The Periodic Table

Michael Harding

12:00 AM

I'm doing Physics and Further Maths

orthocresol

PHYSICAL CHEMIST WARNING

3

Michael Harding

I love physical chemistry <3

I even said it in my ps ahaha

Jan

19 secs ago, by orthocresol

PHYSICAL CHEMIST WARNING

orthocresol

(don't mind us - we are organic people...)

Michael Harding

Here I'll quote myself from my ps :')

'A passion for pure mathematics and quantum physics is the root of the interest I have always taken in Physical Chemistry. In my A-level course I was introduced to the quantum mechanical model of the atom, which instantly captivated me. By studying the full A-level mathematics in a year, I have been able to use my knowledge of functions and calculus to explore Heisenberg's uncertainty principle and probability density functions for electron clouds.'

orthocresol

12:01 AM

Generally around here, there's a bunch of organic people, a bunch of computational people, and a radiochemist.

Michael Harding

Isn't one of the tutors at Teddy Hall a physical chemist?

orthocresol

Generally, every college will have one physical, one organic, one inorganic.

Michael Harding

Ah, I see

Jan

Stop singling out your fellow moderator ;p

orthocresol

> Three years ago, I was selected to be part of the school team in a local science competition. We clinched the first prize in a thrilling buzzer round, but what piqued my interest more were the displays at an adjacent science fair - especially one where the presenters made a mountain of "ice" just by pouring a solution onto a Petri dish.

@Jan Loong is a special person, that's what makes him so valuable :')

Michael Harding

12:05 AM

The thing is, my grades aren't as spectacular as some of the others applying to Oxford, but I love Chemistry and I genuinely enjoy doing it, so I'm hoping my enthusiasm will somewhat shine through in interview and they'll recognise that :')

Loong

@orthocresol ?

orthocresol

@Loong You answer stuff that nobody else does. If I were to disappear, Jan could probably answer everything I answered.

Jan

@orthocresol Not the question I’m rewarding you for, obviously ;p

Michael Harding

It's why I spend so much time on stack exchange reading stuff I don't even understand yet... :') I'm surprised I didn't find this chat earlier ahah

orthocresol

Wildcat could probably do all the quantum-y stuff better than I can.

@MichaelHarding When's your interview again?

Michael Harding

12:08 AM

@orthocresol I have to go for interview on the 13th of December, and they want me to stay until 'some time' on the 14th.

orthocresol

Ah, ok. I think it's because if they reject you, they'll still send your name round to other colleges who might want to interview you.

Michael Harding

Either way, I'm actually sort of looking forward to the experience - whatever comes of it :)

orthocresol

Yup, interviews are great :) You get to meet all the other people.

Be respectful towards the profs, but don't be afraid - they're really nice people (most of them at least - and yours are!)

Michael Harding

Yeah, I'm genuinely looking forward to just listening to what they have to say - I've heard an interview is almost like a tutorial, which is an environment I've never been taught Chemistry in, so it will just be really interesting to have a discussion with them

orthocresol

All the best!! I'll have flown back by then, so won't be around.

Michael Harding

12:15 AM

I have a feeling I'm going to be posting on stack exchange a lot with my Olympiad struggles :')

The thing is, I love helping others, but I'm way out of my depth on many of the questions asked on here ahaha, though I was able to answer someone's question at one point...

Steven Stewart-Gallus

I know certain noble gasses can form compounds. Can any noble gasses form metallic bonds? A helium alloy compound might be cool.

Loong

@StevenStewart-Gallus maybe at high pressure about > 100 Mbar

Jan

12:48 AM

0

A: Would distilling a sodium fluoride solution generate hydrogen fluoride to any noticeable extent?

For all intents and purposes, you can consider a solution of sodium fluoride that of a weak base in water. Remember the formula to calculate an acid constant $K_\mathrm{a}$: $$\begin{gather}\ce{HF + H2O <=> F- + H3O+}\tag{1}\\ K_a = \frac{[\ce{F-}][\ce{H3O+}]}{[\ce{HF}]}\tag{2}\end{gather}$$ Fo...

I did it! Finally! I can stop procrastinating now.

@ortho, still here?

orthocresol

1:03 AM

@Jan Yup!

Jan

Can you delete the last two comments here?

(Name-calling prevention ;))

orthocresol

done

tries to flag chat messages as obsolete

Jan

Ha! I could still delete my last thanks ;)

Michael Harding

Can somebody help me with part h please? :)

Jan

@MichaelHarding What do you think is the most acidic position?

(If I use any expressions you haven’t yet heard, feel free to ask)

Michael Harding

1:12 AM

Is it the hydrogen that's attatched to the chiral carbon in the centre?

Or the hydrogen that's attatched to the nitrogen?

Jan

It’s the one in the centre.

Michael Harding

Why is that? Is it because the N is more electronegative?

Jan

A typical N-H bond has a pKa value of 35; the carbon next to an ester has around 25.

The ester anion is good, because it can rearrange to an enolate which gives stabilisation.

orthocresol

Well, all other things being equal, you'd expect a N-H to be more acidic than a C-H.

This C-H is special though.

Jan

And in that case, it is also in benzylic position.

So two forms of stabilisation.

But also, all other things being equal you wouldn’t expect an alcoholate to be able to deprotonate N-H.

orthocresol

1:16 AM

Yup

Michael Harding

Why not?

(Sorry)

Jan

(Don’t worry ;))

I’ve never actually thought about why a typical alcohol has a pKa of 15 and a typical amine one of 35. Good question o.o''

orthocresol

Probably electronegativity.

Michael Harding

That's what I thought, although that is just a guess

Jan

One of my professors, Professor Mayr, attempted to hammer pKa values into every student’s head. If you wake me at ~~2 a.m.~~ 9 a.m. and ask me to guess the pKa value of organic compound X, there’s a good chance I could get close.

orthocresol

1:18 AM

O being more electronegative, is happier to take on a negative charge.

Jan

@orthocresol That’s probably it, yeah.

Michael Harding

So Anion G looks like this?

Jan

Yup.

Michael Harding

Left out the H on the N by accident

Jan

(Mental note: If I get made a TA again, always look at the entire molecule …)

Michael Harding

1:23 AM

Ahahaha :')

For part i of that question

orthocresol

People ALWAYS leave out the H's on secondary amines

I don't know what it is about secondary amines, but it always happens.

Michael Harding

Would it be the two enantiomers that have the benzene ring going into the page/out of the page and vise-versa?

pentavalentcarbon

@MelanieShebel You can always just bug us...

orthocresol

Yes.

Michael Harding

Ah, okay makes sense :) Thank you very much @orthocresol and @Jan

Jan

1:27 AM

@MichaelHarding Diastereomers.

You can’t actually convert the enantiomers into each other, because the molecule has two stereocentres, of which you can only epimerise one.

orthocresol

Hmph, didn't even spot that...

Michael Harding

Diastereoisomers ah.

Jan

That’s for the secondary amine ;) We’re even now *highfives*

Michael Harding

So @Jan could this be an example of Diastereomers, or am I wrong?

Jan

@MichaelHarding They’re enantiomers.

They only have one stereocentre.

Michael Harding

1:32 AM

Oh.

Yeah.

Yeah, I understand it now.

Jan

(I’m not sure, do enantiomers count as a sub-class of diastereomers?)

Michael Harding

Where was the other chiral carbon in the question I gave above?

Jan

The one next to nitrogen in the six-membered saturated ring; connected to the central one.

orthocresol

@Jan No, they don't.

Michael Harding

Ah, I see it :)

orthocresol

1:34 AM

That chiral carbon would be exactly 50% (R) and 50% (S) though.

Assuming that the metal catalyst does not have some weird ligand on it......

Michael Harding

Onto the next question... Oh it looks like it's a physical chemistry question :D

Jan

Reminds me of my favourite (or one of my favourite) catalytic hydrations … a colleague tried to get a benzyl group off of an amide. Check out her supportings, compound S2 (page 8).

This is the corresponding Beilstein J. Org. Chem. article.

Michael Harding

This question is my kind of stuff :D

That article looks really interesting @Jan , I'll have a (very slow probably) read through of it :)

See if I can understand much...

orthocresol

That yield though :(

Jan

Don’t judge cool compounds by their yields xD

(I would have loved 15 % in my last steps … 15 >> 0 …)

Michael Harding

1:46 AM

Anyway, I'm off to bed, G'night guys. Thanks for all the help @Jan and @orthocresol . I must say Chemistry SE chat is full of lovely people, I've been over in a maths SE chat and didn't feel too welcome... I'll probably be in here tomorrow again! :)

orthocresol

Good night!

Jan

@MichaelHarding Awwwww <3 (づ｡◕‿‿◕｡)づ

See ya o/

orthocresol

I spotted an error in the direct product tables ಠ_ಠ

When I'm done with these I'm going to collate all the typos and email them to the Director of Studies lol

Jan

I feel baited D=

I approved and improved an edit to a post [on hold] D=

orthocresol

Isn't that a good thing?

Jan

1:51 AM

2 days ago, by pH13 - Yet another Philipp

@ToddMinehardt Don't drink and approve edits! xD

Loong

@Jan and voted Leave Closed

Jan

The only thing to do with that post.

Except maybe downvote.

Loong

In case I have to edit such questions, I usually put the whole thing in a > blockquote to indicate that it is just copy and paste homework.

Jan

Yeah, I did that before but I’ve become more careful because … can’t even tell you why.

Jan

2:27 AM

There’s another one!

(This time I remembered to reject)

Jan

2:49 AM

@getafix meta.chemistry.stackexchange.com/a/3051

15

A: Hidden points of editing you probably didn't know

Be judicious when editing questions that are [on hold] or [closed]. Editing posts bumps them back to the top of the main page. Only edit closed questions that you think you can improve them to the point that they can be reopened. There is little benefit to the site when low quality questions wit...

There we go, no it’s inline.

getafix

@Jan lol

Jan

Why lol, of all possible reactions? xD

getafix

I have been guilty of editing old posts, but mostly because I was farming for badges.. haha

@jan

btw coming to japan anytime soon, haha?

Jan

Oh boy, still haven’t sent away any applications =C

getafix

haha, thesis keeping you busy?

Jan

3:02 AM

Very.

It’s keeping me in chat at 4 a.m. busy xD

But no, I’ve almost completed the complete draft after which that has to get proofread by my dad and my PI and it’ll be handed in within a month, I hope.

getafix

haha a kindred spirit when it comes to procrastination.

oh, sweet haha

Jan

What busted a lot of my plans was the fact that I was told not to separate results and discussion — which I had been doing =C

getafix

ah damn..

just out of curiosity, how long does a phd take in germany? is there a a time limit, or you finish when you finish?

Jan

Both.

No, that is not a contradiction ;)

getafix

so what if you don't finish in the given time?

Jan

3:08 AM

Usually, you will get a job (i.e. funding) for three years in chemistry. And the general idea is that you actually hand in your thesis at the end of those three years.

I know a grand total of two people who managed to do that: one was really lucky, was first author on three papers and handed in a cumulative thesis (he was one of the first ripostatine synthesisers) — which was great for him because he was Chinese and we would have had to write it for him because of his bad grasp of both English and German.

The second worked in isolation and … well … how d’you put it diplomaticly …

Basically, she could have ended her work anytime and that’s what she did when the end of the three years approached.

Other than that, most people write up their theses on unemployed benefits (or if you had a grant (like me), on social welfare money, because you’re only entitled to unemployed benefits if you have been employed).

getafix

Ah I see.

Jan

It’s a bit more tense for non-EU PhD students if they are unlucky with their visa. Because if worst comes to worst, they might have to leave the day after employment ends so they’ll get started writing a bit earlier.

getafix

ahh okay. So you got an extension on your grant? or is the grant not time bound?

gannex

so... the way I understand it, getting a PhD is just a commitment to be poor

idk if I can deal with that. I was making a lot more money before I went to university and I'm kinda used to having a little bit in the bank :/

Jan

Poor, overworked, …

gannex

3:16 AM

My plan is to get a masters in a program that does a lot of collaboration with industry and then jsut try to get a job

Jan

I didn’t get an extension, it ended after the three years. Which was in January.

gannex

damn

Jan

There’s also industry-collaboration PhD positions.

gannex

yeah

but do I really need it?

Jan

But I continued working until June. My PI said he wouldn’t care.

gannex

3:17 AM

I'm not enjoying watching all my friends get rich while I'm stuck in school

I'm glad it worked out for you

Jan

Dunno, I know a grand total of one (1) opinions which is from Roche Diagnostics, and they said 90+% of the academics they empoly have a PhD.

gannex

what's your PhD in btw, Jan?

getafix

@Jan I see. Well good job on getting it done

Jan

Rich parents, that’s all … Wouldn’t have worked out if I had the financial situation of some of my colleagues …

Natural product chemistry.

Also known as top or flop chemistry.

gannex

"you know a rand total of one opinions..." what?

getafix

3:19 AM

top or flop? haha

Jan

Back in 2006 I visited Roche and the guy who showed all the students around said point-blunt that 90+% of the academics etc. Sort of to tell the people ‘if you can’t get a PhD after studying (chemistry or biology) then don’t even bother applying.’

But that’s only one data point so …

@getafix You remember I mentioned the guy who worked on ripostatine? It just … worked out. Whereas I had to perform each reaction at least twice (or so it feels) to at least see product, because of the damn compounds I work with.

gannex

hmmm

is PhD the new BsC?

and BsC the new high school diploma

are they just trying to hide the fact that there are no jobs from our cohort?

Jan

I think they want to say that they have two types of jobs: research and robot-work.

pentavalentcarbon

bachelors the new HS diploma, masters the new bachelors, PhD the new masters

getafix

@gannex I think so

@pentavalentcarbon o/

gannex

3:23 AM

fuck

Jan

For robot-work, a B. Sc. is too much, for research they want as many titles as they can get their grubby little fingers on.

(too much = too expensive)

gannex

OK fuck this I'm buying a supercritical CO2 extractor and I'm gonna sell legal pharmeceutical grade oils when the Canadian market opens

pentavalentcarbon

have fun getting a garbage QA/QC or contract position with a BS

o/

Jan

Sometimes I still hope for the national lottery ;)

gannex

I was gonna get an Msc... either that or I go back into forestry

Jan

3:25 AM

Forestry sounds nice …

getafix

what's qa/qc..quality assurance, quality control?

gannex

forestry is the most satisfying type of job I've ever had.

quality control, yeah. Only job you can get with a BsC.

Jan

But isn’t the entire academic chemistry education teaching you how to fail, starting at the ion lottery practical course (qualitative analysis)?

gannex

what?

you mean anal chem?

getafix

xD

anal chem lol

pentavalentcarbon

3:27 AM

That's what it'll feel like.

getafix

@Jan hated that stuff with a passion

Jan

It was our second lab course, second semester (first year). After we had the quantitative analysis (titration and stuff) we were made to do qualitative analysis.

gannex

undergrad anal chem is killing me right now. I can't imagine that being my job.

pentavalentcarbon

I don't know how people do it, tbh. Go to school for 4+ years just for that?

gannex

@pentavalentcarbon you are not a uni student??

pentavalentcarbon

3:28 AM

PhD student

gannex

oh

yeah. no point of BsC only. We're trapped into it

pentavalentcarbon

I'm referring to QC/QA positions after a bachelors, not analytical chemistry in general...there's more to it than just the slave-driving stuff

gannex

personally, I enjoy science, but I refuse to do more research until my life is comfortable and worth living.

well QC/QA is applied anal chem, no?

pentavalentcarbon

the most extreme version, yes

gannex

yeah

this is why my plan is to buy one of these bad boys:

pentavalentcarbon

3:30 AM

That isn't a bad idea, but it might close some doors depending on what you want to do later on, and in which country you want to do it.

gannex

no more school til I have a lab running that actually provides income

pentavalentcarbon

that looks like an industrial chromatography column...?

Is that a supercritical CO2 setup?

gannex

indeed

pentavalentcarbon

And how much does that cost?

gannex

not sure. Just put in a request for pricelist. probably 10-20k

pentavalentcarbon

3:31 AM

WOW

gannex

but right now the most common thing in the medical marijuana industry in canada is hydrocarbon-extracted oils, purged of impurities with vacuum. It's not considered "pharmeceutical grade" though because there's leftover solvent. Only a couple companies are doing supercritical CO2

and now... it's time to do my last ever anal chem report (fingers crossed)!!

getafix

@gannex wow.

how do you plan to foot the bill for sCO2 setup?

sigh..I really want to do research, but at the same time not starve to death

Jan

Oh, you won’t starve to death.

They throw you enough food to survive.

getafix

lol

gannex

idk yet. Money can always be found.

Jan

3:36 AM

Most PIs know that students without food won’t do research ;)

getafix

sigh need to start applying to grad schools in about 12 months..don't know where I'll end up

gannex

what sorta chemistry do you want to study?

getafix

@gannex I am interested in all sorts of things..mostly supramolecular chemistry.

Jan

Supramolecular chemistry is cool.

getafix

big questions I hope to tackle in my life: how does matter become complex, origins of life etc.

Jan

3:44 AM

I did my Master’s thesis on a supramolecular topic.

getafix

@jan yeah I remember, you told me once :)

Jan

I forget who I told what ;)

But there are three more people chatting, aren’t there @gannex @penta @chemo?

pentavalentcarbon

the bot can't respond properly

Chemobot

pentavalentcarbon

!!tea

Jan

3:47 AM

!!gun

Yes it can!

Chemobot

̿’ ̿’\\̵͇̿̿\\з=(ಥДಥ)=ε/̵͇̿̿/’̿’̿

gannex

@getaflix that's cool. The coolest lab in my school is the supramolecular lab. The PI is super into cool antique chemistry equipment, origami, and generally all the parts of chemistry that are beautiful and exciting.

pentavalentcarbon

@getafix chemistry.stackexchange.com/questions/33100/…

getafix

@pentavalentcarbon oh thanks :)

this is obviously gonna help me too haha

Feeds

Martin - マーチン has made a change to the feeds posted into this room

pentavalentcarbon

3:52 AM

ok, that fills my work quota for the day

didn't do what I planned on doing at all...

Jan

One post?

Feeds

Martin - マーチン has made a change to the feeds posted into this room

getafix

lol..I still haven't finished studying for my organic exam on tuesday

pentavalentcarbon

I believe in quality over quantity...

getafix

oh and I still have my statistical physics problem set to do..

which is due tomorrow..omfg!

Jan

3:53 AM

Sure, but on some days I throw in two or three, sometimes four posts (which I assume have quality, but you know, self-judgement …)

gannex

6 lab reports left to write by next week for me/

Jan

I had hoped to have finished fusioning the two thesis parts twelve hourse ago. Oh well …

pentavalentcarbon

Well, when you do all the calculations and plots from scratch that takes time

plus I went out for a bit, etc.

Jan

That’s true; not even drawing elaborate stuff with ChemDraw (usually what costs the most of my answering time) costs as much …

pentavalentcarbon

Ignoring the calculations there is something that saves time. Once you have a way of making a certain kind of plot it takes a lot less time to do it again, in case you ever need to. Just like if you keep using the same LaTeX over again, etc.

getafix

3:57 AM

@pentavalentcarbon btw, are the new extensions for psi4 which give a breakdown of electrostatics, polarization, dispersion, and charge transfer etc. for intramolecular compounds out yet?

pentavalentcarbon

I keep all my Chem.SE posts and calculations in Dropbox and a bigger folder on my work machine so I can always go back and reference stuff.

Nope, I'll let you know. It's out, but not available in conda yet, which is what we're both using.

ayyyy I'm over 2000, no more "suggested edits" for me!

Jan

Welcome to the world of accepting edits then o/

pentavalentcarbon

I have zero problems doing that, I've been looking forward to it.

Jan

I know; it’s much nicer to have responsibilities and separate the world into thumbs up/thumbs down, isn’t it? ;)

getafix

@pentavalentcarbon cool, thanks :). Also, congratulations on 2k

gannex

4:19 AM

hey what are the policies here on talking about things that are directly implicated in our research?

Jan

As in talking about what you do in the lab?

Done!

gannex

well

I'm a bit of a comp chem noob, and I'm trying to figure something out for a research project in comp chem... I was going to ask for advice on techniques to solve my problem, but it might require me showing the exact molecule I'm talking about

then again I think the reaction is actually already published (by a different group). We're just trying to figure out the mecha

I'm going to give this project one last shot, else I'm abandoning it.

Jan

That’s more a question of how your lab sees it, isn’t it?

gannex

4:36 AM

I guess so

I'm in a weird situation. I did a semester abroad at a theoretical chem lab. I'm not there anymore. I can either do a writeup about the (largely unsuccessful) project and get a grade for it, or I can carry on working on the proejct on my own time.

I was really hoping to figure out how the reaction worked

Jan

5:07 AM

Right. 6 a.m. I deserved my bedtime.

gannex

enjoy

it's midnight here. 2 more hours of work, then I'm having a BBQ

getafix

@gannex bbq at 2 in the morning, lol?

gannex

that nighttime schedule.

BBQ still makes a better sausage than the stovetop.

M.A.R.

7:34 AM

0

A: Why does dimethyl ether have a bond angle bigger than 109.5 degrees?

Let us compare the $\ce{C-O-C}$ bond angle in dimethyl ether (110.3°) with H-O-H bond angle in $\ce{H2O}$ (104.5°). The bond angle in dimethyl ether is greater due to the following reason. The $\ce{CH3}$ functional group is many times heavier than the H atom (both act as side atoms). So the eff...

Ideas?

getafix

9:10 AM

does anyone on here know how to prove the weighted geometric mean is greater than the weighter arithmetic mean?

wait..

weighted arithmetic mean is bigger than the weighter geometric mean..

M.A.R.

10:50 AM

@getafix IIRC there was a proof in the Wikipedia page

Inequality of arithmetic and geometric means

In mathematics, the inequality of arithmetic and geometric means, or more briefly the AM–GM inequality, states that the arithmetic mean of a list of non-negative real numbers is greater than or equal to the geometric mean of the same list; and further, that the two means are equal if and only if every number in the list is the same. The simplest non-trivial case — i.e., with more than one variable — for two non-negative numbers x and y, is the statement that x + y 2 ...

getafix

11:07 AM

yup got it done, using jensen's inequality

M.A.R.

11:22 AM

@getafix If you used Jensen's inequality, what did he use?

Aaron Abraham

12:12 PM

@getafix Happen to know if γ-hydroxy hexanal is the same as 4-hydroxy hexanal?

@M.A.R. o/

@Hippalectryon o/

Hippalectryon

\o

Aaron Abraham

@Hippalectryon Donc, any new improvements to @Chemobot lately?

Hippalectryon

Not really, what should I add ?

Aaron Abraham

@Hippalectryon Ah well, I was just curious ;P Don't really have anything on my mind ._.

Or wait...is it possible to get @Chemobot to display specific questions/answers from the main site?

Hippalectryon

!!daily

Chemobot

12:19 PM

21

Q: What do the quantum numbers actually signify?

I know how to calculate them and such stuff, but I wanted to know what they actually signify. I have a vague idea that they have something to do with an electron's position in an atom but what do all of them mean? Any help would be greatly appreciated!

quantum-chemistry

Hippalectryon

so yeah :-)

Aaron Abraham

I see...

I'm only just get used to @Chemobot, actually :P

!!absolute zero

...

@Hippalectryon Oh wait, that's you huh? O_o

Hippalectryon

12

A: Main Chatroom Etiquette Guidelines

Hi there ! I'm Chemobot, the Periodic Table's bot ! I provide various commands in the chatroom. Available commands : For everyone : Meta: !!help : I will link you here Utility: !!img/molecule_identifier : I will send you a picture of the requested compound if I can find it. The iden...

Chemobot

Hi! I'm the almighty bot of ChemistrySE's main chatroom. /!\ If you find me annoying, you can ignore me by clicking on my profile image and chosing "ignore this user" /!\ You can find my documentation here.

Aaron Abraham

@Hippalectryon Whoa, thanks!

Now, lets see...

!!gun

Chemobot

12:26 PM

ლ(~•̀︿•́~)つ︻̷┻̿═━一

Aaron Abraham

Nice XD

@Hippalectryon How long did it take you to program @Chemobot? Seriously, it's amazing!

Hippalectryon

@AaronAbraham I'm not sure, I improved it as time went by. Not too long though :P