User talk:Dirac66/Archive 3 (2013-2014)

orbital hybridisation of hypervalent molecules

Hmm. The linear independence of hypervalent molecule hybrids is a really great revelation for the hybridisation of hypervalent molecules, I must say. I was wondering, if the F p orbitals are counted in the hybridisation as part of the linearly independent set, should we revise the name of the hybridisation to reflect that? Say, sp³x² for SF₆ where x signifies ligand orbital (nonbonding) character? Or is there terminology already given in the paper by Cooper (I don't have access to papers)?--Officer781 (talk) 03:31, 10 January 2013 (UTC)

Wikipedia policy as per WP:OR is not to go beyond what we find in the sources, and I judge that here this means we should not invent new notation. All the literature which I know reserves the term hybridisation for the combination of orbitals centred on the same atom. For example, the paper by Cooper et al. says (for SF₆) the spin-coupled orbitals (of GVB theory) which form the bonds ... "are based on six equivalent sp^x-like hybrids on sulfur, but each of them also has significant F(2p) participation." So the spin-coupled bond orbital includes F(2p) but the hybrid does not. This is probably what you meant by saying that the hybrids are not full orbitals or partial orbitals, although these terms are also not usually used in the literature. Dirac66 (talk) 15:27, 10 January 2013 (UTC)

Hmm. Sorry for the comparatively late "reply", but today I found a source in a book "Pauling's Legacy: Modern Modelling of the Chemical Bond" where a section by Cooper describes, for example, a Cl-F bond in say Cl-F_n as "Cl(sp^x-like)+X(2p) hybrid overlapping a distorted X(2p) function", which seems adequate as an external source with a notation for such a hybridisation. It seems to me to be more appropriate as we need a proper description of pre-bond hybrids in such atoms consistent with the descriptions for non-hypervalent molecules. sp³ hybrids in total would consist of only four orbitals and cannot describe the hybrids in SF₆ for example but S(sp³)+F(p²) can as it would consist of six orbitals. I presume this is adequate to obey the stated Wikipedia policy?--Officer781 (talk) 14:10, 23 February 2013 (UTC)

Interesting. I haven't seen this book, but the sentence seems to describe the bond rather than the hybrid orbital on the Cl. And the length of the phrase suggests that the author is groping to find an adequate label for a concept which is hard to describe. Certainly this notation has not become standard. We can quote the example used by Cooper in the text as a description of the bond, but I would not use this notation in the tables of hybridization types. And generalization to other examples is risky unless we are certain we have it right. For the case of SF₆ there is a pσ orbital on each of the six F atoms directed toward the S, so how we can select only two to be considered bonding? Dirac66 (talk) 01:52, 24 February 2013 (UTC)

According to the text it seems that each hybrid orbital would "borrow" the ligand character from the ligand orbital it is bonding with. That means we select a net total of two equally from all six F orbitals (I don't like this description though. I think we're talking about orbital character rather than full orbitals). I think it's more useful if we consider each hybrid individually as one complete orbital made up of a "partial" central atom orbital character and a "partial" ligand orbital character in the same way an sp3 hybrid is made up of a "partial" 1/4 s orbital character and a "partial" 3/4 p orbital character. And the text's full words are "Each Cl-X bond is comprised of a Cl(sp^x-like)+X(2p) hybrid overlapping a distorted X(2p) function", so I don't think he was describing the bond itself, but the hybrid the bond is comprised of.--Officer781 (talk) 07:00, 24 February 2013 (UTC)

Please, bring the discussion to talk: Orbital hybridisation. Is is not ethical to confine such conversation in a user_talk. Incnis Mrsi (talk) 07:17, 24 February 2013 (UTC)

Sorry about that. I transferred the entire conversation over to the article talk. We'll continue there then.--Officer781 (talk) 07:31, 24 February 2013 (UTC)

Erm, I've got a table for you (Dirac66) to review at the orbital hybridisation talk page. Thanks! --Officer781 (talk) 10:39, 28 February 2013 (UTC)

I am thinking about this and will eventually reply on the article talk page. But this question is quite complicated so it will take me a few days. Dirac66 (talk) 15:29, 28 February 2013 (UTC)

(Copied from the orbital hybridisation talk. Pertaining to the issue of the delocalized hybrid orbitals not fulfilling the basic definition) After conversing with Bduke who knows the theory very well, he explains that the orbitals are not strictly localized due to the partial-delocal nature of spin-coupled valence bond theory, which also uses the partial-delocal Coulson-Fischer function rather than a fully localized bond which resonates as per Pauling's version. If we consider the strictly local valence bond theory, there is no possible explanation for hypervalent molecules where we would have to resort to bonding-nonbonding resonance instead. The requirement that hybrid orbitals have to be "atomic" thus only exists in the strictly-localized Pauling version and there is no clash of definitions in the VB-delocal theory.--Officer781 (talk) 11:03, 7 March 2013 (UTC)

I have overhauled the article somewhat. Could you take a look?--Officer781 (talk) 03:17, 9 March 2013 (UTC)

Links to sections

Please, do not put links to a section with non-compliant header, such as Beta decay#Bound-state β- decay, to articles as you did at [1]. Either fix the header first (we see a non-standard minus sign) and then link it, or make redirects, which are cheaper to maintain than numerous links scattered amid articles. Incnis Mrsi (talk) 08:19, 29 January 2013 (UTC)

I am sorry but I do not really understand the problem of non-standard minus signs. I have tried to read the articles about it but I do not have enough computer background. The minus, dash and hyphen all look the same to me so I just use the one on my keyboard. For the article on electron capture, I just copy-pasted the section title from the beta decay article and the link now seems to work. However if you think it is important to change the section title and/or the link, then I suggest that it would be better if you made the necessary changes. Dirac66 (talk) 15:32, 29 January 2013 (UTC)

Of course, as long the problem is detected, it is not dangerous. Actually, I fixed it (and many other crap) already. But it is not an aim of Wikipedia “to copy-paste” something which “now seems to work”. Wikipedia should be maintainable. There are generally three techniques for linking to a topic which does not currently have a separate article:

1. Use a title which redirects to an appropriate location;
2. Ensure with {{anchor}} that the target will not go away;
3. Use a section header as a fragment identifier.

The case 3 requires a solid assumption that the section header will not change in the foreseeable future. Something non-compliant in a section header is a strong indication that it will change, though. A month (or a year) passed, and somebody will change the section header, without anybody to notice that in some article far away a link become broken. Incnis Mrsi (talk) 12:58, 30 January 2013 (UTC)

Language links

Wikidata is now enabled on the English Wikipedia. To modify the language links, just click on Edit links at the end of the list. —Naddy (talk) 20:55, 15 February 2013 (UTC)

This did give me the Wikidata page, but on top of the list it says Read rather than Edit. (I tried Nitrogen and Nickel) I did look at the revision history for the Wikidata page and I see that you were able to edit it. Is it possible that only administrators can edit the Wikidata page? If so, there should be a procedure to others to request changes to language links. (I don't have any such requests right now, but I may in the future.) Dirac66 (talk) 00:46, 16 February 2013 (UTC)

Update. I can edit Wikidata with Mozilla Firefox, but not with Internet Explorer 8. This seems to be a bug which should be fixed. Dirac66 (talk) 01:39, 16 February 2013 (UTC)

See wikidata:Wikidata:Project_chat#Wikidata and Internet explorer. —Naddy (talk) 01:56, 16 February 2013 (UTC)

Periodic table Giguère reference format

Hello Dirac66. I was puzzled by your edit to the periodic table article. The new format is inconsistent with the formatting used in the rest of the article, is redundant since the old format uses the established format for indicating volume and issue, duplicates the year, and has removed the actual page number within the article supporting the argument being made, for no helpful reason that I can see. I would normally revert however I respect and appreciate your work hence my query. Thank you. Sandbh (talk) 11:42, 22 February 2013 (UTC)

Hello Sandbh. I admit to not being entirely happy with my format, but I thought that the previous format was very confusing with two numbers in parentheses: (12) and (37). In fact I had no idea that (37) indicated the page supporting the argument until I looked at the article (which required a trip to my library as I couldn't find it on-line). I am used to seeing specific pages indicated by a phrase such as "see p.37". The issue number (12) is more common but I thought to make it perfectly clear by adding Dec., although I agree that 1966 should not be repeated.

Anyway I do not insist on my version but I would like to clarify the mysterious (37). How about using the old version but replacing (37) by "see p.37"?

Also Ref.91 (Scerri, The role of triads ...) has an even more mysterious 85 (4): 585–89 (89). Does the last 89 refer to page 589? (It can't be page 89!) This also should be changed to "see p.589" if I have interpreted it correctly. Dirac66 (talk) 17:19, 22 February 2013 (UTC)

Oh, I follow you now. The source of confusion originates in how to list a specific page number within the page span of an article, and how to record page spans. For page spans, the guidance I have been following recently is that these should use as few figures as possible: pp. 402–5, 410–16, 421–39, 440–553. An exception is made for numbers between 10 and 19 in each hundred: 10–11 not 10–1; 13–14 not 13–4; 115–16 not 115–6. For actual page numbers within a span the presumption is that the reference details go from macro to micro, i.e. volume–issue–span–page. Thus the Scerri ref is vol. 85, issue 4, the article runs from pages 585 to 589, and the specific supporting argument is on page 589. I only started using the page span guidance recently so this article may not list spans consistently. I'm not aware of any particular formatting conventions for showing actual page numbers within article spans. I'll think/look around some more about this question. BTW I found the trip to the library to be unusually rewarding—a quite colourful (for its time) and thought-provoking article. The photographs were cool, too. Sandbh (talk) 03:25, 23 February 2013 (UTC)

OK, thanks for the explanations. I understand now, but for Wikipedia I think it is important to use widely used conventions which will be clear to other readers. For page span several ways are acceptable and clear to everyone so I don't really care if the Giguère article is marked 36-39 or 36-9. However putting the actual page number of interest in parentheses is not standard and I think it is confusing; better to write see p.37 which is clear. For books the page number is always preceded by p., and for articles the word see distinguishes the page of interest from the page span. So I will revert the volume, issue and span to the previous way, but indicate the page of interest as see p.37, and similarly for the Scerri ref.

I'm glad you liked the Giguère article, and I hope you also read the French half which is not a translation of the English half but a continuation. Paul Giguère was quite an entertaining fellow; he showed me the original model in his office about 1972. Dirac66 (talk) 21:52, 23 February 2013 (UTC)

Charge-transfer complex

Hi would you look at my comment at Talk:Charge-transfer complex. It seems that the concept of a charge transfer band is mixed up with what one would normally consider to be a salt like material. I am not super-duper expert on this topic, but was considering moving the content about optical transitions to another article, perhaps one that discussed UV-vis spectroscopy or such. But maybe I am missing something. Your advice would be very welcome. Thanks, --Smokefoot (talk) 03:52, 27 February 2013 (UTC)

Molecular orbital diagram

I've seen the page on molecular orbital diagrams and realized that the inner-shell (non-valence) electrons are shown in the article to participate in forming molecular orbitals. From what I've read here (page 142):[2] as well as common MO treatment, I don't think the non-valence electrons participate in forming MOs? although this link may suggest otherwise: [3]. And then there's also this: [4]. I think we don't need the inclusion of inner shell electrons as it may confuse? Molecular orbital diagrams don't normally include non-valence orbitals. This also reflects the fact that non-valence and rydberg orbitals are different from valence molecular orbitals. Mulliken on rydberg orbitals of molecules: [5] (in his words on page 1097, a rydberg methane orbital might be a united-atom 3s orbital rather than an LCAO).--Officer781 (talk) 11:01, 9 April 2013 (UTC)

Inner-shell (or core) orbitals are not involved in bonding, since they have a negligible electron density in bonding regions. However if the molecule contains equivalent nuclei, symmetry requires that the core MOs be combinations of orbitals on different atoms. For dilithium the core MOs are to a first approximation

1σg = (1sA + 1sB)/√2 = 0.707 (1sA + 1sB)

1σu = (1sA - 1sB)/√2 = 0.707 (1sA - 1sB)

More accurately, Levine (Quantum Chemistry 4th edn p.412) gives the results of a minimal-basis set calculation by Ransil (Rev. Mod. Phys. 32, 245 (1960) as

1σg = 0.706 (1sA + 1sB) + 0.009 (2sA + 2sB) + 0.0003 (2pσA + 2pσB)

1σu = 0.709 (1sA - 1sB) + 0.021 (2sA - 2sB) + 0.003 (2pσA - 2pσB)

The traditional energy level diagram in the article (which probably dates to Mulliken) greatly exaggerates the energy difference between 1σg and 1σu. It should really be redrawn to show a ΔE which is much smaller, but still non-zero. Dirac66 (talk) 14:55, 9 April 2013 (UTC)

I have now looked up the energy differences in Ransil's paper. The 1σg and 1σu of Li2 are separated by 0.00028 atomic units = 0.0076 eV. For comparison the bonding 2σg and antibonding 2σu are separated by 0.20889 a.u. = 5.7 eV, which is of the order of valence orbital energy differences as measured by ultraviolet photoelectron spectroscopy (in other molecules). So an accurate diagram would have the core orbital splitting 750 times smaller than the valence orbital splitting. This is impossible to draw, so the diagram should be redrawn with the smallest possible (non-zero) separation between the core levels. Dirac66 (talk) 19:49, 10 April 2013 (UTC)

Hmm. Then I guess there may not be a need to change the images? Because that page is meant to provide a simplified description of bonding for molecular orbitals. My mistake then. I didn't know about the symmetry requirements. Thanks!--Officer781 (talk) 12:13, 11 April 2013 (UTC)

Changes at Night letter

Hello, since night letter isn't a disambiguation page, I'm not sure giving two separate definitions really works, especially since all the content is about the "clandestine leaflet" sense of the word. Instead, I've taken the info you've added and put it as a hatnote at the top of the page using the {{for|OTHER TOPIC|PAGE1}} coding. Hope you agree this both addresses the multiple meanings while not complicating the intro. MatthewVanitas (talk) 21:12, 9 April 2013 (UTC)

OK. I didn't do it that way the first time because the phrase night letter was not in the telegraphy article. But I have now explained it there in the Terminology section, so the information is now available.

You might consider however whether the last two items in the References section belong in Night letter. They were there before I touched the article and they refer to the telegram meaning. Dirac66 (talk) 22:01, 9 April 2013 (UTC)

Alternative view of sp3 hybrids

On the orbital hybridisation article, under the sp3 (pardon me. lazy to keep subscripting) section, there is an alternative view of allowing maximum separation (ie tetrahedral) and then obtaining the sp3 from there. This problem goes back to Gillespie's question of whether it's tetrahedral because it's sp3 or sp3 because it's tetrahedral. To me it seems that it's tetrahedral because it's sp3 because bonding to all four orbitals of carbon would achieve the most stability under four equal hybrids with no bond strain, where the orthogonality condition would force a tetrahedral shape. The shape is not always under maximum separation, because say an sd5 hybridisation will force a trigonal prismatic configuration by orbital orthogonality even though maximum separation rules will predict an octahedral arrangement (hence the failure of VSEPR). It might be useful to clarify this question of Gillespie and treatment of hybridisation in the article too, and maybe remove this alternative view if it's "wrong"?--Officer781 (talk) 14:19, 25 April 2013 (UTC)

First, I think the alternative view starting from C^4- is nonsense and should be removed. Methane is very far from ionic, and NH₃ and H₂O would have different geometries if they were ionic. Remember that Li₂O(g) is linear, explained by the repulsion of two (only) Li⁺ around a spherical O^2-. The lone pairs have no steric effect. So yes, remove this "alternative view".

Also, I don't think VSEPR and hybridization arguments should be mixed. We do after all have a later section with the title VSEPR electron domains and hybrid orbitals are different, so let's be consistent and not use VSEPR to explain other sections. Dirac66 (talk) 01:18, 26 April 2013 (UTC)

Yeah, I wasn't intending to use VSEPR anyway, just a comment. Would it be possible also to simplify the explanation for the sp3 hybrids as well, because the current one is very elaborate and uses terminology such as effective core potential which is hardly mentioned in usual explanations. The problem then would be to find a simpler explanation. Maybe an explanation emphasizing how hybrid orbitals have a lowered energy configuration?--Officer781 (talk) 02:32, 26 April 2013 (UTC)

I was thinking perhaps something like: 1) excitation of the carbon atom to 4 unpaired electrons as 4 bonds would result in a far greater energetic stability than 2 bonds (ie methylene radical), more than compensating for the energy excitation (I would remove the "nucleus of a hydrogen atom attracts one of the lower-energy valence electrons on carbon" as the reason for excitation as that seems dubious) 2) hybridisation as an equally distributed s and p character would result in the greatest energy stabilization for all bonds.--Officer781 (talk) 02:59, 26 April 2013 (UTC)

I agree that the explanation for sp3 should be simpler and shorter. Your version does correspond to (my memory of) the version in most texts. But I also note that this section is completely unreferenced. While rewriting the section, why not put sources in at the same time? As usual, the preferred method is to read the material, then close the book and write in your own words to avoid copyvio. Dirac66 (talk) 01:12, 28 April 2013 (UTC)

I've tried to use the existing explanation as much as I can and remove the (as I perceive) superfluous "as evidence shows" stuff and shift the explanation to the rationale (ie quantum mechanical energetic considerations). Could you check the new explanation and see if it's better and maybe modify it further if so? Also, the section does have one citation of a textbook by McMurray. It could have the relevant information needed to ref the rest of the claims, or maybe the textbook by Levine. I don't own any textbooks beyond the one used for my high school (awaiting conscription before university) but it has hardly any information on this nor is "reputable" so wouldn't dare cite it.--Officer781 (talk) 02:45, 29 April 2013 (UTC)

OK, I have examined the changes to the sp³ section in more detail. In general I agree with your deletions in this section as much of the material was confusing and inaccurate. Two criticisms of the new wording: 1) initial bond formation suggests that the bonds are formed before hybridization, perhaps with pure s and p orbitals!?? Actually everything happens at once, so we should just talk about bond formation without the word initial. 2) "Quantum mechanically, a maximum possible degeneracy of the bonds in the given environment has the lowest energy and this configuration is preferred." I don't understand what is meant by "degeneracy of the bonds"; why not just say "a maximum number of (equivalent) bonds for a given atom".

I will fix these points soon unless you do it first. The references will take longer, but probably they are less essential now that the more dubious statements have been removed from this section. Dirac66 (talk) 18:59, 3 May 2013 (UTC)

Re initial bond formation. I think this phrase comes from introductory textbooks which pretend that CH₄ is made from C + 4 H. In the real world, methane is formed by much more complex routes - see Methane#Production, so in this article we should just talk about the bonds and stability of the final molecule and not how the molecule is made. Dirac66 (talk) 19:31, 3 May 2013 (UTC)

I presume that means we have to overhaul the entire explanation to remove even the "excited state" portion and simply elaborate on why a mixture of s and p functions for a bond is more stable? That would mean a complete rewrite. Perhaps we could get more people on this matter for a better combined content as well as writing? I myself am unsure about exactly what kinds of energetic considerations are involved for the maximum stability to be sp3.--Officer781 (talk) 02:58, 4 May 2013 (UTC)

No, I don't think a complete overhaul is necessary here. I have done a relatively minor revision of your version to eliminate the offending words (initial and degenerate) and use a more standard vocabulary. I think that is sufficient. Dirac66 (talk) 02:05, 5 May 2013 (UTC)

VSEPR theory

Ok, I think that is done. On a side note, at the VSEPR theory page, under the description section paragraph 2, there is a complicating mention of resonance structures. Should it be reworded to remove the mention of resonance structures (some high school and beginner chemistry courses don't teach resonance and VSEPR is independent of VB theory anyway)? Also, perhaps mention that "for steric numbers 5 and beyond, the bonding electron pairs are partially ionic and the molecule does not violate the octet rule as commonly depicted (see hypervalent molecule)" (exact wording hence inverted commas) to dispel the common notion, as many authors have advocated including Gillespie himself, while keeping the wording simple for beginner chemistry courses?--Officer781 (talk) 13:57, 5 May 2013 (UTC)

Resonance: Most of this article is at high school and first-year university level, where VSEPR and resonance are in fact often taught as two compatible aspects of qualitative bonding/structure theory. Their independence only becomes important at a much higher level when their quantum-mechanical basis is discussed. So at this level I would leave resonance in, to help readers apply VSEPR to benzene etc.

Octet rule: Again, at a simple level the theory supposes that steric numbers 5, 6, ... do exist and therefore that the octet rule is violated, so I will suggest a less confusing wording to make the point, say in a footnote to indicate that the point is peripheral to the subject. Perhaps "The VSEPR model is based on simple Lewis structures which violate the octet rule for hypervalent molecules such as PF5 and SF6. However quantum-mechanical calculations for these molecules show that the octet rule is in fact respected if the partly ionic character of the bonds is considered. See hypervalent molecule." Dirac66 (talk) 01:41, 6 May 2013 (UTC)

Hmm, alright. But since resonance is taught to high school and first-year university level, i think the resonance description of hypervalent molecules would be understandable by the students.--Officer781 (talk) 02:54, 6 May 2013 (UTC)

True. So we can forget the QM calculations here and just say that molecules such as PF5 can be represented by both hypervalent (covalent) structures and ionic structures which obey the octet rule (example PF4+ F-), and that the VSEPR model uses the steric number based on the hypervalent structure. The article will be simpler if we do not consider here to what extent the octet rule is actually valid. Dirac66 (talk) 17:33, 6 May 2013 (UTC)

Browser check

Some weeks ago you started this, about the Periodic Table showing bad in one of your browsers (MSIE). Now I have a related request: could you take a check (look) at these two pages, again to see if any problem occurs in your browser-situation? I am building new legends for the Periodic Table, and have demos in my sandbox, and in {{Periodic table/sandbox}}. My user sandbox shows all legend themes at once, while typically we only use one or three legends on a page. Do you see any bad stuff? -DePiep (talk) 22:32, 25 April 2013 (UTC)

It is still as it was at the end of our previous discussion. No element names overlap into the next box, which is good. Some names (ex. Sc, Ti, V) are on two lines, others (ex. Cr, Mn) are on one line which is cut off, e.g. Mn is just Mang. If possible, I think the complete name on two lines is preferable, if we want to give maximum information to readers who have not memorized the element names. Dirac66 (talk) 23:15, 25 April 2013 (UTC)

Actually, I meant to ask to look for the legends, they are the new development. Thanks for replying though. -DePiep (talk) 00:40, 26 April 2013 (UTC)

The legends look OK. (I presume though that the Latin in your sandbox is just for fun and will not go into any article :-)). It has been too many years since I studied it, so I can no longer read it.) Dirac66 (talk) 01:00, 26 April 2013 (UTC)

Thanks. And about that text: it probably is a Latin legend [6]. A heroic story from the printing ages. Writing with boiling lead (plumbum) and so on. Those were the days! -DePiep (talk) 07:38, 26 April 2013 (UTC)

Methenium drawing

Oops! I will fix it asap...

Ellingham

I am glad to see someone upgrade this topic, which is found in many textbooks but is difficult to understand. Not sure if you have seen this article, which is also relevant: Carbothermic reaction. All the best, --Smokefoot (talk) 18:08, 7 July 2013 (UTC)

Thank you for your encouragement. I am a physical chemist and not a metallurgist, so I am concentrating on trying to make the basics understandable to physical chemistry students. No, I had not seen the Carbothermic reaction article before. Probably it can serve as another example, or at least be mentioned at the end as a See Also item. Dirac66 (talk) 01:02, 8 July 2013 (UTC)

Raoult's law - ternary systems vapour pressures deviation

Hi! I've noticed your background and edits on the topics concerning thermodinamics. In this context I request some feedback from you regarding the deviation from the ideal Raoult's law in ternary mixtures in order to fill in the article in this respect.

The article mentions positive and negative deviation in binary sistems. What could happen if a positive deviation binary mixture is mixed with a negative one? Could (it be that) they cancel out their deviation from ideality and the resulting mixture be an ideal one? Do you know some sources regarding this aspect?--188.26.22.131 (talk) 08:39, 15 July 2013 (UTC)

I have no sources but intuitively I would expect a partial cancellation. If for example A-B has positive deviations and A-C has negative deviations, then a molecule of A is attracted more weakly to B molecules than to other A molecules, and more strongly to C molecules than to other A molecules. So in a ternary mixture the average forces on an A molecule should be intermediate between those in A-B mixtures (with the same amount of B as in the ternary mixture) and A-C mixtures. And therefore the vapour pressure should also be intermediate. However I think we need some sources to check my reasoning before actually inserting this in the article - try either advanced textbooks or a Google search. Dirac66 (talk) 19:08, 15 July 2013 (UTC)

Of course some sources must be checked before insertion in article. What advanced sources come in your mind? Useful in this context would be a browsing of ternary azeotropes databases, if there are some.--188.26.22.131 (talk) 09:59, 17 July 2013 (UTC)

As I said, I unfortunately have no sources. If you can find useful information in azeotrope databases, that might be helpful. Dirac66 (talk) 01:52, 18 July 2013 (UTC)

Solid state activity

I've noticed your comments regarding the metallurgical aspects. I was wondering if know some wikimetallurgist who could answer to the topic of what measurement procedures of the activity coefficient of a metal in an alloy are there?--188.26.22.131 (talk) 09:33, 15 July 2013 (UTC)

Sorry, I don't know anyone. Perhaps melting-point as a function of composition? Or vapor pressures which will be very low but can me measured in a Knudsen cell? Dirac66 (talk) 19:26, 15 July 2013 (UTC)

Yes, melting-point as a function of composition is a valuable clue which is connected to Schroeder-van Laar equation of non-ideal systems mentioned in a general thermodynamics and phase equilibria textbook that I've been browsing recently.--188.26.22.131 (talk) 09:53, 17 July 2013 (UTC)

Perhaps you can find information in this textbook which would be useful for the article. Dirac66 (talk) 01:52, 18 July 2013 (UTC)

Compressibility factor and virial coefficients - relation to intermolecular forces

Regarding the insight on intermolecular forces, some more details regarding the relation of intermolecular forces to virial coefficients would be useful. --188.26.22.131 (talk) 10:04, 17 July 2013 (UTC)

They probably would be useful, if you want to try to find the information in a textbook. Dirac66 (talk) 01:52, 18 July 2013 (UTC)

It seems that there are inconsistencies between various sources/textbooks regarding this topic.Some give the next formula for compressibility factor and others for the second virial coefficient:

$Z=1+2\pi {\frac {N_{A}}{V_{M}}}\int _{0}^{\infty }(1-exp({{\frac {\varphi }{kT}}))r^{2}dr}$

or

$B=1+2\pi {\frac {N_{A}}{V_{M}}}\int _{0}^{\infty }(1-exp({{\frac {\varphi }{kT}}))r^{2}dr}$

where varphi is the potential of the forces.

Which one holds?--188.26.22.131 (talk) 14:51, 19 July 2013 (UTC)

There is clearly an error in the second formula because the second virial coefficient which is usually written B₂ should have dimensions of volume. The first one may be right if you have found it in reliable sources - I am not an expert in this. Dirac66 (talk) 01:29, 20 July 2013 (UTC)

Thanks for your answer. Do you happen to know some wikieditor who has an expertise in this topic?--188.26.22.131 (talk) 09:55, 23 July 2013 (UTC)

Variable Hybridization

Talk: Variable Hybridization. Need you there at the talk page for a little help. Thanks!--Officer781 (talk) 03:26, 20 July 2013 (UTC)

Thermal expansivity of mixtures

Do you some relations concerning the relation between the thermal expansivity of non-ideal mixtures and those of pure components? (involving perhaps the activity coefficients).--188.26.22.131 (talk) 09:23, 2 August 2013 (UTC)

Sorry, no. My knowledge of thermodynamics of non-ideal solutions is limited to the content of a few undergraduate textbooks, so I'm sorry I can't help. Dirac66 (talk) 19:32, 2 August 2013 (UTC)

File:Cisplatin and transplatin.gif listed for deletion

A file that you uploaded or altered, File:Cisplatin and transplatin.gif, has been listed at Wikipedia:Files for deletion. Please see the discussion to see why it has been listed (you may have to search for the title of the image to find its entry). Feel free to add your opinion on the matter below the nomination. Thank you. Sfan00 IMG (talk) 20:43, 2 August 2013 (UTC)

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Reworking of oxidation state

Hi,my first draft of oxidation state is at User:Axiosaurus/draft1. It is completely restructured. The refs still need some work, and I am sure that there are a load of typos. Please feel free to hack away at it or make comments. Regards Axiosaurus (talk) 11:00, 19 September 2013 (UTC)

OK, thanks for letting me know. I have made some comments on the talk page for this draft. Dirac66 (talk) 01:33, 20 September 2013 (UTC)

Take group 12 out of transition and into poor metals?

WT:ELEM#Make the group 12 elements poor metals? We are considering changing our default treatment of them!

Just saw your comment from over a month ago at Talk:Transition metal, and thought you might be interested in that discussion. As for the TM article itself, I still think it's not in very good shape (and intend to fix it up – though probably only in late October at the soonest). Double sharp (talk) 14:00, 27 September 2013 (UTC)

Changed explanation for hypervalent molecules for orbital hybridisation

I've decided today that introducing a different wavefunction for the hypervalent molecules for general readers is inappropriate as it invokes a different explanation (ie wavefunction) for regular and hypervalent molecules when valence bond at non-advanced levels is taught only using the HL wavefunction. As such I've simplifed it to include only two examples as an exhaustive explanation of every resonance structure of every shape is too cumbersome. Could you check if this explanation seems sound? Thank you.--Officer781 (talk) 09:11, 3 October 2013 (UTC)

I agree with the removal of Coulson-Fischer which is beyond the level of this article. We had originally introduced it last December to replace the incorrect idea of "partial orbitals", whose return I do not wish to see. The simple explanation we have now in terms of resonance structures is probably best. However I don't know which are the "only two examples" you refer to. Dirac66 (talk) 19:45, 4 October 2013 (UTC)

Oops, those two examples have been converted to a table. I forgot to update this message. My apologies.--Officer781 (talk) 01:05, 5 October 2013 (UTC)

I was also thinking of adding images for the hypervalent lone pairs section to show how the two respective components arise.--Officer781 (talk) 14:05, 3 October 2013 (UTC)

Sorry, here I don't know which components you mean. Dirac66 (talk) 19:45, 4 October 2013 (UTC)

The regular and resonant bonding components, especially how the regular bonding component corresponds to the non-hypervalent counterparts. That explains the similarity in bond angle between SF4 and SF2 for example.--Officer781 (talk) 01:05, 5 October 2013 (UTC)

Answering edit requests

Hey, I just wanted to let you know that when you answer edit requests, like you did at Talk:State of matter, you should leave a response on the talk page using the template {{ESp}}, and mark the request as answered by changing answered=no to answered=yes. See responding to requests for more information. I've already done this for you, but please keep this in mind next time. Thank you for fulfilling this request. --Anon126 (talk - contribs) 00:05, 13 January 2014 (UTC)

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• means there is [[symmetry]] with respect to an inversion center. That is, if all the atoms (are inverted across the inversion center, the resulting orbital would look exactly the way it did

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Willard Gibbs

Many thanks for your assistance and support with making the bio. of Willard Gibbs a featured article. Now I think that we should try to get the article re-assessed as being of top importance in both chemistry and physics, and of high importance in math (it's currently high/high/mid). I've brought this up twice in the corresponding project talk pages. One person commented favorably, but the matter has not really gone anywhere. I'm not very familiar with the mechanics of how to push such an initiative. Do you have any thoughts? - Eb.hoop (talk) 21:41, 16 February 2014 (UTC)

I am glad that Gibbs will be a featured article, which I assume means it will soon be placed on the main page. This will increase the visibility of the article to readers and therefore increase general knowledge of this important scientist.

However I am less certain of the utility of having the article described as of top importance rather than high. Are there readers who decide that they will only read articles of top importance and not of high importance?? Where are the lists of top-importance articles anyway? Certainly not on the main page of Wikipedia like the featured articles. Even on a project page like Wikipedia:WikiProject Physics, I see lists of Featured articles, Good articles and DYK articles, but no list of top-importance articles. The only place I remember seeing a mention of importance is on the talk pages of some articles, but I think that once a typical reader clicks on an article of interest, s/he will decide whether and how much to read based on the content of the article itself rather than on a rating on the talk page. Dirac66 (talk) 20:48, 18 February 2014 (UTC)

Well, in principle the ratings should affect how much attention an article gets from the corresponding projects. I guess this is less important now that the article has progressed to featured status. (It would've been nice to have gotten more input from other editors during the process.) It also seems to be the case that the science projects are relatively less active (compared, for instance, to military history). In any case, I think it would be good to rectify things, as Gibbs is clearly of top importance in chemistry and physics, and probably also of at least high importance in math. But if this is difficult I agree we should not lose sleep over it. - Eb.hoop (talk) 00:20, 19 February 2014 (UTC)

If I understand the latest note by Bencherlite on your talk page, you can speed up the placement of the new featured article on the front page by making a request. Perhaps for April 28 = anniversary of his death? Anyway, since it is already promoted to featured, this might be easier and more useful than the top importance assessment. Dirac66 (talk) 13:14, 20 February 2014 (UTC)

Metalloid FAC

Hi Dirac66

Would you be available for a copy-edit and subject matter expertise sweep of the metalloid article? Background is, User:John did a copy-edit of it. This occured at the suggestion of one of the FAC moderators, Ian Rose. The end result is that the article looks very sharp now. In his closing comments, here, John asked if the article could be looked at by another copy-editor and a subject-matter expert. As I have always appreciated your work on both of these fronts I thought I would check with you as to your availability. If it helps, I think the article is FAC ready now, thanks to John's work, so I wouldn't be anticipating a lot of work. User:R8R Gtrs has also indicated his support for FAC, here.

Thank you. Sandbh (talk) 11:57, 27 February 2014 (UTC)

Much appreciate your quick response. I'll add my comments on the metalloid talk page, shortly. Sandbh (talk) 06:40, 1 March 2014 (UTC)

Hi Dirac66

I've renominated it here. Thanks for your help and astute observations. Made me think a lot and improved the article. Sandbh (talk) 12:00, 9 March 2014 (UTC)

G'day Dirac66

Do you remember asking for the section called 'Honourable mentions' to be called something more scientific? I changed it to 'Nearby elements and allotropic forms'. I'd like to change it back. Reasons are: it better encapsulates the subject matter; it is plainer English; and it introduces an element of novelty that is consistent with high impact scientific papers. Would you have any objections to such a reversion? Thank you, Sandbh (talk) 04:27, 6 April 2014 (UTC)

Bonjour Sandbh

Actually my preference would be to delete the section title and just have two separate sections for Near metalloids and Allotropes. These two now subsections are not really on the same topic, and combining them makes it difficult to find a really satisfactory section title. I am not really a fan of novelty in titles - overuse of novelty just makes everything harder to read in the end. Dirac66 (talk) 14:00, 6 April 2014 (UTC)

OK. I'll change the section title to "Related concepts" and go with the sub-section titles of "Near metalloids" and "Allotropes". This takes up less space and keeps the term "near metalloid" at an appropriate level of prominence. It isn't as good as "honorable mentions" IMO but should be more acceptable from the scientific v novelty point of view. Better? Sandbh (talk) 11:35, 9 April 2014 (UTC)

Yes, I think it is better now. Dirac66 (talk) 18:21, 9 April 2014 (UTC)

Dirac66, would you have the capacity to do a spot check of the metalloid article, as requested here? Thank you, Sandbh (talk) 12:11, 8 May 2014 (UTC)

Well, I can look at a small sample of the 473 citations if that is what you mean by a spot check. Perhaps 10 or 20. Dirac66 (talk) 20:18, 8 May 2014 (UTC)

That would do I suspect. Thank you very much. Sandbh (talk) 03:21, 9 May 2014 (UTC)

Done and posted at Talk:Metalloid#Spot check of citations. Dirac66 (talk) 01:06, 10 May 2014 (UTC)

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• the compound from its constituent elements, with all substances in their [[standard state]]s at 1 [[atmosphere (unit)|atmosphere] (1 atm or 101.3 kPa). Its symbol is Δ''H''_f<sup><s>O</s><

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Boric acid

Your revert was undone by Neeraj.T (t·c) without an edit summary. I reverted it, but did a search on Boric acid and monobasic acid and got a number of hits. Including: Comprehensive Chemistry for JEE Advanced 2014, p15.5 and Competition Science Vision. So, I undid my revert and added a cite . I am not a chemists, so would you mind verifying this, undoing if necessary? Thanks for your help. Cheers Jim1138 (talk) 19:33, 17 April 2014 (UTC)

Thank you for these sources. The Comprehensive Chemistry link just gives me the announcement for the book and says Get print book. No e-book available. If you succeeded in accessing the content, perhaps you could modify this link so others can access it too. Or else just quote the relevant passage.

However the Competition Science Vision (C.S.V.) link is more helpful and I think solves the problem for me. It says in fact that boric acid is a monobasic Lewis acid (or electron-pair acceptor) rather than a Bronsted acid (or H⁺ donor). This is in agreement with references 4 and 5 in the Properties section, although reference 6 says apparently (as I cannot access that either) that boric acid is also a tribasic Bronsted acid. I had thought that Neeraj T meant a monobasic Bronsted acid but your C.S.V. reference does not say this.

So I am thinking of making two changes: in the intro I will change weak monobasic to weak monobasic Lewis, and in the Properties section I will add the C.S.V. excerpt as an additional source. Comprehensive Chemistry I cannot add myself because I have not seen the passage. Dirac66 (talk) 21:09, 17 April 2014 (UTC)

The link works for me. Must be limiting access. What it says:

Boric Acid Boric acid, also known as orthoboric acid, is H₃BO₃, i.e. B(OH)₃. It behaves as a weak monobasic acid. It does not donate proton but accepts OH^-. It can be titrated with NaOH using pheolphthalein indicator.

The added compound must be a cis-diol which forms very stable complex with [B(OH)₄]^-.

B(OH)₃ + NaOH <-- --> Na[B(OH)₄] (another diagram not shown)

In boric acid, B is sp² hybridized forming planar triangle structure. In the solid the boric acid units are hydrogen bonded together into two-dimensional sheets with almost hexagonal symmetry.

If you wish, I could email an image. I'll need your email as wikiemail doesn't seem to allow images. Cheers Jim1138 (talk) 22:52, 17 April 2014 (UTC)

OK, thanks. The key words are "It does not donate proton but accepts OH^-", which is equivalent to saying that it is a Lewis acid as the other references say, except for the Russian one. I won't need an image as I know enough chemistry to translate the words into an image myself. I'll keep the word monobasic along with Lewis, and move both your references to the Properties section where they support the more detailed discussion. Dirac66 (talk) 23:04, 17 April 2014 (UTC)

Whoops, I missed the middle section including the mention of Lewis Acid. Slightly better proofread version follows:

Boric Acid Boric acid, also known as orthoboric acid, is H₃BO₃, i.e. B(OH)₃. It behaves as a weak monobasic acid. It does not donate proton but accepts OH^-. It is therefore a Lewis acid. Its pK_a = 9.25.

B(OH)₃ + 2H₂O <-- --> H₃O⁺ [B(OH)₄]^-

Boric cannot be titrated with NaOH as a sharp end point is not obtained. In the presence of certain polyhydroxy compounds such as glycerol, mannitol or sugars, boric acid acts as a strong monobasic acid. It can be titrated with NaOH using phenolphthalein indicator.

The added compound must be a cis-diol which forms very stable complex with [B(OH)₄]^-.

B(OH)₃ + NaOH <-- --> Na[B(OH)₄] (another diagram not shown)

In boric acid, B is sp² hybridized forming planar triangle structure. In the solid the boric acid units are hydrogen bonded together into two-dimensional sheets with almost hexagonal symmetry.

Thanks for fixing this! Cheers -Jim

Ah, so both your sources explicitly say Lewis acid, and I have now added them as extra support for the statement that the reaction is an example of Lewis acidity. Dirac66 (talk) 15:58, 18 April 2014 (UTC)

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No offense to you

…(at all) but I took the "hydrophobic effect" article to great task, given the number of separate concepts that are confounded, the lack of understanding of the foundational Tanford work, and (esp. ) in light of Talk comments about it clearly being an enthalpic effect (!). I will look to find an expert to provide the needed expertise on this. My old Biochem mentor at Chicago might be willing. Le Prof Leprof 7272 (talk) 02:36, 20 May 2014 (UTC)

OK but why this is addressed to me? On reviewing my edits to this article, all four in Sept-Oct 2009, I see that I did not in fact make any statement about whether the effect is enthalpic or entropic, not being an expert. One thing I did do (on 2 Sept 2009) is add Tanford's book as a reference, which I hope you agree with. I hoped that other editors would consult Tanford and improve the article. I am not responsible if they misinterpreted Tanford. Dirac66 (talk) 16:45, 20 May 2014 (UTC)

Calculation of the Ka value

Hi Dirac66,

The question is about the calculation of the Ka value. For example:

Ka(H2O) = [OH−
]×[H+
]÷[H2O]
        = (Density(OH−
)÷Molar mass(OH−
))×(Density(H+
)÷Molar mass(H+
))÷(Density(H2O)÷Molar mass(H2O))
        ≈ (?g/L÷17.01g/mol)×(?g/L÷1.01g/mol)÷(999.97g/L÷18.01g/mol)
        ≈ ?mol/L×?mol/L÷55.52mol/L

But how to get the Density(OH⁻
) and Density(H⁺
)? Or is it possible to get the [OH⁻
] and [H⁺
] directly?

Thanks. 123.119.16.126 (talk) 14:07, 27 May 2014 (UTC)

Answered at Talk:Acid dissociation constant Dirac66 (talk) 19:14, 27 May 2014 (UTC)

Nuclei/Particles

Thanks for fixing "particles" back to "nuclei" in Beta decay. Hopefully we can find some more good cites to flush out the references section. —METS501 (talk) 23:26, 27 August 2014 (UTC)

Block (periodic table)

G'day Dirac66

Your recent edit to this article has promoted a discussion on the talk page, here, which I thought you may be interested in. Sandbh (talk) 10:36, 9 October 2014 (UTC)

Coordination number

I am working up changes in my User:Axiosaurus/sandbox. You are welcome to have a look and comment.Axiosaurus (talk) 12:41, 4 November 2014 (UTC)

thanks for helpful comments. Axiosaurus (talk) 09:51, 5 November 2014 (UTC)

recurrent attempts

Looking back on an edit I did today, I fear I may have inadvertently done something that perhaps you might find concerning. In my keenness to deal with the recurrent attempts of Dhiraj Sinha to use Wikipedia to promote his work, I took a step to remove a source of temptation. From the article on the second law, I removed the material on the work of the Canberra people. Perhaps you may kindly look gently or indulgently on that action of mine, or wait till DS has been dealt with.

To say a little more about that work. I am not persuaded that it is notable for articles that are primarily about classical thermodynamics. Perhaps I may be mistaken. My thinking is that entropy is a classical quantity. Classical thermodynamics does not admit that it can fluctuate. Fluctuation of a quantity means that it is somehow radically non-classical. These people don't make it sufficiently clear that they are using the word entropy to refer to some radically non-classical quantity. I wrote to Phil Attard (admittedly nothing to do with the Canberra people) asking how to measure second entropy. He said he didn't know. For me, that rules it out of the article on the second law, at least until some strong reason is found to put it in. At least Attard explicitly uses a non-classical name. But the Canberra people don't. So I think their work is probably, from a Wiki viewpoint, for an article on the second law, not reliably sourced or not notable. "Everyone talks about the weather, but no one does anything about it." I feel it may be like that with non-equilibrium entropy at least for the Canberra people.Chjoaygame (talk) 10:49, 22 November 2014 (UTC)

Thanks for the explanation. After looking over your edit, I tend to agree with your decision to remove that section, since it is not really relevant to the second law. However I do think there should be some pointer in the article to the fluctuation theorem for interested readers, so I will just add it to the See also list at the end of the article. Dirac66 (talk) 01:15, 23 November 2014 (UTC)

Thank you for your care in this. Yes, I think you made a good move.Chjoaygame (talk) 05:22, 23 November 2014 (UTC)