The Periodic Table

Manishearth

6:39 AM

GOOGLE=OFF TOPIC

simple

@Fx I pretty much agree with your meta post, so nothing for me to add

Manishearth

6:59 AM

@Fx By the way, any input/improvements here?

1

Q: How can I format math/chemistry expressions here?

This post is meant to teach new folks how to use MathJax and mhchem formatting on chem.SE Waiting for community input - please make edits or leave feedback in comments below.

It's eventually required to fix meta.chemistry.stackexchange.com/questions/82/…

Richard Terrett

7:40 AM

@rcollyer Avogadro -> ORCA -> orca_plot -> VMD -> blender -> cycles

@Manishearth - there's a difference between trivially googleable and sift-through-many-pages googleable

Manishearth

@RichardTerrett hmm..

Richard Terrett

Part of research is knowing what to look for

Manishearth

@RichardTerrett Aah..

Still, "general reference" should be closed

Per-case I guess. If Google turns up the answer pretty quickly, close and link to the search page

Richard Terrett

It depends on how general it is. I don't think there's a binary distinction. Moreover, just because something's the first hit on google, does not necessarily mean that it's the best answer or even accurate.

To be clear, I largely agree with your stance.

Manishearth

@RichardTerrett Yeah, I got that :)

Richard Terrett

7:48 AM

However I also feel that at this formative stage in chem.se stringent closure criteria and narrow scope may scare people away.

You obviously have far greater experience with how SE betas work though

Manishearth

@RichardTerrett Not with betas

With SE, maybe

mainy Physics

and I'm active enough on MSO to know the general community opinions on such stuff

@RichardTerrett The beta policy ought to be the same as the main site--putting aside the incompleteness issues

As in, we shouldn't have policies which change just 'cos we graduate

Richard Terrett

I just hope the beta doesn't get canned due to lack of activity

but it is early days

Manishearth

As a beta, in fact it is necessary for us to filter out bad questions since the early ones represent the site

@RichardTerrett I don't think it will.. The ones which got canned had like a question a day

And that was after a month or two

Richard Terrett

I guess I feel like a few pop-sci questions can't hurt

Manishearth

Though we may take a bit longer to graduate

Richard Terrett

7:52 AM

and that there's no reason why a pop-sci question can't get expert level answers

Manishearth

@RichardTerrett Exactly

We need something like:

8

Q: What is the most efficient way to destroy the universe?

Don't worry... I won't actually do it, just would like to know how.

cosmology

;-)

That has an expert answer, as well as some funny ones

Richard Terrett

speaking of which, i read a paper a while back which has definite pop-sci appeal but a really surprising expert answer - why bubbles form in champagne

Manishearth

@RichardTerrett Actually, those questions are good for the site

Richard Terrett

(it's not because of imperfections in the glass, according to the paper)

Manishearth

everyday-life

Check out Physics' most upvoted questions

physics.stackexchange.com/questions

All of them popsci--but not really bad questions

SOme are actually great!

And the answers are awesome as well

My most upvoted answer is on a popsci question. My second highest has those votes just 'cos it has a floating frog ;-)

Sorry, not popsci--I mean everyday-life

there's a distinction

Popsci=bad

everyday-life=good

The distinction actually comes from how well written the question is, IMO

Alright, got to go

cya!

F'x

8:01 AM

@Manishearth that's good, but I haven't had time to read it thoroughly

@RichardTerrett the standard "close as general reference" reasoning is as follows:

@RichardTerrett I have a collection of paper on my hard driver about fun science and pop-sci questions treated rigorously

including the fairly well-known Will Humans Swim Faster or Slower in Syrup?

(and I've seen a Mythbusters episode on that… I'm a fan of the show)

@All community feedback time: what do you think about this one?

4

Q: Mercury, amalgams and mercury compounds

Mercury is toxic. It forms amalgams and inorganic mercury compounds/salts are available. My question is on toxicity. I am interested in its toxicity, not the mode of action (as it will be part of biology SE) Is amalgam toxic? (sort of yes / no) Mercury salts are toxic? (sort of Yes / no) If me...

metal toxicity

Richard Terrett

8:27 AM

@Fx I've read a paper from JAMA assessing heavy metal levels ayurvedic medicine - suffice to say they expressed concern

*in

@Fx To quote the conclusions: "One of 5 Ayurvedic HMPs produced in South Asia and available in Boston South Asian grocery stores contains potentially harmful levels of lead, mercury, and/or arsenic. Users of Ayurvedic medicine may be at risk for heavy metal toxicity, and testing of Ayurvedic HMPs for toxic heavy metals should be mandatory."

one product recommended for pediatric use had a mercury concentration of 104 mg/g

F'x

8:52 AM

@RichardTerrett at some point, they used mercury as baby powders, because one of the symptoms of mercury poisoning is gum decay, which makes cutting teetch easier :)

Richard Terrett

that's... horrifying

F'x

@RichardTerrett it was used in Britain until the end of WWII

Richard Terrett

oh, calomel, right?

F'x

@RichardTerrett calomel and other mercury salts, yes

Richard Terrett

"Since 1978, at least 55 cases of heavy metal intoxication associated with Ayurvedic HMPs in adults and children have been reported in the United States and abroad." :(

F'x

9:02 AM

@RichardTerrett darwinism in action?

Richard Terrett

@Fx I worked out what your location meant on your profile :D

'hmm, upside down mirror of venus... alchemical symbol? oh right, you're a resident of earth'

F'x

U+2641 EARTH

Richard Terrett

yeah :D

F'x

though mercury is cool: ☿

apparently, I don't have any font with Unicode alchemical characters in it on my computer :(

Richard Terrett

What OS?

F'x

9:07 AM

Mac OS Lion

Richard Terrett

that's odd

F'x

but the mercury above is the planet symbol, not the alchemy one

Richard Terrett

oh right

F'x

these are the ones I'm missing: unicode.org/charts/PDF/U1F700.pdf

Richard Terrett

@Fx how will you write your grimoire?!

Richard Terrett

10:03 AM

@Fx Ah, point groups. I wrote a schoenflies symbol package for latex, but never put in on ctan...

Anil

@RichardTerrett HI

Richard Terrett

@Anil hey there

Anil

@RichardTerrett Reg mercury question, i have got a small clarification. I read the discussion between yourelf and F'x.

Richard Terrett

@Anil - mmm?

Anil

@RichardTerrett I would like to know the concentration of mercury you were discussing are for Hg(0) or Hg(+1) or Hg(+2)?

@F'x are u there?

Richard Terrett

10:06 AM

@Anil The paper assayed heavy metals by X-ray fluorescence so I doubt that data would be obtainable

Anil

@RichardTerrett I could not get u. Can u elaborate?

Richard Terrett

@Anil - They only reported the quantity, no data on the oxidation states

@Anil - As far as I know, XRF does not give that data, though EXAFS might

Anil

@RichardTerrett I think the point lies there. I have got an information from one of the ayurvedic practioner that, Hg(0) is toxic and Hg(+1 / +2) a material. I have to searchre non toxic in salt form. While organic mercury compounds are toxic. But, could not any supporting

Richard Terrett

@Anil - That's not correct - there are many toxic mercury salts, such as calomel (mercury(I) chloride) (mentioned above)

Anil

@RichardTerrett Sorry, some typos. I think the point lies there. I have got an information from one of the ayurvedic practioner that, Hg(0) is toxic and Hg(+1 / +2) are non toxic in salt form. While organic mercury compounds are toxic. But, could not find any supporting material. I have to search

@RichardTerrett OK. I had this confuion. Hence posted the quesion

F'x

10:15 AM

@Anil mercury is toxic to some extent in all forms: metal, organic, inorganic

again, toxicity is not a yes/no question

Anil

@Fx Alright. Agreed. Do u have any info on other mercury compounds which are toxic (apart from calomel)?

F'x

@Anil have you read Wikipedia's “mercury poisoning” page?

Anil

@Fx I could not understand the statement (Yes / no)

F'x

@Anil toxicity is not a black or white thing

any compound will be toxic at some dose

water is lethal if you drink too much

Anil

@Fx That true. Toxicity is concentration dependent.

F'x

10:24 AM

@Anil so, I'd advise you to read the wikipedia page I linked, maybe some of the links in there, and edit your question to something more specific if you still have a question about part of it… your current “are mercury compounds toxic?” is more a textbook topic than a Q&A question

Anil

@Fx I will go thro wiki page and come back.

@Fx OK Has to go. catch u after 3-4hrs / 17-18 hrs

F'x

@Anil great… I'm not an expert, but I find this topic interesting

see you!

Anil

@Fx "Every one is student till they die" thats what elders say. We have to learn by discussing and that is what SE is all about

Richard Terrett

10:48 AM

Hopefully of something other than minamata

mercury compounds are not to be trifled with

@Fx Can mathjax be put in question titles?

F'x

11:15 AM

@RichardTerrett yes

Richard Terrett

@Fx Thanks

F'x

I got confused because other formatting (italics, bold and code) cannot

Richard Terrett

11:50 AM

@Fx When you say invariant, what specifically do you mean?

Richard Terrett

12:10 PM

F'x

1:14 PM

@RichardTerrett I mean, something like "calculating the interial matrix and finding out it reduced to a scalar" or that sort of thing

Anil

1:28 PM

@F'x Hi

F'x

@Anil hi again

Anil

@Fx i had gone thro wiki page on mercury poisoning.

@Fx Some how i am not convinced with metal / meal-ion part (not necessarily mercury). That is why most of my questions are based on metal/metal-ion.

Richard Terrett

@Anil - What are you not convinced of?

@Fx Computational chemistry software uses some funky maths to determine the point group but I can't remember where I read the details

Anil

@RichardTerrett Detection of one in presence of the other, how the property changes because of the change in oxidation states, etc

F'x

@Anil most of this page is fact-based, so it doesn't have to be convincing or not. It just is.

Anil

1:42 PM

@Fx Right its fact based. But, what makes these drastic changes in properties (of course apart from change in oxidation states, size etc)? I mean a comprehensive answer.

Manishearth

/me apologizes for not asking a question today

/me is not able to have chemistry thoughts at the moment

/me is bored

/me has to go

/me leaves

;-)

Richard Terrett

aww

F'x

@Anil again, mercury chemistry is a very wide topic… if you asked the difference between two compounds, you would be likely to get a satisfying answer… but noöne is going to write a compendium on mercury toxicity

Anil

@Fx Definitively not on mercury. In general any metal / metal-ion.

Richard Terrett

@Fx I've actually got a copy of Luoma and Rainbow - Metal Contamination in Aquatic Environments here

F'x

1:46 PM

@Anil my advice is that your question is too broad, and you tell me "no, it's not only mercury, I'm interested in all metals"? :)

anyway, I'm out of here, others might give you different advice, or your question might receive an answer as is… but I wouldn't bet too much on it

see you all!

Anil

@Fx Bye F'x

Richard Terrett

oh that reminds me: this is a great video

►

Anil

@RichardTerrett That mercury amalgam. Mercury when it comes with any other metal, amalgamation starts spontaneously.

@RichardTerrett Any way, cool video

Richard Terrett

yes, i know that

Richard Terrett

2:03 PM

@Anil - Based on Luoma and Rainbow, oxidised forms of Hg are far more soluble and reactive which makes them more toxicologically important

elemental mercury entering the ocean is a serious problem because bacteria methylate it and make it much more bioavailable and toxic

mercury amalgams do release bioavailable mercury slowly over time which is why amalgam fillings cause some consternation

even if the quantity being released is subtoxic, it increases the body mercury burden

If you can get your hands on a copy of Luoma and Rainbow, it has a chapter dedicated to tributyltin and methylmercury

F'x

2:27 PM

@RichardTerrett well, you gotta be punished for all those sweets you had as a kid (and maybe later), gottan't you?

Richard Terrett

@Fx Took me a moment to get your joke :D

I had a go at the tree carbon question, even though an answer has been accepted

Because I thought the really old experiment I read about was too interesting to leave unmentioned

@Fx J.M. has an interesting one on his or her profile

naming challenge

I think it might be [6,6] chiralane

Ooh, it has T symmetry apparently

F'x

@RichardTerrett I can't even begin to visualize the structure of that one

Richard Terrett

2:43 PM

@Fx yep. I believe it was invented by Uncle Al, that guy who turns up on every science site ever

@Fx You're in Germany, right?

F'x

2:57 PM

@RichardTerrett last time I checked, they hadn't invaded the country yet :)

I'm in Paris

Richard Terrett

Oh right

I might have you confused with someone else

i like your neologism 'gottan't'

F'x

@RichardTerrett it seemed logical :)

talking of logical, weather.com forecasts a temperature of 82°C for Paris tonight, I hope they got their °F's and °C's mixed up

Richard Terrett

there is nothing logical about the english language

native english speakers take a lot of constructions for granted which on reflection make no sense, like "got to"

82C, nice

F'x

hum, now I feel that this poor question has attracted a poor answer

/me sheds a tear

Richard Terrett

@Fx I find the notion of dissolving ice problematic

Andrew

3:09 PM

was that question closed?

or am i just imagining things?

F'x

@RichardTerrett yeah, me too

it dissolves water

well, the part after the edit is better than before

I mean, it would almost stands as is

maybe someone could edit it further?

Richard Terrett

@Fx that's a very interesting one about helium-3

helium is bizzare

F'x

@RichardTerrett I didn't know about that

and in fact, I was almost ready to write that statistical physics laws require a latent heat to be positive… but I would have been wrong!

helium-3 is to physicists as water is to chemists; the one compound that behaves like no other

Richard Terrett

@Fx Have you read anything on negative absolute temperature? that's a fun topic.

F'x

@RichardTerrett yes, I teach stat phys and use two examples of that: laser and nmr

usually, the students' reaction is: mind blown

Richard Terrett

3:19 PM

@Fx Oh cool

F'x

especially about the fact that a system with negative temperature is actually hotter than a system with positive temperature :)

all because ß = 1/kT, and ß is a much better variable than T (which is why I show these examples in the first place… I want them to use ß rather than T)

Richard Terrett

is that supposed to be a beta or an eszett?

:D

F'x

well, it's supposed to be a beta, and you weren't supposed to see the difference…

Richard Terrett

Sorry, can't help it

F'x

I don't have my greek keyboard mapping on currently

Richard Terrett

3:22 PM

I saw someone's final graphic design project once