The Periodic Table

9-BBN

3:00 PM

I hope I'm not telling you bad things lol

Rubisco

@9-BBN :o

9-BBN

The sign it show by the colors of lobes

Wut ?

Rubisco

@9-BBN :o

DHMO

@9-BBN the second one... has different signs and is non-bonding

9-BBN

@orthocresol might answer you then, I don't know more than what I said ^^

DHMO

3:03 PM

@Rubisco enzymes should be good in MOs

Rubisco

Well, I don't even know what the question is

DHMO

@Rubisco how do we determine NBMO

from the diagram of the MO

Rubisco

Meow @Wild kitty

Hmm, something clear-cut is hard to come up with

Wildcat

@Rubisco meow :)

9-BBN

Nonbonding molecular orbitals
-may occur when three or more atomic orbitals are combined
-have the same energy as the original atomic orbitals
-electrons occupying these orbitals do not stabilize or destabilize the molecule

cactus.dixie.edu/smblack/chem2310/summary_pages/…

Rubisco

3:06 PM

That doesn't help in finding them.

If the contribution to the bonding is cancelled, it's non-bonding obviously

9-BBN

OK I got it

On you ozone there are three atoms

Rubisco

But how to just look at the diagram and say what the non-bonding MO is . . .

orthocresol

Should we get rid of wavefunction?

No tag usage guidance, 5 questions tagged so far, doesn't seem very useful to me.

9-BBN

So the wave function of the non-bonding it positibe at the left of example, zero in the middle and positive in the other way ? Maybe a begining of answer

I'm looking in my lesson

Because what you show me is for a three atoms molecule and I was speaking for a two one

Rubisco

@9-BBN I'm not ozone

Loong

3:11 PM

@orthocresol We could remap it to quantum-chemistry.

Rubisco

@orthocresol Well, I didn't see when it appeared.

@Loong Yeah good idea

But NOT a good idea since you're my presidential rival.

orthocresol

@Loong Yeah. Nearly all of quantum-chemistry can be tagged with wavefunction.

DHMO

@orthoseal any idea?

how to identify NBMO from diagrams

orthocresol

You know what? I will tell you what I think.

Except for the simplest cases, you cannot tell from the diagram.

9-BBN

To be bonding you need to have to big lobe in same phase
To be non bonding two small or one big and one small

But it is qualitative non quantitative on my diagram

If you want to really know if your theory is good you need to test it

DHMO

3:13 PM

@orthocresol well........

@9-BBN ok thanks

9-BBN

In this case draw things on paper like I did needs to make a lot of approx

orthocresol

Can you define what a nonbonding MO is?

DHMO

@orthoseal another question: is there a rule on how many BMO, how many NBMO, and how many ABMO must be formed from interacting x AOs?

orthocresol

No there is not

DHMO

@orthocresol that neither increases nor decreases the potential energy of blah blah b lah

@orthocresol but I think 2 AOs must make 0+2+0 or 1+0+1?

orthocresol

3:14 PM

@DHMO So how do you tell that from the diagram? Does the diagram tell you anything about the potential energy?

9-BBN

is a molecular orbital whose occupation by electrons neither increases nor decreases the bond order between the involved atoms

DHMO

@orthocresol Oh, I meant the shape, not the diagram

9-BBN

As it is said in the name "non" bonding

orthocresol

Shape for that matter. Does it tell you anything?

DHMO

@orthocresol well... electron density?

orthocresol

3:15 PM

Go ahead and tell me then, how you determine the energy of an MO from the electron density.

DHMO

@9-BBN I believe you have it backwards. Bond order is defined from NBMOs

@orthocresol well... no idea

Loong

@orthocresol You can vote here: chemistry.stackexchange.com/tags/quantum-chemistry/synonyms

orthocresol

@Loong For a moment, I thought you were telling me to vote in elections. :D

@DHMO Take the HOMO of carbon monoxide, for example. That is commonly cited as a nonbonding MO, or very weakly bonding MO. Whatever it is, that's not importnat.

Rubisco

@Loong Why could I upvote that? I don't think I have the required score in the tag

orthocresol

How do you tell me from the diagram that it is bonding or nonbonding?

Loong

3:17 PM

@orthocresol Yes, I nominate wavefunction.

orthocresol

5

A: Why does Thallium form TlF and TlF3 but aluminium only forms AlF3?

Ahh, Thallium is a very nice element. Because it's weird. The +3 oxidation states are favorable except for the heavier elements, such as Tl, which prefer the +1 oxidation state due to its stability; this is known as the inert pair effect. Chemwiki.UCDavis As an example in group 13 the +1...

Rubisco

Ah, that one.

That almost came from nowhere.

orthocresol

chemistry.stackexchange.com/…

Seems that you have a combined score of 10 on quantum-chemistry

9-BBN

From the diagram this is not absolutely sure but it is common when in three AO interactions to get the three king ot MOs, isn't it ?

Rubisco

Yeah yeah, stop showing off your search strings

0

Q: Why does oxalic acid have exactly two water molecules of crystallization?

Why does oxalic acid have exactly two water molecules of crystallization? In other words, in the formula $\ce{C2H2O4\cdot2H2O}$, why is the number before the $\ce{H2O}$ exactly $2$? I tried to see this from the structure of oxalic acid. Also, I tried to invoke hydrogen bonds. However, I don't ...

orthocresol

3:19 PM

@9-BBN That's one of the simple cases. Allyl system is well-studied and it's very obvious that the middle MO is nonbonding. Ozone pi system is exactly the same.

DHMO

@orthoseal your language, lol

9-BBN

That was I was saying when I said the wave function is null in the central atom

orthocresol

Yeah, that is a start.

Rubisco

@DHMO Hmph? I thought @Ortho was an Eskimo or something like that

orthocresol

Because the nonzero coefficients are far apart

So the interaction between them is very small.

Rubisco

3:20 PM

I need to pay attention to nationalities next time.

9-BBN

That is what I'm saying for one hour lol

orthocresol

Heh, sorry, I swept all of that into "simple cases".

DHMO

orthocresol

Another simple case is when there is no other appropriate symmetry AO to interact with.

That is obviously non-bonding.

9-BBN

Do not be sorry everyting is OK for me ;)

orthocresol

3:22 PM

But, I would maintain that for anything more complex than that, you probably need to look at the form of the photoelectron spectrum (or some other experimental method)

DHMO

now how is that sigma NBMO...

orthocresol

Or sit at your computer and press some buttons, depending on what kind of chemist you are...

DHMO

the bond order is three, so it must be a BMO

9-BBN

Quantum chemistry is not the main subject I'm studying. I will have more this year, I love it, I got a A-grade last year but you know how things are, I'ven't done it for months, I'm not too bad haha ^^

DHMO

> They wanna bond

5

A: Why does Thallium form TlF and TlF3 but aluminium only forms AlF3?

Ahh, Thallium is a very nice element. Because it's weird. The +3 oxidation states are favorable except for the heavier elements, such as Tl, which prefer the +1 oxidation state due to its stability; this is known as the inert pair effect. Chemwiki.UCDavis As an example in group 13 the +1...

the language

Rubisco

3:24 PM

I'm having jelly. Who wants some?

9-BBN

Berk

French reaction when an english one wants to it his jelly ^^

eat

typo lol

DHMO

@orthoseal Is it not that 2 AOs must form 1+0+1 or 0+2+0 MOs?

orthocresol

@DHMO I don't know about you, but I don't consider that a rule.

Rubisco

@9-BBN I'm not English

9-BBN

Or sympathizer ^^

DHMO

3:26 PM

@orthocresol well, it cannot from 2+0+0 for example

what about 3 AOs?

orthocresol

If you want to list all the possibilities for $n$ AOs ($n \in \mathbb{Z}^+$), be my guest

DHMO

@orthocresol no, just 3

Rubisco

@Ortho is approximately 45 percent Oxfordian but I'm not

orthocresol

Well, you would probably have to consider the fact that there is a "conservation of energy".

DHMO

@orthoseal Am I correct that the number of bonding orbitals must be equal to the number of anti-bonding orbitals?

orthocresol

3:29 PM

The problem is looking at it in such black and white terms.

Some bonding MOs can be very bonding and some can be barely bonding.

Which is why you are running into issues with the MO diagram of CO above.

DHMO

@orthocresol what issues?

orthocresol

Even N2 is difficult to look at. Because of s-p mixing, the $\sigma$ and $\sigma^*$ orbitals do not "cancel out" in terms of their bonding effects.

DHMO

:o

orthocresol

Someone, please ask about "conservation of energy" in LCAO on main site, please.

I have a burning desire to write an answer.

or even the more consise notation $<i~|~k>$ — porphyrin 57 mins ago

Can I flag this comment for moderator intervention?

user116211

@orthocresol Horror

user116211

3:32 PM

@orthocresol Why not make a canonical post?

DHMO

@orthocresol you can ask it yourself lol

I don't know what you mean by asking about conservation of energy in LCAO

it would be too broad

orthocresol

@DHMO Yes. So, the bond order in CO is 3. However, that does not mean that 1) you can do a clear-cut assignment of which MOs are bonding/non/anti; and 2) each bonding MO exactly "contributes" a bond order of 1.

9-BBN

Tell which question

I'll ask

DHMO

@orthocresol alright

9-BBN

^^

orthocresol

3:33 PM

@MAFIA36790 too minor to be worthy of a canonical post

Elections need to hurry up and be over.

I want to spam meta.

Loong

@orthocresol not constructive

9-BBN

Write the question for me, I ask for you and you'll answer

orthocresol

@9-BBN You just want the rep, right?

These sneaky French *********.

user116211

@9-BBN rep-monster

9-BBN

:P

You will much much better than me for that

orthocresol

3:35 PM

Anyway, there is a sort of energy conservation in LCAO.

9-BBN

I "just" have a bachelor

orthocresol

I don't even have a BSc.

user116211

@orthocresol I very much want to read about it. PLZZZZ

orthocresol

@MAFIA36790 Sum of energies of AOs that go into LCAO = Sum of energies of MOs that come out of it.

Rubisco

@MAFIA36790 I see people are using their creativity after rep-whore was depracated

9-BBN

3:36 PM

I don't know if Feynman did something about it

orthocresol

To some degree of approximation.

user116211

@9-BBN What?

9-BBN

feynmanlectures.caltech.edu

Something everyone should read

A bit hard some times but always good

orthocresol

I will say that I have tried to read it. Most of the time, I don't understand it. My brain is not really cut out for physics at all.

9-BBN

The third volume is about quantum physics

orthocresol

3:39 PM

I actually want to try reading Dirac's book. The one I recommended earlier

So, Feynman can come after Dirac :)

user116211

@9-BBN I've read it completely; he mentioned about Variational Principle in the penultimate chapter in building up of the Periodic Table; but that's it.

user116211

@orthocresol Read it; it's an amazing book.

9-BBN

I haven't begun quantum volume yet because I do not understand the symbols lol

user116211

@9-BBN What?

9-BBN

And I haven't made maths at school for one year

orthocresol

3:41 PM

@MAFIA36790 Only problem, is that Dirac spent a lot of his life in C-word-town.

9-BBN

It begins to be as creepy as my nine

user116211

@9-BBN He develops all the bra-ket symbols in chapter eight.

9-BBN

Symbols used in quantum physics in equation I do not understand what they mean

So I should read 8 first ^^

user116211

@9-BBN No.

user116211

You should start from chapter four.

9-BBN

3:43 PM

OK I'll do when I'll have time

Rubisco

-1

Q: phase rule for chemists

basing on the Phase rule f=c-p+2 how can we differentiate between nummber of components and the composition in a system at equilibrium take an example of CaCO3-----> CaO+ CO2 And hence caculate the value of f.

physical-chemistry

9-BBN

I'm reading the last lessons about motion of planets

orthocresol

I VTC'd.

Rubisco

Glancing, I first read that as 'please rule for chemists'.

orthocresol

Don't we already?

user116211

3:46 PM

in The h Bar, Sep 15 at 9:32, by MAFIA36790

@sanya The point is that the lectures are not highly extraordinary; the materials can be found in any standard undergrad-grad book; but makes them precious is the very way, the technique Feynman explained them. They are amazing. One thing I could remember and liked the most; he used Stern-Gerlach apparatus as filters to explain base states ( basis of vector space) and probability-amplitude interference; that was an insanely fabulous lecture by Feynman ;))

user116211

^^@9-BBN.

Rubisco

What's the command for an en-dash in Mathjax, again?

\textendash doesn't work

9-BBN

@MAFIA36790 obvioulsy

But his approach was to make it intuitive

user116211

@Rubisco yeh; it doesn't work.

user116211

It's indeed; it's really enlightening.

Rubisco

3:48 PM

Thank you for confirming Lord Maf. What's the replacement?

9-BBN

A nitpick approach ^^

user116211

But the volume is not maths rigorous.

9-BBN

This is physics

user116211

@Rubisco $a$-$b$

orthocresol

27

Q: How do I indicate an en-dash while in math mode using LaTeX?

There are four kinds of 'dashes' in LaTeX: hyphen, en-dash(--), em-dash(---) and minus $-$. They are used for, respectively, hyphenation and joining words, indicating a range, punctuation, and a mathematical symbol. My question is: how do I indicate an en-dash (range) in math mode? (as in $S=1 ...

latex

Rubisco

3:48 PM

That's a hyphen, not an endash

user116211

@Rubisco I know; but I have no more tactics to do that.

user116211

@orthocresol checking

orthocresol

Doesn't seem to work eitehr.

Rubisco

I just used a real endash.

orthocresol

Sorry for getting your hopes up

Yeah, that makes sense.

9-BBN

3:50 PM

The goal of a teacher is to inspire students, I have not read a lot of physics book but Feyman is much better than what I had during my sophomores for example

user116211

@9-BBN I have read most of the Vol2; and nearly completed Vol3; they were insanely awesome.

orthocresol

@MAFIA36790 I was quite surprised that that was on SO actually

user116211

@orthocresol That should be in TeX, imo.

Rubisco

@orthocresol 2009. What did you expect?

The rules weren't solid back then.

Think of it as Earth forming and taking its shape.

orthocresol

@Rubisco Well, in my defence, I didn't know that it existed until maybe couple years ago.

flags as off-topic

Rubisco

3:53 PM

@orthocresol Don't . . . They don't bother with old questions AFAIK.

user116211

@Rubisco ohh.

Rubisco

There are a couple of thousands of those that should go to TeX, SU, SF, Webmasters and suchlike.

Aaand the influx of the new crap gets more attention and higher priority.

9-BBN

See you soon

Rubisco

See you late

user116211

@9-BBN o/

orthocresol

3:57 PM

@Rubisco Haha, I didnt

orthocresol

5:03 PM

sees university fees and faints

user116211

5:32 PM

@orthocresol :(

CowperKettle

Namaste, Mafia

user116211

@CowperKettle o/

Chemobot

5:54 PM

ǝʎq╰(«○»益«○»)╯qʎǝ

CowperKettle

рyэ руэ?

Loong

Hm, we have sulfuric-acid, but only five questions use it.

However, we could use it: chemistry.stackexchange.com/…

orthocresol

mineral-acids?

@MAFIA36790 On the bright side, the pound has weakened quite substantially.

I guess all I can really do is try and work hard and make the most of my education.

user116211

Good news?

orthocresol

Well, gotta try and think positively :)

user116211

6:05 PM

@orthocresol Or find some secret Nazi treasure. You will be rich.

orthocresol

@MAFIA36790 They didn't quite manage to get across the English Channel, so probably nothing much here.

user116211

._.

Skeleton Bow

Hello

user116211

!!greet/@SkeletonBow

Chemobot

Welcome to The Periodic Table @SkeletonBow! Here are our chat guidelines and it's recommended that you read them. If you want to turn Mathjax on, follow the instructions in this answer. Happy chatting!

Skeleton Bow

6:07 PM

Um, I want to put a chemical in my question title

Should I format it or leave it unformatted?

user116211

@SkeletonBow Don't use MathJax or Mhchem in title.

Skeleton Bow

Yeah it looks like others aren't

Thanks @MAFIA36790

Pity, it looks better

orthocresol

Gives bad URLs, e.g. http://chemistry.stackexchange.com/questions/11202/balancing-redox-equations-wi‌th-ceh-or-ceh-3o

Skeleton Bow

Ah yeah, makes sense

orthocresol

CeH: Cerium hydride? :D

Skeleton Bow

6:10 PM

Happens all the time in math SE

Though there it's unavoidable really

user116211

Physics has no such restrictions.

orthocresol

Yeah. Here we can make do without, so we try to do so.

5

Q: Is mathjax in titles a problem? And why?

I think the title is self explanatory. I certainly think it looks nicer. I thought it still worked for searches too, as long as its something $\ce{H_2SO_4}$ or $\ce{K}_i$ - certainly does on my browser.

discussion

Skeleton Bow

Yep, that makes sense

Love the site

site's CSS by the way

orthocresol

@Loong What's the most important attribute for a chemist?

Loong

@orthocresol to be able to endure setbacks

orthocresol

6:16 PM

Well said

Skeleton Bow

brb, making a question about H2SO4

Just kidding. Thanks for the help.

user116211

@Loong Valid for all scientists.

Loong

@SkeletonBow Maybe you should edit the extra information from your comment into the question.

orthocresol

I guess my only potential concern with sulfuric-acid is that it can be lumped onto questions that just happen to use H2SO4. For example, a good question for this tag might be this one. But a potentially bad question: "Why does zinc react with sulfuric acid?" Well, it can react with HCl or any other acid. So that would not be a reaction specific to sulfuric acid.

Obviously, we can define the scope however we want. Just thought that it would be a relevant point.

And... NH4 seems to exist.

Jan

6:31 PM

@Wildcat My instincts tell me that I don’t fully trust Zhe (yet?).

orthocresol

@Jan I just don't really catch his post. :(

Jan

That’s the thing … If he’s a new ron he (unfortunately) needs to work on making his posts clearer …

orthocresol

I think there is some substance inside there. The mechanism is probably a biradical, I do remember seeing it. But I just can't be bothered to figure out, which KIE is he talking about? the selectivity ratio is 1:1 or 2:1 for which product?

9-BBN

Does saccharose and ethanol can mix together ?

orthocresol

Sucrose, or saccharin?

Oh, it's sucrose

9-BBN

6:43 PM

sucrose

orthocresol

Solubility: Soluble in water (1 g/0.5 ml @ 25°C; 1 g/0.2 ml boiling water), ethanol (1 g/170 ml) or methanol (1 g/100 ml); moderately soluble in glycerol or pyridine. 1.
Note:1 Sucrose is hydrolyzed to glucose and fructose by dilute acids and by invertase, a yeast enzyme.

I suppose not.

9-BBN

That's not a lot

Skeleton Bow

@Loong I'm not sure I follow, sorry?

Oh, I get it now. Yes, I did that

orthocresol

@SkeletonBow You did it already. :)

Skeleton Bow

Also, I really wanted to say, German is really awesome

Now, if I mention the units of Kw in class, I'm sure people would be impressed

Loong