Talk:Resonance (chemistry)

message: Has anyone actually heard of the term "resonant bonds"?  I've look in texts before, and while I've definately heard of resonance structures, "resonant bonds" just doesn't seem standard.
:The use of verb forms of "resonance" died out with Pauling; even his student Wheland eschewed them.  "Resonant" is like a participial form that is not used because it implies that resonance is a process.  Rather, resonance is a (rather clunky) description of a variety of chemical bonding involving electrons dispersed over more than two atoms.Rectifico (talk) 19:27, 18 June 2010 (UTC)
replies: text: Electrons are continuously whizzing around, so you could say a compound with resonance has an infinite number of contributing structures, with the major ones most often occurring. In that sense, resonance may be considered as a process and the term (defined broader than merely the presence of different Lewis formulas) is not so bad as many think.--Wickey-nl (talk) 10:02, 19 June 2010 (UTC)
thread_title:  Resonant bonds 

message: There's a merge tag over at benzene. That section on resonance would look mighty good here. Isopropyl 21:08, 11 April 2006 (UTC)
thread_title:  Merge 

message: Reasonance diagrams for heteroaromtic compounds would be nice -- Quantockgoblin 23:47, 20 March 2007 (UTC)
replies: text: It does not seem useful to clutter the article with more examples. Heteroaromatic compounds present no particular challenge in drawing resonance diagrams. For example in furan, you simply move the lone pair on the O atom through the other 4 carbon atoms. Resonance diagrams for homoaromatic compounds would be more interesting. Loom91 08:35, 21 March 2007 (UTC)
replies: text: The set of resonance structures of Furan is illustrated at this time, so I'm calling this request . DMacks (talk) 04:34, 4 June 2012 (UTC)
thread_title:  Reasonance diagrams for heteroaromtic compounds? 

message: To clarify this point "Resonance hybrids are always more stable than any of the canonical structures", the wave function Ψ is given by:
: Ψ = a1C1 + a2C2 + a3C3 + ..
where Ψ is the resonance hybrid function and C1, C2, .. are the canonical structure functions. a1, a2 , a3, .. are coefficients chosen to minimise the energy. It follows from the variation theorem that the energy of Ψ is less than or equal to the energy of all of C1, C2, .. taken separately. It would be equal if one of the a1, a2, .. was 1 and all the others zero, and lower otherwise. Loom91 is correct and he gives a good simple reference. In antiaromaticity, the geometry changes to a more stable form. A good discussion is chapter 4 of "Facts and Theories of Aromaticity" by David Lewis and David Peters, Macmillan, 1975. --Bduke 13:37, 12 April 2007 (UTC)
thread_title: Resonance hybrid stability

message: Quotation:
When separating charge (giving rise to ions), usually structures where negative charges are on less electronegative elements have little contribution, but this may not be true if additional bonds are gained.
I believe this statement should be rewritten. Not being a native english speaker, my opinion may be misguided; anyway, to me it looks convoluted and is nearly uncomprehensible.
A statement like this, being a list item, should speak for itself. It remains unclear however, to what phelomenon contribution should contribute.
Bertus van Heusden 10:53, 4 September 2007 (UTC)
thread_title:  Convoluted statement in section "Writing resonance structures" should be rewritten 

message: I see someone changed the units under "resonance energy" to kcal/mol without changing the numeric values.  These should definitely stay as SI units, but someone should now check the correct values.  Unfortunately I don't have time right now. --Slashme 06:53, 10 October 2007 (UTC)
replies: text: The numbers are correct in kcal/mol (the resonance energy of benzene from this type of analysis is closer to 36 kcal/mol, not to 36 kJ/mol, which would be less than 9 kcal/mol, way too low). I don't think that the units should be converted to SI exclusively, although I would recommend giving the numbers in both systems. In my experience, kcal/mol are used more often in physical organic chemistry than kJ/mol, although both systems are commonly seen, and there is some regional variation. --Itub 10:02, 10 October 2007 (UTC)
thread_title:  kcal vs kJ 

message: To me, as a physicist, there are a couple of problems with this article. One is that the article never really explains the reason for the term "resonance," and there is no obvious (to me) physical phenomenon going on that is in any way (that's obvious to me) analogous to resonance. The section near the end about Pauling's introduction of the term doesn't really explain anything very clearly: why the quantum-mechanical treatment of H2+ was relevant to Pauling, or why he used the word "resonance." The other problem IMO is that the article never gives any very transparent physical explanation of what's going on. Although I understand the general argument made above on the talk page that a superposition of trial wavefunctions can be optimized variationally to lower its energy, that argument is so generic that it really has nothing in particular to do with chemical bonds, or even chemistry. If I had to take a stab at it, I would guess that the general physical mechanism is that, compared to a structure made of single and double bonds, the actual structure delocalizes the electrons, which means that they have a larger wavelength, thus a lower momentum and kinetic energy. In the case of an ion like CH3CO2-, I can also imagine that the delocalization would lead to a lower Coulomb energy.--207.233.87.196 (talk) 23:56, 11 December 2007 (UTC)
replies: text: I think your puzzlement is very understandable, and your inferences are perceptive and correct, as far as I can judge.  The term "resonance" was picked up by Pauling from Heisenberg, who noted that the two electrons in an excited helium atom had to be treated by the mathematics used for coupled pendulums, said to be in resonance.  This was then used by Pauling to describe all chemical bonding, although by now it is applied only to cases like those in this article.  Some of us believe that this would be a good case for the old New Yorker column, "Block that Metaphor".
Rectifico (talk) 19:27, 18 June 2010 (UTC)
thread_title: terminology, physical reason

message: I know I'm coming in late into this discussion, but ... 
There are several small problems:
* Use of 'pi' instead of π. 
* I am no expert on the history of the concept, but I doubt very much that Kekulé came up with resonance, as is implied in the 'Examples' section. 
* Whereas ozone is correctly presented as bent and benzene as a hexagon, the allylic cation is linear (?) and the middle H changes position, contrary to rule 1 governing the correct drawing of resonance structures.
The biggest problem I find with this article is that it is not well targeted to the intended audience. 
After all, who will look up 'Resonance' on Wikipedia? The average Joe wouldn't ever. Practitioners don't need to. Only students would -- students who have encountered resonance in their studies and in their textbook, and who need help in understanding it. Their first encounter would be with main group examples (e.g. sulfate ion), but this article barely acknowledges this reality. My evaluation is that this article would confuse more than enlighten. 
Let me be clear: I can live with this article, because I see no substantial problem with the content, but I would never refer any of my students to it. It's simply not written for them and assumes knowledge. 
Specific problems:
* Resonance as a theory and key component of VB theory vs. a diagrammatic tool (I prefer the term 'representational device') vs. its 'True Nature'. Students struggle enough with chemical bonding, and resonance is especially problematic because it is a total misnomer. The presentation of resonance in this article is, I believe, a recipe for confusion. 
* Students want to know what's what. Mixing VB theory, MO theory and resonance in the way that this article does serves poorly to answer their questions "What is the real structure?", "What is going on?", "Why?". 
* Using the undefined phrase 'non-classical' in the very first sentence and the undefined 'conventional model' in the second is counter-productive. 
* Defining resonance, in part, as a 'mathematical description of a molecule using valence bond theory' is unclear and useless. Students are not interested in mathematical descriptions, and want to know how to understand and generate resonance structures.
* The idea that resonance is a way to explain properties that cannot be explained in terms of canonical Lewis structures is not incorrect. This is an empirical approach to discussing resonance, answering the question "How did the idea emerge?", but not the question "What is the real structure?". 
* Defining (a hybrid) structure as an 'average' of 'several simpler but incorrect structures' is misleading. What is really incorrect is the representation of resonant structures with a non-resonant Lewis one, not the resonance extremes ('contributing structures') themselves. Whether these contributing structures are simpler or not is a semantic issue. Delocalized hybrids are more correctly defined as an energy-weighted average of localized structures, not a simple average. 
* "Resonance hybrids are always more stable than any of the canonical structures would be, if they existed." Why? 
* "A canonical structure that is lower in energy makes a relatively greater contribution to the resonance hybrid..." Lower than what? In the context where this sentence appears, one could easily be led to think that there are canonical structures that are lower in energy than resonance hybrids. 
* Returning repeatedly to benzene is repetitive. 
* "This observation of greater delocalisation in less stable molecules is quite general." Greater than what? 
* "The excited states of conjugated dienes are stabilised more by conjugation than their ground states,..." Surely this requires some literature reference. 
* "... causing them to become organic dyes." I know of no simple diene that can ever be called a dye, while this actually says that the excited states are dyes and implies that the ground states are not. The idea of their 'becoming' dyes is disturbing. 
* The "allylic rearrangement" is not real. It is so named because the starting material appears to undergo a rearrangement in forming the product, but this is ignoring the non-rearranging nature of the cationic intermediate. "Isotope labelling experiments have shown that what happens here is that the additional double bond shifts from 1,2 position to 2,3 position in some of the product." What 'additional' double bond? 
* You cannot dissociate a discussion of resonance without talking about orbital overlap, conjugation and energy. 
* Set aside the historical perspective, which is interesting but not to beginning students. 
* The mention of ring currents (and NMR) is inappropriate. 
* The mention of superacids is unneeded. 
* The vector analogy is not wrong but unnecessary and does not merit a sub-heading. The point is that the true structures can be represented as a linear combination of structures. Students understand linear combinations (from LCAO). 
* "In the mathematical discipline of graph theory, a Kekulé structure is a matching or edge-independent set in a graph." Whoopee-do. Unnecessary and unilluminating. 
* "In benzene both Kekulé structures have equal weight." Why? (Don't answer that; I know the answer. My point is that this needs to be substantiated, but nowhere is this explicited.) 
* I disagree that there is a theory called 'resonance'. 
Pgpotvin (talk) 00:23, 11 January 2009 (UTC)
replies: text: This link leads to the article on Kekulé which only had a verbal description of the structure, so I have added the diagram from Commons.  Dirac66 (talk) 01:32, 11 January 2009 (UTC)
replies: text: You are indeed being less than clear. You need to look at the history. I presume you mean links on User:Bduke to wikiversity in general. I did not write the material on wikiversity that you mention (look at the history) and I did not write this article, although I have done a few minor edits. Wikepedia and wikiversity serve a different purpose. --Bduke  (Discussion) 07:38, 11 January 2009 (UTC)

text: Sorry, but where exactly are "Bduke's links to Wikiversity"?? I tried searching Wikiversity for resonance + chemistry, and all I found was this fragment (not by Bduke). 
In any case I don't really think it is useful to have two sets of articles named Wikipedia and Wikiversity. There is enough work to do without having two articles on each subject. Sans compter les articles en d'autres langues.  Dirac66 (talk) 04:47, 11 January 2009 (UTC)
thread_title:  Problems with this article 

message: Yesterday Wickey-nl inserted Template:Essay-like which says that "This article is written like a personal reflection or essay and may require cleanup." The template links to WP:Not#Essay, which I have just read, but it is not at all clear that it refers to this article. In fact the content appears to me quite similar to what is found in chemistry textbooks at various levels (some paragraphs are more advanced than others). Please explain what is personal about this article. 
It is true that very few sources are given. Perhaps a more appropriate notice would be Template:Refimprove which asks for more sources. Dirac66 (talk) 15:39, 4 April 2010 (UTC)
replies: text: Sorry for the late reaction. Indeed the wrong template. I meant to say this is not an ecyclopedic article (despite internal links), but a wikibook. The first  meaning of essay. It is written like a textbook. Funny that the term is used above. Wikipedia is not a textbook. --Wickey-nl (talk) 10:41, 6 April 2010 (UTC)
replies: text: We could modify the tone of some sections. I have started with the section Writing resonance structures, where I have inserted "Chemists use ... rules ..." and removed the word "must" which was used three times. Dirac66 (talk) 14:23, 6 April 2010 (UTC)
replies: text: Ecyclopedic style is principally compact, as much as possible.--Wickey-nl (talk) 15:02, 7 April 2010 (UTC)
thread_title:  Why has this been labelled a personal essay? 

message: In the section Writing resonance structures, rule 4 does not really belong because it is not helpful at an elementary level. Rules 1,2,3 and 5 can each be illustrated in a first-year lecture with simple examples of acceptable and unacceptable structures, and perhaps such examples should be included in the article. 
However rule 4 says "Resonance hybrids can not be made to have lower energy than the actual molecules." This is a special case of the variational principle of quantum mechanics and therefore a true statement. But it is not a useful rule because one cannot quickly determine the energy by inspection, unlike for example the number of unpaired electrons. I propose that this rule be deleted from the article. Dirac66 (talk) 14:14, 4 May 2010 (UTC)
replies: text: Another viewpoint is that rules 1,2,3 and 5 deal with how to choose contributing structures (even if rule 5 now incorrectly refers to hybrids), whereas rule 4 gives a property of resonance hybrids. So instead of deleting rule 4, I will move it to the section on True nature of resonance, where I think it belongs. Dirac66 (talk) 15:21, 4 May 2010 (UTC)
replies: text: What does that sentence formerly known as rule 4 even mean? DMacks (talk) 15:30, 4 May 2010 (UTC)
thread_title:  Writing resonance structures - rule 4 is not useful 

message: :::The resonance hybrid by definition has the lowest energy. May be the two last rules are added later?--Wickey-nl (talk) 15:48, 4 May 2010 (UTC)
replies: text: I interpret it as equivalent to the variational principle - the resonance hybrid corresponds to a wavefunction of lower energy than the individual resonance structures, but higher energy than the true wavefunction. Of course this is only meaningful if one has the means (software etc.) to compute the energy, so it did not belong in a set of rules for drawing chemical structures by hand.  Dirac66 (talk) 17:55, 4 May 2010 (UTC)
replies: text: Yup, that's all right. But that's almost opposite how I read the sentence. Should be that individual resonance-structure contributors are never lower in energy than the resonance hybrid, which approximates the electronics of the actual molecule. At least as my textbooks usually use the terms, the "resonance hybrid" is the nonclassical average of the individual simple Lewis-structures and is nearly the "real picture", and the point of the article is that resonance does pretty well reflect reality (vs this being just another pretty far-off approximation from the true wavefunction). DMacks (talk) 19:13, 4 May 2010 (UTC)
replies: text: Hmm, I had not thought of that interpretation. I presume your "nonclassical average" refers to averaging electron density and not energy. Anyway, at the level of this article we now have two interpretations so the sentence is ambiguous and needs rewording, or ... we can just delete it after all since it doesn't really add much to the (now) preceding paragraph. Dirac66 (talk) 20:55, 4 May 2010 (UTC)
replies: text: Let's explain, without the variational principle and without mathmatics, what the "resonance hybrid" is.Can we say: The resonance hybrid has a wavefunction that is the weighted average of the wavefunctions of the contributing structures? This would implicate that the energy of the resonance hybrid also is the weighted average of the energy of all individual contributing structures (?), so even a bit higher than that of the major contributing structures. The term resonance hybrid would be meaningless.Or would the resonance hybrid be the structure with the lowest possible energy? That would implicate that the resonance hybrid is the structure that reflects the real compound. --Wickey-nl (talk) 10:51, 5 May 2010 (UTC)

text: "Weighted average" is not totally correct here. The hybrid wavefunction is a linear combination, which can be considered a weighted average IF all the coefficients are positive, but this is not always true. The electron density is a weighted average of densities for the contributing structures, but its coefficients involve the squares of the wavefunction coefficients. And the energy of the resonance hybrid is NOT a weighted average of energies of contributing structures (which would be between the highest and the lowest!); instead it is usually lower than the lowest of the contributing structures due to quantum-mechanical interaction between the structures.  Dirac66 (talk) 01:43, 6 May 2010 (UTC)

text: Definitions can change with time, but Linus Pauling (in 1939!) refers to a resonance hybrid as a system that has to be described by the wave functions of more than one structure, without referring to a certain level of energy (see page 12). I think it is best to keep it similarly simple in this article, unless good references can be given for another meaning.--Wickey-nl (talk) 13:49, 6 May 2010 (UTC)

text: This discussion has convinced me that the former rule 4 really adds nothing useful. Three of us have each read a different meaning into it, so it must be unclear and ambiguous. Is it worth trying to clarify? The ΔE between resonance hybrid and exact wave function is really outside the scope of this article, and the ΔE between resonance hybrid and contributing structures is already clear in the section on resonance energy. So I have now decided to just delete the former rule 4 - one step toward a simpler article. Dirac66 (talk) 22:41, 6 May 2010 (UTC)
thread_title:  What is the definition of "resonance hybrid" 

message: Added yesterday:
"If the bond lengths are measured, for example with NMR spectroscopy, no single and multiple bonds can be distinct. All bonds appear to have the same bond length, somewhere between single bond and multiple bond length." 
Two comments:
1. Bond lengths are not usually measured with NMR, but with x-rays in solid state, or by microwave, ir or uv-vis spectroscopy in gas.
2. Can we specify exactly which bonds have the same bond length? Even in benzene, C-C and C-H are not the same length. Do we mean all bonds involved in the resonance? No, because today the thiocyanate ion was added, and the S-C and C-N bonds are not the same length. Do we mean all bonds between similar atoms? No, in ethylbenzene the side-chain C-C is a single bond and longer than the ring bonds. And in naphthalene there are ring bonds which are longer than other ring bonds.
I think what we really mean here as a general statement is that bonds with different bond orders in different contributing structures usually have intermediate bond lengths. Then we can give some examples of equal bond lengths (benzene, carbonate) without claiming that all bond lengths are equal. Dirac66 (talk) 20:20, 8 May 2010 (UTC)
replies: text: Agree totally, but have no time to do anything. --Bduke  (Discussion) 22:34, 8 May 2010 (UTC)
replies: text: I made this section to break the structure of the old article, which prevented improvements. Of course it has to be rewritten completely.I am not familiar with measurement technics, but it is called to emphasise that it is not only theoretical guess, but information from practise. NMR can be replaced by x-rays or so. A separate section about measurement of resonance would be interesting.The characteristic of resonance is that single and multiple bonds are not as could be expected, compared with lengths as measured in simpler (reference) compounds. The reference lengths are mentioned in the current article and in other WP articles e.g the German one. I do not have an overview of all possible bond types. Currently the classical example of benzene is used. Is the differing bond length of adjacent single and multiple bonds (compared with normal single and multiple bonds) better as general characteristic instead of all single and multiple bonds are identical? In the thiocyanate ion S-C versus S=C and C=N versus C≡N.--Wickey-nl (talk) 15:55, 9 May 2010 (UTC)
thread_title:  Bond lengths 

message: Can we delete the chapter True nature of resonance? If not, what part is worth to keep?--Wickey-nl (talk) 11:19, 10 May 2010 (UTC)
replies: text: I think this section is needed to describe the relation of Resonance to the more quantum-mechanically based bonding theories such as VB and MO. I would keep everything except the sentence about graph theory, which is less used by chemists. Perhaps the section title should be changed to "Resonance and bonding theories" or "Resonance and quantum mechanics". Dirac66 (talk) 14:55, 10 May 2010 (UTC)
replies: text: I think it are many words to tell little, lacking any structure. That relationship is not made clear. No one will read it with pleasure.--Wickey-nl (talk) 16:16, 10 May 2010 (UTC)
replies: text: Actually it seems quite clear (except for the graph theory sentence) for advanced readers who already know about bonding theories and a little about quantum chemistry. Admittedly it will not help readers at a first-year level. It can always be improved further, but I believe it should be retained until someone has time to improve it. Dirac66 (talk) 20:30, 10 May 2010 (UTC)
replies: text: For beginners it is worthless, links to VBt and MOt will not help. For advanced readers it is not interesting. I propose to delete all and write (not by me) a new section about the relationship with quantum chemistry, wavefunctions, VBt and MOt. At least I will change the heading.--Wickey-nl (talk) 14:28, 11 May 2010 (UTC)
replies: text: Do not delete until the rewrite has been discussed here. --Bduke  (Discussion) 14:22, 12 May 2010 (UTC)
thread_title:  Delete the chapter ''True nature of resonance''? 

message: This article now contains the word "compound" 14 times, and I suggest they all be replaced by "molecule". First, resonance can be a property of elements too; ozone, graphite and fullerenes come to mind. More fundamentally, resonance structures are a property of the microscopic molecular unit and not of a molecular compound (or element). It is not correct to talk about (Lewis) structures of a "compound". 
Some may argue that "molecule" excludes ions, but we can add "or ion" a few times, or else specify "molecule (neutral or charged)". In any case, "compound" also does not include ions. Dirac66 (talk) 23:21, 1 June 2010 (UTC)
replies: text: That resonance also occurs in elements is really a good point. Changing into compound or element in the first sentence would be an improvement.Compounds include compound ions, but molecules exclude ions. In most cases it regards compounds and in many cases it regards ions, thus replacing compound by molecule would make the article less correct. In most cases only "molecule or ion" will be correct. The number of times a word is used can of course not be an argument. This is not a novel.--Wickey-nl (talk) 12:53, 2 June 2010 (UTC)
replies: text: I agree that "compound" is definitely not the best choice here (not inclusive enough and suggests macroscopic effect). Is "structure" too confusing a term? Resonance really is a feature of the electronic structure, regardless of how one classifies what that entity is. Just have to be clear when we talk about "individual resonance structures" (the two cyclohexatriene forms of benzene) vs "a structure that has resonance" (benzene). DMacks (talk) 03:12, 4 June 2010 (UTC)
replies: text: I have already admitted that changes are needed, but "molecules" is too exclusive. "Structure" is a little confusing between contributing structures, the combination should be avoided. A single word will always be a compromise. "Molecule or ion" will in most cases be most exact. Why can a compound not be just a compound with a special electronic structure? B.t.w., the first sentence clearly indicates that the article is about the electronic structure, not about compounds of molecules in general, but I will adapt it also.--Wickey-nl (talk) 12:38, 4 June 2010 (UTC)

text: No one is talking about compounds on macroscopic scale, nor it is suggested, except on this talk page.--Wickey-nl (talk) 13:18, 8 June 2010 (UTC)
replies: text: OK, instead of "macroscopic", let us say (here on the talk page) that a "compound" refers to an "arbitrary amount" of a (pure) substance containing two or more elements. Since resonance refers to electron delocalization over a single molecule, it is better to use "molecule" in this article. I did leave in the one mention of compounds or elements. Dirac66 (talk) 23:17, 8 June 2010 (UTC)
replies: text: I don't like this word play. Either you don't want to or you cannot get the point. If you say that biochemists use molecule while it is an ion, I can say in general, compound is used also if it is a molecule. With a few exceptions as pure oxygen or carbon, all structures are compounds. This is not a biochemistry article. Dipolar compounds are never called dipolar molecules and I never use compound to refer to an amount of substance.--Wickey-nl (talk) 15:15, 9 June 2010 (UTC)
thread_title:  Replace "compound" by "molecule" everywhere 

message: I still think that "molecule" is the best word in most cases (in this article), because electrons are usually delocalized over one molecule and not over a macroscopic sample of a compound or element. (Graphite is an exception and has no molecules). I will however add "or polyatomic ion" and "or ion" a few times to make it clear that ions are included. The idea that "molecules exclude ions" comes from the simple chemistry of small molecules. Organic chemists and biochemists routinely refer to ions as molecules - try telling a biochemist that proteins and DNA are not molecules just because they are charged!
We can however make the point explicitly that the molecules (and ions) can be of both compounds and elements. Since most of the molecules are compounds, we might include an explicit list of elements: I mentioned ozone, graphite and fullerenes which are all neutral molecules, and an example of an ion is the azide ion N3-. As for "structure" we can use it in a few places where the distinction is clear between the hybrid structure and the contributing structures, but I think it would be confusing to use it everywhere. 
I will try to make these changes now. Dirac66 (talk) 01:16, 8 June 2010 (UTC)
replies: text: No one is talking about compounds on macroscopic scale, nor it is suggested, except on this talk page.--Wickey-nl (talk) 13:18, 8 June 2010 (UTC)
replies: text: OK, instead of "macroscopic", let us say (here on the talk page) that a "compound" refers to an "arbitrary amount" of a (pure) substance containing two or more elements. Since resonance refers to electron delocalization over a single molecule, it is better to use "molecule" in this article. I did leave in the one mention of compounds or elements. Dirac66 (talk) 23:17, 8 June 2010 (UTC)
replies: text: I don't like this word play. Either you don't want to or you cannot get the point. If you say that biochemists use molecule while it is an ion, I can say in general, compound is used also if it is a molecule. With a few exceptions as pure oxygen or carbon, all structures are compounds. This is not a biochemistry article. Dipolar compounds are never called dipolar molecules and I never use compound to refer to an amount of substance.--Wickey-nl (talk) 15:15, 9 June 2010 (UTC)
thread_title: Molecule vs. compound vs. structure

message: I have reverted the last edit. First, the hyperconjugation heading is for a section that is not about hyperconjugation. It is about 3-centre 2-electron bonding with sigma orbitals. As it says, hyperconjugation is about pi electrons. Second, I suggest the gallery is inappropriate. These diagrams could just as well be describing delocalisation with MOs. They are certainly not resonance structures. --Bduke  (Discussion) 02:18, 5 August 2010 (UTC)
replies: text: I have removed the resonance hybrid images. These are misleading as they could equally be MO diagrams. Indeed the circle in the hexagon is generally accepted as short hand for the MOs. The point is already made clearly in the examples where diagrams for ozone and benzene are shown as the clear consequence of mixing resonance hybrids. That is clear. The images on their own are not. --Bduke  (Discussion) 02:26, 5 August 2010 (UTC)
replies: text: Nothing misleading. MOs may be true, but the hybrid images are unambiguous resonance structures. Molecules with delocalized pi-electrons.--Wickey-nl (talk) 10:24, 7 August 2010 (UTC)
replies: text: No, you are wrong. Take a look at the diagrams under the "Examples" heading. The diagrams on the left of the equal sign are resonance structures. The diagrams on the right of the equal sign are not resonance structures. They are just representations of delocalization, which can come, as here, from mixing resonance structures, or equally from MO. Just having diagrams of the right hand side labeled as resonance hybrids is misleading. On the other hand these example diagrams make everything clear. We only need those. There is no need for extra diagrams of the right hand side for benzene and ozone. Note, I am not pushing MO or fighting the old VB v MO battle, so your "MOs may be true" is not relevant. I am asking for clarity about the use of terms. --Bduke  (Discussion) 23:44, 7 August 2010 (UTC)
replies: text: The misunderstanding is that I referred to entities that can be pictured as resonance structures, not to the form of the pictures as I indicated. That is why "identical to signs" are used, not "equal signs". And as this article is about resonance, the context is clear. There is nothing wrong with giving some examples of typical, but different types.--Wickey-nl (talk) 11:17, 11 August 2010 (UTC)
replies: text: I still maintain that they are confusing. I also say that we already have the ozone and benzene diagrams as the right hand side of what you correctly call "identical to signs" (I was not trying to be absolutely correct there - just to point where they are). You were just adding a bunch of unnecessary and misleading images. There is no misunderstanding. What is your background in chemistry? Have you studied bonding theories such as valence bond and molecular orbital to an advanced level? I find it difficult to pitch what I say to you, because I do not know your background. Mine, I think is clear, from my user page. --Bduke  (Discussion) 11:48, 11 August 2010 (UTC)
replies: text: OK, I give you away I haven't studied the subject to an advanced level. I found an article of very poor quality and without appropriate references. Apparently there are no authors willing to write at advanced level. Only to make comments, minor edits and revert edits.--Wickey-nl (talk) 13:57, 11 August 2010 (UTC)
replies: text: OK. I think you are a little confused about what resonance is all about, but you are not alone. I hesitate to wade in on this article for two reasons. First, I am not sure it needs to be written at an advanced level, but it should at least not be wrong. Second, most of my current research is on valence bond theory, so I am sort of an expert. However VB experts notably all disagree with all the other experts in a fairly profound way. I exaggerate, but not much. Maybe that is why there are no authors willing to write at advanced level. Nevertheless I still state very clearly that I think the image in the examples section is the only place where we have these very vague diagrams on the right that just state that the electrons are delocalised. The diagrams on the left are resonance structures and map directly to the wave functions that are then combined to give a VB total wave function. The diagrams on the right have no direct correspondence to any wave function, but rather to several, including the MO wave function, the VB function from those two structures, and the VB function from many structures (6 for ozone and 5 or a lot more for benzene). So in the context the diagrams on the right are OK. However on their own they are not OK and are also misleading. Part of the problem is the name of these images which include the word "resonance". They should not as it should be replaced by the word "delocalization". Does this explain things and are you now happy to leave these images out? --Bduke  (Discussion) 00:18, 12 August 2010 (UTC)

text: (outdent) Agree with Bduke here. A loose collection of images illustrating delocalized electrons isn't resonance, it's more like the result of it. Resonance is the pieces and an explanation behind it. It's great to use them as part of a LCAO diagram because that's how they are relevant to this article. While we're picking at this though, :File:Resonance examples.png is wrong in two ways related to the idea of resonance as a combination of contributors (rather than a "real" MO diagram). First, allyl should +1/2 on each end not + in the middle (formally a + delocalized, but again that's not this article). Second, benzene should have half-bonds (dotted circle) again because we're talking about combining/averaging bond-orders rather than an orbital picture. DMacks (talk) 00:37, 12 August 2010 (UTC)
replies: text: I agree. We just have too many bad diagrams of bonding done by people who do not entirely know what they doing or what the target article is for them. --Bduke  (Discussion) 01:36, 12 August 2010 (UTC)
replies: text: Best I can discern, that image is only used in this same context (i.e., misused) anywhere in the *pedia world. Should I just alter the original, or place it at a new filename? While we're at it, should allyl+) be redrawn bent? Should it be replaced by something with more than just two resonance contributors (pentadienyl+ perhaps)? DMacks (talk) 14:51, 12 August 2010 (UTC)
replies: text: @Bduke. "Resonance hybrid diagrams" can be renamed to "hybrid diagrams". In the paragraph about diagrams the pictures were/are appropriate. I fully agree about the level of the article. The subject is not trivial, but must be accessible. A better text about the wave functions would be appropriate in the section about quantum mechanics, instead of focus again on the example of benzene. Can you indicate in a few words what the disputations are about resonance?@DMacks. If the original is altered it will appear everywhere where used. If you add a new structure I think it may be regarded as a new image.--Wickey-nl (talk) 16:02, 12 August 2010 (UTC)
replies: text: Sorry, no. I have just broken my arm. --Bduke  (Discussion) 08:38, 13 August 2010 (UTC)

text: I am not happy at all with several examples in one image. It limits the possibility to add other examples in an elegant way and no explanation per example is possible. Separated examples are preferable and more flexible.--Wickey-nl (talk) 16:50, 15 August 2010 (UTC)
replies: text:  fair enough. I am having some issues with other images though: the nitrogen atom in the nitrate ion has a positive charge and the oxygen atoms a delta minus charge as in polarity. This should be a -2/3 charge for each oxygen atom. The continuous circle for benzene vs the dashed line is confusing. According to the aromatic hydrocarbon page the full circle representation was invented in 1925 and conveys a different meaning than the one with the dashed lines in the resonance concept of 1928. Also, the single covalent bond image and the double covalent image do not add anyhting to the text and should go. V8rik (talk) 21:26, 15 August 2010 (UTC)
replies: text: The benzene circle diagram should be removed unless you can find a reliable source that uses it in the context of VB/resonance theory. --Bduke  (Discussion) 23:30, 15 August 2010 (UTC)
replies: text: The image of the nitrate ion may be not completely wrong, but is somewhat ambiguous indeed. For the benzene circle: all versions refer to the same delocalized electrons. Just ignore the most widely used symbol is not the right way. The difference can also be explained in the article and I have not a problem at all to use a version with dashed circle. The covalent bond images are used to illustrate the normal bonds in the Lewis formulas.--Wickey-nl (talk) 15:39, 16 August 2010 (UTC)
replies: text: The point is that I do not think that I have seen the circle diagram other than in the context of a discussion of the MO theory of benzene. That is why I asked for a source. It is a reasonable request. --Bduke  (Discussion) 21:54, 16 August 2010 (UTC)
replies: text: OK, that was an overreaction. The cyclohexatriene is the standard, but that is not the point. The point is that the circle diagram is generally accepted as symbol of benzene and thus depictures delocalized π electrons and thus represents the resonance character of benzene (http://goldbook.iupac.org/D01583.html). Second, what is the difference between a continuous and a dashed circle? --Wickey-nl (talk) 15:35, 17 August 2010 (UTC)
replies: text: Per the source you cite, "Delocalization in such species may be represented by partial bonds", which is the dotted-bond notation. A solid-line circle is not a dotted line--it suggests a whole bond rather than the partial. The solid circle is a different representation than the specific idea of the bonding involving resonance. It (some would say more accurately) describes the electronic situation (unified pi orbital around ring, with an broken electron density there) and it's a common notation used in the literature. But it's off-topic here. DMacks (talk) 16:32, 17 August 2010 (UTC)
replies: text: Of course the solid circle is only used for convenience (easy to draw), but can you say it represents something different? No, you can only say the dashed or dotted version is the version that is more consonant with the usual notations.--Wickey-nl (talk) 14:15, 18 August 2010 (UTC)

text: This continues to be wrong in several ways. First, resonance is not restricted to pi-systems, although it is common there. However the main problem is "the essence of resonance is the existence of a system with delocalized electrons" (I have removed the pi). Resonance is just one way to understand delocalized electrons. MO is another quite different way to understand delocalized electrons. It is important to distinguish between talking about delocalization in general, the resonance interpretation of it, and the MO interpretation of it. This is what you are failing to do. Finally, you can discuss delocalized electrons entirely without using resonance, or you can discuss them by using resonance. It is your choice. It is meaningless to talk of compounds without resonance or with resonance. It is not something like carbon atoms that compounds either have or do not have. It is just an idea that some people find useful and others do not. --Bduke  (Discussion) 01:56, 20 August 2010 (UTC)
replies: text: I have to disagree that "It is meaningless to talk of compounds [molecules] without resonance or with resonance." At the level of simple Lewis structural diagrams, some molecules (such as ethane) can be described reasonably well by a single Lewis structure while others (such as benzene) require a combination of structures which we call resonance. It is true that the difference is harder to define for MO calculations which yield delocalized MOs for all molecules, but much of chemistry (especially organic) still uses simple Lewis structures for which the concept of resonance is useful. Dirac66 (talk) 02:58, 20 August 2010 (UTC)
replies: text: But you defined the framework, Of course, if you start with "At the level of simple Lewis structural diagrams", then of course some molecules are represented by one Lewis structure and some by several, but you do not have to start there. On the one hand, you could start with ionic-covalent resonance and then both ethane and benzene have many structures, or you could start with MO when Lewis structures do no even come into it. But all this was about images and I am merely saying the images have to match the appropriate framework and to not assume that images from any framework are appropriate in an article on one framework, This article is about resonance. It is not about delocalization or MO. --Bduke  (Discussion) 04:08, 20 August 2010 (UTC)
replies: text: Dirac66 worded pretty well my thoughts. For the "resonance compounds" the pictures with dashed pi bonds are useful, for simple ones not useful and not needed. Do we have such a picture anyway, for the water molecule e.g.? Again, are there compounds with delocalized electrons, but without resonance? For Bduke: are there compounds with delocalized electrons that cannot be explained within the resonance framework? If not, pictures with delocalized electrons are always appropriate within the resonance framework (because delocalized electrons are a condition for the occurrence of resonance and resonance energy). For the article, however, it is may be more useful to explain the difference between the two types of images. --Wickey-nl (talk) 14:33, 20 August 2010 (UTC)
replies: text: I am going to be pedantic again. Delocalization can be detected from the electron density which is an observable. Resonance can not be so detected. Therefore "are there compounds with delocalized electrons, but without resonance?" is a rather confused question. Delocalisation can be interpreted theoretically in several ways, ONE of which is resonance. "delocalized electrons are a condition for the occurrence of resonance and resonance energy" is false, but one might say that delocalized electrons are a condition for using the explanation of resonance and resonance energy as one possible explanation. "are there compounds with delocalized electrons that cannot be explained within the resonance framework?". No, resonance can always be used as that kind of explanation. However, there are cases where such an explanation is clumsy and seems much less simple than the MO explanation. Two classic examples are the bonding in ferrocene or dibenzene chromium, and large borane structures like B12H14 or the B12H12 dianion. The number of resonance structures is very large, while the MO picture makes use of symmetry and is relatively simple. In the opinion of many, including myself, Pauling lost a lot of credibility in the 1960 edition of his book, "Nature of the Chemical Bond", by only using the resonance approach for those systems with not a mention of the MO approach, which had been used so successfully by Wilkinson, Cotton and Lipscomb. All of these systems are now ones where we naturally use MO, and not resonance, to think about them. --Bduke  (Discussion) 00:38, 21 August 2010 (UTC)
replies: text: To reassure, your point is clear and justified, and I don't want to add a lot of hybrids again (actually it was just an easy and quick way to give a number of examples of compounds that can be  explained with resonance). Pictures are seldom fully self-explaining and the accompanying text is decisive. But a religious approach is not useful.--Wickey-nl (talk) 14:26, 21 August 2010 (UTC)
thread_title:  Last edit, gallery and hyperconjugation 

message: The sentence in the second paragraph, "Each contributing structure can be represented by a Lewis structure, with normal single, double or triple covalent bonds between every pair of adjacent atoms within the structure." is wrong. I see it is supported by the reference to the Gold Book, but it is contradicted by a classic example of resonance for the bridge region of diborane, where the resonance structures have alternating "single" and "no bond" bonds giving each bond in the resonance hybrid to be a half bond. Can anyone suggest a better wording? Note also that diborane also contradicts the statements that imply that resonance is only about pi bonds. --Bduke  (Discussion) 22:24, 5 September 2010 (UTC)
replies: text: First I am defining this comment as a new section, since it does not depend on the previous discussion. My suggestion would be to replace "single, double or triple" with "integer number", which can include not only zero as in diborane, but also in principle quadruple bonds and higher. Also I would eliminate the word "adjacent" which does not appear in the IUPAC source document and is not really well defined here - how does one decide which pairs of atoms are "adjacent"? So "Each contributing structure can be represented by a Lewis structure, with only an integer number of bonds between each pair of atoms within the structure." For distant atoms the integer will of course be zero, unless one includes minor structures such as Dewar benzene. Dirac66 (talk) 00:45, 6 September 2010 (UTC)
replies: text: Exceptions are already mentioned in the last section, but a separate section about sigma bonds involved in resonance is still missing. About the word "adjacent": every bond is connecting adjacent atoms.--Wickey-nl (talk) 16:03, 7 September 2010 (UTC)
replies: text: Several points. There is no need for separate sections on sigma and pi bonds. Resonance can occur in either. "every bond is connecting adjacent atoms" is not true. The 1-4 bond in Dewar structures of benzene can hardly be called connecting adjacent atoms. Another example is the 1-3 long bond in the singlet diradical structure of ozone where there is a massive literature saying that it is important. I agree with Dirac66 that "integer number" should be used and "adjacent" should be removed. --Bduke  (Discussion) 23:48, 7 September 2010 (UTC)
replies: text: OK, done. Dirac66 (talk) 00:57, 8 September 2010 (UTC)
thread_title: Only single, double and triple bonds?

message: The following link (Resonance Theory) clarifies the topic and enhances the material covered.  Material covered in this website is available to anyone and was written by a tenured PhD Organic Chemistry Professor at Utah Valley University.  The website is a non-profit website and is intended to advance students understanding of Organic Chemistry.  
Thanks for your time,
Nickcc20 (talk) 14:45, 19 January 2011 (UTC)
thread_title:  Adding an external link 

message: Pauling's principle of electroneutrality  is  still taught as being the method  by which favourable and unfavourable resonanace structures are "selected". A simple statement is that the charge on an atom should be between +/- 1 (formal charge)with the corollary  that the negative charges should reside on the most electronegative atom and positive on more electropositive. Is this worth a mention? Axiosaurus (talk) 13:04, 17 March 2013 (UTC)
replies: text: Yes, I think this principle is important as it is still used to eliminate some structures which students may draw. It chould be included in the section on Major and minor contibutors. Dirac66 (talk) 18:31, 17 March 2013 (UTC)
thread_title:  Pauling's principle of electroneutrality 

message: I have reread this article and see that it is very molecular in its scope-  why? Ionic structures with "covalent character", metals, intermetallics and other unusual solid state substances were all tackled by Pauling, was he wrong?   Axiosaurus (talk) 16:52, 17 March 2013 (UTC)
replies: text: Here I think resonance is very rarely used to describe solid-state bonding. Probably because a good resonance description of a nonmolecular solid would require a large number of resonance structures. So perhaps Pauling was wrong about the importance and usefulness of this approach, and I would not include it in the article. Dirac66 (talk) 18:31, 17 March 2013 (UTC)
thread_title:  Resonance can apply to ionic compounds, metals etc .- well at least Pauling thought so 

message: The statement regarding ionic contributions reads as if it applies to both to homonuclear and heteronuclear bonds. I am not familiar with the referenced book- however other books by Shaik discuss in detail the Heitler-London treatment of H2, is this where this quote comes from? . Historically ionic contributions in A-B bonds were the basis of the electronegativity concept.Axiosaurus (talk) 06:24, 12 April 2015 (UTC)
replies: text: Historically you also have the Weinberg treatment of H2, which combines ionic structures with covalent structures, so ionic contributions do apply to both homonuclear and heteronuclear bonds. --Bduke  (Discussion) 08:08, 12 April 2015 (UTC)
replies: text:  I added the statement to mention excited states of a molecule partly to add meaning to resonance as most people are only familiar with the "mental exercise" to quote one website on the net, and also to draw a comparison to LCAO as that has negative combinations (anti-bonding orbitals). Reading the book again only some excited states require the inclusion of ionic structures. I think I'll remove that reference to ionic structures.--Officer781 (talk) 08:28, 12 April 2015 (UTC)
thread_title:  Recent edits - Misisconceptions heuristic paragraph 

message: Charge shift bonding is not the the same as ionic-covalent resonance. The claim is that some molecules are stable only because of ionic-covalent resonance. In F2 for example the calculations using just covalent terms do not show bonding. Ionic terms on their own are not that good. The claim is that it is resonance between them that is responsible for bonding. I want to stress that charge shift bonding is controversial. For example a generalised valence bond (GVB) function function gives a reasonable description of bonding for F2. Some workers argue that this GVB is just a description of covalent bonding. There is no ionic-covalent resonance. Others argue that it disguises the ionic terms and thus the ionic-covalent resonance. There are wide differences of opinion between researchers on valence bond theory. Take care. --Bduke  (Discussion) 11:45, 26 April 2015 (UTC)
thread_title:  Charge shift bonding 

message: I am wondering about the exact meaning and validity of the energy diagram added today for benzene in the section Resonance in quantum mechanics. The file description (obtained by clicking on the image) says it is based on the MO diagram for H2, which is of course well known. However that diagram and all the other diatomic MO diagrams are for individual orbitals (one-electron wave functions). This diagram for benzene appears to show the combination of two many-electron (at least six pi-electron) wave functions, one for each Kekulé structure. Is there a source for combining 2 Kekulé structures in an energy-level diagram, as opposed to the elementary diagram which joins the 2 structures with a simple ↔ ? The lower energy level is acceptable, as it is true that the wave function may be written as a (normalized) sum of two functions representing Kekulé structures. But the upper level is quite mysterious - is it antibonding at all 6 C-C bonds? Or bonding and antibonding at alternate positions, so that there are 3 double pi bonds and 3 antibonds? or null bonds? In the absence of a source, a proper answer to this question would require detailed mathematical analysis of the proposed wave function, which of course would be original research. In any case, I think the upper state would be at very high energy and inaccessible by one- or even two-electron transitions, so it is of no experimental interest. 
In summary, I have never seen such a diagram for benzene and I think it requires a better explanation with a source. If this is not available, then I recommend the diagram be deleted. Dirac66 (talk) 15:45, 3 May 2015 (UTC)
replies: text: In fact, the source states that it is the first excited state of benzene. After checking the net it is a single-electron transition to one of the two LUMOs.  the book uses molecular orbital-like diagrams for resonance mixing. See also page 201 which discusses the A1g and B2u state from the Kekule structures.--Officer781 (talk) 02:41, 4 May 2015 (UTC)
replies: text: OK, thanks for the sources. In the article it might be better to add the page(s) where these points are discussed. Dirac66 (talk) 20:36, 4 May 2015 (UTC)
thread_title:  Dubious energy diagram for benzene 

message: I think using NO2 as the example is problematic for several reasons.  Like nitric oxide or triplet O2, nitrogen dioxide has a 2c3e bond due to its unpaired electron.  However, Lewis structures are unable to correctly show the extra half bond, and averaging the structures gives an incorrectly low estimate of the bond order.  Also, there are at least two other important Lewis structures that one can draw.  Though charge separation is less favorable, they cannot be neglected when determining the bond order or structure.  The bond angle is 134 degrees, which reflects the formation of the extra half-pi-bond, and the hybridization is somewhere between sp2 and sp, while the bond lengths are also shorter than expected.  There is no simple way of estimating the bond order in this case (which is somewhere between 1.5 and 2).  For these reasons, NO2 is really a pathological example that shows the limits of the Lewis representation. On the other hand, NO2-, nitrite is much more straightforward, and I tentatively chose this example to illustrate the concept.  Unfortunately, it's hard to find a neutral example of resonance that is simple enough to give. Alsosaid1987 (talk) 03:17, 12 May 2018 (UTC)
thread_title:  Example in lead 

message: It has come to my attention that this article seems to be struggling a lot to explain that resonance structures do not exist but the resonance hybrid does (the very long introduction and repeated assertions in the article is testament to this). It has also occurred to me that nowhere in this article, except the valence bond (ie quantum mechanics) part explains what resonance truly is. Could I suggest an overhaul of this article in that we introduce in the outset that resonance is basically the equivalent of linear combination of atomic orbitals in Valence Bond theory, where the actual molecular wavefunction is a weighted sum of individual resonance structures just like molecular orbitals are a weighted sum of individual atomic orbitals (the analogy goes quite far in fact. We can even take antisymmetric, ie. antibonding, combinations of resonance structures to attain excited states etc).
I'm putting the above as an idea, not sure how to better write this article to be both concise and succinct. From reading this talk page it appears the writing of this article being problematic goes back some time. Opinions?--Officer781 (talk) 14:19, 19 January 2019 (UTC)
replies: text: In principle, I agree.  Essentially, resonance is taking linear combos of canonical structures, rather than taking linear combos of AO's in MO theory.  But this may be tricky.  I think this should be done if a relatively simple concrete example can be given. Ideally, this example should make clear that the true wavefunction \Psi is equal to \sum c_i\Psi_i, in which each \Psi_i corresponds to a canonical form.  There needs to be some explanation of how that correspondence is made, as well as rules or at least some intuition for how to handle the contributors.  (To give a completely rigorous introduction, one might need to start with the Heitler-London model for the bonding of H2, and rules for dealing with spin will also be introduced, but that seems impractical for this article.)  The problem with VB theory is that, done correctly and rigorously, the rules are actually more complicated than the rules of MO theory.  That's why, from a pedagogical point of view, VB is taught to undergrads in terms of qualitative heuristics for Lewis structures (and resulting in some phenomena that aren't adequately explained, like triplet O2 or aromaticity), while MO theory is relatively easy to teach in a semi-quantitative manner as a "more correct" theory than VB.  Shaik and Hiberty wrote a very interesting review that both theories when fully implemented are correct and actually quite similar, but that they handle ionic contributions to bonding differently.  The theories converge to each other when all approximations are taken away. Alsosaid1987 (talk) 15:52, 19 January 2019 (UTC)

text: If it's not already clear, I'm an experimentalist by training (though with a decent undergrad to beginning grad level pure math background), and I don't consider my background in theory to be strong enough to write an intro that is simultaneously clear, concise, rigorous, and introductory.  Most of the intro is currently my writing, but I have no objections to others revamping it on a more rigorous theoretical basis. Alsosaid1987 (talk) 00:13, 20 January 2019 (UTC)
replies: text: I have long been puzzled and unhappy about this article. It seems to be very much like the Irishman who when asked how to get to Dublin, responded by "If I was going to Dublin, I would not start from here". It needs a complete rewrite. However let me deal with "resonance is basically the equivalent of linear combination of atomic orbitals in Valence Bond theory" in Officer781's introduction to this section. I know of no source that suggests this. It is correct that valence bond theory deals with a linear combination of n-electron functions each built with little or no variation from atomic orbitals, while molecular orbitals theory introduces the variation at the atomic orbital level, but I do not think we should start the article off with this point, or indeed even have it in the article. Even what I wrote, "with little or no variation from atomic orbitals", is not strictly correct. In traditional VB theory we just build the total function from atomic orbitals, but in the spin coupled form of modern VB theory, the VB orbitals are built from a linear combination of atomic orbitals, just like in MO theory. However they turn to to be rather localized in contrast to the molecular orbitals which are fully delocalised. We should avoid questions of whether resonance structures exist. They no more exist than molecular orbitals, or even atomic orbitals, exist. However I am perhaps, as an active researcher in VB theory, too close to it all to be helpful. Perhaps the article should start with saying that Resonance is a simple way of describing the bonding in molecules, that it is based on valence bond theory rather than the molecular orbital theory, and that it is just one way or describing and understand bonding in molecules. It could go on to describe the Heitler-London picture of H2 and that move to adding ionic structures and then describe the Kekule structures (2 structures) of benzene, move on to add the Dewar structures (leading to 5 structures) and then mention that if we add ionic structures we add another 170 structures. I might have a go at an introduction later. --Bduke (talk) 00:55, 20 January 2019 (UTC)
replies: text: You should give this a try.  Expertise and accuracy is important on a commonly referenced article like this one.  Wikipedia should be authoritative and not just repeat what textbooks say.  Most people (myself included) reason using resonance structures, but only have a fuzzy understanding of what is going on physically behind the formalism. (Hiding behind the formalism and jargon just exposes ignorance and lack of understanding, to paraphrase Feynman....)  I look forward to a clear, physically intuitive introduction! Alsosaid1987 (talk) 01:58, 20 January 2019 (UTC)
replies: text: I'm going to try to shorten this article by first merging sections into a unified "overview" section instead (Alsosaid1987's overview is actually quite good in my opinion). I would probably need your help (Bduke, Alsosaid1987, etc) in the revamp. Do please edit if you have any ideas for revamping the article.--Officer781 (talk) 02:56, 20 January 2019 (UTC)
thread_title:  Unwieldy struggle in explanation 

message: What is difference between resonance and hyperconjugation? Umer ilyas shaaheen (talk) 15:55, 26 January 2020 (UTC)
replies: text: In organic chemistry, resonance involves mixing (conjugation) of structures which differ in the placement of pi-bonds. Hyperconjugation also involves structures with different sigma bonds or lone pairs. See the article on hyperconjugation. Dirac66 (talk) 22:13, 5 February 2020 (UTC)
thread_title:  Hyperconjugation