The Periodic Table

hBy2Py

04:20

@orthocresol Oh, so now that you're a mod you see everything in megarep, eh? Well THAT'S not pretentious....

@orthocresol Also, see my addendumized answer (@Mart @Jan @M.A.R. @Benz)

Martin - マーチン

@hBy2Py link or it didn't happen :P

hBy2Py

04:58

@Martin-マーチン Oh hey! It seems I did forget to actually paste that link, didn't I? <facepalm>

5

A: A new policy of closure: November 2016

Wildcat's response to #4 fired off a thought: what if the odious aspect of a not enough effort question has less to do with the effort an OP has put into understanding and working on the question, but the effort the OP has put into engaging with the Chem.SE community? That is, what if the behavi...

Martin - マーチン

\(*v*)/

hBy2Py

I really need to up my emoticon game. I'm totally outclassed by just about everyone here.

Martin - マーチン

hahaha... I only have four stored in total

hBy2Py

I'm envious of @penta's "I can't believe you just said that" eyes.

Martin - マーチン

angry: ಠ_ಠ whatever: ¯\_(ツ)_/¯ please: m(_._)m and happy: \(*v*)/

hBy2Py

05:02

How/where do you have them stored?

Martin - マーチン

11

Q: Porkchat: A Chrome extension with lots of chat tweaks!

Install Install from the Chrome Web Store About Porkchat is a Chrome extension that bundles together a lot of scripts I have written for Stack Exchange chat over the years. It is fully configurable - each individual script can be enabled/disabled from the options page. Included Scripts ...

This has a few other useful features and it comes with a little box of preformatted text

hBy2Py

Huh. I now need an emoticon for "I think I just went down the rabbit hole."

But, anyways, I will be catching your response tomorrow. Way past bedtime here. <tips hat>

getafix

05:48

quick question: why would end-fluorinated acenes show co-facial, antiparallel packing motif

user228700

07:23

Hey everyone :-)

user228700

@paracresol: The mnemonic that u use to recall the electronegativity series has been very useful to me. I was wondering, dyou use any for the groups of the periodic table? (Ik there are many that I can (and have) find online, but still.)

Martin - マーチン

08:12

Anyone who wants to learn about unix and stuff: humblebundle.com/books/unix-book-bundle

paracresol

08:24

@Martin o/ Hallo

paracresol

08:50

@Kaumudi Awww, that was touching :3 It's not everyday I get a Tamil grovelling before me for mnemonics 3;)

user228700

-___-

paracresol

@Kau Well, I would, if only those particular mnemonics you need didn't, ahem, reveal my ~~perverted~~ aimless state of mind. ._.

@getafix PEG coughs :)

user228700

Ah, I see. Well, no matter, I found perfectly clean ones that I've memorized now, thanks for the honesty (?) :-P

paracresol

willkommen

Chemobot

◟(`ﮧ´ ◟ )@⋊ɐn

ᴉpnɯnɐ⋊@︵╰(゜Д゜)╯︵@⋊ɐnɯnpᴉ

user228700

08:55

?! —.—

paracresol

._.

> Not sure if this is meant to be a joke or homework. – M.A.R. 2 hours ago

@M.A.R. I see we have a saint here, who doesn't "condescend" anyone ;)

getafix

09:09

@paracresol busy busy ask me again in 4-5 weeks time

I can just send you the links later, if you're interested

hBy2Py

11:55

@Kaumudi I was basically clueless about the transition block until I started my current job doing electrochemical processing. I ended up having to memorize the 3d elements in sequence, but then remembered the groups by association of similarity of the elements within them.

Sc Ti V  Cr Mn Fe Co Ni Cu Zn
Y  Zr Nb Mo Tc Ru Rh Pd Ag Cd
La Hf Ta W  Re Os Ir Pt Au Hg

Sc column are rare earths, love 3+ oxidation state

etc.

I know none of this is actually a mnemonic though, sorry.

user228700

12:12

Oh, I see :-)

user228700

@hBy2Py Haha, yes. No worries.

Chemobot

10

Q: Boys function for Gaussian integrals in ab-initio calculations

A few days ago I mentioned a problem with an Hartree-Fock program I am writing (HF using cartesian Pople's STO-3G basis set). I can reproduce overlap and kinetic integrals of some references for ($\ce{H2}$, $\ce{HeH+}$ and $\ce{H_2O}$). Things start to change (at the third/fourth decimal digits) ...

quantum-chemistry computational-chemistry basis-set ab-initio

paracresol

13:10

@getafix Sure thing! ( slightly dejected )

@getafix I'd like that, but I'm not sure how much of it I'll actually be able to comprehend. ._.

Anyone happen to know why NaBH4 can't reduce this carbonyl group (the one I bubbled)? Apparently it can reduce the other carbonyl group (the one that's a part of the cyclohexane ring) ಠ_ಠ

A friend tells me it's because bubbled carbonyl group is a part of an ester linkage (RCOOR), but I'm not sure how correct that is ._. More importantly, even if it is correct, I can't seem to figure out why simply being a part of the RCOOR prevents the bubbled carbonyl gropud from being reduced. The same 'friend' tells me that LAH can reduce it because "it's a stronger reducing agent".

@Loong Got a minute? ^

Loong

13:28

@paracresol hm?

paracresol

@Loong Organic chem's your thing right?

Apart from radiochemistry, that is ._.

Loong

@paracresol The description is correct. Under usual conditions, NaBH4 doesn't effectively reduce an ester.

paracresol

@Loong May I ask, why it can't reduce an ester? I can't seem to find the answer to the 'Why' bit anywhere ._.

Loong

The C atom of the ketone is electrophilic. Look at the C=O structure of the ketone. Can you draw a resonance structure that shows why the C is electrophilic?

paracresol

@Loong Gimme a sec...

Loong

13:34

ok

paracresol

Alright! Proceed with your explanation Herr @Loong!

Loong

Now try the same with an ester R-CO-O-R.

paracresol

@Loong Gimme a while

Loong

Note that there are lone pairs on the other ester O atom that can participate in the resonance structure.

paracresol

@Loong Yeah, two of them right?

Loong

13:37

Yes, but only one will contribute to the resonance structure.

paracresol

Alright then.

@Loong There you go!

One lone pair taking part in resonance ;)

Loong

ok, now compare the location of the positive charge for the ketone and the ester.

And you should see why the ester C atom is less electrophilic than the ketone C atom.

paracresol

@Loong Yep, I do!

Loong

:-)

paracresol

Pardon my 'denseness' here but...

@Loong With a reducing agent like NaBH4, shouldn't just the nucleophilicity of the carbonyl oxygen matter? I mean, it is (supposed to) accept a hydrogen proton, right? ._.

Loong

13:46

@paracresol But first you have to add a hydride H to the carbon atom.

paracresol

@Loong Oh...yeah ( hits my forehead )

Wait...

@Loong In that case, wouldn't the ester easily accept the H+ ? It is less electrophilic ._.

Oh you're a LOTR fan @Loong? :D

63

Q: What does Sauron need with mithril?

In The Fellowship of the Ring, Book Two, IV A Journey in the Dark, Gandalf explains: The wealth of Moria was not in gold and jewels, the toys of the Dwarves; nor in iron, their servant. Such things they found here, it is true, especially iron; but they did not need to delve for them: all thin...

lord-of-the-rings sauron fellowship-of-the-ring mithril

Well, Mithril does make pretty good armour ;) If it weren't for Frodo's Mithril corset, he'd have been shish kebbabed by the balrog. :)

Perhaps Sauron wants a full body Mithril suit of armour...so some idiot doesn't chop offf his finger again :D

Loong

@paracresol In the first step of the NaBH4 reduction, there is no strong acid to protonate the ester. You add the acid in the second step, after the addition of hydride.

paracresol

....

@Loong Now I'll have to look up the mechanism, I'm kinda lost ._.

P.S- I don't recall any mention of Mithril being used in weapons ._.

paracresol

14:48

0

Q: "Do you know what it does to you, hydrogen cyanide?" - No, I didn't know that

In the 2012 movie Skyfall, the antagonist Raoul Silva rues that the "hydrogen cyanide" he took didn't kill him, leaving him horribly disfigured instead. Firstly; Could it have actually been HCN that he took? From what I know about this, HCN is a gas at room temperature, and gases aren't typic...

toxicity chemistry-in-fiction

@Loong Thanks! I (sorta) cleared it. :D

paracresol

15:12

Wait, another doubt:

Why couldn't the products of this reaction be ethyl iodide and methanol?

@ortho o/

orthocresol

@paracresol It could be, but SN2 at a methyl carbon is faster than at a primary carbon.

paracresol

@orthocresol Ah SN2, >.<

Wait @ortho, what about this then?

(Treated with HI)

orthocresol

Yeah, that is perfectly correct.

paracresol

...

Giimme a sec

Oh wait...I'm okay!

paracresol

15:49

@penta o/

Didn't see ya there :D

pentavalentcarbon

o/

paracresol

Oh Herr @DSVA you're here too? o/

@pentavalentcarbon Didn't you say you had "work" to do the other day? 3;D

DSVA

:D yes

pentavalentcarbon

one thing you learn as you get older is that you always have work to do...most of the time it isn't urgent though

4

paracresol

@pentavalentcarbon Gee, thanks for the spoiler ;)

pentavalentcarbon

15:58

you don't need to ping me, I'm here

paracresol

Alright...

But why are you here? I thought you were exploring the main site ._.

pentavalentcarbon

Otherwise Firefox goes "thunk" and interrupts my music.

No, now I'm doing "work".

paracresol

Sorry!

pentavalentcarbon

it's ok, better a ping party than no party

paracresol

@DSVA You seem like the adventurous kind, maybe this one's for you?

0

Q: What chemical would best adhere rubber to concrete and/or asphalt?

There are already mixtures in place that work well but I'm wondering if there is something better than is currently being used. http://www.jegs.com/p/PJ1/PJ1-Track-Bite/749307/10002/-1 http://www.vpracingfuels.com/page469700.html

everyday-chemistry surface-chemistry

@DHMO o/

DHMO

16:02

@paracresol what the hell?

who are you?

alt. account of @orthocresol ?

paracresol

Nope :3

DHMO

then who are you?

paracresol

@DHMO You're late to the party ;)

I'm @ortho's nemesis

chemistry.stackexchange.com/users/33991/paracresol?tab=profile

DHMO

@paracresol seriously, who are you?

Oh, I know who you are

it's quite easy to search lol

@paracresol

paracresol

Remember the nosy high-schooler that wanted to know the angle b/n 4 vectors spread evenly over a point?

109.5 degrees?

That guy :3

DHMO

16:05

I know who you are lol

paracresol

Who?

/

?

DSVA

@paracresol ew! I'm more the guy for small molecules:-P

DHMO

@paracresol @AaronAbraham

paracresol

@DSVA Verzeihung, ich wusste nicht :O

@DHMO Ja ;)

DSVA

:-D

paracresol

16:09

@DSVA Also if that's grammatically incorrect, pardon me for that too ._. (I have a feeling I could've used something better than Verzeihung )

DSVA

@paracresol no problem. It's technically correct but i guess no one would say it like that. "Verzeihung, das wusste ich nicht" would be better. "Verzeihung" is fine, more common would be "Entschuldigung"

=)

DHMO

!!img/paracresol

Chemobot

paracresol

@DSVA Point taken! ( Not entschuldigen? )

!!flip/@DHMO

Chemobot

◟(`ﮧ´ ◟ )@ᗡHWO

DHMO

16:16

!!flip/@ᗡHWO

Chemobot

(∿°○°)∿@DHMO

paracresol

Okay, that was clever.

But let's see what you do about this!

!!doubleflip/@DHMO

Chemobot

OWHᗡ@╰(«○»益«○»)╯@ᗡHWO

DHMO

!!doubleflip/@ᗡHWO OWHᗡ@

Chemobot

@DHMO OMHD@＼(｀д´)／@DHMO OMHD@

paracresol

16:19

As expected... that'd didn't correct the reversal entirely :3

DHMO

@paracresol well you can't

paracresol

That's why I gave it to you ;0

!!gun

Chemobot

ヽ༼xل͜x༽ﾉ <===== ̿’ ̿’\\̵͇̿̿\\з༼ຈل͜ຈ༽ ε/̵͇̿̿/’̿’̿ =====> ヽ༼xل͜x༽ﾉ

DHMO

...

!!flip/gun

Chemobot

(╯°ਊ°)╯︵ƃnu

DHMO

16:20

!!flip/iiƃnu

paracresol

:3

Chemobot

(∿°○°)∿ᴉᴉgun

DHMO

!!flip/!!gun

paracresol

fufufu

Chemobot

( つ•̀ω•́)つ¡¡ƃnu

̿̿’̿’\\̵͇̿̿\\=(•̪●)=/̵͇̿̿/’̿̿ ̿ ̿ ̿

DHMO

16:20

!!flip/¡¡ƃnu

Chemobot

(∿°○°)∿⅋#І9І؛⅋#І9І؛gun

DHMO

never mind

paracresol

@DHMO Let me guess... you're into inverse functions? XD

DHMO

@paracresol lol sure

paracresol

!!gun

Chemobot

16:23

(‥)←￢~(▼▼#)~~

orthocresol

16:38

@pentavalentcarbon so true

pentavalentcarbon

it sucks man...it means that when I go on vacation I have a hard time not thinking about work stuff

my mind just wanders

orthocresol

I dream about work somewhat regularly. Maybe I should do some work now..

those group theory tables, they are partly there to take my mind off work

still chemistry, but it's something more menial

pentavalentcarbon

I have much nerdier equivalents of that, but the problem is that the menial activity is something you actually need for work.

Which means it should be done on work time, not..."vacation time"...

Haven't had a dream about work in a few years, never about grad school, but I did have a bad undergrad dream about unfinished work...while in grad school. That was scary.

paracresol

3

Q: "Do you know what it does to you, hydrogen cyanide?" - No, I didn't know that

In the 2012 movie Skyfall, the antagonist Raoul Silva rues that the "hydrogen cyanide" he took ("Do you know what it does to you, hydrogen cyanide?") didn't kill him, leaving him horribly disfigured instead. Firstly; Could it have actually been HCN that he took? From what I know about this, H...

toxicity chemistry-in-fiction

Anyone?

Oh, you're back @ortho!

!!doubleflip/ortho

Chemobot

oɥʇɹo╰(ﾟxﾟ)╯oɹʇɥo

pentavalentcarbon

16:52

give it more than 2 hours...

paracresol

I'm impatient. ;P

orthocresol

Is the line between "work" and "vacation" more blurred when you're a computational chemist?

pentavalentcarbon

Yes. Even if it's never explicitly used again you, it's a weapon.

I turn off my email now when I'm on vacation. PI knows not to email me, but others don't.

orthocresol

17:11

I see.

Probably going to be doing organic for the next few years (masters+phd), so..

pentavalentcarbon

If I had to spend even 40 hours a week in a lab/office I'd probably go nuts.

orthocresol

That's what my friends tell me when I say I want to do organic. Or rather, they don't say anything, they just give me weird stares

pentavalentcarbon

I guess it all depends on what you want to do after. Anecdotally, I know so many people at a "low pressure" school that don't like it (organic).

Hexacoordinate-C

17:54

@paracresol as I mention in comment $\ce{HF}$ is also a weak acid and it can dissolve bodies and glass for example...

Zhe

18:15

@orthocresol It's like that in software engineering too... :/

orthocresol

18:26

@Hexacoordinate-C "hydrofluoric acid"

@Zhe Is this the time where I get to laugh at you guys for having real jobs?

Well, I guess it's not very far off for me, I pretty much have to study during holidays too.

pentavalentcarbon

@Hexacoordinate-C you don't need to add the polite thing at the end.

Zhe

@orthocresol You can if you want. :)

Hexacoordinate-C

18:45

@pentavalentcarbon but I like to do it ^^

Is there a template of a ring of 6 like in camphor?

in chemdraw*

Loong

@Hexacoordinate-C Like a norbornane? It's in the "Bicyclics" templates.

Hexacoordinate-C

Yes

OK thanks

orthocresol

19:12

grrr

idk why, but I get really irritated when people mix up molar quantities with "ordinary" quantities

Loong

@orthocresol sigh

orthocresol

@Loong If it makes you feel better (or perhaps more outraged), it's quite widespread even in Oxford.

Loong

@orthocresol and the usual "the molar x of Y is the x of one mole of Y" nonsense

orthocresol

yup

Loong

19:33

@orthocresol Yes, that's what I mean.

orthocresol

2011 exam paper right there

Loong

@orthocresol I usually loath to use so-called dimensional analysis; but in this case it should clearly show that R * T * dimensionless quantity doesn't have the dimension of energy.

orthocresol

@Loong what's wrong with dimensional analysis?

Loong

19:48

@orthocresol It can work for simple calculations: "density is kg per m³, so I have to divide the kilograms by the cubic metres to calculate the density" instead of the proper "density is mass per volume".

orthocresol

oh, I see what you mean

Loong

This can lead to students mixing quantities and units.

And it can fail if similar quantities have the same dimensions, or if dimensionless quantities are involved.

It can also fail if they have to use derived quantities such as joule and they don't know that 1 J = 1 kg m²/s².

Hexacoordinate-C

20:34

13

Q: Can Entropy Increase During Bond Formation?

Recently the question was asked, "Is Bond Formation “Strictly” Exothermic?" As a corollary to that question, what is the relationship between entropy and bond formation? Does the entropy of the bond formation reaction always decrease when a chemical bond is formed?

thermodynamics bond

@Loong it diementional analysis works for everything how hard you want. I use is commonly in chemical engineering ! :)

Thanks too BuckinghamTheorem

Loong

21:04

@Hexacoordinate-C ok, but I guess what most students actually mean when they say "dimensional analysis" is just "I don't know the equation; therefore, I try looking at the units".

Hexacoordinate-C

Very useful to know the units

I look at units every time I do a calculus know i'm able to see a lot of errors in calculus in just seconds

orthocresol

23:12

I'll write a meta post on this one day in the future, but just dropping this here for anybody who might chance upon it: If you're linking to related questions in the comments, or a related journal article, I'd like to propose that instead of simply giving the link, we should include the title of the question or journal article.

So for example instead of

> Related: chemistry.stackexchange.com/questions/1

I'd like to suggest:

It's a bit more effort, but I hope that it might give readers some idea as to whether it might be relevant to them without having to click on the link.

Loong

@orthocresol Yes, I think, I already do it like this.

orthocresol

@Loong Yeah, I noticed you do.

I thought it was helpful :)

Loong

A small disadvantage is that this text doesn't update if the title changes.

orthocresol

True. I guess an outdated title is better than no title.

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