The Periodic Table

Hexacoordinate-C

00:01

And here J as two possible projections which begins hard to imagine how it spins

In the article they said $|0_{00}0>$ is the state of pure para water. What can be a state of both in same time then ?

Or "not pure" ...

Well I think I will ask a question about this I'd really like to have an answer for that like vulgarisation, I just want to understand the basics of that. Even if I said good things (as you agree) I'm not sure to understand what it exactly mean

Loong

00:44

unclear? too broad? chemistry.stackexchange.com/q/63215/7951

Jan

I think too broad. Just dropped a vote.

Hexacoordinate-C

00:55

$\bra{a}$

@Jan how to make bra ket notation in LaTeX ?

Jan

Ask somebody who actually uses that stuff.

Hexacoordinate-C

I found this on wiki and TexSE

Ok well |

from my computer key

and \rangle

or langle

$|0_{00}0 \rangle$

Loong

@Hexacoordinate-C meta.chemistry.stackexchange.com/posts/2989/edit

Hexacoordinate-C

Thanks

user228700

Hey, guys :-) I found this question:

Loong

01:02

That post includes some experiments that don't work so well.

user228700

7

Q: Donation by inductive effect and withdrawal by conjugation

Is there a group that would attached to a benzene ring, donate electrons by inductive effect and withdraw them by conjugation?

user228700

Shouldn't one effect dominate the other? How is it that both effects are in play in the example cited in the answer to that ^ question?

Hexacoordinate-C

01:14

Well see you all I need to sleep :)

hBy2Py

04:20

Ok, @penta, the timings are now for idle CPU conditions.

Ramanujan

Hi chat

How to find gram equivalent weight of Na_2CO_3?

Which valency should we take?

hBy2Py

04:38

All, especially @Mart, @Loong, @ortho -- should this question be tagged with nomenclature?

2

Q: Are homologous series related to functional groups or to the general formula?

I understand that homologous series is a group of compounds with the same functional group attatched to it. I also know of an alternate definition of it as being a series of compounds with the same general formula. But if the first definition is to be considered then how are alkanes, alkenes ...

organic-chemistry alcohols

Martin - マーチン

05:15

@hBy2Py maybe, maybe also terminology, but not sure ...

M.A.R.

09:42

@Jan Nope not really

@para it's not easy to draw a line here

orthocresol

10:37

@Hexacoordinate-C honestly, listen to me: you need a lot more knowledge before you can jump to the rotational spectroscopy of water.

The stuff you're asking is not making much sense. The rotational quantum numbers have no direct link to spin, nuclear or electronic. The nuclear spin affects what rotational quantum numbers are allowed, it doesn't define the quantum numbers.

I can't judge how much QM you know, but you absolutely have to start from basics.

Trying to understand rotational spectra of water without understanding rotational spectra of simple diatomics is really like trying to run before you can walk.

Pick up a textbook, read about the QM system called the "rigid rotor" and read the section about rotational spectroscopy.

And as for nuclear spin isomers, start from dihydrogen; once you understand that, it's easy to convince yourself that ortho and para water is simply a generalisation of dihydrogen.

Basically the kind of in-depth answer you're looking for is pretty much an entire chapter of a textbook. What zhe and myself told you is our attempt to directly answer the question without explaining all the basics. If we were to explain the basics we'd need 2 hours or something like that. So please if you want to understand it properly - look it up. Last night I gave you some textbook suggestions, but really any book will work.

M.A.R.

@Loong Not enough just yet

koolman

11:04

Can someone help in this chemistry.stackexchange.com/questions/63229/…

Hexacoordinate-C

11:59

@orthocresol I offer to someone the possibility to do the longest answer ever on SE :P

I'm reading :)

hBy2Py

@Martin-マーチン Ah, wasn't aware of terminology, yeah I like that better. 'Homologous series' is a descriptive category with a more subjective definition, unlike nomenclature where things are specified rigorously. Thanks!

Martin - マーチン

np

Chemobot

12:19

12

Q: Why are noble gases stable

I was recently asked the question "Why are noble gases stable? with the expectation of providing an answer beyond the general explanation of "they have full valence layers" and I couldn't think of one. I would love to hear a full description of the this stability, I have a solid background in q...

quantum-chemistry stability noble-gases

Loong

12:37

@hBy2Py I agree. The concept of homologous series isn't mentioned in the Blue Book.

Yashas Samaga

16:29

What do (+) and (-) before a monosaccaride's name indicate?

direction of rotation?

Loong

@YashasSamaga yes

Yashas Samaga

ouch

so it is impossible to say if a molecule is +/- unless I do an experiment on it?

sad :(

(+) D-glucose is enantiomer of (-) D-glucose right?

+ and - pairs are enantiomers?

Loong

@YashasSamaga Generally, yes, you have to measure the optical rotation of an actual sample.

orthocresol

@Hexacoordinate-C I wouldn't really mind if I had the time, but don't right now. :(

All the best.

Yashas Samaga

wait it can't be

D glucose cannot be an enantiomer of something which is also D

the D/L deciding carbon won't match

*will match

what shud I answer if the Q asks which of the follow is (+) D-Glucose if the structure of (-) D-Glucose is given?

Loong

16:37

@YashasSamaga ᴅ-glucose is (+); thus, (−) glucose is the ʟ enantiomer

Yashas Samaga

that makes sense

Loong

Therefore, ᴅ-(−)-glucose does not exist.

3

orthocresol

@Loong I like how you're using both small caps and the minus sign.

Loong

@orthocresol heh, yeah, but it slows down my typing

M.A.R.

16:58

@Loong The typography used here is just right

Loong

Bounty Hunter

18:34

17

Q: Natural Bond Orbital (NBO) analyses: Physical significance/interpretation of stabilization energy determined by 2nd order perturbation

PREFACE: I am no expert on this topic. My questions at the bottom may be off base. I have some experience with symmetry-adapted perturbation theory (SAPT) when it comes to analyzing intermolecular interactions. The total interaction energy of a system can be quantified in four different energy...

computational-chemistry theoretical-chemistry orbitals intermolecular-forces

orthocresol

18:50

@Jan chemistry.stackexchange.com/questions/63253

Michael Harding

19:29

" but I don't have pkA chart with me and I don't have time to memorize it"

Hexacoordinate-C

19:41

Why in ortho water which have three different possible states this one (↑↓+↑↓) also have I=1 and then is ortho too ?

Why not 0 ?

orthocresol

Did you learn about singlet and triplet wavefunctions before?

Hexacoordinate-C

I have ever heard about that yes

orthocresol

Yeah, so you should have seen that $\alpha_1\alpha_2$, $2^{-1/2}(\alpha_1\beta_2 + \beta_1\alpha_2)$, and $\beta_1\beta_2$ are the triplet wavefunctions with $S = 1$.

The singlet wavefunction $2^{-1/2}(\alpha_1\beta_2 - \beta_1\alpha_2)$ has $S = 0$.

Hexacoordinate-C

Hum no ^^ but I know that S=1 is triple , S=0 singulet

Well

I understand what you wrote

There is a kind of normalisation into that that's why we got the 1 with the "+" and the 0 with the "-"

orthocresol

It's not normalisation, normalisation refers to the factor of $2^{-1/2}$

You could call it some form of symmetrisation

Because the states $\alpha_1\beta_2$ and $\beta_1\alpha_2$ do not have well-defined symmetry under the permutation of 1 and 2

Hexacoordinate-C

19:50

The main problem I have reading the article is that I have difficulties to understand the sentence in english first and then in physics

orthocresol

:/ I can't help with that

Hexacoordinate-C

I know ^^

M.A.R.

@orthocresol You can read it for him

Hexacoordinate-C

I have wordreference for that and my brain to solve the puzzle

This constrains the allowed combinations of rovibronic eigenstates with spin configurations, the product of the two corresponding symmetry species must be antisymmetric regarding this exchange. Under theconditions of a cold molecular beam, all molecules reside in the ground electronic and vibrational state, both of which are totally symmetric.

Therefore, the restrictions are on the rotational levels corresponding to each spin isomer. Relative abundances are determined by the spin degeneracy for each symmetry.

About which restrictions are they speaking ?

orthocresol

Restrictions on symmetry

Because electronic x rotational x vibrational x nuclear spin must be antisymmetric

electronic and vibrational are symmetric

so, if nuclear spin is antisymmetric (singlet), then rotational must be symmetric (J = 0, 2, 4, ...)

and if nuclear spin is symmetric (triplet), then rotational must be antisymmetric (J = 1, 3, 5, ...)

Hexacoordinate-C

20:04

I see

orthocresol

the triplet nuclear spin case, is called para

and since the rotational ground state is J = 1, its energy is higher than ortho, which has a rotational ground state of J = 0

@orthocresol what a german comma

Hexacoordinate-C

OK I understand

orthocresol

:D

Hexacoordinate-C

Thank you for your patience

orthocresol

so, if you go to H2O instead, the concept is exactly the same

the triplet nuclear spin case has to have an antisymmetric rotational state, which necessarily corresponds to an excited state

Hexacoordinate-C

20:10

Instead of what ?

orthocresol

instead of H2, for example

Hexacoordinate-C

OK

orthocresol

The only difference is that, for H2O, you need more numbers to describe the excited state.

But the concept is exactly the same.

Hexacoordinate-C

I see

pentavalentcarbon

@Martin-マーチン I'm in the process of creating a monster for you, don't worry.

Hexacoordinate-C

20:14

Does the following sentence means the technique is only use for weak-field-seaking states ?

The ground states of both para and ortho water are strong-field seeking (Figure 2), preventing their separation using electric focusing techniques for weak-field-seeking states [26].

"with a rotational temperature of 8 K, corresponding to > 99 % of para and > 96 % of ortho molecules in their absolute ground state, respectively", what is that ?

orthocresol

I have no clue what strong-field seeking means. Sorry

Hexacoordinate-C

And for the rotational temperature ? ^^

No it's ok

I thought it was an english meanning of something

orthocresol

20:35

Rotational temperature is a characterisation of the energy gap between rotational states.

Hexacoordinate-C

Yep I saw on wiki

orthocresol

The rotational constant is $J$, and the energy levels are $BJ(J+1)$, so the larger $B$ is, the larger the separation between rotational states.

$B$ by right has units of energy, and so does $kT$

So, if I remember correctly, the rotational temperature $\theta_\mathrm{rot}$ is defined as $B/k$.

$k$ being Boltzmann constant, obviously.

Hexacoordinate-C

$k_B$ *

^^

orthocresol

Yeah, I'm lazy.

Actually, no. It's $k_\mathrm{B}$.

The issue if you read spectroscopy stuff is that they like to talk in wavenumber units instead of energy units.

So sometimes you will see $\widetilde{B}$

wavenumbers are related to energy by a factor of $hc$, so sometimes you need to account for that.

Hexacoordinate-C

And ortho and para water are rotational states ? (can be consider as)

orthocresol

20:38

Depends on the context.

Well not really, I would call them nuclear spin states.

One nuclear spin state can adopt many rotational states, for example para can have J = 1, 3, 5, ...

so para doesn't correspond to only one rotational state

Hexacoordinate-C

So how would I understand the sentence about the yields and the rotationnal temperature ?

orthocresol

I don't know what it means.

Hexacoordinate-C

All states might be separated by this energy

Zhe

Is this the paper you were talking about in your question?

Hexacoordinate-C

arxiv.org/pdf/1407.2056v1.pdf

Separation about ortho and para water

Zhe

20:40

Yeah, with ortho para water

Hexacoordinate-C

This is a really good exercise for me to read such a publication

I may understand 90% of the english perfectly so I'm impressed by myself. I just need to know more about quantum mechanics. I will buy a copy book and take note about Aktins book

Hexacoordinate-C

21:25

Interesting use of PHIP-NMR

One scan is much much better with p-H2 dans 174 without ^^

Zhe

Yeah, but the p-value here for the single scan peak being significant is not that high... :/

Hexacoordinate-C

You can perform both

pentavalentcarbon

21:46

@Martin-マーチン done

Zhe

21:58

w00t, 2k rep :)

pentavalentcarbon

Welcome to the club! It's shiny.

Zhe

@pentavalentcarbon I just realized you're in Pittsburgh. CMU? Pitt?

pentavalentcarbon

Pitt.

Zhe

Ah cool. I grew up in Monroeville.

pentavalentcarbon

!

We seem to have swapped.

I'm from Lowell.

Zhe

22:06

I see. We did swap :)

Jan

22:19

@orthocresol ARGH! Can’t vote to close as a dupe of yesterday’s D=

Hexacoordinate-C

Hey @Jan, did you have a good week ?

Jan

Pretty much, yeah ^^

Hexacoordinate-C

How to share a link in chat with a "tittle" ?

Something like a word in blue and when you click on it it goes to the link

Jan

Use the same markup you would in comments. [Replacement text](http://example.org/crapstuff.html)

Hexacoordinate-C

link

Thanks

@orthocresol this one might be for you

orthocresol

22:42

@Hexacoordinate-C lol... no way

@Jan Why, what's stopping you?

IIRC, either an upvoted or an accepted answer on the proposed duplicate should make it possible.

But if you couldn't VTC, then I probably didn't remember correctly.

Oh, maybe because it's on hold?

Jan

Probably because the target is a closed question.

orthocresol

Aha :D

Jan

I flagged instead. You do this for me prettyplease kthxbai.

orthocresol

chemistry.stackexchange.com/questions/63253/…

I find this hilarious

Hexacoordinate-C

Me 2

orthocresol

22:45

@Hexacoordinate-C You can't see what I'm talking about, though.

Hexacoordinate-C

Hilarous thing I can

orthocresol

Oh no, you can't see the really funny thing.

It's a deleted answer and you need 0.01 Mrep to see it.

2

Hexacoordinate-C

lol

Show me take a screen

orthocresol

I like how he thinks there's a big difference between n-BuLi and t-BuLi.

Whereas he can't tell the difference between n-BuLi and LiOH.

Hexacoordinate-C

Yeah haha

I don't remember in which reaction they prefer to use s-BuLi

Jan

22:48

@orthocresol Starred that only for Mrep =D

orthocresol

Anyway, t-BuLi is more reactive than n-BuLi; certainly not for steric reasons.

@Hexacoordinate-C I know, it's some kind of Darzens variation with silicon.

Hexacoordinate-C

I'd like to see f-BuLi

f= fulleren

:P

orthocresol

Hexacoordinate-C

Yes but I don't remember of an other one

orthocresol

Don't know of any others.

Loong

22:56

@orthocresol VW-BuLi

Jan

@Hexacoordinate-C It can’t be that common. SciFinder only outputs 284491 reactions with sec-BuLi as a reactant or reagent.

Hexacoordinate-C

"Only"

What means common then?

Jan

Restricting it to 1-step-reactions brings the count down to 18700 though.

It means ‘@Jan was being so sarcastic that they turned pink.’

Hexacoordinate-C

LOL

Mithoron

hello

Do those guys have some exam today or sth with this amide

Jan

23:02

I don’t know but it started yesterday.

Hexacoordinate-C

Where do you see "this" amide ?

I don't understand anything lol

About what are you speaking ?

Jan

Lithium cyclohexylamide.

Hexacoordinate-C

I didn't see it yesterday

Jan

You lucky soul.

yesterday, by orthocresol

Ok, I'm just going to put my answer there and never open it again.

Hexacoordinate-C

People were more comfortable with the synthesis of aldehyde from urea lol

@orthocresol should add in what solvant those pKa were measured in case people have trouble to open the table like me right now ...

I suppose in DMSO

orthocresol

23:12

@Hexacoordinate-C ccc.chem.pitt.edu/wipf/MechOMs/evans_pKa_table.pdf

and no, I used H2O, although it hardly makes a difference tbh.

Hexacoordinate-C

Last time we where speaking about 4.76 or 4.75

Which looked to be a big difference ^^

orthocresol

Yeah, but this is not 0.01 difference in pKa. It's like 10 pKa units difference.

Hexacoordinate-C

Epsilon

Why this link works

orthocresol

23:26

Never thought that my summer project would come in useful here...

0

A: Why is the combination of C-13 and bromine isotopes not indicated in mass spectrum graph?

It does appear. The graphs you're looking at online probably just dumbed it down. Here's some proof if you like, a compound synthesised by yours truly, with molecular formula $\ce{C7H7BrN2O2}$. I clipped the relevant part of the mass spectrum I got. This was done with ammonia gas CI, so instead ...

Jan

Oh god, what a bad-looking question .__.

I could have contributed another two molecules but meh xD

orthocresol

~~Guys please upvote my answer. I only need 62800 more crep until I can protect questions ^^~~

pentavalentcarbon

Crep? Is that the British English version of crap?

orthocresol

No, it's a centi-rep.

pentavalentcarbon

What the hell kind of bad meme is that?

orthocresol

23:32

points towards @Jan

Jan

I started it. I keep referring to 200 rep as 0.2 krep.

Hexacoordinate-C

Do not read centi-*ed

pentavalentcarbon

!!gun

Chemobot

╾━╤デ╦︻ ▄︻̷̿┻̿═━一

Jan

Although I should start saying 2 hrep.

!!gun

Chemobot

23:32

( ﾒ▼Д▼)┏☆====(((＿◇＿)======⊃

orthocresol

!!flip/╾━╤デ╦︻ ▄︻̷̿┻̿═━一

pentavalentcarbon

Ooooohhhh, that's a good one.

Loong

Nov 19 at 20:57, by Loong

Hm, 1000 rep = 1 krep, which sounds like crap.

Chemobot

(╯°ਊ°)╯︵╾━╤デ╦︻ ▄︻̷̿┻̿═━一

Hexacoordinate-C

Why don't you speak in molar reputation ?

Jan

23:33

!!unflip/╾━╤デ╦︻ ▄︻̷̿┻̿═━一

Hexacoordinate-C

That would be fun here

Jan

Because we don’t dissolve it in litres.

Does !!unflip only work with tables? =C

!!greet

!!greet/@Jan

Chemobot

Welcome to The Periodic Table @Jan! Here are our chat guidelines and it's recommended that you read them. If you want to turn Mathjax on, follow the instructions in this answer. Happy chatting!

Jan

Oh, it’s !!untable, that’s why.

Chemobot

┬──┬ ノ( ゜-゜ノ)

Jan

23:35

!!untable/╾━╤デ╦︻ ▄︻̷̿┻̿═━一

Chemobot

┻o(Ｔ＿Ｔ )ミ( ；＿；)o┯

orthocresol

LOL

Loong

@Chemobot !!ungreet

Jan

@Hipp feature-request! !!untable/stuff!

Chemobot

┻o(Ｔ＿Ｔ )ミ( ；＿；)o┯

Hexacoordinate-C

23:37

@Jan you have around 39.7 zmol rep

pentavalentcarbon

oh for crying out loud

Jan

I don’t do those small numbers.

I’m hard-pressed performing reactions in 100 nmol scales.

orthocresol

ouch

Hexacoordinate-C

With NMR you can detect amol so you have a big gap before to have problems

Jan

I managed to get through my PhD without having to resort to Shigemi tubes a single time.

Hexacoordinate-C

23:42

You'll just do TLC ?

And nose predictions ?

What don't you like NMR ?

Jan

@Hexacoordinate-C Postdoc from our lab takes a flask. Sniffs. ‘Smells like tertiary alcohol. Is product.’

Loong

@Hexacoordinate-C With alpha spectroscopy, you can detect the decay of individual atoms. Hence a significant part of my thesis was about counting statistics.

Jan

@Hexacoordinate-C No, I just measured NMR in normal tubes.

Hexacoordinate-C

@Loong can we find it one the web ?

@jan ok

@jan I

@Jan understood :)

Jan

I actually used the reply feature just because I was jumping back and forth replying to different things so it wouldn’t get lost ;)

Loong

23:47

@Hexacoordinate-C Yes, but it is in German.

Hexacoordinate-C

Hum

^^

Ich bin berliner

Loong

Berliner Pfannkuchen

Berliner Pfannkuchen, kurz Berliner oder auch nur Pfannkuchen, oder Krapfen bzw. Kreppel, ist ein etwa faustgroßes Siedegebäck, das schwimmend in Fett ausgebacken wird und aus süßem Hefeteig mit einer Füllung aus Konfitüre besteht. Im deutschsprachigen Raum existieren diverse regionale Bezeichnungen dafür (wie der Berliner Ballen) und auch die Füllung variiert. Die Füllungen des Berliner Pfannkuchens sind regional unterschiedlich. Neben Konfitüre (im Norden eher rote Konfitüre, in Süddeutschland und Österreich eher Marillenkonfitüre) wird in Ostdeutschland auch Pflaumenmus verwendet, in Baden,…

Hexacoordinate-C

Not "ein" but this is the only words I know with the numbers from 0 to billions

Jan

@Loong Krapfen.

Loong

@Jan "Du bist jetzt keine Katze mehr; du bist ein Krapfen."

Hexacoordinate-C

23:49

I looks good

I like those fr.wikipedia.org/wiki/Tarte_trop%C3%A9zienne

pentavalentcarbon

That donut thing looks amazing

Hexacoordinate-C

Or cup

Jan

@Loong Is that a quote? I don’t recognise it.

@pentavalentcarbon The German or the French one?

Hexacoordinate-C

Because there are homeomorph

@Loong does alpha spectroscopy can be used to detect any element ?

Loong

ALF - Comedy Video 1.2 "English"

►

@Hexacoordinate-C no, the nuclides have to be alpha-active.

You could use NAA for many trace elements that are not radioactive.

pentavalentcarbon

23:56

@Jan Hmmm, now that you mention it, both. I'm a sucker for poofy pastry things.

Hexacoordinate-C

@Loong interesting

Jan

Because the German one can also be gotten in England where it’s called a jam donut ^^

pentavalentcarbon

Which I happen to be a fan of.

Hexacoordinate-C

See you all

Jan

Okay, make sure you come to Germany (preferably the South) during carneval season; that’s when the greatest variety of donuts is available.

Transcript for