The Periodic Table

orthocresol

00:24

Oh, another thing I want to drop here for consideration by anybody who's free: A search for "flourine" brings up 19 results. If you have a few minutes to spare, help edit one or two of them to "fluorine". :)

Jan

Say @Loong, you’ll probably know this. Is there a general rule for the strongest or longest-wavelength characteristic X-ray emission of an element? I.e. can something like ‘K_\alpha’ is typically the strongest emission’ be said?

(others who know are welcome to chime in, too)

Loong

@Jan Yes, the K series has the greatest energy.

5

A: Why elements with high atomic mass (like tungsten) are used in the production of X-rays, in the Cathode-Ray Tube?

If a sample containing a particular element is irradiated (e.g. with photons or, in case of an X-ray tube, with electrons) with an energy high enough to excite inner electron orbitals, X-rays are emitted in the de-excitation. In contrast to the continuous bremsstrahlung energy spectrum, the energ...

Jan

00:39

K’s energy is the greatest, but does that mean K’s intensity is also the greatest?

Loong

That's a good question. I have to check. I guess, it also depends on how the atom was excited, but the K_alpha should be the most important.

user228700

00:58

Hi, everyone :-)

Jan

This was why I wanted to know. As always, feel free to correct any chemical misconceptions ;)

user228700

Is anybody familiar w/ the Ostwald-Walker Experiment to determine the relative lowering of vapour pressure?

user228700

I found the following question (and answer) but I still don't quite understand:

orthocresol

@Kaumudi Nope, sorry.

user228700

6

Q: How does Ostwald-Walker method work?

From searching online I found this: The apparatus consists of two sets of bulbs. The first set of three bulbs is filled with solution to half of their capacity and second set of another three bulbs is filled with the pure solvent. Each set is separately weighed accurately. Both sets are conne...

user228700

00:59

OK .__.

orthocresol

@Jan You've actually made me curious about the typography. When I was reading solid state chemistry (specifically, the generation of monochromatic X-rays for diffraction), it was written as $K\alpha$.

Jan

X-ray

X-radiation (composed of X-rays) is a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV. X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. In many languages, X-radiation is referred to with terms meaning Röntgen radiation, after Wilhelm Röntgen, who is usually credited as its discoverer, and who had named it X-radiation to signify an unknown type of radiation...

They use a subscript.

orthocresol

@Kaumudi I'm actually quite curious as to why you guys do so much physical chemistry stuff, actually. The other day @para was asking about adsorption isotherms which I only heard of for the first time last week (in third year of university).

I swear I haven't heard of this Ostwald-Walker method in my life.

user228700

Ah, I see. Our syllabus is definitely quite extensive; in all 3 (Phy, Chem., Math) subjects, actually.

user228700

@orthocresol Haha. This is what I mean:

user228700

01:04

orthocresol

@Jan say, $K\alpha$ is the 2s -> 1s transition, isn't it?

(or $\mathbf{K}_\alpha$ haha)

Jan

@orthocresol 2s -> 1s is forbidden, to the best of my knowledge.

orthocresol

Yeah, that's what I thought. I can't remember if the lecturer mentioned it was 2p.

Jan

It’s the Laporte rule in effect, isn’t it?

orthocresol

Yup.

Oh well, shouldn't be worrying about this now... :p working on Heck reactions

Ah, yes: Kα is 2p->1s and Kβ is 3p->1s.

Jan

01:11

What the heck!

(sorry, couldn’t resist x3)

orthocresol

01:31

@Jan I know, the reaction just lends itself to jokes, doesn't it... :D

Jan

@orthocresol Yeah, but if you’re too Heck-tic about it you may miss one or two.

Loong

The Dieter Thomas Heck reaction?

Jan

01:51

Seeing so many posts by metacresol lately, I’m wondering whether there is a question that was answered by all three cresols … or maybe one of the cresols asked and the others answered.

orthocresol

@Jan :/

I'm a bit ambivalent about all the name-copying, I just hope it doesn't lead to any issues.

Jan

I think I mentioned before I laughed when Aaron did it but I was kinda skeptical when metacresol turned up.

orthocresol

Yeah one is fine.

We'll see, obviously impersonation hasn't been an issue since they are not acting maliciously, so it's been OK so far..

Oh well, the last thing I drop here before I go to sleep: a search for "phosphorous" yields 120 hits... now some of those are legitimately asking about H3PO3, but a lot of them are asking about the element, which should be "phosphorus". So... you guys know the drill by now :)

All those will be posted on meta one day.. one day

Jan

02:07

Which reminds me that we still need a new name for organophosphates …

orthocresol

Did you guys not decide to turn it to organophosphorus-compounds?

Jan

Too long =C

orthocresol

Oh :(

I guess the obvious generalisation is organophosphorus, although Mart said he didn't like it...

Jan

03:08

That moment when you realise you copied the wrong way and instead of copying the corrected version of your thesis into your backup you copied the old backup over your corrected version.

Martin - マーチン

04:59

@Jan How on earth did you do that?

@orthocresol Let's do org-pho-comp after we establish this in the common literature ;)

Winter is coming ... winterbash2016.stackexchange.com (soon)

6

orthocresol

10:42

69

A: Is toothpaste solid or liquid?

Toothpaste is what is called a non-newtonian fluid, more specifically toothpaste is a Bingham plastic. This means that the viscosity of the fluid is linearly dependent on the shear stress, but with an offset called the yield stress (see figure below). This yield stress is what makes it hard to s...

I tried explaining this to the TSA, they didn't buy it. — Anubian Noob Jan 19 '15 at 23:14

user228700

11:03

Does anybody here understand the derivation to find the mean life of a radioactive sample?

Jan

13:51

@Martin-マーチン I thought I was smart. I was too lazy to keep typing scp Other-PC:~/dissertation/filename.end . for wildly different files where no standard bash placeholder would capture them, so I wrote a script. Then, I wanted to do scp filename.end Other-PC:~/dissertation/. yesterday but I totally forgot that the script copied into the other direction …

Martin - マーチン

Well, I hope you didn't kill too much work. I'd recommend to look into rsync. I think there are options available that avoid such things, also it's way faster after the first time.

Jan

No, I just revived a few mistakes my dad had pointed out (which were written down so I could just recorrect them today) and about one sentence of new text.

I was actually thinking of expanding my script to do that. I want programming practice ;D But tbh I never really checked for existing programs.

Martin - マーチン

well good then, but you should really look up rsync anyway ;)

If you're done scripting you should get a review of the script. I learned a lot through it ;)

Jan

Oh, there.

Loong

Nov 17 at 0:23, by Loong

'Automating' comes from the roots 'auto-' meaning 'self-', and 'mating', meaning 'screwing'.

Jan

14:03

Yeah, that was the alphabetic sorting script ;)

Jan

14:39

Can I cite the Evans pKa table in my dissertation or is there a more reputable comprehensive source for pKa values that I could cite?

MartianCactus

ok

so i have a quick question

i saw this image on khan academy

why a, on one side of the molecules , it is written H3C whereas on the other side it is written CH3... they are the same thing right? Then why write them differently?

Jan

@MartianCactus Well, the bond goes to the carbon, not to the hydrogen. So if you have a choice, it is common practise to invert the label if all bonds come in from the right-hand side only.

Thus, if you wanted to write propane with explicit bonds, you could do so in the following way: H3C-CH2-CH3.

The first one inverted (all bonds on the right), the final two can’t revert (at least one bond from the left).

Since they are freely rotatable in space, there is no need to have hydrogens on one specific side.

MartianCactus

" Well, the bond goes to the carbon, not to the hydrogen.", what do you mean. Dont they share electrons?

bear with me, im a 10th grader

Jan

Draw out the molecule. H-C-C=C-C-H (and all the others that go off in different angles that I cannot draw simply inline).

Or maybe it works with monospace:

MartianCactus

i dont really understand..arent we talking about CH3?

why have you drawn 2 Cs?

Jan

14:53

  H H H H
  | | | |
H-C-C=C-C-H
  |     |
  H     H

There we go. Took a while.

MartianCactus

oh ok

Jan

I was drawing out the entire thing ;)

MartianCactus

yeah..

:D

so why H3C on one side and CH3 on the other?

Jan

As I wrote before. The bond from the central double-bonded C=C unit goes to carbon, not to hydrogen.

MartianCactus

how does a bond "go" to a molecule?

Jan

14:57

Bonds are between atoms.

MartianCactus

yeah sorry.

how does a bond "go" to a atom?

Jan

Well, it is a way of saying that there is a single bond between carbon and carbon.

MartianCactus

oh

still dont understand..

Jan

@Jan See this? That is the same cis-configured molecule. Except that I drew out all the C-H bonds rather than writing the shorthand ‘CH3’ (or ‘H3C’).

(Hover over the post to see what it ‘answers’ to.)

Imagine you are starting at the double bond in the middle and then going to the left. You will hit the left C of the double bond first. Then you hit the C of the methyl group. And only then you can hit the hydrogens. Thus, when writing that inline or in shorthand, it makes sense to have the methyl group’s C closer to the central double bond than its hydrogens. Thus, the hydrogens are moved left of the C by typographic convention.

Therefore, H3C-CH=CH-CH3.

MartianCactus

15:38

oh

so its just a way of representing parts of molecules

cool

thanks!

hBy2Py

17:08

@Mart, @ortho, @Loong -- did this edit of mine reach too deep?

chemistry.stackexchange.com/posts/63152/revisions

Jan

@hBy2Py I think it’s fine. It makes the post a lot better with readable images and stuff. Although you introduced a typo ;)

Loong

@Jan structre?

@hBy2Py I think, it's ok.

Jan

@Loong Yeah that one.

hBy2Py

17:24

@Jan –,– Fixed. @Loong

The -ene/-yne half of the question needs to be closed as duplicate, though, looks like.

Loong

Yeah, there are many nomenclature questions that are partly duplicates.

Sanjukta Ghosh

@Leeser I appreciate your previous answer to one of my questions. I have made a similar post. It will be very kind if you could help me out with this too.

paracresol

~~@hBy2Py~~ Brian o/

Hexacoordinate-C

17:40

0

A: Latent Heat and Kinetic Energy

Latent heat isn't heat, it is energy released or absorbed during a constant temperature phase change. The kinetic theory of gasses has little to say about phase changes. (Which by definition involve liquids or solids and may or may not involve gasses, most often "not".) Claiming a phase change re...

How to read that without be scared ? ^^

paracresol

@Hexacoordinate-C Alors c'est comme ca que tu ressembles ;)

Hexacoordinate-C

Tu es Français ?

paracresol

@Hexacoordinate-C Non

I just remember the French I learnt at school ;P

Hexacoordinate-C

We prefer to say "Alors, c'est à ça que tu ressembles" ;)

paracresol

@Hexacoordinate-C And my French needs polishing....

Hexacoordinate-C

17:45

Oui je ressemble à ça. Je suis un BCBG :P

paracresol

BCBG?

Hexacoordinate-C

You're French is ok don't worry :)

paracresol

@Hexacoordinate-C I still don't know what BCBG is ._.

Hexacoordinate-C

Bon chic bon genre

Bon chic, bon genre (English: Good style, good attitude) is an expression used in France to refer to a subculture of stylish members of the Paris upper class. They are typically well-educated, well-connected, and descended from "old money" families, preferably with some aristocratic ancestry. The style combines certain fashionable tastes with the appearance of social respectability. The expression is sometimes shortened to "BCBG" (the fashion company BCBG Max Azria was named in reference to the subculture). Parallels are often seen between this subculture and similar upper-class social groups in...

But I said that as joke

I'haven't that ego to say that

paracresol

@Hexacoordinate-C I kinda figured ;)

Nov 19 at 15:24, by Hippalectryon

Your french is actually very good @AaronAbraham

:3

But it sucks...actually ;P

Hexacoordinate-C

17:49

No it's ok

You just can't know everything

paracresol

Ah well, I can live with it.

@Hexacoordinate-C C'est la vie XD

Hexacoordinate-C

"c'est comme ça que" refers most of (the ?) time to something you or someone else "do" or "make" :)

most of time ?

most of the time ?

Don't know which one to choose ^^

paracresol

Nah, what I meant was "So that's how you look"

@Hexacoordinate-C I'd go pour ca ._.

Hexacoordinate-C

Yes and that is how you need to translate it

^^

paracresol

Point taken ^_^

Hexacoordinate-C

17:52

Or say "c'est à ça que tu ressembles" then

but not use "comme"

Even if it is not wrong it sounds not comfortable in my ears :P

paracresol

@Hexacoordinate-C This one's better :D

@Hexacoordinate-C My bad

Hexacoordinate-C

Bad boy you are

paracresol

Oui, je sais XD

But @Jan's the die-hard linguist around here...if you want a decent conversation in French around here you'll have to look up to that German :D

hBy2Py

@paracresol Have I broken your brain by changing my name? ;-)

paracresol

Oh wait, @Hippalectryon's a Frenchman too ._.

@hBy2Py ....

I'd prefer 'Brian' to h-bar ;)

@hBy2Py P.S- Your python doesn't look like any python I've seen before. ;D

@ortho \o

Hexacoordinate-C

18:08

@paracresol あなたのがっこはなんじからですか。

paracresol

I don't read kanji

Hexacoordinate-C

this are hiragana

The basics ^^

paracresol

I wouldn't know the difference XD

Hexacoordinate-C

kanji are chienese symbols

(look like)

I said "anata no gakkoha nanji kara desuka ?

paracresol

Nothing...

I was reading a manga, so that popped up ._.

orthocresol

18:10

@Hexacoordinate-C are you asking about school?

Hexacoordinate-C

yep

paracresol

:O

o:

orthocresol

i think 学校 is がっこう not がっこ

paracresol

@orthocresol Dafuq...

Hexacoordinate-C

Yes I forgot the last

orthocresol

18:12

of course, I just call it xué xiào...

paracresol

This isn't my turf...

Hexacoordinate-C

わたしはくるまでがっこうへいきます。

When people will not be polite I'll answer them in Japanese

Mithoron

6

Q: What phase of matter is shaving cream?

Our teacher asked us if shaving cream is a solid, liquid, or gas. She didn't quite know herself.

everyday-chemistry phase

Hexacoordinate-C

foam

paracresol

@Hexacoordinate-C Answer them or insult them?

Hexacoordinate-C

18:14

Answer in Japanese

Mithoron

It's annoying when things I want to dupe get to be HNQ :(

orthocresol

@Mithoron HNQ questions are always the "lousy" ones.

Mithoron

sigh

Hexacoordinate-C

@Mithoron ヘリオホアリヨウ？

This is english written in Japanese :P

Mithoron

@Hexacoordinate-C So what? Could be written with russian, hindu or elven letteres too ;)

paracresol

18:19

@Mithoron Hindi mind you ;P

Hexacoordinate-C

Hebraic must be fun too

Mithoron

@paracresol devanagari :D

paracresol

All hail Chem.SE

^That was English written in German XD

@Mithoron ...

Mithoron

@Hexacoordinate-C or greek

Hexacoordinate-C

But greek is commonly used in physics

paracresol

18:21

@Hexacoordinate-C German's far more common ._.

But what's even more common is... English

Mithoron

@paracresol name of alphabet in India?

paracresol

@Mithoron Curious: Do Poles speak Russian or Polish?

Mithoron

@paracresol Very funny

paracresol

@Mithoron I am Indian, I should know hmpf

@Mithoron I'm serious .-.

I'm not into eastern-european trivia

Mithoron

@paracresol Every Slavic nation has it's language

paracresol

18:25

I wasn't aware of that 0_0

Mithoron

Asking this particular question can be thought as insulting :(

paracresol

@Mithoron More like Learning ._.

Mithoron

@paracresol I see you really didn't knew, but it could be a insult otherwise

paracresol

Sorry >.<

Mithoron

We're sort of proud nation I guess :D

Hexacoordinate-C

18:29

Distilling Mercury

►

paracresol

@Mithoron But the Germans dealt with you guys fairly quick ._.

Mithoron

@paracresol Haha better stay sorry then ;)

paracresol

!!wiki/Invasion of Poland

Chemobot

Invasion of Poland

The Invasion of Poland, also known as the September Campaign, or the 1939 Defensive War in Poland (Polish: Kampania wrześniowa or Wojna obronna 1939 roku), and alternatively the Poland Campaign (German: Polenfeldzug) or Fall Weiss in Germany (Case White), was a joint invasion of Poland by Nazi Germany, the Free City of Danzig, the Soviet Union, and a small Slovak contingent, that marked the beginning of World War II in Europe. The German invasion began on 1 September 1939, one week after the signing of the Molotov–Ribbentrop Pact, while the Soviet invasion commenced on 17 September following the...

paracresol

@Mithoron But the Poles were quite plucky all the same :)

hBy2Py

18:35

@paracresol I was just going to use the official Python logo, but I didn't want there to be any chance of a misunderstanding that (1) I'm some sort of Python expert or (2) I'm endorsed by the Python community in any way.

paracresol

Just when I was gonna come down on you on behalf of the Zoology community for using a non-existent snake XD

Sanjukta Ghosh

19:40

An open question to all.
I was performing titration along with my class using the same analyte and titrant as everybody. I found that the amount of titrant needed to reach end point varied among groups. I'm sure I didn't make any mistake, followed the manual and verbal instructions word by word but at the end of the experiment there was someone who reached the endpoint with 0.72 ml of titrant while mine was 2.2 ml. I can't figure out what was behind this huge variation. We took the analyte individually i.e simple water from a running tap, could it matter? Or are there other factors as well …

Jan

So I’ve turned into a die-hard linguist; wow xD

2

Loong

@SanjuktaGhosh What parameter did you analyze?

Jan

I wish I had already figured out how to turn my keyboard to kanji/kana on this PC … if only to annoy @hexa … xD (Also I agree with gakkou)

Sanjukta Ghosh

@Loong Amount of dissolved CO2 in water samples.

Loong

@SanjuktaGhosh I see. In this case, I guess, the representative sampling of the tap water and the stability of the sample are your main problems.

Sanjukta Ghosh

19:51

@Loong What do you mean by stability of the sample?

Loong

@SanjuktaGhosh When you take a water sample, how do you make sure that the amount of dissolved CO2 doesn't change before you perform the chemical analysis? If the water sample is open to the atmosphere, it can exchange CO2 with the atmosphere. And if the temperature of the water sample changes, the solubility of CO2 in the water changes, too.

Sanjukta Ghosh

@Loong Well I ensured that no O2(g) got dissolved by covering the mouth of conical flask with my hand. May be the other one didn't do that.
Thank you, anyways.

orthocresol

20:27

@orthocresol Just to clarify, I usually don't think they're actually lousy. As with all science sites, the Chemistry HNQs just tend to be the more layman-accessible questions, which can make them less "interesting" depending on what one finds interesting.

paracresol

You...pinged yourself?

Jan

@paracresol Yeah that works.

paracresol

Ooh! Let me try! @paracresol :3

...

Loong

20:48

XXX has chemicals is not a way to start an answer on scientific page. — Tomáš Zato 8 hours ago

hBy2Py

21:00

@paracresol Technically, he replied to his own chat message.

You have to scrape the chat message id from the permalink and then construct the 'reply' syntax manually:

http://chat.stackexchange.com/transcript/message/33811390#33811390
|
V
:33811390 Ta-daaa!

@hBy2Py Ta-daaa!

orthocresol

What sorcery is this

paracresol

@hBy2Py This is why we need a Python at The Periodic Table :3

hBy2Py

<bows>

@Jan To be fair, it can sometimes sneak up on one.

DSVA

21:15

good evening

orthocresol

I am asking for a mechanism of reaction that I couldn't get, and it has no relation with a homework (it's not) — Cici Ben 40 secs ago

DSVA

but pliiiiz

orthocresol

When I read that title, I already knew I was going to close it...

Jan

Same.

0

Q: The mechanism of this reaction pliiiz?

What is the mechanism of this reaction ? What is the products from this reaction ? Ketone + water = ??

organic-chemistry

DSVA

what I don't understand is that those are usually not extremly simple questions. So I would expect them to be a little bit older but still they use stupid titles (like "help please!") and expect someone to help.

orthocresol

21:23

@DSVA I think that is why we still need strict schedules in university. :)

DSVA

I think that's why we need the exact opposite:-P

orthocresol

True, true, maybe it should be the other way round :D

gannex

23:41

does anyone know where to find a big fat list of metal carbonyl v(CO)s?

orthocresol

23:52

@gannex you might get lucky with an organometallic textbook, perhaps

I suspect Elschenbroich might have such a table.

gannex

I'll check it out

I've got crabtree out right now, but they just have a little table. I guess it's kinda more of a handbook really.

orthocresol

Crabtree's a really good book to read, but it's short.

So I'm not surprised that it just has a small table :p

gannex

I love it. I read the whole thing on the bus :)

orthocresol

Yup, I recommended it to lots of people last year haha

gannex

I wish I could get english copies of these seminal German texts like Elschenbroich and Holleman-Wiberg

orthocresol

23:57

They do exist

That said, they're pretty hard to get.

gannex

yes, but not as free PDFs

orthocresol

Oh yeah, not as pdfs.

Transcript for