The Periodic Table

user228700

14:00

@DHMO: I'm stuck now. Still thinking. Do u have a theory?

DHMO

@Kaumudi same as yours, but still a guess

I was finding online while you were typing your hypothesis

and I just found something:

> In general, more polar bonds are stronger, because the bonding electrons are held more tightly at one end of the bond. This means to redistribute those electrons evenly throughout the bond so it can then be broken homolytically would require more energy than to just break a bond which already has evenly distributed electrons (i.e., a nonpolar bond).

> The O-H bond in acetic acid is more polar than the alpha C-H bonds, meaning it's harder to break homolytically, and thus has a higher BDE. However, it's much easier to break the O-H bond heterolytically than it is to do the same to the C-H bonds. See the deal?

user228700

Lol, I was looking up the same thing :-P

Martin - マーチン

@hBy2Py I wouldn't have much insight to offer, too, but considering that for most of the functionals the amount of votes is around 70% only, it seems like it might be already enough if you just put in the functionals for whatever functional you use most. And as I said earlier, if one of the most hated functionals ends up on #3, what's the whole thing worth in the first place...

user228700

Hm, emphasis on the word homolytically.

DHMO

@Kaumudi BDE must be homolytical

user228700

14:04

Yep. Hm...

DHMO

by the way, source

user228700

Well, with this definition in mind, I think it's safe to say that the atoms now attract each other some more and hence, the bond length decreases.

user228700

Gimme one second.

DHMO

i suppose so

Martin - マーチン

@hBy2Py SEDE can be quite terrifying and you really need to work yourself into the whole thing. It's like learning a language. You could start here:data.stackexchange.com/help The disadvantage is, it's not real time. Searching is, and the advanced keywords are given here. It's easy to use, too.

DHMO

14:11

!!greet/@MelanieShebel

Chemobot

Welcome to The Periodic Table @MelanieShebel! 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!

user228700

Yes, so I guess that makes sense. Shall we move on..?

DHMO

@Kaumudi surely

user228700

We're done with bond lengths. Let's talk bond angles.

DHMO

@Kaumudi surely

user228700

14:13

Firstly, it depends on the hybridization of the central atom, of course.

DHMO

surely

user228700

Let's not discuss this point since the dependence is obvious (not so much when u think about it along the lines of QM, but never mind that, for now)

user228700

@DHMO Copy, paste, copy paste? :-P

DHMO

@Kaumudi oh, sh!t, I didn't even notice it

user228700

OK, I believe u :-P The next point is the number of lone pairs on the central atom.

user228700

14:18

Wait, I thought I had this one figured out...huh.

user228700

@DHMO: Anything? I'm still thinking.

DHMO

@Kaumudi What is the question?

You didn't even bring out a statement.

user228700

Oh, but I did:

user228700

5 mins ago, by Kaumudi

OK, I believe u :-P The next point is the number of lone pairs on the central atom.

DHMO

"the number of lone pairs on the central atom" is not a statement

user228700

14:22

Well, I didn't tell how my textbook thinks it'll affect the bond angle.

user228700

@DHMO So..? That's the next factor upon which the bond angle depends.

DHMO

Alright

that is plain VSEPR

user228700

Yep.

DHMO

so where is your doubt?

user228700

I'm trying to frame it in a way that makes sense.

DHMO

14:23

just use VSEPR, lol

user228700

:-P I'm making notes. I can't write "Just use VSEPR, lol".

DHMO

@Kaumudi "for the case of number of lone pairs, just use VSEPR, lol"

user228700

The increased density of electrons around the central atom causes the repulsions b/w these electrons and the bond pairs. So, the bond angle decreases?

Zhe

Hmm... I wonder if there is a fast back of the envelope way to use MO for getting the same results as VSEPR

DHMO

@Kaumudi yes, which is essentially VSEPR

@Zhe no

Zhe

14:26

@Kaumudi NOOO

DHMO

VSEPR is a failed theory

Zhe

Bond angle decreases

DHMO

oops, missed that

Zhe

No, I'm just talking about bond angles

user228700

Yeah, typo :/

user228700

14:27

I don't get it, tho.

Zhe

Can you quickly indicate that moving to $C_{3}$ point group from $T_{h}$ will reduce bond angles...

Probably not...

user228700

How come the bond angle decreases?

user228700

$C_{3}$ and $T_{h}$. Dunno these notations.

Aaron Abraham

Anyone good at stoichiometry ?

DHMO

@AaronAbraham state your question

user228700

14:32

..? What about my question?! :-o

Aaron Abraham

Regarding chemical equivalence; I'm told that an equivalent of an element is the amount of that element that combines with a mole of Hydrogen atoms. Right so far? @DHMO

DHMO

@Kaumudi well, consider AX4 vs AX3, right

Zhe

@Kaunudi Because the lone pair pushes the other bonds closer

@AaronAbraham Depends on the reaction

user228700

@Zhe Why does it push the other bonds closer?

Zhe

equivalent is relative to another reactant

Aaron Abraham

14:34

@Zhe what kind of 'dependence' exactly?

Zhe

In VSEPR, you would've said that the lone pair is more energetic and takes up more space

user228700

@Zhe OK..?

Zhe

@AaronAbraham depends on your reaction. What is it?

@Kaumudi If it takes up more space, the bonds take up less space so they get pushed together

user228700

@Zhe Hm, OK...

Zhe

That's why it's called Valence Shell Electron Pair Repulsion

It's just another heuristic that works a lot of the time

user228700

14:35

OK...

user228700

@DHMO: Next point?

DHMO

@Kaumudi ok

user228700

Now we're talking about the size of the central atom.

user228700

As the size increases, the electrons now have more room to occupy and hence, the bond angle increases. Makes sense?

Aaron Abraham

@Zhe Alright, if it does depend on the reaction, I guess that clears stuff up a bit. The book I'm reading cites H2O ( @DHMO ) and then proceeds to say that the equivalent weight of oxygen is 8g ; but then H2O2 popped into my mind and that's what caused the muddle . From H2O2, I reckon oxygen's eq.wgt, should be 16. So I'm right?

DHMO

14:38

@Kaumudi decrease?

Aaron Abraham

@orthocresol Hiya!

DHMO

@AaronAbraham embarrassed

user228700

@DHMO Increase...

DHMO

@Kaumudi for example?

Zhe

That's not how we use equivalent

Equivalents has a reserved meaning for when you run a reaction with an excess reagent, and the number of equivalents is the mole ratio between one reagent and another

Generally you set the number of equivalents of the limiting reagent to 1

user228700

14:41

@DHMO Don't have one :/ Why do u think it decreases? .

Aaron Abraham

Oh you're Mods now! I only just found out. Congrats @Loong and @orthocresol !! [ @Loong The Bundeswehr would be proud of you :'/ ]

DHMO

22

Q: Why does bond angle decrease in the order H₂O, H₂S, H₂Se?

I know that bond angle decreases in the order $\ce{H2O}$, $\ce{H2S}$ and $\ce{H2Se}$. I want to know the reason. I think this is because lone pair repulsion but how?

@Kaumudi my thought was that larger central atom -> more diffuse side atoms -> less repulsion

user228700

@DHMO What do u mean by more diffuse side atoms?

DHMO

@Kaumudi diffuse = distant from the central atom

orthocresol

@AaronAbraham Hi, thanks.

user228700

14:46

You mean more diffusED side atoms?

DHMO

@Kaumudi ........

user228700

That's just me being a pedantic idiot, sorry.

DHMO

@Kaumudi no

dictionary.com/browse/diffuse

>
adjective
6.
characterized by great length or discursiveness in speech or writing; wordy.
7.
widely spread or scattered; dispersed.
8.
Botany. widely or loosely spreading.
9.
Optics. (of reflected light) scattered, as from a rough surface (opposed to specular ).

the 7th sense

Aaron Abraham

@orthocresol Welcome! Least I ought to do for my favourite fellow Common-Wealth seal ;)

user228700

OK, sorry. Also, thanks :-P

user228700

14:51

Riight, OK, I see ur point. Alright, I think that makes sense.

user228700

The next point is regarding the electronegativity of the central atom.

DHMO

@Kaumudi what....

user228700

Uh, how the angle depends on the electronegativity of the central atom. What's wrong?

DHMO

@Kaumudi how?

user228700

Well, when the electronegativity of the central atom is high, the electrons (constituting the bond) spend more time near the nucleus. So, the repulsion b/w bond pairs increases. Hence, the bond angle increases.

Zhe

14:57

@DHMO Carbon quadruple bond example?

DHMO

@Zhe read the comments

user228700

Oh, crap, I must go to have my dinner. @DHMO: Will u still be here in about 30 mins?

DHMO

@Kaumudi depends

Zhe

ugh

DHMO

@Zhe in chemistry there is only one rule: there is no rule.

user228700

14:59

Okay. I'll risk it. In case u're not here, just wanted to thank you for spending time to discuss with me :-)

DHMO

you're welcome

Zhe

@DHMO strongly disagree

DHMO

@Zhe i'm just kidding

Zhe

;)

Actually, I strongly agree

Because all of the "rules" are just to generalize

We can't handle the complexity

DHMO

in that case, i'm not just kidding. by all means i am serious

Zhe

15:00

QM isn't a rule

DHMO

what is it?

Zhe

anyway meeting time

DHMO

always, nice chatting with you

Zhe

It a firm theoretical grounding!

DHMO

@Zhe I think you should make your first comment as an answer

M.A.R.

15:15

Yo

Ashish Ahuja ツ

@M.A.R. o/

M.A.R.

I again missed Zhe.

imgur.com/gallery/mRHmt

imgur.com/gallery/gCuYmeT

Haha the one above is full of Trump speech jokes in the comments.

Aaron Abraham

@Zhe

user228700

15:47

@DHMO: Have u gone?

DHMO

@Kaumudi yes

user228700

Ah, so u're busy now?

DHMO

no, i was just kidding

user228700

OK :-P So, yeah, electronegativity of the central atom.

DHMO

for example?

user228700

15:49

Do u agree with my line of reasoning?

user228700

?

DHMO

no

user228700

OK, look:

DHMO

I thought we discussed polarity before

user228700

15:52

@DHMO We'd discussed with regard to bond length, not angle.

user228700

Why don't u agree with my line of reasoning?

DHMO

@Kaumudi unfair, all are less electronegative than H

@Kaumudi well, decreased bond length -> less diffuse -> more repulsion -> larger angle

user228700

Uuugh. I'm unable to think of other examples.

DHMO

I also have no idea

user228700

But I'm pretty sure...okay, Googling.

user228700

15:57

BTW, I still don't think that "less diffuse" is the correct way to use that word.

DHMO

@Kaumudi correction + source?

user228700

I think it should be less diffusion. They diffuse to a lesser extent would be correct.

DHMO

diffuse is an adjective

using diffuse as a verb or diffusion as a noun would not be the same meaning

user228700

No, diffuse is a verb.

DHMO

do i have to cite the same link to you again?

the verb "diffuse" and the adjective "diffuse" have different meanings

user228700

16:09

Not so different...

user228700

en.oxforddictionaries.com/definition/diffuse

DHMO

quite different

"diffuse" as a verb is a movement

"diffuse" as an adjective is a location

user228700

Hm, OK...

user228700

Little confusing it was.

DHMO

surely

user228700

16:12

OK, I'm reading this:

user228700

4

Q: What affects bond angles?

I have three factors in mind: 1) vdW repulsions 2) Bond length 3) Electron-electron repulsions. I know that vdW repulsions between ligand atoms push the atoms apart. And bond length obviously influences bond angle; if the bonds were very long, then the bond angle can shrink without bringing...

bond

user228700

Did u read answered David BasedMathematician Coven's answer?

DHMO

@Kaumudi yes

no idea why

user228700

Why don't u agree with my line of reasoning?

DHMO

increased electronegativity of the central atom might lead to less polarity

user228700

16:19

How so?

DHMO

if the side atom is more electronegative than the central atom

increased electronegativity of the central atom would be catching up

user228700

Oh, dude, I've been saying increased(/decreased) electronegativity of the central atom, this whole time!

DHMO

so?

let's say central atom is -2.98

while side atom is -3.50

so you increase the negativity of the central atom

it becomes -3.33 vs -3.50

and the polarity decreased

user228700

I'm talking about those cases when the central atom is more electronegative than the terminal atom. My reasoning only works for those cases...

DHMO

you didn't mention it

user228700

16:23

Thought it might be obvious, sorry.

DHMO

sorry

user228700

NP. I really dunno if we can comment on the bond angle when the electronegativity is higher but not higher than the terminal atoms so u've made a good point...

user228700

And lastly, the size/electronegativity of the terminal atom:

user228700

DHMO

are you sure that it is not because of the size?

user228700

16:37

What is not?

DHMO

never mind

user228700

Why?!

user228700

Tell me, what did u mean..?

DHMO

I meant, in your tiny experiment, you changed two factors...

user228700

Which experiment?

DHMO

16:41

comparing PF3 and PCl3 and PBr3 and PI3

user228700

Two factors?

DHMO

yes

the electronegativity difference as well as the size of the terminal atoms

user228700

Well, yeah...

user228700

We can't really do it any other way.

DHMO

alright

user228700

16:49

Hm, alright. This took too long, I'd argue, but I guess it was worth it. I hope u benefited too, at least a little...

user228700

Thank you :-)

DHMO

thank you too

user228700

OK, goodnight :-)

DHMO

bye

orthocresol

17:05

I'm enjoying the closehammering.

M.A.R.

I do not like assumptions when there is no evidence provided. You need to first prove that Seems this problem is much more common ... much more correct answers being downvoted with comments pointing out problems that not exist. I understand your frustration but you haven't linked to any credible sources to back up your answer. Saying this as an untrained eye, but I do not see why the two answers don't align well. You speak of perfectly flat surfaces, and as that is hard to come across, hBy2Py neglected the fact that it might happen. That doesn't make his answer wrong. 'Wrong' is too strong. — M.A.R. 5 mins ago

@orthocresol And I'm MAR. Nice to meetcha

orthocresol

17:20

0

Q: Organic chemistry Empirical formula Homework

Hey need help with this: Find the empirical formula of the compound which contains 0.5 g of hydrogen and 6 g carbon and 8 g of oxygen. Thanks.

organic-chemistry homework

This guy managed to beat the closehammer.

Not bad.

M.A.R.

BTW I'm gonna post the AMIRITE policy discussion in thirty minutes or what.

That is, if I don't get distracted.

orthocresol

That's great. Is there any chance you could post it earlier? I gotta go off in around 45min.

M.A.R.

Then don't chat so I focus on the post.

Zhe

@AaronAbraham Just saw your post. What's the question regarding equivs again?

M.A.R.

17:46

@ortho ortho, I posted.

1,3-feeds

0

Q: Policy on AMIRITE questions

Intro Consider two likely scenarios: Q: How many grams of $\ce{O2}$ are there in one mole of oxygen gas? I know that O is 16, so it should be 16 grams, AMIRITE? Please halp ugrant kthxbye Q: How many grams of $\ce{O2}$ are there in one mole of oxygen gas? I know that O is 16...

discussion allowed-questions scope homework

M.A.R.

What should be our policy on AMIRITE questions? Please weigh in.

3

orthocresol

If needed I'll convert my comment to an answer properly another time.

M.A.R.

@orthocresol The only problem here is that @Mart is going to remind me every 15 minutes beginning tomorrow for the next month that meta is slow and I should give it time.

orthocresol

18:02

I just hope more people pitch in, we know that lots of people do head round to meta, we just need them to say something

Even if it's just "I agree with XYZ because <short reason>."

M.A.R.

Well, we don't have an election anymore, so meta is going to be dead quiet.

orthocresol

Yeah.

Like, I don't think anybody was opposed to your HW experiment. It's just that there was no sign of agreement.

M.A.R.

But Mart, Brian, Jan, Todd and Klaus are the only people who're gonna chip in anyway.

@orthocresol Well, people started not voting to close the next hour I posted that thing.

When people disagree with you on meta and they're not telling you, they keep doing what they're doing until you realize they disagree.

Nothing of the sort happened.

orthocresol

You could cheat, and simply create several answers with the possible solutions, and see which gets upvoted most. That lets people voice opinions without having to bother justifying themselves.

M.A.R.

Yeah, but I just felt too lazy all of a sudden.

orthocresol

18:06

I know what you mean.

Well, I've gotta go off, all the best

M.A.R.

I haven't been writing a meta question post thingy for a Loong time.

@orthocresol Cya

BTW @Ortho could you feature that post so we'll get results quicker? We have a heavy backlog of things to do.

Zhe

18:38

@M.A.R. Were you trying to get a hold of me before?

Noah P

Hi All

Out of methanoic and ethanoic acid, which would give a brown precipitate when potassium permanganate solution was added?

Zhe

@NoahP what do you think?

Noah P

I believe that methanoic acid will turn brown and ethanoic will not

@Zhe but I'm not 100% sure and wanted to confirm

Zhe

OK. So why do you think that?

Noah P

Because the methanoic acid can be considered to contain an aldehyde group

Which I'm unhappy about - but apparently, that's the case

And thus, it oxidises

@zhe

Zhe

18:51

SGTM.

Noah P

SGTM?

Zhe

sounds good to me

Noah P

So it would be the methanoic?

M.A.R.

@Zhe Were I?

Zhe

19:06

"I again missed Zhe."

M.A.R.

Yeah, that's because I did miss you

Throws something at Zhe

Zhe

duck

M.A.R.

I again missed Zhe.

M.A.R.

19:31

dev.to/rly

pentavalentcarbon

22:04

@M.A.R. tsk tsk

!!espresso

orthocresol

Seems like there's no coffee.

pentavalentcarbon

I've had 5 double espressos today and I'm ready to go

orthocresol

What's on?

pentavalentcarbon

time to give my unqualified opinion on AMIRITE

orthocresol

Excellent :)

pentavalentcarbon

22:28

enjoy

I'm out

orthocresol

23:18

@M.A.R. Should we make it into a poll?

DHMO

@NoahP scripts.iucr.org/cgi-bin/paper?S0567740877007845

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