Wikipedia talk:WikiProject Physics/Archive April 2022

LiquidO Detection

The newly created article at LiquidO Detection is clearly created by a SPA with a massive conflict of interest. But the article can be repaired. (I've already rewritten the lead.) However - is it worth it, or should this article be submitted to AfD as WP:TOOSOON? There is at least one peer reviewed primary source article, but not much in secondary sources that I could find. Thoughts? PianoDan (talk) 16:39, 28 March 2022 (UTC)

I think this is too soon. The secondary sources I can find don't go into much depth at all. This is barely a mention, and this review gives it only a sentence (The potential for improving the identification of inverse beta decay and reducing background is apparent with a novel detector using a dense array of optical fibers immersed in opaque scintillating liquid). Maybe it can be cut drastically down and merged somewhere, but I can't make a case that it needs a whole article. XOR'easter (talk) 16:55, 28 March 2022 (UTC)

References

At the very least, I feel WP:TNT applies. Poor formatting, promotional tone, etc... I would sent to AFD. Headbomb {t · c · p · b} 16:53, 28 March 2022 (UTC)

Done. PianoDan (talk) 17:02, 28 March 2022 (UTC)

Orphan. Speaks volumes. Lithopsian (talk) 18:50, 28 March 2022 (UTC)

Big wall-o-text from the author on the AfD page. I tried to make a coherent response, but if someone with more experience wants to say something more artfully, feel free. PianoDan (talk) 20:55, 4 April 2022 (UTC)

Another example of Wikipedia:Don't call it "Wiki"... XOR'easter (talk) 21:16, 4 April 2022 (UTC)

I may have gone a bit heavy at the coal face here, but I've added an elaboration with hopefully less technical language. I usually only lurk here, but this one smells funny to me - 70 scientists at 22 institutions and nobody bothered to learn how wikipedia works first? - car chasm (talk) 21:55, 4 April 2022 (UTC)

Talk:Chaos theory#Chaos as a Topological Supersymmetry Breaking

This discussion at the Chaos theory talk page may be of interest to the community here. XOR'easter (talk) 13:50, 5 April 2022 (UTC)

Is this "supersymmetry" the same as that described in our article Supersymmetry which would have bosons and fermions mixing? JRSpriggs (talk) 01:34, 6 April 2022 (UTC)

"Supersymmetry" as a mathematical topic covers a bit more broad territory than that; see, e.g., [1]. XOR'easter (talk) 04:29, 6 April 2022 (UTC)

Article for deletion: Gravitationally-interacting massive particles

I have nominated the article Gravitationally-interacting massive particles for deletion, this article is currently listed as within the scope of WikiProject Physics with rating of start-class and mid-importance. The discussion can be found at [2].

Reason for deletion is that the only claim relating the GIMPs that is even remotely reliable is that they are a hypothetical particle that would only interact gravitationally. All other claims are original research/unreliably sourced (WP:NOR and WP:Reliability respectively). LewriBaedi (talk) 14:42, 6 April 2022 (UTC)

FAR notice on Hubble Space Telescope

Article about to be dethroned with issues noticed [3]. 2001:4455:30B:6C00:45B7:D10F:374A:178A (talk) 12:58, 6 April 2022 (UTC)

I'm still trying to bring the FA reviews for Mars and Solar System to successful conclusions, so I don't know how much I can help there, but maybe somebody can. XOR'easter (talk) 21:06, 6 April 2022 (UTC)

To be clear, there have been some issues raised at Talk:Hubble Space Telescope, but no FAR process has been started. Firefangledfeathers (talk | contribs) 21:34, 6 April 2022 (UTC) - striking 05:32, 7 April 2022 (UTC)

The standard process is, I believe, to give 2–3 weeks after raising issues on the article's Talk page before going to FAR, but if anyone can tackle the points mentioned there in less time than that, it'd be great. XOR'easter (talk) 23:41, 6 April 2022 (UTC)

An important correction. Thanks. Firefangledfeathers (talk | contribs) 05:32, 7 April 2022 (UTC)

I've gone through and addressed the {{citation needed}} tags that were present, but I have not made a thorough sweep for outdated material. XOR'easter (talk) 05:25, 7 April 2022 (UTC)

Weird, thought this was on my watchlist. I'll see what I can help out with. Primefac (talk) 07:21, 7 April 2022 (UTC)

Much appreciated! I've taken a stab at general maintenance and will try again when I find the time, but if anyone can beat me to it, so much the better. XOR'easter (talk) 18:08, 7 April 2022 (UTC)

Particle Accelerator Infobox

As part of my ongoing sporadic efforts to improve accelerator science articles on WP, I've tried to start mocking up a particle accelerator infobox. This is my first whack at making one of these things, and there's definitely technical things are going to need to be tweaked. But now that I have at least a starting draft, I thought I'd toss it out here.

• Does the concept seem worthwhile? We have well over fifty pages it could easily be applied to.
• Does the content of the implementation seem reasonable? Are there facts that should be included or omitted?
• What are the obvious technical errors? I'm sure there's code stuff that's fundamentally broken about the draft right now.

Thanks! PianoDan (talk) 17:13, 8 April 2022 (UTC)

If it can be used on over 50 pages, I would say that an infobox would be appropriate to standardise and summarise the most important content. Given that it's somewhat of a niche topic, though, it might be worth wikilinking some of those labels but I couldn't say from a quick look which or where would be best.

Code-wise, you've gone the smart route and not over-complicated things; just headers, labels, and data! Can't see anything flawed there. Primefac (talk) 19:26, 8 April 2022 (UTC)

I wikilinked luminosity, and then fell down a rabbit hole trying to find the best target for brightness. I finally realized I had to rewrite the target for that one first before I could link it. Ah, adventures in niche subtopics. :) PianoDan (talk) 21:08, 8 April 2022 (UTC)

Notability of scientific journals

The discussion at Wikipedia:Teahouse#Rejection Query about Draft:IEEE Photonics Technology Letters could use some input. StarryGrandma (talk) 21:30, 8 April 2022 (UTC)

Soft modes

Man, condensed matter is NOT my thing. Ran across this page: Soft modes. It's basically a stub, and I suspect it would be better as a redirect, but I'm not sure, because condensed matter makes my brain hurt. Are these just another term for Goldstone bosons? PianoDan (talk) 16:40, 12 April 2022 (UTC)

I'm not aware of a well-established difference in meaning between "soft mode" and "Goldstone mode" (and the one source cited in that stub does act like they're synonymous). There may be some subfield of condensed-matter physics that draws a distinction, because there are many subfields of condensed-matter physics, but it probably makes more sense for us just to have one article. XOR'easter (talk) 19:46, 12 April 2022 (UTC)

As far as I am aware, a soft mode is a fairly broad concept--different condensed matter fields may have different names for their excitations, but I'm not aware that any have appropriated the term "soft". I would redirect to Goldstone_boson#Goldstone's_theorem, where soft modes == Goldstone modes are briefly mentioned. --{{u|Mark viking}} {Talk} 21:34, 12 April 2022 (UTC)

Done. PianoDan (talk) 18:11, 13 April 2022 (UTC)

Creation of Carbon nanotubes in 6th century BCE India

Please see WP:FTN#6th century BCE Carbon nanotubes where a paper is being discussed that says the creators "were aware of the uniqueness of these materials and the methods of synthesizing it." Thanks. Doug Weller talk 15:35, 17 April 2022 (UTC)

"pottery was discovered whose coatings appear to contain carbon nanotubes", in other words, soot. JRSpriggs (talk) 18:01, 17 April 2022 (UTC)

Noble metals

​​​​Why are noble metals defined differently in physics v chemistry?

In chemistry there are seven to eight elements generally recognized as noble metals namely gold, the six platinum group metals, and usually, but not always, silver. Generally, the noble metals are called noble in recognition of their disinclination to combine with oxygen in ambient conditions and that fact that, at least for Au and the platinum group metals, they usually occur in native form. Whereas the most important source of silver is in the form of its sulfide ore.

OTOH, in physics (and metallurgy), the noble metals are limited to copper, silver and gold, in group 11. I get that the noble metals in this sense, unlike the preceding transition metals, have a full complement of ten d electrons each occupying a d band lying several eV below the Fermi level of a conduction band containing one s electron ("s-d hybridization is negligibly small"). But in what sense is this "noble", and what unique property or properties does this convey that the other transition metals and the other chemistry-based noble metals don't have?

In Structure-property relations in nonferrous metals (2005, p. 302) Russell and Lee write:

"Transition metals to the left of group 11 experience complex interactions between s electrons and the partially filled d subshell that lower electron mobility. In group 11 metals, the d subshell is filled, thereby improving the mobility of the s electrons and making the group 11 metals excellent electrical and thermal conductors."

That's fine, but I see no connection to the sense of being "noble" metals.

thank you, Sandbh (talk) 14:08, 15 April 2022 (UTC)

Noble metals is a term used mainly by nonchemists. So fussing about these definitions is not very productive IMHO. I mean, who works with metals? Ans: metallurgists. Chemists work with compounds, and there is nothing particularly noble about gold chloride or tetrairidium dodecacarbonyl. They're just compounds.--Smokefoot (talk) 14:43, 15 April 2022 (UTC)

Chemical definitions of this term are discussed in the article Noble metal. Dirac66 (talk) 17:07, 15 April 2022 (UTC)

Smokefoot, Dirac66: thanks for chiming-in so quickly.

1. Recent articles in ACS and RSC journals mentioning noble metals mostly focus on their catalytic applications. Minor mentions are to medicine, sensors, batteries, and sustainable non-metal recovery. Dr Google further returns hits in dentistry, geochemistry and mining. The noble metal article has various shortcomings that are being discussed at talk page. This is the context in which my question arose.

2. The metallurgists seem to be in lockstep with the physicists. The Metallurgical Society published a proceedings monograph in 1986 on noble metal alloys, with 24 articles, every one of which was confined to Cu-Ag-Au. I was't able to discern anything from this tome aside from the fact that, upon alloying, "the Pt bands can drop below the Fermi level, causing Pt to be noble-metal like. When alloyed with an element as electropositive as La, it takes only one La to five Pt to cause this; LaPt₅ is diamagnetic." (p. 5).

3. Another article I found is, "Making a noble metal of Pd": doi:10.1209/epl/i2005-10075-5. It says in part, "In the atomic state Pd has fully occupied d-states like the noble metals Cu, Ag and Au. However, as soon as Pd atoms are involved in bonds, the sp-band becomes partially filled at the costs of the d-band occupancy. Consequently, Pd is not a noble metal, being often used in catalysis" [Italics added: Does this passage mean Cu-Ag-Au are not used in catalysis, at least not in the same that the PGM are, hence they're regarded as "noble"?]. The rest of this article presents, "theoretical and experimental data concerning the possibility of inducing in Pd properties characteristic of a noble metal" without being clear on what these "characteristic properties" are, and how such properties differ from the rest of the noble metals/platinum group metals, aside from having a filled d band, and a negligibly occupied sp band.

4. Among the transition metals, having a filled d band and a single s electron evidently has a special significance from a physics point of view. Incidentally, most metals are paramagnetic, with diamagnetism occurring only in Be, the group 11 metals, and the post-transition metals. But this doesn't appear to explain why, in physics, the "noble metals" are confined to Cu-Ag-Au.
--- Sandbh (talk) 06:38, 16 April 2022 (UTC)

Thanks for the comments. My general point is that Wikipedia editors sometimes seem to focus on defining terms with the implication that practioners follow those definitions, when in fact practitioners rarely fuss about such definitions. The disconnect arises because few editors are practitioners but implicitly purport to speak for them. No harm done I guess, except that definitions are just definitions: definitions are no substitute for facts, and the exposition of facts is supposed to be the main job of editors. Of the tens of thousand of publications appearing annually, no doubt the term noble metal occurs often. To which I say, so what? My specific point is that noble metal is about metals (bands, corrosion, heterogeneous catalysis), but nobility is irrelevant to compounds and ions.--Smokefoot (talk) 13:54, 16 April 2022 (UTC)--Smokefoot (talk) 13:54, 16 April 2022 (UTC)

I'd hazard a guess that physicists at least occasionally say "noble metal" when they mean "metal that's pretty unreactive in the conditions we care about". I know my people, and that's how we treat words.... XOR'easter (talk) 15:24, 16 April 2022 (UTC)

There are of course many scientific terms which do have a single definition on which everyone agrees. But "noble metal" is not one of them, as is clear to those with a knowledge of the use of this term in scientific literature. Dirac66 (talk) 17:05, 16 April 2022 (UTC)

My impression is that "noble metal" is one of those words where there is an obvious great example of what one means by it (Au), and then surrounding it is a sort of Euler-diagram of worse examples. The worse examples don't have an absolute order, because it depends on what exactly you want to look at. For example by reactivity Rh is more noble than Ag, but by electrode potentials it's the other way round. (You could even look at electronegativity, but the scales don't agree, and actually relative electronegativity for metals doesn't seem too important to me unless you want to look at intermetallic compounds.) Therefore criteria will naturally vary and definitions will depend on that. (As one approaches the borders of what one might sensibly consider "noble", even the definition of "metal" itself might come into play, e.g. are As and Sb noble metals? Surely that also partly depends on whether the author thinks they are metals in the first place.) Evidently the filled d-shell thing is important for some applications, and since Cu, Ag, and especially Au are very unreactive, I can see how it would make sense for physicists to use the term "noble" to describe that distinction. (I don't actually know if that's how it happened, but it seems plausible.) Double sharp (talk) 03:22, 17 April 2022 (UTC)

​​​​​​ Smokefoot, You gave me a lot to think about, thanks.

I can't speak for other editors and a possible disconnect between definitions and practice. OTOH, MOS:FIRST suggests that the first sentence of the lead should tell the nonspecialist reader what the subject is, be in plain English and, if the subject is definable, then the first sentence should give a concise definition. Since the term "noble metals" is ill-defined, the best that can be done is to survey the literature and sketch a defintion on that basis. The facts will vary depending on the source, and judgements will need to made about which facts to include and any differences between sources. Since chemistry is replete with fuzzy definitions the result ought to be par for the course.

The "so what" of noble metals, as I see it, is to wonder what is so special about them that merits categorising them as such.

I kind of get your distinction between metals, and compounds and ions, in that we do not speak of noble compounds or noble ions. And few chemists work with pure elements, so I can see that the notion of "noble metals" wouldn't be immediately relevant. OTOH, noble metals form solvated aqueous ions, and Schweitzer and Porterfied (2010), in The Aqueous Chemistry of the Elements, discuss Ru, Rh, Pd, Os, Ir and Pt together under the rubric, "Introduction to the Noble Metal Elements". Rayner-Canham (2018), in "Organising the transition metals", assigns the PGM + Au to a cluster, on the basis of their behaviour under oxidizing conditions: doi:10.1093/oso/9780190668532.003.0013. Much has been written about the analytical chemistry of noble metals. This all strikes me as "chemistry" over and above the metals by themselves, at least as far as their behaviour in ionic form is concerned. For the compounds, at least the noble metals are more of less characterized by the unstable nature of their oxides, which have a reputation for decomposing when heated.

Brooks (1992, p. 9), in Noble metals and biological systems: their role in medicine, mineral exploration, and the environment, adds that:

"The most noteworthy feature of compound formation in the noble metals is their ability to form complexes. It is these complexes that determine their abundance and transport within the biosphere, and it is these complexes that govern the development and use of noble metal drugs in medicine."

(Obviously, complex formation is not limited to noble metals but it is evidently the combination of properties of the noble metals that make them distinctive.)

Double sharp, yes, the category of noble metals is similar to attempting to distinguish between metals and nonmetals. There is universal agreement that Au is a noble metal, just like there is universal agreement that Cs is a metal and F is a nonmetal. From there, Au and Pt are universally regarded as noble metals in chemistry whereas Cu-Ag-Au are counted as the noble metals in physics. After that, the broadest definition of what is a noble metal extends to the other ten metals having a positive standard reduction potential: Tc, Re, the other 5 PGM; Hg, Bi, Po. And then there are As and Sb which are among the elements commonly recognised as metalloids. That said, the other five PGM and Hg are the only ones I've seen being unambiguously counted in the literature as noble metals.

The answer to my original physics-based question appears to lie in three sources:

1. A Physics Stack Exchange Q&A (2019) on "Role of 𝑑 -band in metals";
2. a Nature article (1995) on "Why gold is the noblest of all the metals", and
3. a ChemPhysChem article (2020), "Chemical causes of metal nobleness".

Some of the physics invoked in these sources is beyond by my ken so feel free to point out my errors, in the following interpretations.

Source 1 says that d states have less spatial extent than s- or -states, and that in transition metals the more localized outer 3d-, 4d- and 5-d states screen the interaction of the half-filled outer s-band with other states. So, early TM supposedly react more readily with e.g. O than later TM. This screening is most efficient if the outer d-shell is completely filled as in Cu-Ag-Au. While I don't understand everything written in this source I've hopefully understood the gist of it.

Source 2 says in its abstract:

"Gold is the least reactive metal towards atoms or molecules at the interface with a gas or a liquid. The inertness of gold does not reflect a general inability to form chemical bonds, however—gold forms very stable alloys with many other metals. To understand the nobleness of gold, we have studied a simple surface reaction, the dissociation of H₂ on the surface of gold and of three other metals (copper, nickel and platinum) that lie close to it in the periodic table. We present self-consistent density-functional calculations of the activation barriers and chemisorption energies which clearly illustrate that nobleness is related to two factors: the degree of filling of the antibonding states on adsorption, and the degree of orbital overlap with the adsorbate. These two factors, which determine both the strength of the adsorbate-metal interaction and the energy barrier for dissociation, operate together to the maxima] detriment of adsorbate binding and subsequent reactivity on gold."

This is consistent with what Source 1 said in the following passage:

"In the case of Cu, Ag, and Au, the screening effect is particularly strong, because the upper 𝑑-bandedge lies energetically deep below the Fermi-level (due to complete 𝑑-band filling as explained above), and thus corresponding anti-bonding states in the vicinity of this edge are (generally) more or less completely filled leading to a strong suppression of interaction with the reactant."

Source 3 is remarkably comprehensive. Here's the abstract:

"Humans have appreciated the 'noble' metals for millennia, yet modern chemistry still struggles with different definitions. Here, metal nobleness is analyzed using thermochemical cycles including the different bulk, gas, and solution states implied by these definitions. The analysis suggests that metal nobleness mainly reflects inability to fulfil the electron demands of electronegative oxygen. Accordingly, gold is the most noble metal in existence, not because of d-band properties of the solid state, but because gold’s electronegativity is closest to that of oxygen, producing weaker polar covalent bonding. The high electronegativity arises from the effective nuclear charge due to diffuse d-states, enforced by relativistic effects. This explanation accounts for the activity series, corrosion tendency, and trends in oxygen chemisorption, which other models do not. While gold is the most noble metal, the ranking of Ag, Pt, and Pd depends on the thermochemistry as discussed in detail.

Here's what I noticed in this article:

• In the abstract, I don't understand the reference to "diffuse" d-states (but I return to this later on).
• "These [noble] metals are less reactive towards oxygen, the major oxidant of this planet’s atmosphere, and are less willing to give away their electrons in solution, otherwise a hallmark of metals, as measured by their high standard half reduction potentials." (p. 3)

The reference to oxygen as the major oxidant of Earth may explain why the corrosion of Ag by S is overlooked in some cases whereas in a few other occasions its noble status is queried.

• "...the relative nobleness of metals depends substantially on the reactivity considered and the theory applied... [italics added]" (p. 3)
• "Surprisingly, whereas single [italics added] theories have been applied to rationalize metal nobleness in several cases, a combined perspective and analysis of the most important features that define nobleness seems missing in the literature." (p. 3)

In classification science, classes are usually classified by more than two criteria.

• "[This] analysis is particularly aided by thermochemical cycles that feature both the solid bulk metal state, the metal atoms in gas phase, and the aqueous solvated metal ions. Much of the confusion relates to the fact that the defining processes do not always involve the same of these states. For example, the "physicist" definition of nobleness focuses on the properties of the d-band and orbital overlap of the bulk metal interacting with an adsorbed atom^{[source 2]}, whereas the "chemist" definition focuses mainly on the solution electrochemistry." (p. 3)
• "From the analysis, it emerges that nobleness is not primarily caused by the d-band structure [italics added] of the bulk metals but to the state-independent and thus more universally applicable electronegativity of the metal atoms... Since the descriptor applies to all thermodynamic states, which e.g. d-band properties do not, it lends promise to estimates of metal reactivity and nobleness in systems without band structure, e.g. single-atom catalysts, solvated ions, clusters, and superatoms of much interest in current research efforts.^[20–24]" (pp. 3–4)

At this point I thought, "Far out! Really?" Mere EN is the primary cause of nobility in metal atoms?

Table 1 in the article (p. 5) then ranks the nobleness of Ni, Pd, Pt, Cu, Ag, Au, and Hg according to 12 descriptors/properties relevant to understanding nobility.

• the standard half reduction potential of the divalent metal ion, E° (M²⁺ + 2e^– → M)
• the reactivity towards pure strong acids HCl and HNO₃
• the experimental and computed enthalpy of chemisorption of O2 to the bulk metal surface
• the d-band center energy of the solid metal
• the first ionization potential and electron affinity of the gas-phase metal atom
• the Pauling electronegativity
• the bulk polycrystalline metal work function
• the relativistic s-shell contraction and oxophilicity of the metal; and
• the cohesive free energy (free energy of atomization) of the bulk metal state.

These 12 properties are then discussed,

• "The values of the listed properties are not necessarily exceptional to the noble metals. For example, the first IP of the group-12 metals mercury (10.4 eV) and zinc (9.4 eV) are higher than that of gold (9.2 eV) due to their complete s- and d-shells." (p. 5)
• "The common view that gold is the most noble metal is directly rationalized by gold having the highest rank when averaged over the properties in Table 1 typically associated with nobleness. It is this consensus, rather than any single property alone, [italics added] which explains the universal acceptance of gold as the most noble metal." (pp. 4–5)
• "In contrast, the second place is fiercely contested. Specifically, the relative ranking of Pt, Pd, and Ag is a matter of substantial interest and disagreement: Thus, it has been argued that the completely filled d-shell makes the coinage metal Cu (and by inference Ag) more noble than Pt and Pd^[19], and DFT-computed O2-chemisorption enthalpies put all coinage metals before platinum^[29], yet, no other property of Table 1 supports the notion that Cu is noble. Electrochemical^[27] and corrosion data^[40,41] and electronic properties suggest that Pt and Pd are particularly noble." (p. 6)

In fact the average rankings across the 12 properties are: Au 1.5; Pt 2.58; Ag 3.0; Pd 3.75; Hg 4.8; Cu 5.08; Ni 5.5, so there is no contest for second place: Pt is the winner.

• "As discussed further below, the electrochemical definition involves two specific states of the metal, the bulk solid state and the hydrated metal ion state." (p. 7)
• "Resistance toward strong acids is part of the chemist’s typical definition of nobleness...Aqua regia, the famed mixture of HCl and HNO3, solvates gold but not silver, whereas HNO₃ can dissolve silver but not gold, i.e. the reactivity depends on both the metal and acid as a pair." (pp. 7–8)
• "A useful definition of nobleness is the negative heat of chemisorption (ΔHchem) of molecules to the bulk metal surface. A more exothermic chemisorption implies that the metal surface binds more strongly to the adsorbed atom, which again implies higher reactivity. A previous attempt to explain nobleness^[19] used H₂ chemisorption as defining reaction. A more logical choice is chemisorption of O₂, because... it is the atmospheric oxygen responsible for the corrosion that has inspired the concept of noble metals for thousands of years much more than reactions with H₂." (pp. 9–10)
• "Without relativistic effects, Ag can appear the noblest of all metals, perhaps explaining its absence in the previous study^[19]. Later more complete computations^[30], tabulated in Table 1, confirm this, i.e. that the non-relativistic d-band center is lower for Ag than for Au, clearly not explaining why gold is more noble than silver. Finally, Cu was found to be much more noble than Pt and was referred to as a “noble metal” together with Au^{[Source 2]}. These points should not be taken as a criticism of the d-band center^[55], which remains a useful descriptor in particular if corrected for relativistic spin-orbit effects^[53] and structural and charge perturbations on the metal surface^[56]. Hg, Cd, and Zn have lower d-band centers, so one needs to invoke the antibonding states of the adsorbing molecule, and neglect of spin-orbit coupling makes the d-band inherently more uncertain than the experimental descriptors in Table 1. In conclusion, both the d-band center and the total number of valence d-electrons correlate decently with the empirical tendency of nobleness, as also summarized in Table 1." (p. 12)
• "The most important fundamental variation in the d-transition series is the increased effective nuclear charge moving towards the right, which arises from the gradual occupation of spatially diffuse d orbitals. This effective charge stabilizes the valence electrons of the late transition metals, which makes them less reactive towards electronegative elements such as oxygen, which requires a partial electron transfer from the d-band to the electronegative adsorbate atom." (p. 12)

It seems that the reference to spatially diffuse d orbitals is referring to the relatively poor shielding capacity of the d electrons.

• "The nobleness of Pt and Au is significantly enhanced by relativistic effects." (p. 13)
• "The noble metals are among the least oxophilic, or most “thiophilic”, in the periodic table^[38], although even these metals can be oxidized under aggressive conditions such as ultraviolet light and ozone^[65]. Accordingly, they are less reactive towards oxygen and favor sulfur and other less electronegative adsorbing atoms in competition with oxygen, as is well-reflected in their most prominent mineral ores." (p. 15)
• "The noble metals generally tend to adopt cubic closest packed structures, which is probably not a coincidence but relates to the same underlying cause, the high effective nuclear charges producing small metal radii in these metals. A good negative control of this hypothesis is supported by the group 12 metals with larger radii (Zn, Cd, Hg) adopting hexagonal or other structures. The major drivers of nobleness, as explained above, are ultimately, after account of the sizable relativistic effects on the 5d/6s states, the effective nuclear charge and the resulting electronegativity, which should be considered in context with the adsorbate atom’s electronegativity to estimate the strength of the adsorption." (p. 22)

The crystalline structures of the TM are:

Sc  Ti  V   Cr  Mn  Fe  Co  Ni  Cu  Zn
HCP HCP BCC BCC αMn BCC HCP FCC FCC HCP
---------------------------------------
Y   Zr  Nb  Mo  Tc  Ru  Rh  Pd  Ag  Cd
HCP HCP BCC BCC HCP HCP FCC FCC FCC HCP
---------------------------------------
La  Hf  Ta  W   Re  Os  Ir  Pt  Au  Hg
αLa HCP BCC BCC HCP HCP FCC FCC FCC Rho

• "Because electronegativity is a major driver of metal nobleness and reactivity, it also partly explains why noble metals are very proficient at forming alloys with metals that differ from them, notably d-transition metals." (p. 24)
• "The d-band is not the reason for nobleness but only a modestly correlating feature. This finding is important because research increasingly addresses nano-sized systems and clusters and even single-atom catalytic systems where d-band considerations are inappropriate^[20,22,77]." (p. 25)
  

Conclusions

• I think I have enough now to be able to provide a simple explanation of the physics-based notion of a noble metal and how a complete set of 10 electrons contributes to nobility.
• Source 3 provides an almost solid outline of what noble metals are:

"In the periodic table, metals to the lower right of the d-transition series such as gold, platinum, silver, and palladium are the most noble according to human experience. These metals are less reactive towards oxygen, the major oxidant of this planet’s atmosphere, and are less willing to give away their electrons in solution, otherwise a hallmark of metals, as measured by their high standard half reduction potentials. Humans have appreciated them for thousands of years due to their rarity, malleability, and exceptional resistance to corrosion, making them ideal stores of value and coinage metals."

• But this isn't quite right since Os is unworkably hard and brittle even at high temperature. An overlooked consideration is that the PGM and Au are the only metals that usually occur in native form. But that would exclude Ag.
• I'm especially impressed by the 12 properties or diverging definitions of nobleness used to understand nobleness.
• I'd earlier wondered about W and its EN of 2.36 and what bearing this had on the nobility question. There's evidently more to W than its high EN. When I looked up the values for its other 11 properties, and worked out where its average place was compared to Au 1.5; Pt 2.58; Ag 3.0; Pd 3.75; Hg 4.8; Cu 5.08; and Ni 5.5, I got a figure of about > 4.83 i.e. maybe in the vicinity of Hg and Cu, which seems like an OK outcome. W doesn't occur in native form whereas Hg can rarely be found as the pure metal in droplets trapped in rocks. W too, is quite oxophilic. On a normalised scale of oxophilicity (low = 0; 1 = high) W has a rating of 0.8 compared to 0.0 to 0.4 for the PGM, Au and Ag: doi:10.1021/acs.inorgchem.6b01702, p. 9463.

--- Sandbh (talk) 04:28, 20 April 2022 (UTC)

Introduction to angular momentum

The article Introduction to angular momentum has been hidden from view since 2015 by being redirected to Angular momentum. This was done without discussion or notification to the Physics Project group. I have restored it to mainspace. See Talk:Introduction to angular momentum#Restore to mainspace. Dolphin (t) 13:11, 22 April 2022 (UTC)

Electron cloud densitometry

User Samsiq, whose article Electron cloud densitometry is currently up for deletion here, seems to have added images and text about the technique to a LOT of pages. Thing is - the images ARE kinda neat, and I don't hate a lot of them. But I'm not sure if they're legit, and the text accompanying them is almost always overblown. Some of them have been added in places like article leads. A "main article" link was added to the top-level page, Atom, where I'm also relatively sure it doesn't belong.

What's the consensus here? If the technique turns out not to be notable, do the pretty pictures all need to go too? Are the pretty pictures even real? PianoDan (talk) 18:56, 21 April 2022 (UTC)

I removed that part from Atom. The American Journal of Engineering Research is very likely a predatory journal [4][5][6], and nothing cited to it should be used here. XOR'easter (talk) 20:23, 21 April 2022 (UTC)

The image in chemical bond just looks like blobs to me. It's supposed to be graphite, but it could be a bad photo of Orion's belt in the infrared for all I can tell. Without the caption, it would convey no information, and the caption badly needs editing. XOR'easter (talk) 01:18, 22 April 2022 (UTC)

The more I look into these edits, the worse they look - ungrammatical, full of irrelevant information, and cited to this same predatory journal. PianoDan (talk) 06:03, 22 April 2022 (UTC)

Of everything that linked to electron cloud densitometry, the only image whose caption was cited to a non-predatory journal was in Graphite#Structure, but there it was crowded in with four other pictures including an STM image. It's not clear why we need both an STM and a TEM-by-nonstandard-name picture wedged into the same tiny section. XOR'easter (talk) 14:49, 22 April 2022 (UTC)

Finishing the FA review of Mars

On the off-chance that some of the people who hang out here have some experience with astronomy, could anyone lend an additional pair of eyes to double-check the figures in the Mars infobox? This is the sort of thing where different sources can quote values that vary in the later decimal places, the values in the box might have been derived from a source in a way that's not covered by WP:CALC, etc. The infobox needs to be completely sourced if the article is to stay Featured. XOR'easter (talk) 02:24, 23 April 2022 (UTC)

Lagrangian mechanics

• Lagrangian mechanics (edit | talk | history | protect | delete | links | watch | logs | views)

Recent edits at this article need attention from someone who understands the topic. For example this section displays "because of the constraint equations...</ref>" (with the visible ref). I looked at the history to work out when that was broken but there are several edits in the last few months that should be checked. Johnuniq (talk) 05:15, 23 April 2022 (UTC)

I removed that close ref, but something strange is going on with the history because the diffs do not show how it got there. JRSpriggs (talk) 06:26, 23 April 2022 (UTC)

@Johnuniq, this change removed the opening part of the footnote, leaving part of the contents and the close of the note. All that should either be taken out or go back in. StarryGrandma (talk) 06:50, 23 April 2022 (UTC)

Thanks, but what about the other edits in the last few months? There have been some subtle but significant changes and the article needs attention from someone who can recognize whether the edits need to be reverted. Johnuniq (talk) 07:09, 23 April 2022 (UTC)

It turns out the change was isolated enough it could be reverted, so I did. Removing two references and changing content without providing new ones is a problem. StarryGrandma (talk) 08:00, 23 April 2022 (UTC)

Now I'm wondering about two diffs. On 19 April 2022, "non-conservative forces" was changed to "conservative forces", and on 28 December 2021 the mapping interpretation regarding tangent bundles was changed. That was added on 17 May 2021 by StrokeOfMidnight. Johnuniq (talk) 09:07, 23 April 2022 (UTC)

I think the first change was wrong and the second one was technically correct, in that the tangent bundle $TM$ can naturally be projected down to the configuration space $M$ so the latter doesn't have to be included separately, but a parenthetical shoved into the lede like that with no elaboration later just makes the article more cluttered and less useful. XOR'easter (talk) 13:04, 23 April 2022 (UTC)

For an article this comprehensive and important, that lead is a bit of a mess. I'll see if I can make it a bit clearer. PianoDan (talk) 14:43, 23 April 2022 (UTC)

OK, it could use to be fleshed out a bit more, and I haven't put in any citations yet because all my reference books are at work, but I think it reads more like an intro section accessible to a lay reader now. PianoDan (talk) 15:06, 23 April 2022 (UTC)

Yes, I think that's an improvement. Thanks! I doubt citations in the intro are strictly necessary, since it just summarizes what comes later, but since the article already has a decent start at a bibliography and one of the books in it was close to hand, I added one reference per paragraph. XOR'easter (talk) 16:43, 23 April 2022 (UTC)

User script to detect unreliable sources

Main page: User:Headbomb/unreliable

I have (with the help of others) made a small user script to detect and highlight various links to unreliable sources and predatory journals. Some of you may already be familiar with it, given it is currently the 39th most imported script on Wikipedia. The idea is that it takes something like

• John Smith "Article of things" Deprecated.com. Accessed 2020-02-14. (John Smith "[https://www.deprecated.com/article Article of things]" ''Deprecated.com''. Accessed 2020-02-14.)

and turns it into something like

• John Smith "Article of things" Deprecated.com. Accessed 2020-02-14.

It will work on a variety of links, including those from {{cite web}}, {{cite journal}} and {{doi}}.

The script is mostly based on WP:RSPSOURCES, WP:NPPSG and WP:CITEWATCH and a good dose of common sense. I'm always expanding coverage and tweaking the script's logic, so general feedback and suggestions to expand coverage to other unreliable sources are always welcomed.

Do note that this is not a script to be mindlessly used, and several caveats apply. Details and instructions are available at User:Headbomb/unreliable. Questions, comments and requests can be made at User talk:Headbomb/unreliable.

- Headbomb {t · c · p · b}

This is a one time notice and can't be unsubscribed from. Delivered by: MediaWiki message delivery (talk) 16:02, 29 April 2022 (UTC)