The Periodic Table - 2016-10-12

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1:00 AM

Hey, question was flagged as opinion-based. I don't see it, though. Just wanted resources. Am I in the wrong? Let me know and I'll close it: chemistry.stackexchange.com/questions/60686/…

0

Q: Isn’t this question basically ‘what should I study’?

After having been away overnight and then scrolling through the list of active questions since my last visit I came across this one. If I try to boil this down to its bare essences, it would be one of the following: Which research area would fit these criteria? What can I study doing X a...

discussion allowed-questions scope

I suppose, but I really want to know the breadth of computational chemistry under the umbrella of organic chemistry. Should I re-word the question?

I suppose the background I included in the question does make it "what should I study?" I will edit it.

2 hours later…

pentavalentcarbon

2:53 AM

@MelanieShebel I see the edits, and based on the rules of the site it should probably be closed.

There are just too many possible answers, and you've already received some junk in the comments.

It's a good question from a certain point of view, but it could set a bad precedent for "soft questions".

At least, if it is closed, the answers it's already received are good.

3:29 AM

@DHMO Oooh, learning German now are we? ;)

4 hours later…

Martin - マーチン

7:30 AM

@hBy2Py I am so busy right now, and now the meta... I need time to process all.

I can't wait to have this election done :D

@Aaron When you edit questions you can also kill any form of salutation: "thanks", etc... see also here Apart from that... thanks!

8:07 AM

4

Q: f-electrons in chemistry of heavy transition metals

In one lecture on recent MCR-X conference I was puzzled by a side-note "f-hole is critical to describe DoS of $\ce{IrO2}$ correctly." The context was DFT periodic plane-wave calculations with pseudization for core electrons. This implies, that f-electrons are somewhat involved into chemistry of...

quantum-chemistry transition-metals

@Martin-マーチン Can site mods edit this page: chemistry.stackexchange.com/help/notation ?

Martin - マーチン

lemicheck

@Loong yes

ok, nice, thank you

Could you fix the arrow in $$\ce{H2O +HCl <-> H3O+ +Cl-}$$ ?

Martin - マーチン

hmmmpf....

@Loong no I can't... there is something wrong with how MJ is interpreted on these sites

bug status-bydesign

8:27 AM

aha, ok

at least it's good that there is a link to our usual starting point on meta: meta.chemistry.stackexchange.com/a/88/7951

Martin - マーチン

yes... iirc this page spawned because there were serious limitations on the format of the help pages

but at least you managed to make me find another issue... there is still the beta-page in it...

@Martin-マーチン I can imagine.

8:49 AM

I was just thinking about optimizing our MathJax help and guidelines.

The existing meta answers are nice, but they are scattered and only discuss isolated issues. Many topics are incomplete; other topics are redundant or even contradictory.

However, if we try to make it thorough in one place, it would be terrible like the meta Sandbox.

For example, this answer is only about units: meta.chemistry.stackexchange.com/a/2978/7951

I guess, I could write a similar amount about quantities.

Using such large posts with many MathJax expressions is painful.

Hence, I am checking other options.

just use category @Loong

i mean tag

2 hours later…

10:40 AM

I was thinking that we can have one main FAQ for formatting, which covers the really basic stuff, and then links to the more detailed posts like those that you've done.

My experience is that the number 1 problem with new users' formatting (and sometimes even regulars) is that they typeset chemicals in italics.

I feel like the existing FAQ is already a bit too detailed.

For example, I don't think I've actually used any bonds apart from single and double bonds.

I don't think new people need to be told that \frac 12 results in the same as \frac{1}{2}.

They just need to be told: Hi, you can format maths expressions like this. Please format chemical expressions like this. And then we can link to the more detailed stuff.

@orthocresol Yes, I had the same idea. And in order to find a suitable structure for that, I was looking at the potential starting points (such as chemistry.stackexchange.com/help/notation or meta.chemistry.stackexchange.com/a/88/7951).

@Martin-マーチン I'll keep that in mind...while I'm sober, that is ;) [Kidding, heck I'm not even at the legal age to drink :'( , Ich werde drehen 18 jahre März ]

[I know I screwed up somewhere.....]

{Usually it's the agreement}

Martin - マーチン

lol

@orthocresol Yes, problem number 1 is probably writing things in italics (units, chemical formulas, etc.), followed by missing spaces (units), and wrong operators ($log$ instead of $\log$ etc.). But when you start to think about it, you may find more and more things, and soon the page is too large again.

Mmhmm.

10:55 AM

@orthocresol Heh, I always think the same when I read that line. :-)

I've used curly braces all my life haha

(But I also don't like the word "protip".)

Blame Manish.

Martin - マーチン

ಠ_ಠ

without him we wouldn't have anything to start with ...

!!doubleflip/Manish

11:00 AM

ɥsᴉuɐW╰(«○»益«○»)╯Wɐuᴉsɥ

So, the starting point is this meta.chemistry.stackexchange.com/a/88/7951 (or something shorter, cleaner).

The next step is the content of this answer: meta.chemistry.stackexchange.com/a/444/7951

Then we could also provide links to lists of useful operators and other symbols. I already have some lists in the sandbox.

Is there any pertinent information that hasn't actually been written yet?

13

Q: Thermodynamic and kinetic products - carbocation stability

The professor wants to know which is the thermodynamic product and which is the kinetic product. He says there are only two products - the two on the right that result from the resonance-stabilized complex. I can see a third product - the product on the far left with the question mark over an...

organic-chemistry carbocation reaction-control

@Chemobot o.o so we did have a question on addition of HBr to dienes

@orthocresol Hm, some things are relatively thin. I have written almost everything that there is to know about units, but almost nothing about quantities.

And "How to set tables in MathJax" is hidden in some sandbox examples.

11:23 AM

Hmm, I could write some stuff about mhchem if necessary.

A minor preliminary edit: I would like to make this link more prominent in the answer:

I think this meta-post should also be linked here: meta.chemistry.stackexchange.com/q/443/4945 — Martin - マーチン ♦ Jan 19 '15 at 10:51

Are there any objections?

Although the documentation at mhchem.github.io/MathJax-mhchem actually already seems like a good description. I don't think we need to duplicate that.

Nah, no objection.

@orthocresol Yes, I think the mhchem documentation is good. We only need a short introduction and a link to that page or to the pdf.

Mmhmm

Ok.. lunchtime. :)

2 hours later…

user228700

1:26 PM

Hi everyone :-)

@Kaumudi hi

user228700

I've got a small doubt; apart from act as a measure of the stability of a specific arrangement of atoms in a molecule, what does the formal charge really give?

user228700

Also, I'm a little bit dumb, so forgive me for asking this but these two formulas as equivalent, right?

user228700

1: formal charge = (number of valence electrons on the neutral, uncombined atom) - (number of covalent bonds to the atom in the current structure) - (the number of unshared electrons [not pairs] on the atom in the current structure)

user228700

2: Formal charge = [# of valence electrons] – [electrons in lone pairs + 1/2 the number of bonding electrons]

user228700

1:37 PM

*formulae are

@Kaumudi yes, that's equivalent

if you count a double bond as two covalent bonds

user228700

@Loong Right, OK.

user228700

And what about my first question..?

user228700

22 mins ago, by Kaumudi

I've got a small doubt; apart from act as a measure of the stability of a specific arrangement of atoms in a molecule, what does the formal charge really give?

1:54 PM

@Kaumudi Your doubt is justified. The formal charges do not necessarily correspond to the actual charge distribution in a molecule.

user228700

2:10 PM

OK..?

@NickAlexeev @Loong is acetic acid monobasic?

2

Q: Hydrogen in submarines: "keep below 8%" rule of thumb?

In the book "Against the Tide: Rickover's Leadership Principles and the Rise of the Nuclear Navy", Rear Admiral Dave Oliver (Ret.) narrates some of his experiences in the USS George Washington Carver, SSBN-656, launched in 1966, and in which he was hired as reactor controls officer. In particula...

measurements marine-engineering

@DHMO yes

@Loong how to know that the H-C does not count? It does have a pKa value

@NickAlexeev interesting

2:21 PM

like, if it is too high, then where is the bar?

@NickAlexeev That's one reason why we put so-called recombiners in our nuclear power plants

user image

@DHMO The pKa applies to the first hydrogen. When the -COOH hydrogen of acetic acid is removed, it's much more difficult to remove a second H+.

@Loong but it is still possible

is there a number beyond which the H does not count into the basicity?

@DHMO In aqueous solution, the limits are the pKa or pKb values of the corresponding water species (H2O, H3O+ etc.).

@Loong so 14?

2:39 PM

@Loong so hydrogen peroxide is monobasic because its pKa is 11.6?

Also, the pKa of CF3CH2OH is 12.5

2 hours later…

4:23 PM

!!daily

chemobot please

pH13 - Yet another Philipp

I think not everyone is allowed to do this

I see

2 hours later…

6:55 PM

How many times did we explain why the unit symbol "amu" is not correct? And still some long-term users use it. So by now I think they do it on purpose.

7:42 PM

amu is a correct symbol

Yes, it it is – but for an obsolete unit. It's not the correct symbol for the current unit that is used in various questions and answers.

It is correct

As Loong told me in one of my very first answers...

@9-BBN The international system of units, IUPAC, and ISO disagree.

Oh wait, the comments are deleted haha

7:46 PM

I'm joking bro :P

@orthocresol haha, oh man, how many hours did I spend with searching for old comments (which I couldn't find because they had been deleted)

We really need a comment search function. :D

Often I have just given up searching for comments. Searching for questions is hard enough already.

yes, indeed

It was on this answer: chemistry.stackexchange.com/a/38083/16683 but they're all gone.

Hullo @Wildcat

@orthocresol =^.^=

7:51 PM

@orthocresol sometimes I use Google with site:http://chemistry.stackexchange.com loong

Never thought of that..

And I really played too much with my last enthalpy of vaporization answer.

I even made a T-s diagram:

user image

That's almost a Rankine cycle for a primitive power plant.

However, the feedwater pump is missing.

And it would probably kill the turbine.

8:53 PM

0

Q: Kinetic isotope effect - why transition states taken as isoenergetic

I am working on the derivation of the equation below for the difference in activation energies for the two reactions (1) and (2). I've done the derivation, but I am unsure on some of the approximations I have used. When considering the activation energies I have just used the zero point energy...

physical-chemistry kinetics

lol, I recognise this

2nd year phys chem paper

2 hours later…

10:54 PM

Is hypochlorite anion stabilized by resonance?

11:35 PM

if the electronegativity order is really F>O>Cl>N then why do we say F>O>N>Cl?

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Transcript for

Oct '1612

The Periodic Table

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