View source for Wikipedia:Reference desk/Archives/Science/2018 July 16

<noinclude><!-- From archive header-->
{{#ifeq:{{PAGENAME}}|Special:Undelete| |{{#if:|<div style="display:none;">}} {{#ifeq:{{NAMESPACE}}|Wikipedia|{{#switch:{{NAMESPACE}}|= |<div style="display:none;">}}|{{error:not substituted|Archive header}}<div style="display:none;">}}}} {{#if:|</div></div>}}{| width = "100%"
|-
! colspan="3" align="center" | [[Wikipedia:Reference desk/Science|Science desk]]
|-
! width="20%" align="left"  | &lt; [[Wikipedia:Reference desk/Archives/Science/2018 July 15|July 15]]
! width="25%" align="center"|&lt;&lt; [[Wikipedia:Reference desk/Archives/Science/June 2018|Jun]] | [[Wikipedia:Reference desk/Archives/Science/July 2018|July]] | [[Wikipedia:Reference desk/Archives/Science/August 2018|Aug]] &gt;&gt;
! width="20%" align="right" |{{#ifexist:Wikipedia:Reference desk/Archives/Science/2018 July 17|[[Wikipedia:Reference desk/Archives/Science/2018 July 17|July 17]]|[[Wikipedia:Reference desk/Science|Current desk]]}} &gt;
|}
{| align=center width=95% style="background: #FFFFFF; border: 1px solid #003EBA;" cellpadding="8" cellspacing="0"
|-
! style="background: #5D7CBA; text-align: center; font-family:Arial; color:#FFFFFF;" | '''Welcome to the Wikipedia Science Reference Desk Archives'''
|-
| The page you are currently viewing is {{#ifexist:Wikipedia:Reference desk/Archives/Science/2018 July 26|an archive page|a [[Wikipedia:Transclusion|transcluded]] archive page}}. While you can leave answers for any questions shown below, please ask new questions on one of the [[Wikipedia:Reference desk|current reference desk]] pages.
|}


__TOC__
</noinclude>
= July 16 =

== Fed wasabi peanuts to seagull ==

Yesterday, I threw a few of my wasabi coated peanuts to a seagull.

I was under the impression that birds couldn't taste spicy food, but obviously I was wrong in this case. The poor thing started shaking its head, running back and forth, scratching at its mouth and then vomited. Seems that wasabi does the same to gulls as it does to people who don't like it.

(didn't do it on purpose just to mess with it, I swear - it seemed okay afterwards and was eating the pieces of sandwich I threw out)

I've seen birds eating habaneros with no issues. I don't think it even affects them in the same way it does people. What's different about wasabi?  <!-- Template:Unsigned IP --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/91.207.175.200|91.207.175.200]] ([[User talk:91.207.175.200#top|talk]]) 08:28, 16 July 2018 (UTC)</small> <!--Autosigned by SineBot-->
:Have you never notices that the hit from [[chillis]] is completely different from that of wasabi (as for that matter, black pepper, Sichuan pepper and galic)? The 'heat' from chillis comes from [[Capsaicin]]. As mention in that article, it causes a burning sensation when it comes into contact with mucous membranes in mammals. The hit in [[wasabi]], whether real wasabi or most of the stuff you get in the West (and I think even a lot in Japan), green coloured [[horseradish]], comes primarily from [[Allyl isothiocyanate]]. (Also mustard and radish.) As mentioned in the wasabi article but not in the other articles, it primarily comes in the nasal passage in humans. And it isn't hydrophobic like capsaicin so is more easily removed with water where oils (including an emulsion like milk) is the best solution. While our article doesn't specifically mention the effect in birds, it does mention animals not mammals. And the places where it is present in plants as a defense mechanism against herbivores suggests the plant wouldn't want any animal who consumes it unaffected. (Although as our article on capsaicin sort of indicates, while it's advantageous to the plant that birds are unaffected by capsaicin, we can't be sure how much of a factor this was in its evolution.)  [[User:Nil Einne|Nil Einne]] ([[User talk:Nil Einne|talk]]) 09:10, 16 July 2018 (UTC)

::It may depend on the bird.  Anecdotally, some parrots appear to enjoy eating wasabi (or at least things marketed as "wasabi").  Google for parrots and wasabi, and you can find examples of people giving them as treats to birds that apparently like them.  I don't know if they are sensitive to the wasabi but eat it anyway, just like some people like spicy things, or if they just aren't sensitive to it.  To give another anecdote from a different species, we were trying to train a young puppy to stop chewing on furniture, so we got a spray that is intended to taste/smell awful and deter them.  We quickly found this particular spray was worthless because she would follow us around and lick it off anything we sprayed.  I assume she was tasting something, but she clearly didn't perceive it as undesirable.  [[User:Dragons flight|Dragons flight]] ([[User talk:Dragons flight|talk]]) 09:26, 16 July 2018 (UTC)

:::Some more research found [//academic.oup.com/mbe/article/31/3/708/1011696] who found cloned chicken [[TRPA1]] was activated by allyl isothiocyanate. Then again they also found it was activated by capsaicin. (There's some more research into how capsaicin affects chicken TRPA1 later which I didn't read in detail.) This is also looks interesting: I haven't looked at the paper [//www.jstage.jst.go.jp/article/biomedres/38/3/38_149/_article], but the abstract suggests they found that one of the mechanism allyl isothiocyanate affects mammalian or at least mouse TRPV1 appears to be by binding to the capsaicin binding site and so this doesn't occur in chicken TRPV1. That said, this is fairly remote from the question. Maybe because my searches are too technical, I haven't found any source which actually mentions whether birds are known to show any response to allyl isothiocyanate. It's easily possible of course that the effect observed by the IP was not due to allyl isothiocyanate but due to something else. I'd also note it may depend on quantity, some of the sources I read make me wonder whether birds are really completely immune to capsaicin as commonly suggested or the effect is just a lot milder so you'd need a very strong dose for them to notice anything. [[User:Nil Einne|Nil Einne]] ([[User talk:Nil Einne|talk]]) 10:33, 16 July 2018 (UTC)
:::BTW on the evolutionary point I made above, I probably should also mention while there may be real evolutionary advantage for birds to be unaffected, there may also be little advantage for birds to be affected since I'm not sure if many are likely to eat the parts. [[User:Nil Einne|Nil Einne]] ([[User talk:Nil Einne|talk]]) 10:41, 16 July 2018 (UTC)
::::I suspect that the "parts" is really the key to understanding this. In chili peppers, the capsaicin concentrates in the fruit. This makes some evolutionary sense: mammals chew their food, especially plant-eaters, so seeds could well be crushed or damaged by them. It pays off for the plant to have mammals avoid them. On the other hand, birds tend to swallow stuff whole. So, peppers eaten by birds would be transported and deposited whole in the feces - exactly what the plant "wants". Quite an elegant solution. Wasabi, horse-radish, and radish are set up differently. In those cases, it is the stem/root with the concentrated toxins. Since it's almost never in the plant's favour to have this portion eaten or damaged, it makes sense that a more widely applicable material would be used. [[User:Matt Deres|Matt Deres]] ([[User talk:Matt Deres|talk]]) 16:29, 17 July 2018 (UTC)
::::: <small>The bird eats a whole chili pepper in one bite?  Remind me not to cross that bird. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 20:02, 18 July 2018 (UTC)</small>

== Molecular term symbols and electronic configurations ==

I think that I've made some progress in learning to interpret molecular term symbols, given available molecular orbitals. Taking dicarbon, and it's first eight electronic states, I've determined the electronic configurations to be as follows:
*''X'': [He{{Su|p=|b=2}}] 2σ{{Su|p=2|b=''g''}}2σ{{Su|p=2|b=''u''}}1π{{Su|p=4|b=''u''}}
*''a/A'': [He{{Su|p=|b=2}}] 2σ{{Su|p=2|b=''g''}}2σ{{Su|p=2|b=''u''}}1π{{Su|p=3|b=''u''}}3σ{{Su|p=1|b=''g''}}
*''b/B'': [He{{Su|p=|b=2}}] 2σ{{Su|p=2|b=''g''}}2σ{{Su|p=2|b=''u''}}1π{{Su|p=2|b=''u''}}3σ{{Su|p=2|b=''g''}}
*''c'': [He{{Su|p=|b=2}}] 2σ{{Su|p=2|b=''g''}}2σ{{Su|p=1|b=''u''}}1π{{Su|p=4|b=''u''}}3σ{{Su|p=1|b=''g''}}
*''d/C'': [He{{Su|p=|b=2}}] 2σ{{Su|p=2|b=''g''}}2σ{{Su|p=1|b=''u''}}1π{{Su|p=3|b=''u''}}3σ{{Su|p=2|b=''g''}}
I'm fairly sure that I've correctly determined the first five configurations, but I'm uncertain about the last two. Should I opt for a configuration where the 2σ{{Su|p=|b=''u''}} is fully occupied and the 1π{{Su|p=|b=''g''}} is not left empty? It just seems odd to me to have the lower orbitals partially occupied while the HOMOs are full. However, the configuration that matches my suggestion requires additional unpaired electrons that looks like it would be unfavourable, for it to retain the same term symbol.
*''d/C'': [He{{Su|p=|b=2}}] 2σ{{Su|p=2|b=''g''}}2σ{{Su|p=2|b=''u''}}1π{{Su|p=2|b=''u''}}3σ{{Su|p=1|b=''g''}}1π{{Su|p=1|b=''g''}}
For reference, the term symbols can be found at https://webbook.nist.gov/cgi/cbook.cgi?ID=C12070154&Units=SI&Mask=1000#Diatomic. Also, are my first five determinations actually correct? [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 12:37, 16 July 2018 (UTC)

:I have no idea, but let's put some links on the table for context:  [[term symbol]], [[dicarbon]], [[Swan band]], [[Molecular_term_symbol#Alternative_empirical_notation]].  [http://rspa.royalsocietypublishing.org/content/royprsa/137/833/575.full.pdf This old paper] gives a subjective sense of the energies involved (page 10) - the difference between their two bonding states is enough to leave the lower state's bond vibrating from 1.1 to 1.7 Angstroms in length! ... [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 18:26, 16 July 2018 (UTC)

::That should really be renamed <nowiki>'Supplementary empirical notation'</nowiki>, as it is used in conjunction with term symbols, not in place of. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 22:36, 16 July 2018 (UTC)

:Note that a and A are not the same. the lower case sequence is in the triplet state, with two electron spins the same, whereas the capital sequence have the singlet state, spins opposite. [[User:Graeme Bartlett|Graeme Bartlett]] ([[User talk:Graeme Bartlett|talk]]) 03:48, 17 July 2018 (UTC)

::I know. It's just that they are both representable by the same electronic configuration short-hand where spin is not accounted for. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 06:15, 17 July 2018 (UTC)

:::I have a stupid question ... but I can't help it.  I thought the first superscripted number was the [[spin multiplicity]], which I thought was the singlet/triplet thing.  So why does the NIST table have an entry for d <sup>1</sup>Σ<sub>u</sub><sup>+</sup> when all the other lowercase entries have a 3 at the beginning, which I take to mean that they are triplets unlike the X <sup>1</sup>Σ<sub>g</sub><sup>+</sup> ground state? [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 20:19, 17 July 2018 (UTC)

::::I'm reasonably sure that it's a typographical mistake for exactly that reason, and because there is already a d state listed with lower energy. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 04:21, 18 July 2018 (UTC)

:::::Well, that helps ''me'', at least. ;)  And that means the D <--> X in a column to the right is consistent with all the others, in defining a transition from this state to another (in this case ground).  I should also note the B state you mention seems to be missing, though I'd think there ''has'' to be one, since it's empirical!
:::::Again, just to put down some links and get this straight in my mind (it won't be new to the original poster) the u and g are nicely illustrated at [http://internal.eps.hw.ac.uk/subjects/chemistry/teaching/14_2QI2/notes/intro.html], which makes it apparent for example that p<sub>u</sub> is bonding and p<sub>g</sub> is antibonding, unlike with s and d.  <small><s>(I could still use a better notion of what "inversion" means; flipping the picture upside down would work the other way if the p orbitals were rotated 90 degrees; maybe these are viewed from within a nodal plane)</s> [after I RTFA: inversion is through a point, i.e. x,y,z to -x,-y,-z. ''g''erade (even) = no change in sign].</small>  s, p, d, f come from the atomic orbitals joined, and thus indicate the number of lobes (or homogenous for s=0) around the interatomic axis.  The numbers before s/p/d are [[principal quantum number]] and indicate total energy for the MO and hence I would presume the number of concentric shells going in and out toward the axis, less angular momentum.  (that's ''not'' shown in the link above; I ''assume'' their example atomic orbitals are 1s, 2p, 3d to avoid that kind of node)  When combined to molecular orbitals, these appear to get levels that start at 1 (1 shell, no concentric nodes), so the 1π in [https://about.illinoisstate.edu/standard/Documents/CHE%20362/Course%20Handouts/362diatomicMOs.pdf] is produced from two 2p orbitals, as is the 3σ.  The same two molecular orbitals appear at [https://www.youtube.com/watch?v=BwJGfDNKfI4] labelled as π<sub>2p</sub> and σ<sub>2p</sub>, with numbers based on what they were formed from.  In either case the sigma is lower energy than the pi in oxygen and up, due to attraction to more protons; it is a sigma because the p orbitals point at each other and thus remain symmetrical around the axis.  Anyway, we can use the diagram from the illinoisstate reference above to visualize where we are putting these electrons (not quite per the [[Aufbau principle]]).  The NIST gives thermal energy for each energy level, albeit in cm<sup>-1</sup>, which might need to be multiplied by hc (in some convenient unit) per E = hc/&lambda; for conversions, but so far I haven't managed to see how to confirm your chart by the energy levels, which will be influenced by pairing for example. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 19:57, 18 July 2018 (UTC)

::::::I'll put the configuration in chart form to show my dtermination. Maybe it would make more sense to you:
::::::[[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 20:44, 18 July 2018 (UTC)
{| class="wikitable" style="text-align:center"
|-
!  !! ''X''&nbsp;<sup>1</sup>&Sigma;{{Su|b=''g''|p=+}}<br />r < 3.2 !! ''a''&nbsp;<sup>3</sup>&Pi;<sub>''u''</sub> !! ''A''&nbsp;<sup>1</sup>&Pi;<sub>''u''</sub>!! ''b''&nbsp;<sup>3</sup>&Sigma;{{Su|b=''g''|p=−}} !! ''B''&nbsp;<sup>1</sup>&Sigma;{{Su|b=''g''|p=+}} !! ''c''&nbsp;<sup>3</sup>&Sigma;{{Su|b=''u''|p=+}} !! ''d''&nbsp;<sup>3</sup>&Pi;<sub>''g''</sub> !! ''C''&nbsp;<sup>1</sup>&Pi;<sub>''g''</sub> !! <s>''d''</s>&nbsp;<sup>3</sup>&Pi;<sub>''g''</sub> !! <s>''C''</s>&nbsp;<sup>1</sup>&Pi;<sub>''g''</sub> !! … !! ''E''&nbsp;<sup>1</sup>&Sigma;{{Su|b=''g''|p=+}}<br />r << 3.2 !! … !! ''G''?&nbsp;<sup>1</sup>&Delta;<sub>''g''</sub><br />r > 3.2
|-
| &Delta;E (cm<sup>-1</sup>) || 0 || 716.2 || 8391.00 || 6434.2 || unlisted! || 13312 || 20022.50  || 34261.3 || 20022.50  || 34261.3 || … || 55043.7 || … || unlisted!
|-
|1π<sub>g</sub>* = π<sub>2p</sub>*
|
|
|
|
|
|
|
|
|(+ )&nbsp;(&nbsp;&nbsp;)
|( -)&nbsp;(&nbsp;&nbsp;)
|
|
|
|
|-
|3σ<sub>g</sub> = σ<sub>2p</sub>
|
|(+ )
|( -)
|(+-)
|(+-)
|(+ )
|(+-)
|(+-)
|(+ )
|(+ )
|
|(+-)
|
|(+-)
|-
|1π<sub>u</sub> = π<sub>2p</sub>
|(+-)&nbsp;(+-)
|(+-)&nbsp;(+ )
|(+-)&nbsp;(+ )
|(+ )&nbsp;(+ )
|(+ )&nbsp;( -)
|(+-)&nbsp;(+-)
|(+-)&nbsp;(+ )
|(+-)&nbsp;( -)
|(+ )&nbsp;( -)
|(+ )&nbsp;( -)
|
|(+-)&nbsp;(+-)
|
|(+-)&nbsp;(&nbsp;&nbsp;)
|-
| 2σ<sub>u</sub>* = σ<sub>2s</sub>*
| (+-)
| (+-)
| (+-)
| (+-)
| (+-)
| (+ )
| (+ )
| (+ )
| (+-)
| (+-)
|
|
|
| (+-)
|-
| 2σ<sub>g</sub> = σ<sub>2s</sub>
|(+-)
|(+-)
|(+-)
|(+-)
|(+-)
|(+-)
|(+-)
|(+-)
|(+-)
|(+-)
|
|(+-)
|
|(+-)
|}

::::::: I stole your table above and messed with it a little so I can add to it more easily -- hope that's OK, you can revert if I screwed it up. ;)  (I'm afraid if we start multiple copies they will get the Hook.) [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 22:30, 18 July 2018 (UTC)
::::::::I don't mind. Actually, I think it better this way, I just made an adjustment to the labelling of the highest MO, and moved the anti-bonding asterisks to the labels. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 22:34, 18 July 2018 (UTC)
:::::::::Yeah, my foulup ... you ec'd me before I could fix. ;)  I've added some energies though <s>the labels above them are confusing me a bit.</s> oh, never mind, there were two options for C and d from the beginning. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 23:27, 18 July 2018 (UTC)

:Ow.  There are a bazillion sites with those MO diagrams showing "energy" as an axis ... trying to find one that puts ''numbers'' on that ruler is a whole other thing.  But in searching I stumbled across [http://www2.chem.umd.edu/groups/alexander/chem691/Chap3.pdf] which gives the wavefunction of the <sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup> state of C<sub>2</sub> as ... well, I don't know the math markup well enough to write it, check page 30.  There are ''four terms'' with expansion coefficients depending on the radius... somehow this has to do with why a singlet state is most stable, see their explanation.  I think I am in my familiar haunts, "not even wrong" territory, all over again. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 23:39, 18 July 2018 (UTC)

::OK, so now that it's neatly diplayed, what do your recon - which configuration for d and C should be more stable from a theoretical point of view? I'm not asking about c right now because I can't come up with a more reasonable alternative. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 03:26, 19 July 2018 (UTC)

::: Well, putting the labels on top, the issue I think you mentioned initially is that the first two don't seem right in terms of spin.  AFAIK if two electrons have opposite spins, then any angle you measure them from they should cancel out; but if they have the same spin, you can look from the "equator" and get zero, or look from the "pole" and see two half-spins adding up to 1.  (to the degree that this mystical landscape exists)  Your second choice is consistent with that, as are all the others.  However, these may be just one possible term contributing to these energy levels...  that last source I gave certainly should make good reading.  I should note that it actually plots very different energies for a "1<sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup>" and a "2<sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup>" on page 29 ("complete-active-space (CAS) SCF calculations", for reference) ... is the latter from 3s orbitals?  I don't recall this nomenclature.  Their Figure 17 on Page 31 shows the <sup>1</sup>&Pi;<sub>u</sub> and <sup>3</sup>&Sigma;<sub>g</sub> at equal stability (that's "orbital energy in [[hartree]]s", likely a useful search term) at a radius of 2.2 Bohr - sigma is more stable further out and pi closer, as you'd expect since a straight-on overlap of orbitals should reach further.  Tug the molecule to 2.5 bohr and a <sup>3</sup>&Pi;<sub>u</sub> is the lowest energy state; take it to 3.5 and b <sup>3</sup>&Sigma;<sub>g</sub><sup>-</sup> becomes the lowest.  (Incidentally, I don't know the basic issue if you can spin a molecule in vacuum like a planet and rely on conservation of angular momentum to make these actually ''be'' ground states by "centrifugal force", or if molecules necessarily are able to drop the angular momentum together with energy of rotation photon by photon until they are at rest) [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 12:01, 19 July 2018 (UTC)

::::I just fixed it up a bit. I could have sworn that I had the spins for the first d/C set around the right way. I also filled in the B term symbol. I'm reasonably certain that each state has only one term symbol, since a state is defined precisely by the electron configuration. Your reasoning sounds solid and all, but how does it apply to which ''d''&nbsp;<sup>3</sup>&Pi;<sub>''g''</sub> and ''C''&nbsp;<sup>1</sup>&Pi;<sub>''g''</sub> configuration (state) is most stable? [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 13:06, 19 July 2018 (UTC)

::::: There's a tutorial [https://www.youtube.com/watch?v=ww6HEEXwrbk here]; the TMP Chem channel there seems like it may contain more useful content, though I have yet to find an index.  It doesn't cover C2, but illustrates that even a single partially filled molecular orbital can end up leading to all manner of term symbols! [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 21:57, 19 July 2018 (UTC)

::::::I see what you intend, but that not what I'm trying to figure out. In the example for B<sub>2</sub> in the tutorial, it is demonstrated that there are multiple ways of partially occupying degenerate pi orbitals, corresponding to unique states shown by their term symbols. However, I'm trying to work backwards - I already have the term symbol, and I want to figure out the most likely configuration of the electrons that would genenerate said symbol. I'm essentially trying to solve problem seven of the text book chapter that you linked to earlier. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 06:56, 20 July 2018 (UTC)

Assuming I have the configurations for state A and c correct, then they have bond orders of one and two halves, and two and two halves, respectively. Observing that the increase in interatomic distance (r) between c and d is relatively small when compared to A and c, I would surmise that the difference in bond order is less than one. The bond order for my first proposed configuration for state d is also two and two halves, whereas the bond order for my second proposal is zero and two halves. Ergo, this would stand to reason that my first proposal is more likely. By the same reasoning, my first proposal for C is also more likely. Do you agree? [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 05:52, 21 July 2018 (UTC)

:The problem is still that AFAICT there are multiple combinations of MOs for each term symbol.  The term symbol only defines four or five things:  a) how many unpaired electrons spin the same way, b) the angular momentum around the axis (sigma, pi, etc.), c) the symmetry of inversion through a point, d) the "reflection through a plane", and e) some total quantum number (the different curves for 1<sup>1</sup>&Sigma; and 2<sup>1</sup>&Sigma; on that graph I mentioned above, which most other sources don't talk about.  It appears the reflection symmetry (d) basically depends on how many pi orbitals are involved - with two, one is reflected through a plane and one is not, so it becomes antisymmetrical.  This is explained on page 8 of [http://www2.chem.umd.edu/groups/alexander/teaching/C2_orbitals.pdf] which is all about C2 and specifically gets into the + and - issue.  But it is confusing, because all the orbitals of all the electrons are multiplied together.  I get that the product doesn't end up with every nodal plane of everything multiplied into it because there aren't really nodal planes - a true p orbital goes around +1, +i, -1, -i and the "nodes" are constructed for illustrations only when a standing wave is considered where the angular momentum is either way.  I *think* this means that only two half-filled pi orbitals can make a sigma minus, not two full pi orbitals (because that's -1 x -1!)???  Anyway, that source talks about various contributions to excited states but I haven't worked through all of it, nor done it from scratch as I was sort of setting up to above. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 12:18, 21 July 2018 (UTC)

::I'm not sure I understand what is going on here. Are you trying to figure out how MTSs work for yourself before trying to answer my original question? I ask because, just understanding how they work does not mean you'll be be able to answer my original question. You'll need to have knowledge regarding relative orbital mechanics, which can't be obtained from pure geometric theory. Otherwise you'll simply run into the same roadblock as I - I don't have the intiuition neccesary to determine which of two options is more likely given their geometric properties. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 14:11, 21 July 2018 (UTC)
::: Reading that source again, I may have been a bit confused.  It does look like they say the <sup>3</sup>&Sigma;<sub>g</sub><sup>-</sup> state is what you have for b (apart from putting 3 electrons in one of the sigma orbitals; I think none of us are perfect).  They also describe a state like what you have for B, but call it <sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup> not -; they have an argument about that involving the determinant which I really ought to figure out...  And they describe a <sup>1</sup>&Delta;<sub>g</sub> state where both pi electrons are in one orbital and nothing in the other; that's not on your list.  Now as for d/C, well, on page 10 it seems to be saying that a 3&sigma;<sub>g</sub><sup>1</sup>1&pi;<sub>u</sub><sup>3</sup> state can give rise to both <sup>3</sup>&Pi;<sub>u</sub> and <sup>1</sup>&Pi;<sub>u</sub> terms.  I would assume this depends on whether the unpaired electrons in the table have the same sign.  Looking back, these seem to match your two entries on the left, rather than the two on the right.  (And seriously -- four unpaired electrons, including one in a high antibonding orbital?  I'd expect that would be more like an "M" or something than a "C" ;)  That said, I still don't know if that orbital contributes at least nominally -- it ought to have the same angular momenta and the same spin, since it's just pi* instead of pi, although the "g"/"u" is another question.  [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 17:31, 21 July 2018 (UTC)
::::Did you say I or they put three electrons in a sigma orbital for state b, because I put three into the pi not the sigma. I concede on the error in state B, I forgot about the spin pairing of two pi electrons. As for the delta state, I also found one, but I dismissed it as it did not appear on the NIST list and every state up to g and F has been accounted for. I suppose it does exist, but only at energies higher than for all those states. Four unpaired electrons doesn't seem so outlandish when you consider the possibility that the sigma and pi* molecular orbitals may be very close to one another, energetically speaking. As for he g/u issue, I do believe that pi* is a g MO, which is why having one unpaired electron does not make the molecule u, sine there are still an even number of electrons in the two pi orbitals. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 22:29, 21 July 2018 (UTC)
:::::For the three electrons: it was them, not you!  But the term symbols at the top row of the chart seem to be getting further off the mark... check your references again. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 03:03, 22 July 2018 (UTC)
::::::I corrected the term symbol for state B and struck out the alternatives for states d and C. Other than that, they should be right on the mark. Just be carefull when refering to textbooks - they notorious for being full of errors. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 09:21, 22 July 2018 (UTC)
::::::: These things ''are'' a pain, aren't they?  <s>The symbol for B now matches the electronic configuration you have (given the thing about the determinant as cited above)</s> no, I'm not sure about that either, I may have fouled this up...  The problem now is ... that's the same as X.  Which brings us back to the four different terms for X, which include a 25% contribution from something with a bond order of 4.  I ought to add that one in a new column.  Meanwhile, what ''is'' B?  It's not in the NIST table; nothing I looked at went over it.  Honestly, I don't know where this letter comes from except it's between A and C. ;) [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 12:39, 22 July 2018 (UTC)

::::::::That is not really a problem, it's just how term symbols work - distinct states can share the same term symbol. So to correct, state B is like state X, in so far as their angular momenta and group representations are concerned; but are certainly not degenerate or equivalently configured. The likely reason that it's not on the NIST table is because it is difficult to probe, spectroscopically speaking, hence there is not yet experimental data for it. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 13:12, 22 July 2018 (UTC)

{{od}}
:{{re|Plasmic Physics}} I think you're definitely wrong about giving those other X configurations I added their own letters.  I apologize -- the PDF format was set up by a bunch of copyright fundamentalists who have a "free reader" that pastes everything character by character with linebreaks without formatting and anything else they can do to fuck it up, so I said I couldn't paste it above.  But to remake the whole damn thing in Wiki format, 

:"We can write the wavefunction of the <sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup> state of C<sub>2</sub> as 
:{{ket|<sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup>}} = C<sub>1</sub>│...2&sigma;<sub>g</sub><sup>2</sup>2&sigma;<sub>u</sub><sup>2</sup>3&sigma;<sub>g</sub><sup>0</sup>1&pi;<sub>u</sub><sup>4</sup>│ + C<sub>2</sub>│...2&sigma;<sub>g</sub><sup>2</sup>2&sigma;<sub>u</sub><sup>0</sup>3&sigma;<sub>g</sub><sup>2</sup>1&pi;<sub>u</sub><sup>4</sup>│ + 2<sup>-1/2</sup> C<sub>3</sub>(│...2&sigma;<sub>g</sub><sup>2</sup>2&sigma;<sub>u</sub><sup>2</sup>3&sigma;<sub>g</sub><sup>2</sup>1&pi;<sub>ux</sub><sup>2</sup>│ + │...2&sigma;<sub>g</sub><sup>2</sup>2&sigma;<sub>u</sub><sup>2</sup>3&sigma;<sub>g</sub><sup>2</sup>1&pi;<sub>uy</sub><sup>2</sup>│)

:Now as you see from this, these states are hybridized together, I would assume much like sp<sup>2</sup> orbitals.  They explain that the "additional flexibility introduced by these two additional configurations helps to lower the energy" of the singlet ground state in this case.  You really should read over that whole reference; I haven't found better online about this system.  Someday, when the last pusher of the copyright intellect-as-property system has been fixed on the last impaling pike, physics will be easy for us to learn.  Alas, this is not that day. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 15:42, 22 July 2018 (UTC)
::I'm saying that you are misunderstanding their statement - there is no such thing as an all encompassing <sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup> state, but there are is an interaction between several states that yield a stabelising effect on the lowest <sup>1</sup>&Sigma;<sub>g</sub><sup>+</sup> state. [[User:Plasmic Physics|Plasmic Physics]] ([[User talk:Plasmic Physics|talk]]) 20:56, 22 July 2018 (UTC)
::: {{re|Plasmic Physics}} It's quite possible I'm confused, but so far I'm not seeing it.  The relevant term is [[multi-configurational self-consistent field]] theory (MCSCF), which turns out to lead a bunch of articles like [[configuration state function]] and [[Slater determinant]] and [[complete active space]] and [[complete active space perturbation theory]].  I won't say I ''understand'' those articles, but the first seems to agree with my interpretation of the section of the chapter about hydrogen, where even a H<sub>2</sub> molecule's ground state needs to be seen as a linear combination of bonding and antibonding states.  (The Wikipedia article seems to make a curious claim that this is because the 1&sigma;<sub>g</sub> electrons are somehow leashed together in the mathematics, so that they can't readily be one on one hydrogen and one on the other at large separation; I should try to understand this...)  All these MCSCF things use linear combinations of multiple MOs, while the [[Hartree-Fock]] method apparently doesn't - but as a result, is seriously inaccurate at predicting energies. [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 12:39, 23 July 2018 (UTC)

== Planting with a machine gun ==

I had a crazy image in mind of a Vietnam-era helicopter planting crops by machine gun and, to my surprise, actually found real web references:  [https://www.huffingtonpost.com/entry/biodegradable-bullets_us_58740b0de4b043ad97e54f4e seeds in bullets wanted] (from the final halcyon days of Obama), [http://hiconsumption.com/2013/12/flower-shell-shoots-flower-seeds-instead-bullets/ for home defense or something] (with a YouTube video that, like ''every'' video worth watching that used to be on YouTube, has been censored) even [https://rngr.net/publications/tpn/14-1/PDF.2004-08-12.3245/at_download/file tree planting] (though not actually fired at range.  But all these are written as if they're the only ones who ever thought of it - I don't know any general ''terms'' to use, or principles that apply.  I would suspect, for example, that [[plowing]] may be hard to do without, and seeds planted this way might never compete for enough nutrients to be agriculturally relevant; yet I've read at times claims that plowing is actually avoidable - I'm no farmer to know.  ''Is'' it possible to embed seeds in biodegradable bullets and plant a reasonably successful crop from the air? [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 17:46, 16 July 2018 (UTC)

:...perhaps your subconscious mind conjured this misinterpreted imagery after you heard an agronomist discussing [[Seed_dispersal#Ballistic_dispersal|ballistic dispersal]]?  [[User:Nimur|Nimur]] ([[User talk:Nimur|talk]]) 18:00, 16 July 2018 (UTC)
:: It's more likely I once glanced at the Obama-era headline; ballistic dispersal is about making seeds fly, not embedding them in the ground when they land.  <small>(That I know of ... there's probably some crazy species out there I don't know about that leaves a vine growing out the body of some wretched herbivore... [[The Ruins (film)|yummm, Shawn Ashmore...]])</small> [[User:Wnt|Wnt]] ([[User talk:Wnt|talk]]) 18:17, 16 July 2018 (UTC)

:[[Guerrilla gardening]] has popularised the term [[seed bomb]]. See [https://www.gardenista.com/posts/diy-wildflower-seed-bombs/ DIY: Make Your Own Wildflower Seed Bombs]: "The instructions are simple enough, a bit like making chocolate truffles. Takes 30 minutes." [[User:Carbon Caryatid|Carbon Caryatid]] ([[User talk:Carbon Caryatid|talk]]) 20:36, 16 July 2018 (UTC)

* https://www.sbir.gov/sbirsearch/detail/1207769 --[[User:Guy Macon|Guy Macon]] ([[User talk:Guy Macon|talk]]) 04:12, 17 July 2018 (UTC)
:I'm surprised the seeds would survive the shock from explosions. I'd have thought it would cook the seeds.. [[User:Dmcq|Dmcq]] ([[User talk:Dmcq|talk]]) 08:21, 17 July 2018 (UTC)
::A rail gun would avoid the explosion and greatly reduce the heat. It would, obviously, induce a heavy ionized field which may or may not affect the seeds. However, I've never seen any design at all for a rail "machine" gun. All functioning models I've seen are one-shot deals with a lot of setup between shots. [[Special:Contributions/209.149.113.5|209.149.113.5]] ([[User talk:209.149.113.5|talk]]) 17:09, 17 July 2018 (UTC)
:::Some seed varieties would probably survive. Some almost certainly wouldn't. This keen collector of home grown seeds can tell you that a normal bean seed won't survive the fall from a table to a concrete floor. (Probably why nature invented those nice packages for them that we call beans.) So I doubt they would survive a machine gun. [[User:HiLo48|HiLo48]] ([[User talk:HiLo48|talk]]) 23:21, 17 July 2018 (UTC)

::::Not a machine gun, but a cannon was successfully used by [[John Murray, 4th Duke of Atholl]] to plant trees on an inaccessible crag near [[Dunkeld]] in Scotland in 1788. A special type of [[canister shot]] was devised by the artist [[Alexander Nasmyth]], who was also an amateur inventor, and they were fabricated by a local tinsmith. The trees are still growing apparently. See [http://www.gardenhistorygirl.com/2014/05/on-planting-by-cannon.html ''On Planting by Cannon''].  [[User:Alansplodge|Alansplodge]] ([[User talk:Alansplodge|talk]]) 20:08, 19 July 2018 (UTC)
There was a scheme in the seventies to fly pine tree seedlings up to northern Canada and freeze them in molds so they had a cone-shaped lump of soil on the roots, then drop them from the air into soft soil during spring, I heard it worked well, but don't have any references about it. It seems like a brilliant idea, I wish I'd thought of it!![[Special:Contributions/1.128.107.192|1.128.107.192]] ([[User talk:1.128.107.192|talk]]) 06:57, 21 July 2018 (UTC)

== When Trans woman get breasts from hormones or surgery, can they feed babies breast milk? ==

What is best scientific answer to this question? [[User:Sphinxmystery|Sphinxmystery]] ([[User talk:Sphinxmystery|talk]])  <!--Template:Undated--><small class="autosigned">—Preceding [[Wikipedia:Signatures|undated]] comment added 18:30, 16 July 2018 (UTC)</small> <!--Autosigned by SineBot-->

:They can only do that after babby is formed. [[Special:Contributions/173.228.123.166|173.228.123.166]] ([[User talk:173.228.123.166|talk]]) 20:17, 16 July 2018 (UTC)

:According to [[Male lactation]], even some men can breastfeed. According to [[Witch's milk]], even some babies produce this nutritious life-fluid. [[User:Carbon Caryatid|Carbon Caryatid]] ([[User talk:Carbon Caryatid|talk]]) 20:40, 16 July 2018 (UTC)
:Implants would be of no use, and can even be problematic. Hormonal treatments would be necessary to induce lactation, just as Caryatid mentioned.--[[User:Khajidha|Khajidha]] ([[User talk:Khajidha|talk]]) 12:32, 17 July 2018 (UTC)
 
:[[Gynecomastia]] is a common condition in which male breasts start developing the same as female breasts do during puberty. In some cases the enlargement disappears after a couple of years and in others it persists. It typically happens during puberty. If the man is obese the breasts may look like those of a typical woman. They can certainly produce breast milk. The cause may involve fluctuations in estrogens and androgens, but the male can have quite normal appearance otherwise. The cure is typically mastectomy, in that the mammary tissue is removed in a minimal operation. Since it is a cosmetic operation and the breast is not typically cancerous, removal of large amounts of tissue is not necessary, and the nipple is preserved. [[User:Edison|Edison]] ([[User talk:Edison|talk]]) 14:30, 18 July 2018 (UTC)

:Since some of the comments thus far have been speculative or tangential, or have not truly addressed the OP's inquiry, here's a source (remember folks <u>reference</u> desk; I happened to have heard about this case study when it first surfaced, but it would have come up as one of the first search terms with just about any on-point selection of search terms): [https://www.newscientist.com/article/2161151-transgender-woman-is-first-to-be-able-to-breastfeed-her-baby/].  In short, there has been exactly one known case of a trans woman breastfeeding and it was relatively recent. The woman in question had already transitioned, but doctors needed to add additional elements to her hormone regimen, alongside suction stimulation, to stimulate milk production.  There is not data at this time as to the nutritional make-up and suitability of the milk thus produced.  If nutritionally sufficient, there is no reason to believe the process could not be replicated for most trans women; as previous responses have noted, it is not unheard of for even cis males who are not on hormone therapy to lactate under certain circumstances. ''[[User:Snow Rise|<b style="color: #19a0fd;">S</b><b style="color: #66c0fd">n</b><b style="color: #99d5fe;">o</b><b style="color: #b2dffe;">w</b>]] [[User talk:Snow Rise|<sup><b style="color: #d4143a">let's rap</b></sup>]]'' 10:09, 22 July 2018 (UTC)

== [[Horse chestnut]] sap causing blue colour ==

Following a recent discussion I have been trying to find information about the chemical reaction that is happening when young horse chestnut twigs are put into water and the sap causes a distinct bluish colour in the water. I have witnessed this effect on many occasions but the effect and its cause seems curiously absent from the web. Or perhaps I am inept. I wonder if there are any chemicobotanists  or anybody in the house that might give me some direction or indication of the cause of the phenomenon. [[User:Richard Avery|Richard Avery]] ([[User talk:Richard Avery|talk]]) 22:45, 16 July 2018 (UTC)
:[http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:60450399-2 This article] about a closely-related species, ''[[Aesculus indica]]'' states that [[aesculin]] is the source of the blue color, which turns from clear to blue at the correct pH, see [https://www.thoughtco.com/home-and-garden-ph-indicators-601971 here].  --[[User:Jayron32|<span style="color:#009">Jayron</span>]][[User talk:Jayron32|<b style="color:#090">''32''</b>]] 02:51, 17 July 2018 (UTC)

::Thanks Jayron, that adds to the meagre info I have. [[User:Richard Avery|Richard Avery]] ([[User talk:Richard Avery|talk]]) 18:44, 17 July 2018 (UTC)