Philosophy: Coming to grips with the fuzzy nature of chemistry
NB: I’ve prefixed the section title with "Philosophical:" so that those of us less enamoured by such matters can skip the whole section.
In this JChemEd article from 2002 [5], about electronegativity scales, the author warns us that certain central notions of chemistry are broached, in chemistry textbooks, from a set of diverse and not always concordant explanations.
18 years later, a couple of philosophers analysed that 2002 article [6].
Here are some extracts and observations from their open access article:
1. …on certain occasions, such as for scientific and didactic purposes, in order to avoid confusion either in learning or in the development of an experimental process, the simpler option is better; that is why traditional scales are so popular even nowadays.”
2. OTOH, “Real science is home to a wide variety of scales, and associated conceptualizations, that coexist in the scientific communities...The question is not one about which scale should be chosen, but is instead about the reasoning for choosing only one.”
3. “Objective and univocal truth is not an aim of scientific practice.”
4. "The teaching of a 'mummified' chemistry, free of conceptual problems and the associated debates, does not reflect the scientific practice."
5. "At the same time, we believe that scientific monism, according to which there is only one scientific story about the world that can be told, should be avoided as far as possible as well."
6. "There is a vast philosophical literature and a scientific practice that supports this perspective…objective and univocal truth is not an aim of scientific practice. Pluralism must engage in cultivating multiple scientific systems and lines of enquiry, as science is a multi-aimed enterprise, not the search of literal truth…"
7. "But why is it better to be pluralistic? Why keep multiple systems of knowledge alive? The immediate reason for this is the sense that we are not likely to arrive at the one perfect theory or viewpoint that will satisfy all our needs...If we are not likely to find the one perfect system, it makes sense to keep multiple ones."
Suggested implications for WP:ELEM 1. Writing about e.g. the chemistry of the elements and the periodic table is hard.
2. In many case there is no one true way. At the same time, "for scientific and didactic purposes, in order to avoid confusion…in learning…the simpler option is better."
3. The question will not be about which approach should be chosen, but instead about the reasoning for choosing only one.
4. The teaching of chemistry free of conceptual problems and associated debates does not reflect scientific debate.
5. Some pragmatism and judgement will inevitably required in order to accommodate the desirability for simplicity and the fuzziness of chemistry.
Sandbh, when I said that your article touched on areas that are not sufficiently explored in the literature, this is exactly the sort of material that I had in mind. It is, IMO, central to some of the problems with writing an article on the PT, starting from considering who are the readers. It goes then to a more general question as to what the PT actually is. Is it a tool for summarising information about the properties of elements? Is it a tool for students to use to learn relationships between elements (like valency and what the formula of phosphorous(III) oxide is)? Is it a convenient summary form for relative atomic masses for use in carrying out stoichiometry? Is its purpose to provide electron configurations? Is it really meant for use by scientists and so should incorporate complexities even if these are confusing to students and lay people? Should there be different tables for different groups or different applications, each tailored to specific needs? Is including complexities an aid to student learning about multiple and co-existing models or is the confusion produced a hinderance – or is it both, an exemplar of the Perry Model in action?
There are a wealth of interesting question here, ones that are well-suited to the literature and rather less well-suited to an encyclopaedia while the discussions continue unresolved. If we had an article on the Perry Model, this would be a suitable topic for it, but the question for the project (and certainly for discussion at talk:Periodic table is how to take what is in RS and give it DUE weight to present a clear and readable article that provides our readers with what they want / need to know about the periodic table.
As a chemistry educator, I regularly think about these issues. I make sure to introduce students to the idea that a model is not the same as reality, that models are tools that do not fit / work well in all circumstances. A classic example (for me) is in introducing oxidation states. This is a model with great power for analysing redox processes, but at the same time is predicated on assumptions that are fanciful. I know that dichromate oxidation of 2-butanol to butanone involves reduction as chromium goes from CrVI to CrIII, but I also know that this model seeing dichromate as a Cr6+ cation surrounded by oxide anions and with no covalency in bonding is ridiculous. I value the model of oxidation state for its utility in understanding redox chemistry, whilst simultaneously looking at it as a tool with limitations and not as a reflection or representation of reality. I have the freedom when teaching to explore this concept. However, as a Wikipedian writing about oxidation state, I do not have the freedom to work in content on models and representations of reality without RS on the subject with sufficient coverage to pass DUE for inclusion. Otherwise, I am engaging in OR and SYNTHesising what I know of models and learning and the literatures of those areas and applying them to a chemistry topic in a way unsupported by the literature.
For the Perry Model and multiple models, I introduce / explore these when discussing acids and bases as students often first try to choose between Arrhenius, Lowry–Bronsted, and Lewis models as if one is true. I encourage them to see each model as useful for different circumstances, each model being more complicated than the last but the simplest model that is valid being the wisest to choose for a situation. None of them are reality or truth, each is simply a model to understand reality, and choice of model is dependent on which best fits the situation. Like ArbCom being a sledgehammer and the right tool to use to crack some disputes, in circumstances where it is the wrong tool, its use may not have the desired result.
I also explore the breakdown of models in discussing gas laws and explain that the ideal gas law is a mathematically-constructed model to approximate reality, based on assumptions, and that when those assumptions are unjustified, the model's approximations to reality become unreliable.
I'm happy to chat more about such topics on one of our user talk pages, but for the continuation of the discussion here, I ask we concentrate on how the topic you raise can be implemented (if at all) in article space in line with policy, and to which articles it is supported by RS given DUE weight to apply. EdChem (talk) 04:19, 14 November 2020 (UTC)
PS: This is also overlapping with the comments made by DGG at the ArbCom case request – Who are our readers? Students? Experts in Chemistry? Lay persons interested in Chemistry? And, what is it that they need from us in terms of what content we cover and how? There is the problem, however, that if the RS literature consensus sees the PT as (say) a tool for chemists / experts to use in their work then WP must say so, even if that group is not our typical reader... and raises consequent challenges of covering RS and giving DUE while producing understandable and appropriate encyclopaedic content. To your point, Sandbh: yes, writing about chemistry and the PT is hard but we have guidelines from what RS tells us on what to say and from considering our readers in deciding how to say it. EdChem (talk) 05:02, 14 November 2020 (UTC)
EdChem, (btw, as background, I'm a biochemist who has also worked as a chemistry librarian). Since the PT is a tool used by chemists to organize and conceptualize their work, of course we should say so and explain how they use it. But the PT is also a teaching device, central to both the teaching of general chemistry and to what the public knows about chemistry, and we need to discuss this aspect also. (Similarly, we discuss other aspects, such as the historical aspects (best handled I think in the frWP article), and its use as the prototypical organizing device in other fields, sometimes seriously, sometimes humorously). This problem of the dual goals of being understandable and being accurate has long been a problem with all encyclopedic coverage in WP and in other encyclopedias of such fields as mathematicvs and much of physics. But I don't think this is so esoteric that it need to be split into two articles on the analogy of Introduction to general relativity .This problem of the dual goals of being understandable and being accurate has long been a problem with all encyclopedic coverage in WP and in other encyclopedias of such fields as mathematics and much of physics, and is now confronting us also with biology--and the subject of a recent arb case in which I did not participate--Wikipedia:Arbitration/Requests/Case/Medicine. DGG ( talk ) 06:08, 14 November 2020 (UTC)
EdChem; DGG, The PT article is not “mine”. I recall adding some content leading up to the FA process , but wasn’t the instigator of it.
The PT is a model, that’s all. The important thing is to explain the context for the particular model in use. This is relatively easy. The La form remains popular. The colour categories are the relatively popular ones: AM, AEM, Ln, An, TM, metalloids, halogens and noble gases. That just leaves the metals between the TM and the metalloids; and the nonmetals between the metalloids and the halogens (plus H).
Those categories illustrate the L-R progression in metallic to nonmetallic character going across the table, and the top-down increase in metallic character seen in most notably in the p-block. This is traditionally taught by contrasting the alkali metals with the halogens.
As long as I’ve used RS, I’ve never understood what the “undue” concern is about SYNTH and DUE etc. The RS keep me on track. As long as the end result is a better encyclopaedia. I’ve seen other editors who view minor IGF infringements of SYNTH and DUE as relatively harmless. YMMV.
I kind of agree with everyone here. The questions EdChem raises are matters that are extremely interesting and, I daresay, peeve-inducing once you get to know about them. But the fact of the matter is that for many of those cases the situation is that the literature is not really settled and a lot of different things are taught to students. For example, just try finding a universally accepted definition of what a block is in the literature. The fact that you'll never find one doesn't stop people from using the term, however. And if that's the situation, then we should tread somewhat carefully and mostly follow the textbooks. Are they sometimes just plain wrong and contradicting themselves with specialised RS being able to prove it? Yes – but we can't say that here because that would give the issue disproportionate significance and rather defeat the point of explaining things to laymen. It might make a good commentary for JChemEd, but their goals are not ours. Does the way they write sometimes lead to inevitable hands raised at the back of the classroom? Yes – but I guess these things ought to be discussed, if at all, in footnotes. Because having tried to explain periodicity myself in a way that I would find completely accurate to literature esoterica and still understandable, it seems to me that while it's not impossible, what you end up with if you try it becomes far far far to the extremes when it comes to what most textbooks do. Which is not, I think, what an encyclopaedia should be doing. Double sharp (talk) 11:16, 14 November 2020 (UTC)
Thanks for your comments, DGG, and I do agree that issues such as those raised here and elsewhere in the disputes / discussions have parallels in other areas and pose challenges that have been solved in other contexts on WP before.
Sandbh, I agree that no one WP:OWNs any WP article. I did comment at talk:Periodic table that you and Double sharp are the originators of more than 50% of the bytes in that article, according to the history and page statistics tools, but that tells us nothing about which parts. It's an FA with strong and weak parts and I don't know who contributed what, nor do I plan to investigate. I just hope we can all work together to improve the weaker parts.
As for your comment on RS, DUE, SYNTH, etc, I am reminded of the movie Reach for the Sky about WW2 fighter pilot Douglas Bader, where he and Harry Day exchange the maxim "rules are for the obedience of fools and the guidance of wise men." EdChem (talk) 20:59, 14 November 2020 (UTC)
Keep in mind that any model is inevitably a simplification of reality that spares the reader overwhelming complexity. A central question for each article using the PT is "Who is the audience for this article?" What we often miss at Wikipedia is that for every editor there are hundreds of silent readers. We need to think about what will serve the reader best. Sometimes less complexity is more valuable. We can have daughter articles that go into greater depth. We can provide links to deeper treatments of the topic. JehochmanTalk05:15, 15 November 2020 (UTC)
The overall readership for periodic table is millions per editor. The pattern of readership is cyclical – a peak in September and a steady decline to August. As this aligns with the academic year, this indicates that the readership is mainly schoolchildren and students rather than professional chemists. Understanding of the periodic table is commonly tested in chemistry exams – see this syllabus, for example. This should inform our coverage of the topic. Andrew🐉(talk) 11:24, 15 November 2020 (UTC)
Book chapter: Why don’t we really teach about the periodic table?
Rayner-Canham G 2020, Advances in teaching inorganic chemistry, vol. 2: Laboratory enrichment and faculty community, Chapter 6, pp 69–77, ACS Symposium Series, vol. 1371 doi:10.1021/bk-2020-1371.ch006
From the intro:
"We lie to students. Such lies are often justified by saying that we are “simplifying” the topic. But in the process of simplifying, are we hiding the fascinating “messiness” of the periodic table? In this chapter, I focus on two facets of the periodic table. First, that richness, complexities, and controversies, should be highlighted in our teaching. Second, that terminology, sometimes used inconsistently or ambiguously, needs unambiguous definitions to give to our students. In the first half of this discourse, four of the many issues will be addressed; others are addressed elsewhere [7], particularly the very divisive issue of the lower members of Group 3 [8]."
Rayner-Canham covers the placement of H; do we overdo group trends; do we underdo other trends; and where do the early actinoids belong?
--- Sandbh (talk) 12:09, 19 November 2020 (UTC)
Sandbh I read some of it, it was fascinating. I have to admit however that I do not think his proposed solution to group 3 (sometimes Lu, sometimes a gap before Lu, sometimes a gap) will actually stop the issue from being divisive, on the grounds that the current compromise IUPAC table with a gap below Y has been around for decades and if anything the debate actually got more divisive since it came out. So I will continue to wait for IUPAC. ^_^ Double sharp (talk) 12:20, 19 November 2020 (UTC)
@Sandbh:, my concern is not about telling lies to children, but rather about following the sources. I don't see any significant sources in English doing this sort of striping, so I do not feel we should do it. The source situation may be different between English and German: I have not checked because I'm not an active editor on German Wikipedia and therefore I'm not involved in checking if their content is supported by their literature situation.
Again, please understand that when I support ACS/LANL/2010 for WP, I mean that I think it best reflects the coloured-tables literature to do so, not that I think the colouring is all that great personally. There are a number of things like that on WP, where I currently support the WP table showing He in group 18 and La in group 3 on the grounds of most of the literature saying that, even though if you asked me personally my viewpoint is that both are serious mistakes. And that's why my current opinion for WP is that group 3 should not be revisited until we hear from IUPAC, not because I feel that would impact the scientific situation (it might if new arguments are presented, but that's not my main point) but because I feel that would impact the source situation that matters for WP. About the same thing goes for calling Ts a halogen and Og a noble gas from my perspective: I don't like it, if I was writing outside WP I'd probably call it a serious mistake as well, but I feel it's not WP's place to say it if most sources are doing it anyway. Similarly I think of the whole metalloid-line problem as an issue of an "original sin" of not clearly stating definitions, and would favour giving the children the physical-based definition "a metallic element has to have a Fermi surface in all stable or metastable allotropes at standard conditions" which mostly matches the chemistry (and then the metal-nonmetal dividing line runs between Be and B, between Al and Si, between Ga and Ge, between Sb and Te, probably between At and Rn, and in the 7th period everything is a metal but Cn and Og probably). I feel it makes sense because "metal" seems to have started as a physical term according to Origin and use of the term metalloid which you wrote, most people are more familiar with the physical idea of a metal than the chemical one (K is by far a stronger metal chemically than Au, yet the latter is for everyone the king of metals, and the former was found so weird it was sometimes called a "metalloid"!) and the chemistry just mostly correlates because the same thing of easily mobile electrons is behind both (though the correlation is not perfect). And I'd do that if I were writing some sort of text on periodicity. But again, to a first approximation people don't do that, there's no clear consensus definition in the literature, and so I feel my personal preference here means nothing for WP no matter how persuasive I find my own argument. So, I've listed three issues, containing a mixture of agreement and disagreement with your view, where I have a personal view and don't advocate it for WP because I don't feel the current source situation supports it. The fact that you probably have a different preference for some of this is for me further proof that trying to analyse the sources ourselves for some sort of scientific correctness is not the way to go; because of differing philosophies, some arguments of mine won't be found convincing by you, the same goes the other way, and nothing can get done that way for an encyclopaedia. There we have to present the views in the literature given their weight there; each following our own philosophy is something that only works if we write a separate monograph each, which isn't what we're doing here. That's why I feel that this sort of thing should be left to monographs and papers, leaving encyclopaedias to just describe the majority situation first even if we both agree that it sucks and there's some minority situation around that is better; I feel that's consistent with WP:DUE anyway. In other words: if most of the sources are lying to children, then I feel it is our duty to be following that even if mentally I cannot help but protest. You don't have to agree, but I'd ask that you understand where I'm coming from. And please don't try to convince me that the lying to children is bad; you'd first of all be trying to convince me of something I'm already convinced by, and second of all not be addressing my actual argument and therefore probably not manage to change my mind. ^_^ Double sharp (talk) 11:40, 20 November 2020 (UTC)
P.S. A table drawn according to how I would prefer if I was writing outside WP can be found at User:Double sharp/Template Periodic table. I hope its drastic difference from everything I am proposing for WP makes my view above clear. I wish to also make clear that while I personally, speaking with the scientist/educator's hat on, think this is the best way to go; putting my encyclopaedist's hat on, I have precisely zero intention of proposing that as a general WP table; and if it appears somewhere, it will only be in something off-WP which I, or perhaps I and somebody else, write in the future. And even then I would not propose it for the WP general table, despite my personal belief in its superiority, unless most people adopt it – which, even if it does happen, will probably take a long while. I hope that clarifies what I've said above. Though maybe it would be a good and fun exercise for everyone here to draw the PT to personal inclinations once, just to see how great the differences are and why I feel that the best way forward is to unquestioningly adopt something common in the literature rather than seeking to create something better by analysing it ourselves. ^_^ Double sharp (talk) 12:15, 20 November 2020 (UTC)
Double sharp, A picture is just a form of words. No doubt you'd've heard the expression, "A picture is worth a thousand words?" The p-block in the German PT picture is probably the most representative of the entire English RS literature. How do you see this now?
On lies to children I suggest this is a question of the quality of RS. Very crudely, there are: 3. less RS; 2. RS; and 1. "top-tier" RS, with reputation. Lies to children (ltc) RS fall between tiers 3 and 2. There's no need to necessarily rely on ltc-RS, since plenty of RS and top-tier RS are available. Indeed. a theme of distinguishing RS based on e.g. publisher reputation, author reputation, age of publication, etc pervades WP:RS.
Well, Sandbh, I understand that there may be a difficulty when it comes to the difference between what exactly is the best that can be shown from sources (e.g. for the superheavies), and what individual sources say, and I confess I am not sure what I believe in here anymore. I am also unsure if I really feel strongly for any of the schemes in particular in the first place as opposed to others at the moment. For the time being, I'd say you can go ahead with your RFC, because I feel like I have to think about this and what I feel should be there in WP. To edit effectively, I think I do need to to some extent believe that what I'm doing is the best path for creating an encyclopaedia, and frankly I'm not sure exactly what is at the moment. So I'm also not sure if I should set something before the community to pass judgement on if I only half-heartedly believe in it myself. I will have to think about it. Maybe go on semi-wikibreak mode to do so, hopefully with no hard feelings attached since we resolved all mutual issues.
(That being said: if your RFC is planned to be as at User:Sandbh/Nonmetal rfc, then I suggest you consider removing the "Aim" section. Reason being that it makes the thing look not quite neutral by arguing against "reactive nonmetals". Feel free to take or ignore this advice as you see fit, of course. ^_^) Double sharp (talk) 22:14, 20 November 2020 (UTC)
Double sharp, righto. No hard feelings whatsoever. The discussion has been engrossing. I'll have a look at the aim section. Maybe rewrite it into a context section. Not sure yet. Sandbh (talk) 00:34, 21 November 2020 (UTC)
Thanks for emailing me the article, Sandbh. Since a significant part of this seems to be about what is over- or under-emphasised in the literature, I guess I will not comment about it much for WP coverage of the periodic table in that overview article, but it is interesting and could maybe be used to cite a couple of warning examples that the typical trends are not as straight as the ones typically chosen (maybe good for a footnote there). I also like his classification of Sb as a metal rather than a metalloid, but only personally, since most people still include it. ^_^ Double sharp (talk) 23:31, 22 November 2020 (UTC)
Interesting publications (2020)
When a publication gains traction and responses, please start a separate thread
Eric Scerri YouTube workshop
This workshop (1h 41m) was conducted remotely via Zoom. 150+ people from 16 countries registered. It was organized by the American Chemical Society in association with Yale University.
Here’s an extract from Bray & Latimer 1949, A course in general chemistry, 3rd ed., Macmillan, New York, pp. 89–90. It’s the first time I’ve seen a concise explanation of these five terms, in one place.
”The oxides of Group I and of the heavier elements of Group II react readily with water to form hydroxides which are soluble strong bases; i.e., their solutlons contain hydroxide ion and the ions of the metals. The oxides of the nonmetallic elements are soluble in water, with but few exceptions, to form acid solutions. This difference in behaviour depends mainly upon the size and charge of the positive kernel or ion.
The oxides of the remaining metals, in general, do not react with water; but compounds (hydrous oxides, hydrated oxides, or hydroxides) are usually formed when solutions of the positive ions are made alkaline. In a few cases the precipitate is the anhydrous oxide. When the precipitates consist of particles of the oxides with an indefinite amount of absorbed water they are called hydrous oxides, e.g., SnO2 • xH2O. If there is a definite number of water molecules combined with the oxide, the name hydrated oxide is applied, e. g., Al2O3 • H2O. However, the hydrated oxides may absorb an indefinite amount of water to form gelatinous precipitates or hydrous hydrated oxides. In some cases the precipitate has a definite hydroxide structure, especially with ions having a +2 charge, e. g., Fe(OH)2 and Mg(OH)2 and these may be correctly called hydroxides.
If, as is often the case, additional absorbed water is present they may be referred to as hydrous hydroxides. The character of a hydrous precipitate varies with the method of preparation and changes upon ageing and drying. For the sake of simplicity, we shall often write the hydroxide formula without implying that this is correct.”
Dupasquier A,Traité élémentaire de chimie industrielle, Charles Savy Juene, Lyon, pp. 66–67
…and was struck by how advanced it was, for its time—a quarter century before DIM published his periodic table.
Dupasquier was a doctor, pharmacist and chemist. Per Google translate, here's his nonmetal taxonomy:
"There are 13 metalloids: nitrogen, boron, bromine, carbon, chlorine, fluorine, hydrogen, iodine, oxygen, phosphorus, selenium, silicon and sulfur.
To facilitate the study of metalloids, they will be divided into four groups or sections, as in the following table:
Section
Name
Constituents
1st
Organogens
O, N, H, C
2ns
Sulphuroids
S, Se, P
3rd
Chloroides
F, C, Br, I
4th
Boroids
B, Si
Organogenic bodies, as their name indicates, are those which constitute, as essential elements, organized matter, plant or animal. Plant matter is mostly composed of oxygen, hydrogen and carbon; animal matters generally have one more principle, nitrogen. There are exceptions to this rule; nitrogenous vegetable substances are known, and some matters of animal origin, which do not contain nitrogen.
The prototype of sulfuroids is sulfur; their general characteristics are: To be solid, volatile at an average temperature between 100 degrees and red heat, very combustible, and very inflammable. They have more affinity for the oxygen gene, with which they form powerful oxoacids, than for hydrogen. They can be divided into two secondary sections: 1 ° sulfuroids forming acid combinations (hydroacids) with hydrogen: sulfur, selenium; 2 ° sulfuroid in basic combination with hydrogen: phosphorus.
Chlorine is the prototype of the third section; the four bodies which constitute it have between them a great analogy of nature and properties; their main characteristics are: To be gaseous or very volatile at ordinary temperature; to give off a strong odor similar to that of chlorine; to have a lot of affinity for hydrogen and very little for oxygen; to form strong hydroacids, gaseous or very volatile, very greedy for water, and easily decomposable oxoacids; finally to constitute by their union with the metals combinations haloids. (See salts in general.)
The fourth section, which is boron-type, contains only two bodies, both fixed, odorless, of dull brown color, both forming solid, fixed, odorless oxoacids, and other acids, gaseous and volatiles, by their combination with fluorine and with chlorine."
Comments
The organogens + the sulfuroides = our other nonmetals
F was not isolated until 1866
The discovery of the noble gases occurred from 1895 onwards.
"Averaged Scale in Electronegativity Joined to Physicochemical Perturbations. Consequences of Periodicity"
Antonio Campero and Javier Alejandro Díaz Ponce
ACS Omega 2020 5 (40), 25520-25542 [10]
"Concerning the periodicity in electronegativity of La and Lu, La belongs to three tendencies: group G3, period P6, and lanthanides. In the case of Lu, it only belongs to the last two, but the other lanthanides to any of the three sequences, and Hf only belongs to period P6. Then, the orbital f functions as an orbital intern between the 6s and 5d orbitals to give continuity in the electronegativity from groups G1 and G2 to group G3 in period 6, not considering the increment of atomic number Z. This continuity is not present for orbital d between orbitals s and p for the post-transition elements. We conclude then that the natural sequence of atomic number Z in the large periodic table, as Scerri has explained,(52c) implies that La is in group G3. The tendency of the electronegativity values in absolute values and ratios of the elements near to La and Lu, with their associated overall physicochemical properties, reaffirms this conclusion. Also, the electronegativity values determined in this work are correlated to similar chemical behavior of the ions through Knight’s, isodiagonal, vertical, and horizontal periodicity."
Graham RP & Cragg LH 1956, The essentials of chemistry, George G. Harrap, and Co., London. p. 148 (reprinted ’59, ’62, ’64, ’65, ’66, '67):
"Some students are disturbed by the fact that some elements refuse to fit neatly into either the metal or non-metal categories, and feel that such elements are exceptions to the rule. They are not exceptional—they merely illustrate the fact that the very idea of metals and nonmetals is not something in Nature itself, but something that chemists try to impose on Nature. Within bounds, the classification is useful, and that is its justification. But its application, like that of many good ideas, should not be pushed too far.*
* Surely you know girls who cannot be classified as either blonde, brunette, or redhead. And for that matter, when you do get a girl classified as one or the other of these, can you be sure she’ll always stay in that category?"
Drs. Judith Hartman and Eric Nelson have posted a "draft for comment" of a paper on "Working memory limits and chemistry instruction", an 18-page review of strategies cognitive neuroscientists and cognitive psychologists recommend to maximize student learning in “science major” chemistry courses.
Quick summary: In designing chemistry instruction, what scientists who study the brain recommend is different in many respects from what is recommended in chemistry education journals. --- Sandbh (talk) 01:15, 29 December 2020 (UTC)
History of discovery
Here's my idea to replace the color-coded graphic at Periodic table § History. Just a rough idea, needs to be refined. Actually, maybe the best of all would be an animated picture. But to me, this is more understandable than the color-coded one.
@YBG: I like the idea. Although personally I'd scrap the 2000 one; there is not that much change from 2000 to 2012 and nothing interesting seems to have really happened as a paradigm shift in 2000. Also, I don't think 2012 makes sense; 2010 seems better as the year when Ts was discovered and the last gap was filled.
That being said, I also notice that we're supposed to be writing a history section for the periodic table, rather than for the chemical elements. Obviously the latter is necessary for the former, but I worry about over-emphasising it. Double sharp (talk) 09:56, 29 January 2021 (UTC)
OK, I've removed 2000 and relabeled 2012 as 2010. As for hair-tearing. Not really a concern in this graphic because the defining characteristic is what element appeared in a given list/PT. YBG (talk) 10:19, 29 January 2021 (UTC)
@YBG: I'm sorry to say that a little bit of hair-tearing is still necessary, even if not as much. ;) Take strontium for example. It was discovered in 1787, yet it does not appear on Lavoisier's 1789 list of elements. Maybe the news hadn't reached him? Calcium and barium were known to Lavoisier, but only as earths (oxides), not the elements. Do those count? Terbium had been discovered before Mendeleev's table, but Mendeleev did not include it. I would prefer the line of "does it appear on this table or not", myself (so Sr should not appear for Lavoisier and neither should Tb for Mendeleev). But what to do about Lavoisier considering light and heat as elements? Double sharp (talk) 11:24, 29 January 2021 (UTC)
Urgent request for clarification: Why, User:YBG, did you start this ==-section here at all? What does it relate to? At least, could you keep a sound TOC setup in mind. Please. -DePiep (talk) 00:09, 30 January 2021 (UTC)
Some comments after a quick perusal of Periodic table after the recent changes:
Periodic Table § Categories - Now that we are not showing en-wiki categories in our main table, the color swatches are largely meaningless. Moreover, one wonders why the AM, AEM, and NG are described here rather than under Groups. My personal opinion is that this sub section should be renamed "Other sets of elements", morphed into a summary of Named sets of chemical elements, and moved after Groups, Periods and Blocks.
Several PTs should be replaced with block-colored versions: the update of Dmitri's PT; the 32-col PT, Bentley's PT, the three Group 3 options.
The PT sidebar interferes with the main PT when the table of contents is collapsed.
I have an alternate graphic for the history section rumbling in my brain. I shall have to develop it and see others like it.
This section is to wind down this talkpage, WT:ELEM.
Last year many threads were started, often handling multiple topics and intertwined with other threads; also often no stable consensus was reached. The WP community has concluded that the discussions were not always performed to the best of Wikipedia. Also, the sheer volume of this page (at this moment, 700k in 100+ TOC lines) requires some organised slimming down to regain a workable situation.
How to proceed? Some thoughts:
Idea 1: The WT:ELEM existing TOC is frozen per Jan 5 2020. Refactoring can only be done after explicit consensus.(A not good idea. We are serious grown-up wiki-editors. -DePiep (talk) 23:03, 6 January 2021 (UTC))
Adding well-considered (sub)threads is OK, please think beforehand (community-serving, on-topic, useful next step, no doubling)
Idea 2: Per main thread (section level ==) we try to decide a conclusion. Could be?: Keep open/Close & archive/Split/Archive & reopen anew/...
Idea 3: Keep posts short. TL;DR only should do (without the 'TL;DR').
Idea 4: Some topics may deserve their own discussion, continued or renewed. Then, a new ==-start is appropriate? For example: Article Periodic table, Chemical categorisation, Colors of categories, Group 3. (Some may be considered closed just as well).
Idea 5: Action proposal: Shall we open a subthread per toplevel section (15) here, to meta-discuss its future?
These two sections on interesting publications are a strange mix. Some are potential resources for article work. Some are curiosities posted for the sake of interest – which does little harm but is quite FORUMy. The philosophy / what we teach material is interesting (to me, anyway) and is suitable for article space so long as there are sufficient RS to support it and with a related issue being "where"? It doesn't fit the PT article, for example, and while there is a lot that I could say about the topic, much would be SYNTH or OR and thus unsuited to article space. I don't know that there are the resources for a non-OR NPOV article on the issues... and consequently, I don't know what to suggest about some of these sections. EdChem (talk) 22:48, 9 January 2021 (UTC)
I can easily agree with EdChem in all of this. Now, this section only wants to 'clean up' talkpage & threads, without going into content.
Talkpage-technically, these posts (separate 'interesting publication' posts, with or without gaining responses) were gathered=subthreaded to get some talkpage overview. I still think this was a good plan ;-) . But, since they are ===-subthreads now, one cannot simply Archive a single one (however reasonable). What do we think about this? I propose:
Added "(2020)" to section title. Creates an aging date. Any issue that comes back to live can be lifted or linked. -DePiep (talk) 01:33, 24 January 2021 (UTC)
Up for archiving. The two treads lived ca. 14–22 Nov 2020 only. Even by old WT:ELEM bot settings (old:2 months) they would have been archived by now. Interested editors can search & pull them up from Archive. -DePiep (talk) 21:19, 26 January 2021 (UTC)
Important (and ongoing) topic that needs a resolution, though what colours to use follows from how many we need, etc. EdChem (talk) 22:48, 9 January 2021 (UTC)
Further thought: Logically (to me) arises after categorisation is sorted, though work on how we can do 5 or 6 or ... or 118 colours (would one per element be over-categorised? :P) can occur in parallel. EdChem (talk) 03:14, 14 January 2021 (UTC)
- Finished. Archive. One of our self-evaluating discussions, that will not continue (not this way, this thread). Safe in Archive for reference if needed. -DePiep (talk) 20:53, 6 January 2021 (UTC)
-Subsection § Consenus requests (with 9 subthreads/topics) be split into new ==-section. They can remain, and be dealt with separately. Then Archive the remaining part. No promising discussion is open in there. So: split & archive 1st part. -DePiep (talk) 21:08, 6 January 2021 (UTC)
A new thread, with convenience links for previous discussions, seems sensible to me. I do keep wondering if the discussion on the PT article itself should be moved to the article talk page, though... Thoughts? EdChem (talk) 03:14, 14 January 2021 (UTC)
I am happy for the ANI part to be separated and archived, renaming / changing heading levels is fine with me. EdChem (talk) 22:48, 9 January 2021 (UTC)
I have changed the § ELEM future plans to a level 2 header and support archiving of the reduced ANI section. DePiep, I didn't change the title to avoid breaking links and I wasn't trying to force the focus to the PT article specifically. I am open to other comments / suggestions, though. :) EdChem (talk) 03:14, 14 January 2021 (UTC)
-Important showing of archiving and esp refactoring problems of this WT:ELEM page. YBG wrote this. By now, we are supposed to understand how to tread here. Also, cleaning up this WT:ELEM page helps reducing the need for refactoring. If discussion is needed, a new thread will do. -DePiep (talk) 21:02, 6 January 2021 (UTC)
I have no objection to archiving this, though the topic should be re-raised the moment any editor feels there are problems with page management / archiving. I know DePiep has taken feedback on board and I appreciate the way he is seeking consensus and discussing the necessary slimming-down of this page at present. YBG and R8R, as two editors who have been uncomfortable before, I hope that you will feel able to comment if this concern recurs. Christian75, as an editor who commented in that thread, do you have any further thoughts to share / comments to make? Thanks. EdChem (talk) 03:14, 14 January 2021 (UTC)
I think this task-&-section has reached its purpose: clean up the WT:ELEM talkpage (say, 2020 topics & threads) nicely and gently. Respecting all contributions & contributors, without blaming. I tried to keep all topics searchable, including the /Archives; sometimes by adding the 2020/2021 annum split. Thanks for your contributions. -DePiep (talk) 23:41, 31 January 2021 (UTC)
By now, I think we can archive this thread (Before, we better set expanded all collapses to support Archive search). -DePiep (talk) 12:23, 11 February 2021 (UTC)
Will archive now. I have not met controversies in this handling, recent weeks. So I think it's fine, & done now. -DePiep (talk) 22:26, 11 February 2021 (UTC)
Consenus requests (2020)
@DePiep and EdChem: Please be advised that EdChem asked me tidy of these requests for consensus, by dividing them up into the proposal, followed by the rationale, and the discussion, or the like.[21] I said it would be OK for EdChem to do so. As he has not got a round toit, I'll now do so. Sandbh (talk) 22:50, 30 December 2020 (UTC)
3 Periodic trends and patternsCurrent Proposed
3.1 Electron configuration Metallic character
3.2 Atomic radii Atomic radii
3.3 Ionization energy Ionization energy
3.4 Electronegativity Electron affinity
3.5 Electron affinity Electronegativity
3.6 Metallic character Electron configuration
Rationale: My reasoning is that vertical and horizontal trends are the most important trends and they are explained in the Metallic character section. Mingos (1998) thus allocates 185 pages to the modern use of vertical, horizontal and diagonal trends originally highlighted by Mendeleev.
I'll address diagonal trends in my next consensus request.
After that, Atomic radii is the most important trend. As Atkins (2019) wrote:
"The periodic table and the concept of the elements of education inspires all manner of other thoughts. One is the desert-island thought: if you were asked to identify the central elemental concept summarized by the periodic table which, with you isolated on a conceptual desert island and asked to set about rationalizing chemistry, what would it be? My choice would be atomic radius. In molecular biology a common precept is that shape determines function, with shape interpreted as including size, I think that the same maxim applies in the less elaborate region of chemistry. Atomic radius correlates with ionization energy and electron affinity, and thus it correlates with much of the energetics of bond formation. Atomic radius controls perhaps even more than simple energetics the numbers and arrangements of bonds that an element can form, and so is central to considerations of bonding and the formation and stereochemistry of compounds.
"Atomic radius plays a crucial role in the mechanisms of reactions, both in organic and inorganic chemistry, especially in the formation of intermediates and transition complexes. Atomic radius plays a role in the arrangement of electrons around nuclei, as well as that arrangement affecting the radius. When the elements form compounds, the sizes of the constituent atoms affect the size of the molecules and through that size (and the underlying aspects of the energetics of electron excitation, itself size-dependent) the intermolecular forces that determine the physical properties of the compounds. It is hard, in fact, to identify a property that cannot, with sufficiently deep probing, correlate in some way with atomic radius."
Then come ionization energy, electron affinity, and electronegativity, as these are correlated with metallic or nonmetallic character (Yoder et al. 1975). Electronegativity is the third property in this triad as it is a unit-less property.
Electron configuration is last as there is no clear line of sight between the properties of an element and its electron configuration. As Jensen (2015) brilliantly wrote:
"Though there are many misconceptions concerning the nature and function of the periodic law and table, perhaps the most prevalent among modern chemists is the belief that the periodic table is nothing more than an electron configuration table. While there is certainly a significant correlation between electron configurations and chemical periodicity, the correlation is, as already noted, far from perfect. The increasing prevalence of irregular configurations among the d- and f-block elements, the increasing lack of correlation between minor irregularities in these configurations and actual chemical behavior, and the ever present empirical question of how to properly divide an atom’s configuration into the chemically relevant categories of valence versus core, all require a careful balancing of both chemical and physical evidence rather than an appeal to authority and a naive, and apparently arbitrary, freshman [sic] chemistry application of spectroscopic atomic ground states."
References
Atkins P 2019, "Elements of education," Chemistry International, vol. 41, no. 4, pp. 4–7, doi:10.1515/ci-2019-0404
Jensen WB 2015, "The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table: an update", Foundations of Chemistry, vol. 17, pp. 23–31, doi:10.1007/s10698-015-9216-1
Mingos DMP 1998, Essential trends in inorganic chemistry, Oxford University Press, Oxford
Yoder CH, Suydam FH & Snavely FA 1975, Chemistry, 2nd ed., Harcourt Brace Jovanovich, New York, p. 78
No, not now. For example: how is this #3 section conceived? As we know, the overal reconstruction of periodic table is under wider consideration. It also might loose it's FA status. By the way, Sandbh, since you have time to edit could you reply to my serious request, here: [22]? -DePiep (talk) 23:20, 27 December 2020 (UTC)
DePiep: I explained how #3 section is conceived, above. This proposal will have no impact on the overall reconstruction of the article. Yes, the longer it takes to fix the PT article the more likely it is to lose its star. It has lost its star before, and regained it, a process in which I played a part (a key part according to either StringTheory11, or Nergaal, I forget which one). Sandbh (talk) 05:57, 29 December 2020 (UTC)
Consensus requested: Diagonal relationships
Proposal: To reinstate a short Diagonal relationships section to the Periodic trends and patterns section of the periodic table article, just after the Metallicity section, as follows:
32-column lanthanum table (condensed) showing examples of isodiagonality. Aluminium has been reproduced in group 3, for this purpose. The elements in bold text are the most well known isodiagonal pairs. A less well-known isodiagonal relationship can be seen, for example, along calcium-yttrium-cerium.[n 1]
Diagonal relationships in the periodic table are seen between elements including lithium and magnesium; beryllium and aluminium; and boron and silicon. Such relationships were recognized by both Mendeleev and Newlands, from as early as 1860.[1] They are, in some ways:
"…a general attribute of the properties of the chemical elements. For example, the metal-nonmetal divide forms an almost diagonal demarcation."[2]
Mingos counts diagonal relationships as one of the three patterns that characterise the periodic table, along with vertical and horizontal trends.[3]
References
^Rayner-Canham, G. (2011). "Isodiagonality in the periodic table". Foundations of Chemistry. 13 (2): 121–129. doi:10.1007/s10698-011-9108-y.Rayner-Canham, G. (2020). The Periodic Table: Past, Present, and Future. New Jersey: World Scientific. pp. 213–234. ISBN978-981-121-848-4.
^Edwards, P. P.; Sienko, M. J. (1983). "On the Occurrence of Metallic Character in the Periodic Table of the Elements". Journal of Chemical Education. 60 (9): 691–696. doi:10.1021/ed060p691.
^Mingos, D. M. P. (1998). Essential Trends in Inorganic Chemistry. Oxford: Oxford University Press. pp. 213–234. ISBN978-0-19-850108-4.
Notes
^All three elements are strongly basic. Similarities between calcium and the lanthanoids (including cerium) are well known. Yttrium is a member of the rare earths, as are the lanthanoids. All three elements exhibit predominantly ionic chemistry. In atomic number terms the three elements form a triad: 20 (Ca) +58 (Ce) = 78; 78/2 = 39 (Y). Scandium-yttrium-lanthanum too form such a triad: 21 (Sc) +57 (La) = 78/2 = 39 (Y).
Rationale: In revising this sub-section I have taken into account concerns previously expressed by Double sharp. Thus, 1. Al is shown in two places: shaded over Sc and non-shaded over Ga. The caption text explains what is going on. 2. The most common diagonal relationships are in bold, the rest of them are in ordinary font. 3. I moved some of the caption text into a footnote, in order to reduce the size of the caption.
--- Sandbh (talk) 06:00, 27 December 2020 (UTC)
Discussion
No, not convinced, not fit for the article. Sure, "the metal-nonmetal divide forms an almost diagonal demarcation" exists, but that is only the easiest diagonal, the metalloids. And even then this diagonal is not scientifically clarified (not in the source's intro). I say: fringe. Better be not in this article, possibly in a detailing article (like PT detail issues). By the way, Sandbh, since you have time to edit could you reply to my serious request, here: [23]? -DePiep (talk) 21:45, 27 December 2020 (UTC)
Consensus requested: Between Deming's 1923 18-column table and the rise of the modern form
Proposal: As reverted by DePiep[24], I propose to reinstate a short summary, in the History section, of what happened between the popularity of Deming's 1923 18-column table and the rise of the modern form, as follows:
Deming's table had B-Al over Sc in group 3, rather than over Ga in group 13. This configuration, which dates back to 1893,[1] was also adopted by Rydberg(1913) and Pauling(1970, 1988).[2] Seaborg (1945) published a periodic table with Al over Sc and Ga. With the further development of quantum theory, (B)-Al over Sc came to be deprecated.[3][n 1]
Notes
^Deming's 1940 table, for example, had B-Al over Ga.[4].
References
^Rayner-Canham, G. (2020). "6". Advances in teaching inorganic chemistry, vol. 2: Laboratory enrichment and faculty community. ACS Symposium Series. Vol. 1371. Washington, DC: American Chemical Society. pp. 69–77. doi:10.1021/bk-2020-1371.ch006. ISBN0-8412-9856-4.
^Pauling, L. (1970). General chemistry. San Francisco: W.H. Freeman and Co. p. 182.; Pauling, L. (1988). General chemistry. New York: Dover Publications. p. 182.
^Parkes, G.D.; Mellor, J.W. (1943). Mellor's modern inorganic chemistry. London: Longmans, Green and Co. p. 6977.
^Deming, H. G. (1940). Fundamental chemistry: An elementary textbook for college classes. New York: J. Wiley & Sons. p. 267.
The external links in this proposal (such as to a meta-synthesis.com PT) should be notes or references. Was Pauling really using a B - Al - Sc table in 1988, 45 years after it was deprecated? Or was this just for a single purpose in the book and a more typical table elsewhere? EdChem (talk) 03:01, 31 December 2020 (UTC)
Consensus requested: Oxidation number trends
Periodic table showing oxidation number trends. R = reactant.
Proposal: To reinstate a short Oxidation number trends section to the Periodic trends and patterns section of the periodic table article, just before the Metallicity section, as follows:
Mendeleev compared the chemical properties of the elements by comparing their oxides and hydrides. He selected hydrogen and oxygen for this purpose due to their reactivity and their capacity to form compounds with most of elements. [1]
The accompanying image shows the pattern of oxides going from left to right across the periodic table (R = reactant) and the trends going down each column.[2][3]
References
^Jensen, WB (2005). Mendeleev on the period law: Selected writings, 1869–1905. Mineola, New York Diego: Dover Publications. pp. passim. ISBN978-0-486-44571-7.
I really don't understand this PT. Iron, for example, has its common oxides as FeO, Fe 2O 3, and Fe 3O 4. Ferrate(VI) is not its most stable form yet the text for the yellow suggests to me that it is. Similarly in the halogens, F does not form compounds in a +7 state. Isn't gold most stable in oxidation state 0, being a noble metal and found typically in elemental form or as Au / Ag alloys? Oxidation number trends certainly are basic chemistry but this presentation of them is confusing me. Also, Zn, most stable ON is its group number (12)? And 13 for Al, B? EdChem (talk) 03:08, 31 December 2020 (UTC)
Consensus requested: Metallic character
Proposal: to improve the Metallic character section of the article, from what it is now, to this:
Metallic to nonmetallic progression
The L-R progression in metallic to non-metallic character across the periodic table, shown here in the form of four classes of metals (#1–4) and nonmetals (#5–8). Here, the noble metals are composed of a subset of the transition metals.
Going across the periodic table there is a progression from active to less active metals, and from less active to more active nonmetals, concluding with the noble gases.[1]
"Active" metals then, which include the alkali metals, are mostly strongly electropositive metals, with a few of the actinoids being only moderately electropositive.[2] The transition metals are, for the most part, moderately to weakly electropositive in nature.[3] Several other transition metals are chemically very weak (or noble), like platinum, with these representing the noble metals. Most of the other metals such as tin and bismuth, are chemically weak.[4][n 1]
It has been know for over 120 years that the metalloids behave predominately like chemically weak nonmetals.[5] The other nonmetals are neither as reactive as the halogens nor as chemically restrained as the weakly nonmetallic metalloids.[6] For the noble gases, they have their counterparts in the noble metals.[7]
The metallic to metallic progression is seen in values of ionization energy, electron affinity and electronegativity. The lower the values, the more metallic character the element has; conversely the higher the values the more nonmetallic character an element has.[8]
Metallic character further tends to increase going down a group (or column or family), with some irregularities (mostly) due to poor screening of the nucleus by d and f electrons, and relativistic effects[9]. Thus, the most metallic elements (such as caesium) are found at the bottom left of traditional periodic tables and the most nonmetallic elements (such as neon) at the top right. The combination of horizontal and vertical trends in metallic character explains the stair-shaped dividing line between metals and nonmetals found on some periodic tables, and the practice of sometimes categorizing several elements adjacent to that line, or elements adjacent to those elements, as metalloids.[10][11]
Notes
^Dingle (2017, p. 101) writes: "…with no-doubt metals on the far left of the table, and no-doubt non-metals on the far right…the gap between the two extremes is bridged first by the poor [other] metals, and then by the metalloids – which, perhaps by the same token, might collectively be renamed the poor non-metals"
References
^Rutherford, F.J. (1993). Benchmarks for science literacy. American Association for the Advancement of Science. New York: Oxford University Press. p. 78. ISBN978-0-19-508986-8.
^Scott, E.C.; Kanda, F.A. (1962). The nature of atoms and molecules. New York: Harper & Row. p. 385.
^Kneen, W.R.; Rogers, M.J.W; Simpson, P. (1972). Chemistry, Facts Patterns, and Principles. London: Addison-Wesley. p. 489.; Atkins, P.A. (1995). The periodic kingdom: A journey into the land of the chemical elements. New York: Basic Books. pp. 18–19. ISBN978-0-7867-2527-4. Between the "virulent and violent" metals on the left of the periodic table, and the "calm and contented" metals to the right are the transition metals, which form “a transitional bridge between the two” extremes.
^Vernon, R (2020). "Organising the metals and nonmetals". Foundations of Chemistry. 22: 217–233. doi:10.1007/s10698-020-09356-6.
^Newth, G.S. (1894). A Text-book of Inorganic Chemistry. London: Longmans, Green, and Co. pp. 7−8. {{cite book}}: Cite has empty unknown parameter: |1= (help); Friend, J.N. (1914). A Text-book of Inorganic Chemistry. Vol. 1. London: Charles Griffin and Company. p. 9. Usually, the metalloids possess the form or appearance of metals, but are more closely allied to the non-metals in their chemical behaviour.
^Welcher, S.H. (2001). High marks: Regents chemistry made easy (2 ed.). New York: High Marks Made Easy. p. 3-32. ISBN978-0-9714662-4-1. "The elements change from…metalloids, to moderately active nonmetals, to very active nonmetals, and to a noble gas."
^Wiberg, N. (2001). Inorganic Chemistry. San Diego: Academic Press. p. 1133. ISBN978-0-12-352651-9. In place of the noble gases, the transition metal grouping has the noble metals.
Proposal: To reinstate a short Groups that bridge blocks section to the Periodic trends and patterns section of the periodic table article, as follows:
32-column periodic table showing, from left to right, the location of group 3; the heavy group 4 and 5 elements; lutetium and lawrencium; groups 11–12; and the noble gases
On the group 12 metals (zinc, cadmium and mercury), Smith[1] observed that, "Textbook writers have always found difficulty in dealing with these elements." A 2003 survey of chemistry books showed that they were treated as either transition metals or main group elements on about a 50/50 basis.[2] They are sometimes regarded as linking the d block to the p block. Notionally they are d block elements but they have few transition metal properties and are more like their p block neighbours in group 13.[3][4] In a like manner, the relatively inert noble gases, in group 18, bridge the most reactive groups of elements in the periodic table—the halogens in group 17 and the alkali metals in group 1.[4]
Chemically, the group 3 elements, lanthanides, and heavy group 4 and 5 elements show some behaviour similar to the alkaline earth metals[5] or, more generally, s block metals[6][7][8] but have some of the physical properties of d block transition metals.[9]
Meanwhile, lutetium (at the end of the f-block) behaves chemically as a lanthanide (with which it is often classified) but shows a mix of lanthanide and transition metal physical properties (as does yttrium).[10][11] Lawrencium, as the heavier congener of lutetium, would presumably display like characteristics.[n 1] The coinage metals in group 11 (copper, silver, and gold) are chemically capable of acting as either transition metals or main group metals.[14]
Notes
^While Lr is thought to have a p rather than d electron in its ground-state electron configuration, and would therefore be expected to be a volatile metal capable of forming a +1 cation in solution like thallium, no evidence of either of these properties has been able to be obtained despite experimental attempts to do so.[12] It was originally expected to have a d electron in its electron configuration[12] and this may still be the case for metallic lawrencium, whereas gas phase atomic lawrencium is very likely thought to have a p electron.[13]
References
^Smith, D. W. (1990). Inorganic substances: A prelude to the study of descriptive inorganic chemistry (2nd ed.). Cambridge: Cambridge University. p. 113. ISBN0-521-33738-0.
^Greenwood, N. N.; Earnshaw, A. (2001). Chemistry of the Elements (2nd ed.). Oxford: Elsevier Science Ltd. p. 1206. ISBN978-0-7506-3365-9.
^ abMacKay, K. M.; MacKay, R. A.; Henderson, W. (2002). Introduction to Modern Inorganic Chemistry (6th ed.). Cheltenham: Nelson Thornes. pp. 194–96, 385. ISBN978-0-7487-6420-4.
^Remy, H. (1956). Kleinberg, J. (ed.). Treatise on Inorganic Chemistry. Vol. 2. Amsterdam: Elsevier. p. 30.
^Phillips, C. S. G.; Williams, R. J. P. (1966). Inorganic Chemistry. Oxford: Clarendon Press. pp. 4–5.
^King, R. B. (1995). Inorganic chemistry of main group elements. New York: Wiley-VCH. p. 289.
^Spedding, F. H.; Beadry, B. J. (1968). "Lutetium". In Hampel, C. A. (ed.). The Encyclopedia of the Chemical Elements. Reinhold Book Corporation. pp. 374–78.
Consensus requested: Theodor Benfey's spiral periodic table
Theodor Benfey's spiral periodic table
Proposal: To reinstate Theodor Benfey's spiral periodic table to the Alternative tables section of the periodic table article. The colour scheme to be updated to reflect the current scheme.
Rationale:
Probably the best known alternative table.
The updated eight-column DIM periodic table which is there now, is not really an alternative periodic table.
It can go back (in a smaller form) into the History section, which is where R8R originally asked for it to be.
Proposal: To change the last sentence in this paragraph…
Helium is an unreactive noble gas at standard conditions, and has a full outer shell: these properties are like the noble gases in group 18, but not at all like the reactive alkaline earth metals of group 2. However, helium only has two outer electrons in its outer shell, whereas the other noble gases have eight; and it does not have electrons in p-orbitals, whereas the other noble gases do. In these ways helium better matches the alkaline earth metals.[91][100] Therefore, while helium is nearly universally placed in group 18[101][102] which its properties best match,[100] helium outside all groups may rarely be encountered.[99][100]
…to this:
While helium is nearly universally placed in group 18[101][102] which its properties best match[100] it may rarely be encountered above beryllium[1][2] or outside of all groups, floating above them.[99][100]
References
^Scerri, E (2008). "The Role of Triads in the Evolution of the Periodic Table: Past and Present". Journal of Chemical Education. 85: 585–589. doi:10.1021/ed085p585.
^Stewart, P. J. (2018). "Amateurs and professionals in chemistry". In Scerri, E.; Restrepo, G (eds.). Mendeleev to Oganesson: A Multidisciplinary Perspective on the Periodic Table. Proceedings of the 3rd International Conference on the Periodic Table, Cuzco, Peru 14–16 August 2012. Oxford: Oxford University Press. pp. 66–103(69–70). ISBN978-0-86380-292-8.
Rationale:
To provide a more complete account of where helium can be found.
.svg)
