yb as natural f-block subfamilies. (When we get to a half-filled or filled subshell, delocalisation of those electrons becomes less favourable.) The effect is weaker for succeeding rows as usual.
M | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga |
---|---|---|---|---|---|---|---|---|---|---|---|---|
M3+/M2+ potential | very high | −2.3 | −0.9 | −0.255 | −0.42 | +1.56 | +0.771 | +1.92 | +2.3 | +2.4 | very high | −0.8 |
M | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In |
M3+/M2+ potential | very high | −2.8 | ??? | −0.9 | −0.2 | +0.3 | +0.24 | +0.7 | ??? | +1.8 | very high | −0.49 |
M | Ba | La | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
M3+/M2+ potential | very high | −3.1 | −3.2 | −3.1 | −2.7 | −2.6 | −1.55 | −0.35 | −3.9 | −3.7 | −2.6 | −2.8 | −3.0 | −2.2 | −1.05 | −2.7 |
M | Ra | Ac | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr |
M3+/M2+ potential | very high | −4.9 | −4.9 | −5.0 | −4.7 | −4.7 | −3.5 | −2.3 | −3.7 | −2.8 | −1.6 | −1.3 | −1.1 | −0.1 | +1.4 | −2.6 |
The standard reduction potential trends across the two subfamilies La-Eu and Gd-Yb are smooth, like those of Sc-Mn and Fe-Zn; they reach maxima at the half-filled and filled subshell elements as expected as then it is more difficult to ionise an extra electron past the half-filled or filled subshell. Same goes for 3rd ionisation energies, and same goes for melting and boiling points (more difficult to delocalise those electrons).
We use +2 oxidation states as a baseline to compare like with like: this way the s electrons are ionised, the configurations involved are (almost always!) dn and fn, when they are not the difference in energy to that is usually small enough to ignore, and we can probe the stabilising effect of the real half-filled and filled shell. Of course you may artificially shift to the +3 state and get different results, but it has about as much meaning as plotting 2nd ionisation energies to "prove" that the periods should go from group 2 to group 1:
element | He | Li | Be | B | C | N | O | F | Ne | Na | Mg | Al | Si | P | S | Cl | Ar | K | Ca |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2nd IE (kJ/mol) | 5250.5 | 7298.1 | 1757.1 | 2427.1 | 2352.6 | 2856 | 3388.3 | 3374.2 | 3952.3 | 4562 | 1450.7 | 1816.7 | 1577.1 | 1907 | 2252 | 2298 | 2665.8 | 3052 | 1145.4 |
I hope we can agree that this is self-evidently absurd.
Conclusion
For these reasons I claim that the La form has no scientifically sound basis. It is not a good chemist's periodic table because yttrium is closer to lutetium than lanthanum, and because lutetium and lawrencium are far more like transition metals than lanthanum and actinium. It is not a good physicist's periodic table, because it goes away from the blocks that underlie the periodic table. And clearly teaching the Madelung rule is going to be pedagogically better than teaching the Madelung rule and then giving an exception for La that doesn't even match reality, given its 4f involvement.
This matches the criteria for putting elements in the periodic table as stated by Jensen, particularly arguments 2 and 3 (4f in La and its complete lack in Lu).
“ | In actual fact, when assigning an element to a position in the periodic table the above factors are not simply applied as a haphazard empirical blend or combination, rather they are applied in a strictly hierarchical order, consisting of four steps or stages (Jensen 2009):
|
” |
— William B. Jensen (2015), The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table: an update |
Q23: Are there any other La arguments that you haven't refuted above?
- Differentiating electrons
Sandbh seems to believe in the importance of the "differentiating electron" of an element, which is the electron that differentiates it in its ground-state gas-phase configuration for the previous element. For example, since titanium is [Ar]3d24s2 (ground-state gas-phase), and vanadium is [Ar]3d34s2 (same), vanadium has a 3d differentiating electron.
I do not see why this should be important, given that we are not generally in the business of building elements up by adding one proton and one electron from the previous one. Also differentiating electrons are for the gas phase, and we've already discussed above that this is not relevant for chemistry because atoms usually have a different configuration when chemically bound from what they have sitting alone by themselves. Neither is it that clear all the time what exactly the differentiating electron ought to be. Passing from vanadium [Ar]3d34s2 to chromium [Ar]3d54s1 we have added two 3d electrons and subtracted one 4s one.
But all right, suppose we grant that. A usual argument Sandbh gives for why this should supposedly be important is looking at silver. It has a 5s differentiating electron as opposed to the 5d one of its heavier homologue gold, and this supposedly explains why the chemistry of silver is more main-group-like than gold:
“ | [Double sharp has argued that] Differentiating electrons make no difference to the chemistry of the elements and are therefore irrelevant. In fact, a counterexample is silver, the d/e of which is expected to be a d-type, but in fact turns out to be an s-type. Silver then acts predominately as a main-group metal rather than a transition metal. ... --- Sandbh (talk) 03:01, 15 July 2020 (UTC) | ” |
On the other hand, technetium also has a 5s differentiating electron as opposed to the 5d one of its heavier homologue rhenium. Judging by how happy technetium is to interconvert between its many oxidation states like the transition metal it really is, this does not seem to do anything at all to make it more main-group-like at all.
- Group divides
If you look at KCl, CaCl2, ScCl3, and TiCl4, the first three are ionic solids and the last one is a volatile liquid. So group 3 has to be cleft from group 4.
I used to believe this, but it doesn't really work. We may equally well observe the melting points of Cs2O, BaO, La2O3 or Lu2O3, HfO2, Ta2O5, WO3, Re2O7, OsO4. These are all high melting-point compounds until WO3, and the melting points keep increasing (showing ionic character) until HfO2. And we can multiply other counterexamples like Na2O, MgO, Al2O3, SiO2 (melting points increase till MgO).
Any way you look at it, this doesn't support any natural group divide at all. Mostly because there is no such thing outside the fundamental one (noble gas | alkali metal).
A related argument states that group 3 is more similar to group 2 than group 4 because group 3 acts like a trivalent version of the main group metals. But for group 4 you can find aqueous cations with noble gas configurations that make them like a tetravalent version. Simply make the pH low enough. −1 will do, you'll easily find things like Zr4+ and Hf4+, maybe even Ti4+, then. Well, look at Fajans' rules again. Cation polarising power, hence acidity, depends on charge and radius. Following Gary Wulfsberg's Principles of Descriptive Inorganic Chemistry, the usual dependence is on charge squared divided by ionic radius. We can then draw his table:
Z2/r ratio | Pauling EN | Category | pKa | Examples |
---|---|---|---|---|
0.00–0.01 | <1.8 | Nonacidic cations | 14–15 | Most +1 ions in s block |
0.01 | >1.8 | Feebly acidic cations | 11.5–14 | Tl+ |
0.01–0.04 | <1.8 | Feebly acidic cations | 11.5–14 | Most +2 ions in s, f blocks |
0.01–0.04 | >1.8 | Weakly acidic cations | 6–11.5 | Most +2 ions in d block |
0.04–0.10 | <1.8 | Weakly acidic cations | 6–11.5 | All +3 ions in f block |
0.04–0.10 | >1.8 | Moderately acidic cations | 1–6 | Most +3 ions in d block |
0.10–0.16 | <1.8 | Moderately acidic cations | 1–6 | Most +4 ions in f block |
0.10–0.16 | >1.8 | Strongly acidic cations | (−4)–1 | Most +4 ions in d block |
0.16–0.22 | <1.8 | Strongly acidic cations | (−4)–1 | |
>0.16 | >1.8 | Very strongly acidic cations | <−4 | |
>0.22 | <1.8 | Very strongly acidic cations | <−4 |
And indeed, we find that while the group 4 cations are indeed strongly acidic, they are not so acidic that they react irreversibly with water: the pKa is not quite low enough. Sure, you'll soon get a precipitate if their cations are introduced to aqueous solution at all but pretty low pH. But you can redissolve that precipitate in concentrated hydrochloric acid, at least if it hasn't aged too much. It's cations like Nb5+ and Ta5+ that are "very strongly acidic": too acidic to exist in water at all. So, apparently the group divide is really between groups 4 and 5 instead.
But probably the clearest way to rebut this whole idea is to look at what happens in the p block. Group 13 metals Ga, In, Tl can form aqueous cations in their group oxidation state. Group 14 metals Ge, Sn, Pb cannot, they are too acidic. (Remember what I said before? Elements in higher oxidation states are more electronegative and hence more acidic, whence how Pd2+ is more acidic than Be2+.) So this seems to also support B-Al-Sc if you apply it consistently. I think that is not a good sign.
The chemistry of group 3 is not more similar to that of group 2 to group 4, so that justification is also out. Observe the aqueous chemistry of group 4 and the organometallic chemistry of group 3. Not to mention that the standard "transition metal" property everyone knows from high school is forming coloured paramagnetic compounds with incomplete d orbitals. If you think scandium should be disqualified, because you will have a tough time finding stable lower-oxidation state compounds of Zr-Hf-Rf in group 4 and Nb-Ta-Db in group 5, those suddenly are also in danger of being disqualified. And as for the other s-block property of forming hard, class-A cations – the elements up to group 6 show that. Everything is a continuum here, and transition properties are no exception: they go in slowly, they come out slowly. All peripheral groups in blocks have properties similar to their block neighbours, there's no reason why to emphasise the property this much for group 3.
- Ions
According to this argument, lanthanum cannot start the f block because La3+ fails to have an f electron, and there is complete regularity down Ce3+ to Lu3+ in showing f1 to f14. But such a common stable oxidation state for everybody only exists in the f block, and actually only the 4f elements, not the 5f ones. So this argument is about as local as you can get and doesn't work as part of the periodic law.
I also note that by this logic La cannot be in the d block either, since La3+ is d0. In fact it cannot be anywhere in the periodic table either, since La3+ is also s0 and p0. And there are no s block elements either except helium (the least s-block-like of them), because in their common oxidation states (+1 for the column H-Li-Na-K-Rb-Cs-Fr, +2 for Be-Mg-Ca-Sr-Ba-Ra) they are all s0. Why should we use criteria that only apply to one block?
Finally, La had been [Xe]4f16s2, all this argument would surely never have started: a La-Yb f block (i.e. a Lu table) would be absolutely standard. But it would still lose the f electron in the +3 state anyway, so this argument would still argue for Ce-Lu anyway. That seems hard to accept.
- A Pair Out of Place
According to this argument, advanced by Lavelle, La and Ac cannot be put in the f block because they would represent the only case of two elements going into a block with no outer electrons in common with their block.
Of course, this is predicated on the gas-phase ground-state configurations, which is not that relevant. Also, how does this deal with Lu and Lr? Neither of them have any outer f electrons, they also form a pair out of place. So the argument is as much for the Lu table as it is for the La table.
Q24: Weren't you on the other side of this last time?
Indeed. I learnt more, I changed my mind. All thanks to Droog Andrey (= A. V. Kulsha). You may enjoy the periodic table poster he and one of his colleagues created too (link is to version of 2019). ^_^
Q25: So what's wrong with the old arguments that you were using then?
I've addressed them all above.
Questions 26 to 30
Q26: So how do I know you won't be fervently arguing to change it back again in four years?
I don't, that's because I believe in the scientific method. If I find out something falsifying my stand, I change my mind. You can argue it if you want... ;)
Q27: Why now? Why not wait for IUPAC?
It's not possible to be neutral. Sc-Y-* is also a side. I also think Sc-Y-* is chemically just weird (those f electrons are not core electrons, and while asking La-Lu to share one flat makes some sense, it's really weird for Ac-Lr), and Jensen agrees.
Q28: Why start it now and not earlier?
Because my ideas about this were not clear enough till this round of argument with Sandbh started. Now they are.
Q29: Do you have nothing better to do than write long screeds here about this?
Well, at R8R's suggestion it is now behind a collapse box, and most of the long screeds have been replaced by very short answers.
Q30: Do you have anything against Sandbh personally?
No, I just find myself in disagreement with his stand on logic and falsifiability.
Mass summoning
@ComplexRational, DePiep, Droog Andrey, Officer781, R8R, Sandbh, Дрейгорич, AzaToth, Tazerdadog, Maproom, CuriousMind01, Silvio1973, and Timtempleton: Pinging all megathread and previous RFC participants. And also AnthonyDu0122 who raised it above. ^_^
Unacceptable behaviour
I object, in the strongest possible terms, to the way Double sharp initiated this RFC.
I allege that Double sharp's background to the RFC is biased; incomplete; out-of-context; contains inappropriate content; and—at 33,000 words—is too long for anyone to gain an informed understanding of the issue at hand. This follows other unacceptable behaviour alluded to on his part, including his hack work on our periodic table article; removing some of my citation supported content; slandering me; swearing; and effectively demanding I provide a falsifiable hypothesis when I was under no obligation to do so.
The context for my objection is my long-term participation in the Group 3 debate, including two submissions to IUPAC on the matter, one with Double sharp (which he has now dissociated himself from).
My other objection is that an article written by me will soon appear in the journal Foundations of Chemistry, entitled "The location and composition of Group 3 of the periodic table". I have the proofs in hand. The article has been reviewed by three PhDs and accepted for publication by Eric Scerri, a world authority of the periodic table. Scerri is also the chair of the IUPAC Group 3 project.
Double sharp knows all this, yet chooses to go ahead with the RFC. So much for taking into account "reliable sources that focus on the matter." So much for extending me the courtesy of professional respect. So much for working collegiately within WP:ELEMENTS.
Here again is a continuation of his pattern of unacceptable behaviour.
Most of the rest of the editors who have voiced their opinions for Lu, it seems to me, do so on the basis of a personal preference or a very limited grasp of the full extent of the arguments and literature involved in this case.
I'm not holier than anyone. I do claim, along with Double sharp, to have maintained a depth of familiarity and interest in this question since at least 2016. In my case I've been arguing the question with Scerri, on and off, since 2008. And along the way, Double sharp and I have changed our minds about Group 3 as we both learnt new things along the way.
As Jones (2010) has written:
- "Scientists should not lose sleep over the hard cases. As long as a classification system is beneficial to economy of description, to structuring knowledge and to our understanding, and hard cases constitute a small minority, then keep it. If the system becomes less than useful, then scrap it and replace it with a system based on different shared characteristics."
- Jones 2010, Pluto: Sentinel of the outer solar system, Oxford University Press, p. 171
As Schwerdtfeger, Smits & Pyykkö (2020) wrote:
- "Fuzzy concepts like chemical similarity often lead to unnecessary disputes concerning the PTE."
- Schwerdtfeger P, Smits OR & Pyykkö P, 2020, "The periodic table and the physics that drives it". Nature Reviews Chemistry, vol. 4, pp. 359–380
That is why we have an IUPAC Group 3 project team, to assess the literature and address these unnecessary disputes.
And the IUPAC project team has reported that, based on a survey of chemistry textbooks and other sources, that the La form dominates by a 4:1:1 margin, where the two 1's are the *-** form and the Lu form.
As Scerri wrote:
- "…the majority of textbook and other periodic tables in the 18-column format show the elements of this group as scandium, yttrium, lanthanum and actinium…"
- Scerri ER 2020, "Recent attempts to change the periodic table", Philosophical Transactions A, here
As WP:Elements member R8R wrote:
- "…I'll say that the 4:1:1 consideration will be very important for the upcoming RfC, especially given that it's something that can be found on IUPAC's official website. I agree that consistency with literature is of the uttermost importance for Wikipedia if literature itself goes shows such a consistency; Wikipedia is meant to be a tertiary source. It'll be the thing that will hold me from supporting the motion on WP right now…--R8R (talk) 16:51, 19 July 2020 (UTC)"
Precisely.
The way ahead, as I see it, is (1) cancel the RFC until my article appears on line; and (2) Double sharp and I to agree on a balanced introduction to a new RFC, should Double sharp wish to proceed with another RFC. Failing this I will take up the matter on WP:AN. --- Sandbh (talk) 03:27, 21 July 2020 (UTC)
- The supposed consistency of the literature has been addressed above by noting that most reliable sources focusing on the issue support Lu, and that the 4:1:1 for La:Lu:* is of questionable relevance due to (1) Google results showing instead 1:1:4 for periodic tables, (2) general ambiguity resulting from * appearing in the same cell as La, and the fact that (3) there are some things that have been demonstrated many times in reliable sources but tend not to be taken up by textbooks, e.g. the refutation of d orbital involvement for hypervalent molecules. Incidentally, in the article Sandbh links to, Scerri supports Lu under Y.
“ | Given these points I would like to propose that although there is no objective way to distinguish the tables shown in figures 10 and 12 [Lu and La respectively] one should nevertheless opt for the former of these as the official IUPAC periodic table. The factors that might lead us to favoring figure 10 have already been mentioned. They are that the d-block of the periodic table remains unified and intact, whereas the table in figure 12 requires that the d-block be separated into two highly uneven portions consisting of one and nine groups respectively. | ” |
— Scerri ER 2020, "Recent attempts to change the periodic table", Philosophical Transactions A, here |
- I have added a thread at WP:AN#Dispute on an RFC. Double sharp (talk) 04:17, 21 July 2020 (UTC)
- To address Sandbh's concern about length, I have removed the long bottom-up explanation of periodicity, leaving only the arguments. Since we have been arguing about this for nearly seven months now at WT:ELEM, I think trying to create a balanced introduction to a new RFC that will please both of us may well be futile because our approaches diverge very early: many arguments that one of us consider decisive are not considered so by the other. However, I have absolutely no objection to him adding his own view of the background next to mine. Double sharp (talk) 04:58, 21 July 2020 (UTC)
On the "supposed" consistency of the literature
Here is what Double sharp neglects to mention.
Mathias (1969) grumbled about La in group 3 being the most popular form. Myers, Oldham and Tocci (2004, p. 130) found La and Ac to be the most popular form of periodic table, a sentiment echoed by Clarke and White (2008); and Lavelle (2008; 2009). My article (Vernon 2020) will reiterate this.
- Clark RW & White GD 2008, "The flyleaf periodic table", Journal of Chemical Education, vol. 85, no. 4, p. 497
- Lavelle L 2008, "Lanthanum (La) and actinium (Ac) should remain in the d-block", Journal of Chemical Education, vol. 85, no. 11, pp. 1482–1483, doi: 10.1021/ed085p1482
- —— 2009, "Response to misapplying the periodic law", Journal of Chemical Education, vol. 86, no. 10, p. 1187, doi: 10.1021/ed086p1187
- Mathias BT 1969, "Systematics of superconductivity", in PR Wallace (ed.), "Superconductivity: Proceedings of the Advanced Summer Study Institute on Superconductivity", McGill University, Montreal, vol. 1, Gordon and Breach, New York, pp. 225−294
- Myers RT, Oldham KB & Tocci S 2004, Holt chemistry, Holt, Rinehart and Winston, Orlando
- Vernon RE 2020, "The location and composition of Group 3 of the periodic table", Foundations of Chemistry, open access (in press)
As noted, IUPAC and Scerri have confirmed this. Double sharp knows it but neglects to mention it. There is no support in the literature for his WP:OR interpretation.
Scerri has noted (pers. comm.) that he distinguishes between his personal view as a chemist, and his role as the chair of the IUPAC Group 3 committee. Once again Double sharp demonstrates that he does not know what is going on here.
I reject Double sharp's assertion that it would not be possible for is to reach agreement on a balanced approach to an RFC. Once again he resorts to unwarranted—act of desperation—escalation i.e. 1. the hack work on our periodic table; 2, this RFC; 3. unilateral escalation to WP:AN. 08:05, 21 July 2020 (UTC)
Last try at being reasonable
@Double sharp: So, are we going to cancel this RFC and come up with an NPOV version, suitable for another RFC post online publication of my article, or are you going to waste everyone's time and some poor WP:ADMIN's? Sandbh (talk) 08:19, 21 July 2020 (UTC)
- @Sandbh: RFC tag removed (I understand this withdraws the RFC).
- Now I have stepped back and thought about it. I have gone overboard, and I apologise for it. I am still not at all convinced by your arguments and believe the Lu form is significantly better. However, since I also believe helium over beryllium is significantly better, yet recognise that that approach has no chance to become the default on WP, I am willing to let this one go provided we add notes to the relevant articles like what I did on helium explaining that there is a dispute. So, I have decided not to start a new RFC even after your article is published.
- I do not wish to discuss the issue further on WP at present. Everything relevant has already been said far too many times, and it seems unlikely that either of us are going to change our minds if it is said more times. It is also true that the fact that most textbooks discuss Sc, Y, La, and Ac together is, for Wikipedia, probably definitive at this moment. So, let's drop the issue until and unless IUPAC decides eventually on Lu under Y. In that circumstance, I think no one will argue that an RFC will be justified, but we do not have it at the moment.
- Respectfully, Double sharp (talk) 08:51, 21 July 2020 (UTC)
Discussion
- Strong Support for change to Lu form, per what I wrote above. Double sharp (talk) 10:08, 20 July 2020 (UTC)
- Also, per Michael D. Turnbull, below: I strongly support that periodic table article should show both forms and briefly discuss the difference. When I suggest changing to the Lu form, it is in the context where we simply show the periodic table as a template, e.g. for navigation like the infobox on neon or other elements. Double sharp (talk) 12:13, 20 July 2020 (UTC)
- Comment I think the reader would be aided massively if there were a one-line response to each question and the rest of the answer were hidden in a collapsed (but uncollapsible) box.--R8R (talk) 10:30, 20 July 2020 (UTC)
- @R8R: You raise a good point. I'll do it soon. Double sharp (talk) 11:22, 20 July 2020 (UTC)
- @R8R: Done Double sharp (talk) 12:40, 20 July 2020 (UTC)
- @R8R: You raise a good point. I'll do it soon. Double sharp (talk) 11:22, 20 July 2020 (UTC)
- I will assume that I do not need to read this giant thing before giving my input? < Atom (Anomalies) 11:33, 20 July 2020 (UTC)
- @AnomalousAtom: I am working on adding one-line responses and collapsing the big ones per R8R's suggestion. In the meantime there is a summary. Double sharp (talk) 12:13, 20 July 2020 (UTC)
- @AnomalousAtom: It is now significantly less giant since all the detail is now in collapse boxes. Double sharp (talk) 12:40, 20 July 2020 (UTC)
- @AnomalousAtom: I am working on adding one-line responses and collapsing the big ones per R8R's suggestion. In the meantime there is a summary. Double sharp (talk) 12:13, 20 July 2020 (UTC)
- I will assume that I do not need to read this giant thing before giving my input? < Atom (Anomalies) 11:33, 20 July 2020 (UTC)
- Neutral on the change but Strong support that the periodic table article should show both forms and give some (brief!) discussion of why some reliable sources use La and others Lu. There is no such thing as the periodic table, it has been presented in numerous forms over the years and Wikipedia should reflect that. However there is only one periodic table article and we need to put a summary there reflecting WP:NPOV on the various forms. Michael D. Turnbull (talk) 11:37, 20 July 2020 (UTC)
- Now Against the change after the useful clarification that we are really only talking about the appearance of Wikipedia templates like
{{Periodic table}}
(See top of this RFC thread). We should stick to the same version as IUPAC currently endorse, i.e. IUPAC (2018-12-01). "PERIODIC TABLE OF ELEMENTS". since that's what most readers would expect. (Even British chemists don't use sulphur now, only sulfur.) Michael D. Turnbull (talk) 13:49, 20 July 2020 (UTC)- Actually it is not quite true that IUPAC endorses the form. They write on their website "While IUPAC has no recommendation for a specific form of the periodic table, i.e. 18-column or 32-column format, the version here presented is in the conventional long form and is yours to use."
- Now I can see the argument for using * under Y as that's what IUPAC shows on their webpage, even if they seem to be planning to change it away from * under Y eventually. But it does make things awkward for the 32-column forms encountered in
{{Compact periodic table}}
etc. Will scandium and yttrium have to be stretched over 15 columns? The only way it becomes less awkward is if we change those to the 18-column form too. Which is a bit odd as the 18 and 32 column forms are supposed to be saying the same thing in a different layout. Double sharp (talk) 13:56, 20 July 2020 (UTC)
- Strong support on changing to Lu as per arguments above. I was involved in the discussion itself as a minor participant. ― Дрейгорич / Dreigorich Talk 12:29, 20 July 2020 (UTC)
- Support change to Lu per arguments above; I also was a minor participant in the group 3 megathread. I would also like to comment that the IUPAC standard is intended to be deprecated (
that is why this RfC does not consider Sc-Y-*-*;(not originally considered here but later added) it is possibly even more incorrect to place all 30 inner transition metals below Sc and Y, and it still doesn't address how to structure the 32-column table), and the remaining arguments strongly suggest that Lu is the better choice. ComplexRational (talk) 14:11, 20 July 2020 (UTC)- @ComplexRational: BTW, I just added Sc-Y-*-** as an option since Michael D. Turnbull is in favour of it. So now it is not accurate anymore that the RFC does not consider the option. It is however correct that I am against that option. ^_^ Double sharp (talk) 14:18, 20 July 2020 (UTC)
- Extremely strong oppose (I have to make this prominent to balance and counteract the supports above) Just about all the arguments are irelevant and we should just use the traditional form eith La and Ac under Y. If needed we can use the place holder * or **. Graeme Bartlett (talk) 07:52, 21 July 2020 (UTC)
- Illegitimate RFC due to breaching Neutral point of view, Verifiability, No original research, and Lack of civility. Sandbh (talk) 08:15, 21 July 2020 (UTC)
- @Sandbh: RFC tag removed (I understand this withdraws the RFC).
- Now I have stepped back and thought about it. I have gone overboard, and I apologise for it. I am still not at all convinced by your arguments and believe the Lu form is significantly better. However, since I also believe helium over beryllium is significantly better, yet recognise that that approach has no chance to become the default on WP, I am willing to let this one go provided we add notes to the relevant articles like what I did on helium explaining that there is a dispute. So, I have decided not to start a new RFC even after your article is published.
- I do not wish to discuss the issue further on WP at present. Everything relevant has already been said far too many times, and it seems unlikely that either of us are going to change our minds if it is said more times. So, let's drop the issue until and unless IUPAC decides eventually on Lu under Y. In that circumstance, I think no one will argue that an RFC will be justified, but we do not have it at the moment.
- Respectfully, Double sharp (talk) 08:51, 21 July 2020 (UTC)