The Periodic Table

12:28 AM

Getting rid of widows and clubs in one’s thesis is a pain in the … <-- pick your choice.

Yeah, you always have to fix something manually. But your typesetting software has no automatic widow and orphan control at all?

Jan

It does, but in most cases it decides to keep the widow rather than introducing whitespace. Apparantly, underfull boxes always have a penalty of 10000 (which is infinity).

Loong

fuzzy logic typesetting? ;-)

or xkcd.com/534

Jan

And even if I define the strech under or above floats (which should really be a good way to introduce a tad more whitespace) to be slightly larger, that seems to get ignored for some unknown reason …

But what really seems to help is pushing images (and tables) to the top or bottom of the page with the [tbp] flag. Rather than implicitly having it be [htbp] as in standard.

Loong

12:51 AM

@Jan Slightly larger baseline stretch? That sounds like a guaranteed way to mess up the register accuracy (i.e. the grid).

Jan

Not \baselinestrech. \floatsep and \textfloatsep, i.e. the space between figures/tables and the text around them.

@Jan I shouldn’t have written strech up there, it should be space. Or glue, as I’m using TeX.

Loong

ah, ok

Jan

3:12 AM

Finished!

2

MartianCactus

7:20 AM

so we all know the PT of Dobereiner

in which he introduced triods and stuff

my question is-

why arent Be, Mg and Ca triads?

nvm i asked the question on main site

0

Q: Why arent Be, Mg and Ca triads?

so we all know the PT of Dobereiner in which he introduced triods and stuff my question is- why arent Be, Mg and Ca triads? i mean the average of atomic masses of Ca and Be is aprroximately equal to the at. mass of Mg and all 3 have similar properties too right? Then why arent they considere...

periodic-table

Martin - マーチン

8:04 AM

@Jan There is a reason why you should not use [h] as a parameter for floats

@Jan Congratulations!

hBy2Py

12:06 PM

Is anyone here intimately familiar with the innards of the Gaussian CUBE format?

@Jan That may be, but throwing lithium cobalt oxide is a lot worse: assault with battery. (@Mel)

Loong

@hBy2Py off topic – migrated to law.stackexchange.com

hBy2Py

@Loong Either that or EE.SE....

1,3-feeds

12:31 PM

0

Q: Should we enforce including actual citations instead of just linking to sources?

In our post about the recommended style of citing on chemistry.se we state: The highest principle should always be: Give credit. I like it how many answers substantiate their explanations with external references. Giving the citation correctly is especially important when (block) quoting f...

discussion

paracresol

1:00 PM

@M.A.R. Kills M.A.R

@Martin-マーチン Is now a good time?

@Loong o/ ; How familiar are you with Lagrangian (Mechanics)?

@geta o/

Thank God you're here :O

getafix

Quick question--"Knoevenagel" condensation..how do you pronounce the name in quotes?

I'm looking at you, german speakers :p pls help.

@paracresol hullo!

paracresol

@getafix Kuh-no-evan-ah-gehl

The 'g' is pronounced a lot like the one in "gah!"

Or wait, even better... Kuh-noe-ven-ah-gehl

@getafix Wait, what year are you in at Uni?

getafix

ah okay thanks

third

paracresol

1:15 PM

B.Sc right?

@getafix How good's your Physics?

getafix

B.Eng but yeah whatever, doesn't matter

It can be good, and it can be bad depends on the topic lol

Loong

Vorlesung Organische Chemie 2.43 Prof. G. Dyker

@Loong o/

@paracresol hi

@Loong Thank you :)

1:21 PM

@getafix How good are at Lagrangian Mech?

getafix

average..

paracresol

@Loong About that Latin expression I asked you about ... ._.

@getafix That's good enough for me ^_^

^ So a question?

getafix

shoot..It's been a while though..I did take a course in analytical mechanics but that was two semester ago, and I don't remember much

paracresol

@getafix How about this situation? (P.S- You'll have to follow the link back to the original convo though)

yesterday, by paracresol

~~@hBy2Py~~ Brian For example, there's this classic situation we come across in physics: A ball placed on top of a smooth hemispherical shell (of radius R). It's given a little push (which imparts a, practically, negligible velocity), just enough to cause it to roll off without slipping. Determine the height at which the ball...um..."detaches" from the hemisphere. (Take the acceleration due to gravity = g)

@Loong Do Mods have the power to delete chat rooms?

Loong

@paracresol yes

getafix

1:27 PM

@paracresol okay, so what do you need help with?

paracresol

@Loong Could you delete one for me right now? (I created it, but I don't need it for the time being though)

chat.stackexchange.com/rooms/51709/der-bunker

getafix

Now my physics intuition is bad, and I come up with really bad ways of solving problems..but I would cast it into polar coordinates

paracresol

@getafix That struck me too ._. (But I'm not used to Polar :'( )

Loong

@paracresol done

paracresol

Danke :)

getafix

1:29 PM

Well I recommend getting used to it, in my experience depending on the problem, some can be completely intractable in cartesians

paracresol

@geta Hold on a minute...

getafix

so the V = mg*some function of theta..

paracresol

@getafix I see stuff like that a lot... sighs

getafix

measuring theta from say the z-axis, pointing vertical up, what you basically need is a projection that gives you the height from the ground(zero of your gravitational potential) at any given point

next, you need to convert the velocity to polar coordinates..so try and figure out the derivatives of the basis vectors..

it's a simply exercise in algebra and using the chain rule

Write down the lagrangian, apply the euler lagrange equation, solve the differential equaltion..and you have the classical path..voilà

paracresol

@Loong and @geta In a couple of months time, is it alright if I invite you both to another chat room so I can clear (conceptual) stuff with you guys (The "stuff" is usually within the realm of Physics and Chemistry...but since I hope to have a few Germans there too...hopefully we can delve into the topic of Oktoberfest beer). Same invite goes out to @hBy2Py @Mart @pH and @ortho,

@getafix Ah...about that...

Blank expression

getafix

1:34 PM

yeah I don't mind

paracresol

@getafix Well, I wanted to know if I could figure out the height using Lagrangian at all...

@getafix Gee, thanks!

getafix

You can

one extra thing..

paracresol

Hmm?

getafix

you need a constraint function..which is nonzero when your particle is on the hemisphere, and zero when it deattaches

paracresol

@getafix Ouch... what do you recommend I take?

@getafix You do realise I'm still in high school, right?

getafix

1:37 PM

yeah basically the "constraint" is the reaction?

there's a reaction when the ball is on the hemisphere, and none when it isn't

paracresol

:O

@getafix But, can I express that as a function?

getafix

yeah so your potential should be V = mgrcos\theta + (constant) (r-R) ..i think

where r is the radial position of the particle and is function of sin(\theta) and cos(\theta)

and, umm...yeah both theta and r change in time..

to give you the trajectory

paracresol

@getafix Wait, this isn't a problem, right? I mean, me...asking you physics...over here...when you're probably pretty bored ._.

@getafix r being the height?

getafix

position in polar coordinates..

paracresol

I think, I might've annoyed @Loong... that or he's pretty busy...he rarely replies :'(

@getafix God, I've got to read up on it again :(

*Polar coordinates

Wait, what year did you guys start Lagrangian in?

getafix

1:44 PM

So here's the difference between Newtonian and Lagrangian..the former is local in a sense, but the latter is non-local..(at least the way I understood it) you look at the whole trajectory...all at once, and the classical path is the one that min. the action

2

paracresol

@ortho o/

@getafix Trying to comprehend it

Oh wait, okay.

getafix

I don't know about chemistry curriculum elsewhere, but it's really not necessary..i just took it cause it seemed like it would be useful for QM..

but the prof was horrible

paracresol

^ Ouch

getafix

and I am generally bad at physics sometimes

paracresol

^ You don't look like it...at least from a high-schooler's perspective ;P

getafix

1:46 PM

so in cartesioan, you label postion as x, y in polar you label it r, angle..

DHMO

How do people prove that a substance is an element?

paracresol

@getafix Hold on!

@DHMO Duplicate ;)

DHMO

@paracresol of?

@getafix yes

r, theta

getafix

@DHMO I know ;) I am telling @para

paracresol

^Some question I saw a couple of months ago...It'd be a pain to hunt it down ._.

DHMO

1:48 PM

@getafix alright

paracresol

@getafix If I heard correctly, when you choose a coordinate system for Lagrangian, they ought to be 1)Complete, 2)Independent, 3)Holonomic, right?

getafix

I forget what holonomic means...does that mean the coordinates don't have a time dependance?

paracresol

Looks the other way

Something to do with degrees of freedom...

getafix

yeah but something like that..there's some freedom in choosing coordinates

paracresol

^ Yup....

But..

getafix

1:51 PM

you obviously need enough to describe the system, but you can have as many as you want essentially

maybe try solving simpler problems first..? practice Lagrangian mechanics in cartesian first..then practice changing coordinate systems..

paracresol

In that particular problem (hemisphere-ball thingy), if I use Cartesian, it wouldn't be Independent right? I mean, say, if I fixed the x-coordinate, the motion of the ball's immediately arrested...which is why I fear, Polar coordinates are the only way out :(

@getafix Oh for the want of a decent problems book

getafix

Yeah exactly, some situations naturally lend themselves to certain coordinate systems

Taylor Classical Mechanics, Goldstein etc.

people.fas.harvard.edu/~djmorin/chap6.pdf

paracresol

^ That was quick ;)

getafix

but anyway Lagrangian >> Newtonian in my opinion

The trick is setting up the problem, and writing down the lagrangian, once you have that the problem is as good as done

paracresol

@getafix Me too (from the little I know about it). Which is why I'm at pains to learn it :P

@getafix I'm a long, long way off...

getafix

1:55 PM

Like i don't a simple almost trivial exercise that you can do is that show that for a free particle

the classical path is a straight line

paracresol

sighs again

I'll give it a go...

getafix

free => V = 0

T = ??

L = T-U

paracresol

@getafix (mv^2)/2 ?

getafix

yup

paracresol

@getafix Do you know what book that's from?

getafix

1:58 PM

physicsinsights.org/lagrange_1.html

paracresol

^ You're prompt :)

getafix

It's just a simple exercise most professors use in their first lecture

then assign devilishly hard hw problems soon after.

paracresol

@getafix What do you guys do when you can't solve one of those?

orthocresol

@getafix Hahah

getafix

That's why make friends with physics majors, and math majors

paracresol

2:01 PM

ORTHO ._.

getafix

@orthocresol hullo! o/

orthocresol

I have these 25 mark questions, that ask me to compare and contrast the chemistry of two random elements.

getafix

lol

orthocresol

Well, they aren't 100% random, they're chosen that you have something to write. But still..

getafix

I am making a presentation on how Mars redesigned the packaging for M n Ms in 2003-2007

hBy2Py

2:03 PM

@paracresol Don't mind the invite; again, depending on how deep you get into physics, I may not be much help. :-)

orthocresol

I was puzzled for a while because I was wondering how a planet could design packaging.

paracresol

@ortho Are you fine with that idea?

getafix

hahaha lol, it can if it tries really hard

paracresol

@hBy2Py Ah, it's primarily chem though ;)

orthocresol

@paracresol In two months' time, I will be very busy. You're welcome to try, but I cannot guarantee anything.

hBy2Py

2:04 PM

@paracresol Ok, there I can often be of some use. :-)

paracresol

@orthocresol "Busy" as in?

getafix

@paracresol yeah to be honest, given the way things are headed, in two weeks time I might be dead

paracresol

@hBy2Py Glad to here that 3:D

orthocresol

Real-life busy.

paracresol

@getafix You've got examinations too, huh? XD

~~@hBy2Py~~ Brian, so if I have any Chem. queries...which ones do I ask you? In other words, what topics are you (primarily) at ease to deal with?

DHMO

2:07 PM

@paracresol I don't get the invite :/

paracresol

@DHMO I haven't sent it out yet ._. Once I jump into this whole business (in a couple of months), then I'll create the room (and I'll send an invite your way). I'd rather not create the room now since it'll just take up space...

getafix

@paracresol 9 finals..two weeks..haven't started studying yet

still have stupid assignments to deal with

paracresol

Plus @geta I'll be AWOL soon... Boards in March -_- Wish me luck!

getafix

good luck!

paracresol

@getafix Speechless

@getafix How did you find the Boards...when you took it?

@getafix This is why I don't wanna be an engineer ._.

getafix

2:12 PM

to be honest none of my 'engineering' classes have exams lol

I have to make a presentation about M n Ms packaging tomorrow, and that is 30% of my grade..lol

and it is about 3 min..so guess that makes it hard

paracresol

@getafix Wasn't that a Google-Interview question? 3;P

getafix

I don't know

hBy2Py

@paracresol General chem, kinetics; simple inorganic chem; mishmash of computational chem stuff. Pretty random mix.

I'm a chem engineer by training, so I don't know any advanced subject in especial detail.

Loong

@getafix You should present something about the difference between the left and right twix.

paracresol

^ XD

@getafix Arrgh! I had to do a presentation on diabetes at class (a couple of months ago)...I took no less than 1.5 hours...It happens for every presentation I ever do ... so I know how much of a pain in the arse the 3 min gap is :(

getafix

2:16 PM

@Loong hahaha lol

paracresol

@hBy2Py How about organic?

@Loong And I was told that our friends, the Krauts, had no sense of humour X'D

@geta So how long does a typical Lagrangian Mech. course take?

getafix

the one at our university was especially bad we basically crammed Lagrangian+Hamiltonian in one semester (15 weeks)..there was a follow up course (which I did not take)..which had advanced topics in both + relativity (15 weeks)

paracresol

I guess a basic idea about Lagrangian would suffice (for my purposes 3:P ). Now don't laugh, but, in your opinion @geta, how useful do you think Lagrangian (as compared to Newtonian) when you're trying to solve JEE or AIPMT mech. problems?

DHMO

Mass spectrum of phenol.

There is a peak at 66, corresponding to $\ce{C5H6+}$.

Problem is that it is not aromatic... what makes it stable?

paracresol

Oooh, serial upvoter :3

I wonder who it was? ._.

@geta was it you? ;D

getafix

2:28 PM

@paracresol I honestly don't know

paracresol

@getafix O_o

DHMO

Another peak is at 39, corresponding to $\ce{C3H3+}$.

paracresol

@getafix Oh, the questions...right...

DHMO

Porblem is that it isn't the allyl cation also...

paracresol

@getafix Would you happen to know if there's a PDF version of Taylor's anywhere online? I got Goldstein's but not that one ._.

@Loong If I put a user in my "Ignore user" list... will he/she still be able to see what I post (in chat)?

getafix

2:34 PM

hmm libgen

Loong

yes

paracresol

Oh and another thing, @Loong...how busy are you (nowadays)?

@getafix Lemme check...

@getafix I think libgen's down ._.

getafix

well that's a shame

gen.lib.rus.ec

no it isn't

paracresol

@getafix Great! Thanks! But which option do you recommend?

gen.lib.rus.ec/…

DHMO

2:49 PM

@Xasel you are welcome

paracresol

Shoots @Xasel

getafix

@paracresol whichever works

btw some of them are .djvu

Xasel

@paracesol I am under @DHMO protection...bullets reflects off ;)

getafix

so if you dont have a reader, get the pdf

paracresol

@Xasel That was an MG43 on full auto... nothing on God's earth could reflect that -_-

@getafix attempts to download PDF

@geta Um...a little help?

gen.lib.rus.ec/book/…

getafix

2:55 PM

yup?

paracresol

How the heck do I download the PDF version?

@DHMO Looks like you've gained a disciple ;)

getafix

ah that's the djvu

DHMO

@paracresol lol

paracresol

~~@hBy2Py~~ Brian, you're back! \o/

@getafix Deja vu? O_o

hBy2Py

@paracresol Organic was very specifically omitted from that list. Talk to @ortho or @Jan if you want organic -- ich bin nein ein organichemischer (or whatever that would be)

getafix

2:57 PM

bookfi.net/dl/1107511/6cdd06

hBy2Py

@paracresol I'm going to be in and out. Have to actually do "work" here.

paracresol

@hBy2Py Yeah, that's fine ;)

@hBy2Py "Work"? Sure 3;D

getafix

@paracresol it is about 54 mb..good luck haha

paracresol

-_-

getafix

@paracresol I think @hBy2Py has a job in the "adult" world lol

hBy2Py

2:58 PM

@paracresol Yep. I have to dissolve a pit into a steel plate.

Two, actually.

paracresol

@getafix You do realise that "Adult world" has more...dubious meanings 3;P

getafix

@hBy2Py Out of curiosity, what kind of field do you work in?

@paracresol yeah no innuendo

paracresol

@hBy2Py Bu...but...why?

DHMO

5

Q: Reason for endothermic nature of NaHCO3 + C2H4O2 reaction

Why is the classic baking soda and vinegar reaction endothermic? Here are some possible answers I've come up with: The dissolution of the sodium acetate absorbs energy, The release of the carbon dioxide from solution absorbs energy, or Some combination of the above.

acid-base reaction home-experiment

paracresol

@getafix Sure

XD

@getafix I'm trying to download the torrent...looks like it's working! :)

getafix

3:03 PM

cool

i'm gonna head to bed now

good night

paracresol

Ah well, I'll be off then! Thanks! @geta, ~~@hBy2Py~~ Brian, @ortho and @Loong

@getafix G'nite!

@getafix Goddamit, can't view the file -- *Sighs*...at least I have Goldstein ..

DHMO

3:27 PM

3

Q: Why is 1-ethylidene-4-methylcyclohexane chiral?

As far as I can tell, there doesn't seem to be a chiral carbon in this compound. C-4 of the cyclohexane ring has two groups with exactly the same connectivity, and the exocyclic double bond can't give rise to optical isomerism. What am I missing?

organic-chemistry stereochemistry chirality

@orthocresol How on earth do you not know the answer to this lol

hBy2Py

5:22 PM

@DHMO Did you notice that @ortho self-answered that question? ;-)

@getafix This is where I work; you can get an idea of the sorts of things I'm working on by checking out my (ResearchGate profile](researchgate.net/profile/Brian_Skinn). We do industrial electrochemical process R&D: electropolishing, electroplating, etc., with the focus of innovation on using pulsed waveforms (square-wave, usually) to provide improved control, capability, etc. of processing.

In my spare time, I dabble in running quantum chemical computations, so far all with ORCA, and writing utilities related to comp chem (and other stuff) in Python (and sometimes VBA/VB.NET).

@hBy2Py Gah, fouled up the link syntax. >:-O

Loong

6:04 PM

→ 2 messages moved to Trash

orthocresol

7:36 PM

@M.A.R. My first thoughts are: I'm inclined to think the unanswered questions are low-quality.

Not bad enough to be closed, but bad enough such that nobody wants to answer.

A good example is this question on the front page right now:

0

Q: Finding pH using the mass of an acid, Kw and the volume that is produced

I'm curious about how one would go about this. As an example: 9 grams acetic acid (CH3COOH), mixed with enough water to produce an 800 mL solution. Find the pH. My progress: 8.7 g / 60.05 g/mol CH3COOH = 0.14 mol CH3COOH 0.14 mol CH3COOH / 0.8 L = 0.175 M CH3COOH I'm aware that I need to fi...

equilibrium ph

M.A.R.

@orthocresol Hmm, then we should run a search to see what percent of those are worth saving, and what percent are not

Either way, we should do something about it.

Either mass-purging, or mass-answering.

orthocresol

Mm. Yes, we certainly need more evidence than simply my personal observations, which are likely to be biased. ;)

M.A.R.

Or a mixture of both

orthocresol

SEDE doesn't retrieve deleted questions, does it?

M.A.R.

@orthocresol chemistry.stackexchange.com/…

@orthocresol It has separate tables to provide limited info about deleted posts

But they're usually very general stuff

You could go there and find out for yourself

orthocresol

7:40 PM

Okay.

Loong

@M.A.R. The roomba script will automatically delete a significant number of these questions.

M.A.R.

@Loong We won't touch those

Good for us

Still, asking a question, having it neglected and then deleted is not a very good experience

We're definitely not the size of SO, so we should bite our tongue not to come up with stuff like ''that stuff happens''

Loong

We could look for old questions that are clarified and answered in comments but don't have a formal answer, and encourage users to write proper and useful answers for these cases.

M.A.R.

Hmm, can we search for comments longer than an arbitrary length using SEDE?

We might come up with interesting results if we find questions with long comments but no upvoted answers.

I mean, really.

I'm aching.

Let's do some action before I have to get lost again

orthocresol

for(all comments){
if(comment.length >= 20) MAR.suspend();
else MAR.suspend();
}

You'd have to ask somebody else about SEDE, I can't do anything with it.

M.A.R.

7:50 PM

I have people to ask from, don't worry

but we should first decide what to do

orthocresol

I guess perhaps the first step is to take a sufficiently large sample size and see whether such questions are "good" or "bad". However, that raises the issue of what is good and what is bad

Loong

@orthocresol error – MAR.suspend is a function that takes one argument and returns no value

M.A.R.

@Loong No wonder I voted for you

I did vote for him/it too, but that's irrelevant

orthocresol

suspendUser(MAR);

M.A.R.

You don't have the authority to suspend the MAR

orthocresol

7:55 PM

Anyway, as we go along, if we spot those questions that are answered-in-comments, then we can collate them on a meta post or something.

Loong

@orthocresol We could need @Melanie for that. ;-)

M.A.R.

Heh, yeah

Her enthusiasm reminds me of . . .

orthocresol

@M.A.R. Of?

M.A.R.

OF

orthocresol

That's a rather unstable compound.

M.A.R.

8:07 PM

Well, you should fill that slot.

@orthocresol Unstable is enthusiastic

orthocresol

Her enthusiasm reminds me of @MelanieShebel

M.A.R.

Oh, that sounds familiar

I've probably heard it in a movie

Hippalectryon

9:22 PM

0

Q: CHEMISTRY !!!URGENT!!! PLEASE HELP RIGHT NOW!

1)How many moles of CO2 are in 225g of the NO2 gas? 2)How many grams are in 3.50 moles of K2Cr2O7? 3)How many molecules of CH4 are there in 6.55 moles of CH4? 4)How many moles are there in 3.55 x 10^29 atoms of Ag? 5)How many molecules are in 15.5g of CH4? 6)How many formula units are in 3.6...

homework stoichiometry

>.>

hBy2Py

@Hippalectryon Yeah, this is basically the prototype question for the 'homework' VTC. Oy.

Loong

Another one for the closed/unanswered statistic.

Melanie Shebel

9:55 PM

Okay what now?

Whose enthusiasm reminds you of me?

Jan

Oh boi, what’s been going on here? Great battery pun by the way! =D

Loong

@MelanieShebel Don't let @M.A.R. and @ortho confuse you.

Melanie Shebel

I have no idea, but @M.A.R. @orthocresol and @Loong are so in trouble! :P

Oh! Oh! Look who it is? I'm O-F?

:P

Loong

@MelanieShebel Uh-oh

Jan

Total confusion rules!

Melanie Shebel

10:00 PM

Yes!

No, seriously, what's up? I missed all that.

It's a shame you guys closed this question... couldn't you see the guy needed urgent help?

-5

Q: CHEMISTRY !!!URGENT!!! PLEASE HELP RIGHT NOW!

1)How many moles of CO2 are in 225g of the NO2 gas? 2)How many grams are in 3.50 moles of K2Cr2O7? 3)How many molecules of CH4 are there in 6.55 moles of CH4? 4)How many moles are there in 3.55 x 10^29 atoms of Ag? 5)How many molecules are in 15.5g of CH4? 6)How many formula units are in 3.6...

homework stoichiometry

Loong

2 hours ago, by Loong

We could look for old questions that are clarified and answered in comments but don't have a formal answer, and encourage users to write proper and useful answers for these cases.

2 hours ago, by orthocresol

Anyway, as we go along, if we spot those questions that are answered-in-comments, then we can collate them on a meta post or something.

Melanie Shebel

He could have been bleeding out and in need of emergency care.

Jan

@MelanieShebel Wouldn’t that make it a personal health question?

Melanie Shebel

Well, perhaps he was trying to perform first aid and needed to know the number of moles of CO2 he was using for...

...

the pump for his insulin? (Man that thing is rapid fire!)

It's obvious he needed "urgent help right now" as seen in the title of his request. :P

orthocresol