The Periodic Table

01:30

@bon The answer is: You can't. And it does not matter where you live, you just can't. I don't know if it is off-topic though. I don't see much use in the question in the first place. And why would it be bad just because it is shipped from Hong Kong? I have however no idea, which reason to give as a close reason. (cc @Jan, @pH13)

9 hours ago, by Wildcat

Don't fret! I'm trying to write (a) canonical answer(s) to this question, will hopefully get it done tomorrow. — inɒzɘmɒЯ.A.M Aug 21 at 20:28

Is that the massive 30k answer, that was promised? @inɒzɘmɒЯ.A.M?

Martin - マーチン

01:55

@Wildcat If TD-DFT offers you only a messy solution, it is probably wrong 0.o And for open shell systems it is probably meh. all the way any way always... I just reread your question, you seem to have quite a bit of spin contamination in there... maybe there is too much multireference character...

Martin - マーチン

03:56

@inɒzɘmɒЯ.A.M ron -> no action needed; Dalton's Atomic Theory; in the queue

Wildcat

07:12

@Martin-マーチン, to be honest, I don't even remember what the system was. :D

Martin - マーチン

I can absolutely understand

Wildcat

I think it was some heavy metal complex.

Martin - マーチン

if it was a doublet you are still quite close

i had an s² of >3.5 for my doublet

Wildcat

XD

Martin - マーチン

so in principle complete garbage

Wildcat

07:15

Anyway, the problem is that in many cases TD-DFT is the only option for excited states calculations.

You can suspect multireference character from the beginning and still use TD-DFT just because there is no choice. :(

Martin - マーチン

yeah... mcscf still goes a long way...

it's just like dfa in general... sometimes right for the wrong reasons, seldom right for the right reasons, and often just wrong .... what a pity

and when you get close to the right/right combination, you have so much comp effort, that you can prolly do wave function calcs

Wildcat

:D

Martin - マーチン

07:35

I am just learning (again) mcscf and friends, because of this awful misfortune...

inɒzɘmɒЯ.A.M

09:46

@Martin-マーチン Yes.

Still a month to go.

Martin - マーチン

y?

inɒzɘmɒЯ.A.M

@bon It's 'unclear'.

@Martin-マーチン I want to haz a necromancer badge. (/¯◡ ‿ ◡)/¯ ~ ┻━┻

Martin - マーチン

meh. ┬─┬ ノ( ^_^ノ)

user161117

10:59

@inɒzɘmɒЯ.A.M I was just playing around with some numbers and remembered you said you didn't like the octet rule. Maybe we should just call it the double square rule and that would work right? :P

inɒzɘmɒЯ.A.M

@StevenGrigsby Let's call it eightet rule.

user161117

lol

user161117

yeah but double square rule encapsulates 2, 8, 18, and 32

Wildcat

:O

user161117

if electrons didn't pair up we could just call it the square rule rofl

user161117

11:02

although I think this is also going to come with exceptions unfortunately since you have some transition metals with 16 instead of 18 due to the s and d orbitals but w/e

user161117

ok ok double square doesn't sound good but how about the 'paired squared' rule? xD

user161117

To be honest I came to this calculation because I had heard that neutron stars are basically giant atoms and could be modelled using QM sometimes so I thought I'd try to figure out how many valence electrons it might have haha

inɒzɘmɒЯ.A.M

I thought there were no electrons in neutron stars.

I don't know enough about them to judge.

But I thought they were, d'uh, made of just neutrons.

That also would explain their immense density, so I wasn't skeptical.

So you're saying neutron stars have electrons @Steve?

user161117

Haha beats me

user161117

I never looked into it

user161117

11:18

I was just sitting in my hammock reading a book and then I got to thinking that orbitals add in consecutive odd numbers and hold a pair of electrons so I could try to look beyond the periodic table since this pattern is 2n^2

user161117

oh cool

user161117

inɒzɘmɒЯ.A.M

@StevenGrigsby nom nom nom'

user161117

lol yeah it does look surprisingly tasty like mochi or something

Secret

11:36

hi steven, I am back and ready to read your explanation

user161117

12:14

oh what explanation I don't know if I gave one

inɒzɘmɒЯ.A.M

Haha you should hide @Steve.

user161117

lol "Dear diary, today I continued to ignore advice from that backwards name guy, love Steven <3"

Secret

12:58

@StevenGrigsby the quantum mechanical contribution to chemical energy besides the thermodynamical one

Wildcat

13:39

@Secret, what is this mysterious "chemical energy" you folks are talking about? :O

inɒzɘmɒЯ.A.M

@Wildcat It's yoga stuff cats don't know about.

Wildcat

:D

@inɒzɘmɒЯ.A.M, cats know everything!

inɒzɘmɒЯ.A.M

@Wildcat . . . that relates to their eating something.

Anyway I'm leaving off for kung fu class. o/

Secret

@Wildcast

Wildcat

@Secret, you ask about a thing ("chemical energy") which does not have a standard meaning.

So, first you have to define it and then ask is it just something or not in accordance with the definition.

Wikipedia has a rather vague definition.

Chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction to transform other chemical substances.

Secret

13:50

I am trying to double check my understanding on whether electrostatics between electrons and nuclei is the only type of energy that allow molecules at ambient conditions to react with each other when they bump into each other at the correct orientation

Basically I am trying to check the nature of all energy in a molecule in terms of energy types in physics only

Wildcat

There are at least 5 terms in the total energy of a molecular system:

kinetic energy of nuclei;

kinetic energy of electrons;

Secret

put it in another way, assume there's never a subejct called chemsitry, how will physicists describe all the energy changes that take place in the molecules, like what are the names they will use the label those energies

Wildcat

and three potential energies of Coulomb interactions (e-e, n-n, n-e)

Secret

Steven then said something I never aware before (unless he is referring to the eigenvalues of the hamiltonian of the wavefucntion of the molecules) "No, chemical energy is not just electrostatics, it's also quantum mechanical which does include coulomb forces but also some things to do with how probability works on small scales that's a lot different than macroscopic probability. At least this is the best way I can think to describe it."

This caused me to ask for clarification on this thing I have not considered about, but at that time, my time zone means I have to sleep early and he also …

Wildcat

@Secret, it is difficult to understand what the heck are you talking about there.

Total energy of a molecule not just electrostatics. Sure, of course, it is not.

1) It contains kinetic energy and not only potential.

2) Potential energy terms are not classical electrostatic interaction terms, but rather quantum mechanical.

Secret

13:59

(Sorry, typed too slow...)
So basically, he description gives me an impression there is a type of energy of quantum mechanical nature that is neither the Hamiltonian nor the zero point energy of the system, and I am curious on what he is saying

Wildcat

So, yeah, they are expectation values of the corresponding operators, not classical energy terms.

@Secret, no, energy of a molecule is nothing but the expectation value of the total molecular Hamiltonian.

Secret

ok I see

Wildcat

I think @Steven referred to potential energy terms being not a classical electrostatic ones.

That is true.

But this is the same story as with any quantum system. Nothing special about molecules.

On the way to success

@Wildcat: HEy there

Wildcat

@Onthewaytosuccess, hi!

On the way to success

14:03

@Secret: helloo

Secret

hi

On the way to success

there is water in mars

Google told me

@Wildcat: Hey how the quantum chemistry is like?

I have never studied it

Wildcat

@Onthewaytosuccess it is... different! :D

On the way to success

What is the different

Is it go into much deep or what>

Wildcat

@Onthewaytosuccess yeah, it goes as deep as you need (for chemical purposes)

and when you go so deeply things are totally different from what one might expect

On the way to success

14:12

May be sound no-sense?

Wildcat

At least counter-intuitive.

On the way to success

When I started to learn chemistry , it gave me no clue

I mean all those elements properties and kinda like that

@Wildcat: Have you done programming

Wildcat

@Onthewaytosuccess, yes.

Secret

@Wildcat you said there's a difference between computational chemistry and quantum chemistry. What does it like?

Because right now I am doing some molecular dynamics calculations via quantum mechanical methods and wikipedia is not very helpful in showing how quantum chemistry is distinct from computational chemistry

Wildcat

@Secret, I would say that compchem is broader term then qchem.

Compchem includes qchem but is not limited to it.

Say, MM calcs are a part of compchem as well.

Classical MD calcs are also there.

But neither MM or classical MD are quantum.

Secret

14:29

makes sense

is there exists modern quantum chem approaches or concepts that does not require computer programs?

simailr to how theoretical physics don't always need computers

Wildcat

Plus you have a lot of other staff in en.wikipedia.org/wiki/Cheminformatics

which is also a related area

@Secret not sure that I understand it fully

but I'd say no

you need a computer

Secret

I mean,
e.g. Quantum field theory (QFT) formalism in theoretical physics can be done on blackboard when they are trying to build equations to describe some particles. These equations can be formulated without needing help form a computer. The computer part only comes in when you are using it to calculate something. Also there's feymann diagrams etc.

But as far I know, whenever people talked abotu quantum chemistry, they seemed to always tied it with computer programs or molecular softwares to do things like DFT or ab initio calculations

Wildcat

@Secret everything is done on a blackboard first.

For wave function theory you could look at this infamous book, for instance, amazon.com/…

Secret

O cool I have the blue one

Wildcat

@Secret, Szabo & Ostlund is a good starting point.

Helgaker et al. is a Bible. XD

the Bible of Quantum Chemistry

I mean

pH13

14:42

@Wildcat meh

pH13

16:15

@inɒzɘmɒЯ.A.M you there?

inɒzɘmɒЯ.A.M

16:46

@pH13 I there.

pH13

I got my answer @Loong time before

but do you know sth equivalent to a possible general-chemistry?

inɒzɘmɒЯ.A.M

Wha do you mean?

pH13

what I wrote

inɒzɘmɒЯ.A.M

You're looking to tag a question, but I don't even know what it is. So gimme a link.

pH13

there is no general-chemistry right now ... but maybe there is sth equivalent and you know it but I don't

inɒzɘmɒЯ.A.M

16:51

Why would we need a terrible meta tag like that?

pH13

why meta?

inɒzɘmɒЯ.A.M

Because we have better stuff.

Hippalectryon

17:22

boo !

pH13

:O

Jan

*jumps*

Hippalectryon

2spooky4u

Now on to serious things :P the internet is full of good websites to learn maths at all levels, but I have yet to find a good, free one for chemistry :/ the closest I know would be chemwiki.ucdavis.edu, but it really lacks clarity in several subjects, and the organization is pretty random

Know any ?

bon

@Hippalectryon This is a good organic chemistry textbook. www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/intro1.htm

Also, we now have a post for exactly this sort of thing

5

Q: Resources for learning Chemistry

Based on various other Stack exchange site (Mandarin Chinese, Russian and German), we adapt this project here for chemistry, since it's a great idea to have all kinds of resources in one place. This is a specifically created Community Wiki which gathers resources for learning Chemistry. The list...

Jan

> Now on to serious things: The internet […] (Hippalectryon, 2015)

Spot the mistake.

Hippalectryon

17:28

Thanks :D @bon

Yu Bin Lee

@Hippalectryon you could try the chmistry crash course...

Hippalectryon

@YuBinLee What is that ?

pH13

and also: where is that? :)

Hippalectryon

@bon Most of those are books though :/ in terms of websites (and modern-looking websites) it's pretty scarce

bon

Yeah there is always more to add to it. I just wanted to publicise that it now exists

inɒzɘmɒЯ.A.M

17:34

@YuBinLee No thanks I'm not planning to go in a TLC.

Hippalectryon

Why is Chemistry so much harder to learn on the internet than physics and maths :c

Jan

@Hippalectryon It's all because chemistry is superior to physics and maths.

3

inɒzɘmɒЯ.A.M

@Hippalectryon I think I always get better results when I search for an answer to a question not a tutorial.

And there's that.

Hippalectryon

@inɒzɘmɒЯ.A.M You gotta know stuff to ask questions though

Jan

*sigh* What to do with this guy:

-1

A: What are the correct resonance structures of nitrous oxide?

Assume that all of the atoms in N2O were sp3 hybridized, then bonding the 3 atoms together could produce a hexagonal ring structure with 3 bent, angular, indirect bonds , also called "banana bonds" of the Linus Pauling "Bent-Bond" theory where all of the atoms are sp3 geometrically tetrahedral st...

orthocresol

17:48

No offence but the guy seems a little odd. He claimed that ozone formed a hexagonal structure and that there were ten Fe-C bonds in ferrocene.

And that's my first contribution to chat ever!

Jan

Welcome to the table @orthocresol

Exactly what I was implying. Hexagonal ozone structures?! Please! I mean, banana bonds all aside but he's just taking it two steps too far and to obnoxiously …

inɒzɘmɒЯ.A.M

@orthocresol Welcome to the Table @Ortho!

orthocresol

Thank you! However I shall go off to sleep immediately after showing myself as it is rather late ^^ currently GMT+8......

Jan

@orthocresol Lake Baikal's timezone =D

inɒzɘmɒЯ.A.M

Oh boy, Australia I take?

bon

17:52

Hexagon love :D

inɒzɘmɒЯ.A.M

For your amusement.

bon

lol

Hippalectryon

But... did we find the movie ? :P

Jan

To be fair, it was probably only just edited xD

orthocresol

born in Malaysia, residing in Singapore, studying in UK and going back there in a week's time. I checked out Baikal it's really pretty! A good evening to all of you and good night to me :D

inɒzɘmɒЯ.A.M

17:58

For your amusement

Hippalectryon

> searching for an easy physics experiment to do & analyse for a "research" project during the year
> searches "easy experiment" in arxiv's abstracts
> I don't understand a single paper :c

inɒzɘmɒЯ.A.M

Man today is full of surprises.

@orthocresol Nighty night!

Hippalectryon

Anyone got an idea of a cool experiment/subject I could use ? Or somewhere I could find one ? It's supposed to be a personal research project on any good enough subject, it should have some "theoretical" part and some "experimental" part. Last year I studied the deformation of ferrofluid under the action of a magnet and caracterized the surface in function of the different parameters using fluid mechanics and whatnot, but I'm out of ideas this year :(

It shouldn't be too easy (the research needs to have some value) nor too hard (I should understand it well)

inɒzɘmɒЯ.A.M

@Hippalectryon How dangerous can/should it be?

Hippalectryon

Not too dangerous, but it doesn't have to be extremely safe either

For instance it could involve 2W lasers, if I only I had that

But it shouldn't be like "pour two Kg of sodium into water. Observe closely"

:P

inɒzɘmɒЯ.A.M

18:05

I was thinking of some kinda degredation.

Hmm, hydrazine is a bit expensive . . .

Hippalectryon

I'm willing to spend a bit of money in material/... (up to €50) if necessary

It's better if it's a bit 'original' or 'homemade' (for instance 'How fast should I walk in order to keep my tea from spilling on the floor' is better than 'How can I maximize a solar panel's efficiency')

Jan

@orthocresol yeah, I was there like three weeks ago. Loved it. Wish I could have stayed another day <3 Sleep tight!

Hippalectryon

@inɒzɘmɒЯ.A.M Do you think I should also ask in the h bar ?

Jan

18:24

I don’t know why I’m bothering. — Jan 35 secs ago

Re chat.stackexchange.com/transcript/message/24400213#24400213

@Hippalectryon You probably should. More opinions are usually better.

By the way, I love how that guy's average answer score is -5 xD

Hippalectryon

The h bar is dead :(

~de profundis~

Jan

@Hippalectryon Sad that it happened. Let's sing a funeral song. Look for a Haiku.

inɒzɘmɒЯ.A.M

18:39

So many stars today. (づ｡◕‿‿◕｡)づ

Jan

I feel like a star. Sparkling brightly in the sky. Outspoken will come!

Damnit, why didn't I write down the exact mass of C9H18O2 [M+Na]+?

Jan

19:24

What the HECK just happened?

Loong

@Jan many sites are affected. The mods are looking into it.

bon

Ummmm...interesting

Loong

24

Q: Can we raise the bar for reputation for late answers to enter the review queue?

I would like to raise the bar for late answers to enter the Late Answers Review Queue to 50 rep, which is the threshold after which users gain the ability to comment. Here are some answers that were posted by users with between 10 to 50 rep (yes, there's a little selection bias to be sure. I susp...

feature-request status-completed review new-users late-answers

inɒzɘmɒЯ.A.M

@Jan 24 in chem.

Well, time for some reviewing and editing.

Loong

get your review badges

Jan

19:28

Yeah, something like that. Helpful to get towards that reviewer badge x3

Damnit, I can only review 20 late answers D=

Give me a table I can flip!

inɒzɘmɒЯ.A.M

（ノT＿T)ノ＾┻━┻

Hippalectryon

Here ┻━┻⊂(▀¯▀⊂)

Jan

@Hippalectryon （ノT＿T)ノ＾┻━┻ Thanks!

pH13

(/¯◡ ‿ ◡)/¯ ~ ┻━┻

Wildcat

Stop doing it!

I was sleeping and watching dreams!

Hippalectryon

19:38

༼ ͠ຈ ͟ل͜ ͠ຈ༽ง︵┻━┻

Jan

Were they good, cat?

Chemistry people were much quicker reviewing xD (But I wanted the badge on German more.)

Wildcat

They were good. Until all you started making noise by turning tables! :|

Hippalectryon

At least put the tables back q_q ┳━┳ ヽ༼ಠل͜ಠ༽ﾉ

Jan

@Hippalectryon How's about no? （ノT＿T)ノ＾┻━┻ D=

Hippalectryon

┬━┬ ノ( ゜¸゜ノ)

Loong

19:40

@Jan got to physics:

Wildcat

hehe

Hippalectryon

The table is getting tired of being flipped over and over :c

ノ┬─┬ノ︵ ( o°o)

pH13

ʕノ•ᴥ•ʔノ︵ ┻━┻

Hippalectryon

@pH13 (╬☉д⊙)＝◯)๏д๏))･;’.

pH13

(ﾉ＾◡＾)ﾉ︵ ┻━┻

Hippalectryon

19:43

kamehamehamehamster ! ( つ•̀ω•́)つ・・*:・:・゜:==≡≡Σ=͟͟͞͞(✡)`Д´）

what are we even doing

pH13

we're flipping tables

(/¯◡ ‿ ◡)/¯ ~ ┻━┻

Wildcat

@pH13, stop doing it! Let's better create a room to discuss resources thread!

:D

pH13

hm, that's a good idea

Jan

Let's create a room full of tables that we can flip to our hearts' desire! （ノT＿T)ノ＾┻━┻

Hippalectryon

Flipping couches is funnier (╯°□°）╯︵ ส็็็็็็็ส

pH13

19:45

we can flip them here

Resources for learning Chemistry (Dis…

This is the official chat for discussions about the Resources ...

inɒzɘmɒЯ.A.M

40 reviews done. ᕙ(⇀‸↼‶)ᕗ

Jan

Why did it let you do 40 but me only 20? D= Y,…,Y

@inɒzɘmɒЯ.A.M Tell me, how many were 'This answer is old, the question is older; let's click "No action needed"'? ;)

inɒzɘmɒЯ.A.M

Hmm, about 5 were 'no action needed' in chem. Lemme look.

@Jan 3 'No action needed' in chem.

5 in ELL.

Jan

Oh, you did 20 on each of two sites! That explains it ^^

inɒzɘmɒЯ.A.M

And now, let's pin my getting to be the top reviewer thingy.

Jan

19:51

That is pinning rights abuse! （ノT＿T)ノ＾┻━┻

inɒzɘmɒЯ.A.M

(•_•)=ε/̵͇̿̿/'̿'̿ ̿

Jan

Remember I'm a vampire. You can't shoot me x3

inɒzɘmɒЯ.A.M

Kills @Jan

Jan

YESS! Added eight HRMS values to my thesis \o/

Wish I could have added ten, but two molecules just wouldn't show up in their spectra.

@inɒzɘmɒЯ.A.M *gets up again, unamused*

Hippalectryon

Reddit and le h bar have no idea for my experiments :c

Wildcat

19:56

@Jan, what the heck is HRMS? :O

inɒzɘmɒЯ.A.M

@Wildcat Hermes, God of speed.

pH13

high resolution MS

Jan

@Wild what pH said.

inɒzɘmɒЯ.A.M

Hungry Revolting Master Squirrels

pH13

her royal massiness the spectrometer

user161117

22:20

Woah just found some fun stuff about Mobius aromaticity and how it can be used to predict pericyclic reactions without having to know anything about molecular orbital theory or the Woodward-Hoffman rules! :O

user161117

I'm trying to see if I can't figure out like the simple case for energy levels without cheating by solving the particle on a mobius strip instead of on a ring

user161117

for a wave function f(x) with boundaries as a mobius band does it make sense to have condition be f(L)=-f(0) so that it takes two full rotations to make a complete cycle, f(2L)=f(0) ?

Resources for learning Chemistry (Dis…

Transcript for