The Periodic Table

Please take a look at the homework policy to see how you can improve your post. Essentially, you need to explain what specific issue you are facing, or show what you have tried to obtain the answer. meta.chemistry.stackexchange.com/questions/141/… — Zhe 6 hours ago

@Zhe is that copy pasted from one of my comments? ;)

Nothing wrong with that. Just wanted to give you a heads up that the homework policy is likely to be modified in the near future and until then all my comments will be customly written.

I'm just not 100% sure how to summarise our current stance in one "stock comment". I don't really want to say "homework copy-pastes are not allowed" because that feels a bit unfriendly

M.A.R.

12:50 PM

Oh, I just realized how the dramatic the message you quotes is. Sheds some tears And regarding the first one, it was a 'generic' Klaus, meaning Klaus, you, and a bunch of people I missed. Anyway thanks for voicing your opinion. — M.A.R. 6 hours ago

Shit. Autocarrot randomly inserted a bunch of words into my first sentence. It looks HORRIBLE

DHMO

1:12 PM

So formic acid and hydrogen peroxide are weak oxidizers

but when combined, they form the strongest oxidizer

?!

DHMO

1:31 PM

sporcle.com/games/starwars314159/…

See how many you get right!

Zhe

1:42 PM

@orthocresol Hey, if it's not broken, don't fix it. :)

DHMO

@Zhe interested in the short quiz above?

Zhe

8/12

Not horrible after being out of lab for 6 years

Though I'm pretty sure 4 carbon diacid should have two answers

...

DHMO

@Zhe which two?

user228700

Hi :-)

DHMO

@Kaumudi interested in the short quiz above?

user228700

1:53 PM

@DHMO: When was the last time u chatted w/ Ramanujan?

Zhe

Maleic and succinic are both 4 carbon diacids

DHMO

in Mathematics, 23 hours ago, by Ramanujan

And if I ever want to see further , i stand on the shoulders of DHMO

user228700

@DHMO No, not right now. Need to get some Math done. I've bookmarked it tho, thanks :-)

Zhe

I only know because the anhydrides are pretty common

user228700

@DHMO Oh, crap. Alright, thanks :-)

DHMO

1:54 PM

@Zhe ah, cis-butenedioic acid

but I think the quiz is asking about acids derived from straight-chain alkanes

Zhe

oops

Apparently being out of lab also makes me bad at reading

DHMO

@Zhe this isn't in the quiz

Zhe

?

DHMO

just my deduction

the quiz didn't say that it is asking about acids derived from straight-chain alkanes

Zhe

Oh, not maleic

Malonic

sorry

DHMO

1:57 PM

propanedioic acid

it is 3-carbon diacid

Zhe

I should also know that because it's used to make barbituates

DHMO

I see

apparently malonic acid + urea -> barbituric acid + 2 water

Zhe

Well, you need to activate the acids for that reaction

DHMO

Barbituric acid

Barbituric acid or malonylurea or 6-hydroxyuracil is an organic compound based on a pyrimidine heterocyclic skeleton. It is an odorless powder soluble in water. Barbituric acid is the parent compound of barbiturate drugs, although barbituric acid itself is not pharmacologically active. It remains unclear why the German chemist Adolf Baeyer chose to name the compound that he discovered "barbituric acid". In his textbook Organic Chemistry, the American organic chemist Louis Frederick Fieser (1899–1977) initially speculated that the name stemmed from the German word Schlüsselbart (literally, the beard...

Zhe

Looks like the link uses $\ce{POCl3}$

DHMO

2:01 PM

How is this not named 2,4-diazinane-1,3,5-trione?

> 2,4,6-trihydroxy-1,3-diazine

hydroxy????

Zhe

tautomer

@DHMO

DHMO

@Zhe nice, thanks

Zhe

They be tricksies

:/

I wonder why we even draw it the other way

The aromatic variant has got to be better...

DHMO

2:25 PM

@Zhe I agree

M.A.R.

3:13 PM

@Zhe Hehe MS paint?

!!greet/ramanujan

Chemobot

Welcome to The Periodic Table ramanujan! 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!

M.A.R.

Welcome to chat @rama!

Ramanujan

I?

Zhe

No, it's the default Ubuntu paint on my workstation.

KolourPaint

Ramanujan

8 mins ago, by Chemobot

Welcome to The Periodic Table ramanujan! 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!

Who Ramanujan are you talking about?

DHMO

3:28 PM

@Ramanujan you

Ramanujan

@DHMO now I got

Aaron Abraham

4:09 PM

Anyone happens to know what the C-Cl bond moment in CCl4 is? Can't seem to find it anywhere :/ [Although I did find out that the C-Cl bond moment in CH3-Cl is: 1.86 Debyes, I have a feeling it won't be the same for CCl4 ]

orthocresol

4:19 PM

@AaronAbraham Are you sure that is the individual C-Cl dipole moment? That looks like the dipole moment of the overall molecule.

M.A.R.

I wonder who this U. Grant is we’re supposted to be helping and whether that person is related to Mr Research Grant. Pls tel lme kthxbai. — Jan 2 mins ago

HEADLINES

Jan tried to make sense, couldn't

orthocresol

@M.A.R. You think this is an answer? chemistry.stackexchange.com/questions/6568/…

Aaron Abraham

4:39 PM

@orthocresol Well, I'm not really sure about it ._. Got it from here...chemistry.stackexchange.com/questions/6780/… ...the internet hasn't proved to be particularly helpful :/

orthocresol

5:02 PM

@AaronAbraham I see. This is quite ambiguous, but I strongly suspect those are values for the overall dipole moment.

@orthocresol Oh, wait... nvm... I figured it out. Sorry about that @M.A.R.

Bernard Meurer

6:30 PM

Halp

M.A.R.

7:12 PM

@BernardMeurer kthxbye

@orthocresol WhadidIdo

orthocresol

@M.A.R. Nothing.. Just wanted to consult you on that. It got flagged. It turns out that ringo's edit removed the flag-worthy sections :)

M.A.R.

Well, you're the only guy that pings me for something and says 'sorry for pinging' by pinging again

orthocresol

@M.A.R. Sorry for sorry for pinging.

M.A.R.

I wish I could ping-attack a mod.

A certain mod.

Bernard Meurer

Chem exam tomorrow

I has question

orthocresol

7:17 PM

Is it ugrant?

Bernard Meurer

How do I determine the electroaffinity of an atom? I have a periodic table alas it doesn't show it

is it inversely proportional to electronegativity?

orthocresol

I don't think you should ever have to determine the absolute electron affinity of something. It should always be predict a trend.

M.A.R.

en.wikipedia.org/wiki/Electron_affinity in case anyone missed it

In my courses, Bernard, I only had to memorize special electron affinities and I was good.

Bernard Meurer

@orthocresol I have Cl and Ar, and I need to say which one has more electron affinity giving quantitative arguments. It's clear to me that Cl is more into electron-sex than Ar, after all Ar is in a serial relationship with it's 2s2 and 2p6 orbitals

But how to quantitatively argument on that I'm not sure, my prof doesn't enjoy my human behaviour analogies I believe

M.A.R.

Then it's clear to me that you're done here

@BernardMeurer You can't, and don't need to quantitatively do it.

You'll never get a meaningful number anyway.

Bernard Meurer

7:24 PM

@M.A.R. It says right here on the question, Justify quantitatively which one has more electroafinity

M.A.R.

O.O

Bernard Meurer

I can do it qualitatively, just dunno which number to throw in to make it seem like I know what I'm doing

@M.A.R. Do you happen to read portuguese? I can link it for you :p

M.A.R.

And no info is provided in the question?

There should be a reaction enthalpy or something.

Bernard Meurer

Lemme translate this

"Predict, justifying quantitatively, which of the following elements, Cl or Ar has:

M.A.R.

Could you take a screenshot?

Bernard Meurer

7:26 PM

a) Higher ionization energy

b) electroafinity

M.A.R.

There should be some reaction 'delta energy'.

Bernard Meurer

c) Justify argon being monoatomic

No such thing

orthocresol

I think this is just a fundamental misunderstanding of what "quantitative" means.

There's no way you can magically pull out a number from a hat without doing some experiments.

M.A.R.

Doesn't pull out a number from a hat

orthocresol

I would venture a guess that here it is just asking for a logical explanation.

@M.A.R. ?

M.A.R.

7:29 PM

Modabuse™

Bernard Meurer

@orthocresol Well, this prof tried teaching us 3-dim schrodinger on spherical coordinates on our first week of class.

I'm a computer engineer

I haven't had calculus yet

(Well, I'm taking analysis right now)

M.A.R.

@BernardMeurer He(?) is showing off

Bernard Meurer

@M.A.R. He, yeah

The man is nuts sometimes

He has like 80 publications though

M.A.R.

Inb4 we realize Bernard means LordStryker.

Bernard Meurer

And the resemblance to an Oompa Loompa is uncanny

@M.A.R. Lord who?

M.A.R.

7:31 PM

@BernardMeurer One of our old-timers.

Bernard Meurer

@M.A.R. who was an insane freshman prof?

M.A.R.

That much I can't guess

He taught general chem.

Bernard Meurer

@M.A.R. Was he insane?

M.A.R.

He wasn't

I'm not sure what impression we'd've gotten in his class though

Bernard Meurer

Why in the MOT diagram of NO, once you fully populate the bonding sigma and pi orbitals of 2p the remaining electron goes to the antibonding pi and not the antibonding sigma?

i.e. this

orthocresol

7:43 PM

Aufbau principle? Heard of it?

Bernard Meurer

Nope

:/

Also, does my MOT diagram look okay? I know the anti-bonding sigma for 2s should've been visibly higher than the bonding one is lower (weird to say this) but I ran out of space :v

orthocresol

Electrons having lower energy is a good thing.

Just like how if you drop a book from the top floor of a building, it falls to the ground.

That minimises its gravitational potential energy.

Bernard Meurer

::throws book through the window::

I see!

orthocresol

So, here, you want electrons to go into the lower orbitals first

Bernard Meurer

So the rule is simply, fill them bottom up

orthocresol

7:47 PM

Exactly.

Wikipedia says aufbau is a German noun that means construction or "building-up".

Bernard Meurer

b/c lower orbitals of the diagram have lower energy unless you drew it wrong

orthocresol

That's exactly what you do: go from the bottom.

Bernard Meurer

That's what she said

Sorry, I can't hold myself sometimes

orthocresol

Haha

Bernard Meurer

NO, NO-, NO+, which one has the longest internuclear distance

NO+, right?

Because then O is less electronegative, and they are less interest in electron-sex

@orthocresol ?

9-BBN

8:09 PM

Hello

Bernard Meurer

8:36 PM

@M.A.R.?

M.A.R.

Here.

Bernard Meurer

*NO-

To the above question, here's my train of thought

1. the more electronegative the atoms are, the closer they will be when bonded

M.A.R.

@BernardMeurer The one with the least bond order.

Bernard Meurer

2. If an atom loses an electron it becomes more electronegative

3. Thus NO+ is the closest nuclear distance

M.A.R.

Oh my. You're doing it wrong.

Bernard Meurer

8:37 PM

:/

M.A.R.

If they're asking you to do this, they're doing it wrong.

9-BBN

@BernardMeurer what about diflurine then ? :)

M.A.R.

I mean, your reasoning is correct, but it's unnecessary.

48 secs ago, by M.A.R.

@BernardMeurer The one with the least bond order.

This much suffices.

Bernard Meurer

They just asked me to figure out which of those had the closest nuclear distance, period

M.A.R.

But I guess that's not in your course, so you can insult someone right now.

Bernard Meurer

8:38 PM

@M.A.R. Bond order? Dunno this in english. How many electrons are paired?

9-BBN

Wrong chat sorry

Bernard Meurer

@9-BBN Dunno what that is, not a chemist :p

M.A.R.

@BernardMeurer Depends on how you define 'paired'.

It's not like electrons are married couples.

Bernard Meurer

@M.A.R. covalent bonds

@M.A.R. No, then half of them would divorce and it'd be really hard to make long-lasting bonds

M.A.R.

NO and NO+ have a bond order of two.

Ugh, this is getting complicated.

I'm reaching the answer drawing some Lewis structures and some qualitative statements.

Bernard Meurer

8:41 PM

@M.A.R. Isn't my logic solid for most cases though?

I mean, it seems to make sense

M.A.R.

TL;DR; since NO+ has less electrons, the distance is the most.

But this is not a rule.

@BernardMeurer Yes, but IIRC it gets counter-intuitive in some cases.

And that's when things start getting uneasy.

orthocresol

@M.A.R. I suspect that "draw the MO diagram for NO" was an earlier part of the question, and then the follow up is the bond order in NO+, NO, NO-.

M.A.R.

@orthocresol I don't think so.

He's MADE to use EN to answer this.

HORRIBLE.

orthocresol

Oh, really? I haven't been paying attention.

M.A.R.

I guess this far into the course, Bernard, your logic is the only possible logic.

So it makes sense.

Until you learn to use realer chem logic.

Bernard Meurer

8:45 PM

Oh Bond order!

orthocresol

I don't even think that anything involving EN comes close to an answer. Either Lewis structures or MOT works.

Bernard Meurer

I know what it is, the number of bonding orbitals - antibonding ones /2, right?

9-BBN

To obtain the electronic configuration of NO from NO+ diagram you need to add an electron in an antibonding orbital. Then the strengh of the bond will be reduce and the it will increase the size. So NO+ has a smaller bond than NO.

orthocresol

@BernardMeurer Yeah, exactly. Although to be honest, you don't even need to count antibonding or bonding electrons.

Yeah, precisely what @9-BBN said.

Or you think of it the other way round: to produce NO+ from NO, you remove one electron from an antibonding orbital. This strengthens the bond which makes it shorter.

Either way works perfectly fine.

Bernard Meurer

The bond order for NO is 1/2?

No, this can't be

Wait

orthocresol

8:47 PM

But for bonus points on your assignment, you might as well count the bond orders. You'll find that they are 3, 2.5, and 2, respectively.

Bernard Meurer

Sorry, 2.5

then 3 and 2, AH

BREAKING NEWS: Chemistry is not completely insane

@orthocresol Oops

M.A.R.

@BernardMeurer You're going our exact way

9-BBN

@BernardMeurer 2.5 yes

Bernard Meurer

And the ionization energy will be inversely proportional to the nuclear distance, right?

So NO- has the highest one

M.A.R.

Highest bond order.

orthocresol

8:50 PM

I'm not sure how it correlates to the internuclear distance. I would look at the energy of the highest occupied orbital.

Bernard Meurer

@M.A.R. I am basically Mendeleev right now

9-BBN

LOL

M.A.R.

@orthocresol I guess they mean that stronger bond is shorter.

@BernardMeurer RISE. RISE FROM THE GRAVE.

Bernard Meurer

Onto my last question, and the one I have less of a clue about:

orthocresol

@M.A.R. Yeah but ionisation energy doesn't correlate to either bond strength or length

M.A.R.

8:51 PM

@orthocresol I know, but we're talking HS BS here.

orthocresol

@M.A.R. <shrug emoji>

Bernard Meurer

"Using the periodic table, calculate the dipole momentum in Debye of the simple bond N-O, indicate in which atoms are the partial positive and negative charges"

orthocresol

What magical data are you given in your Periodic Table that lets you calculate the dipole moment in Debye?

Bernard Meurer

Okay, seeing the direction of the momentum vector is easy, it just points to the most electronegative atom, right?

orthocresol

Yeah.

Bernard Meurer

8:53 PM

N->O

M.A.R.

@orthocresol The magix constant

Bernard Meurer

What's that formula for getting the dipole moment with the % of ionic character?

orthocresol

@M.A.R. denoted $c_\mathrm{m}$

@BernardMeurer I don't know of any such formula, to be honest. If you want an actual dipole moment the only way I know of to calculate it is the physics way: $\vec{\mu} = \sum q\vec{d}$

Bernard Meurer

@orthocresol There's a Electronegativity delta/% of ionic character table

M.A.R.

@BernardMeurer It should be in your textbook or something. It's gotta be something ridiculously inadequate and useless

orthocresol

8:55 PM

Can't help you with that, I've never seen that before.

Bernard Meurer

@M.A.R. I don't have my tetxtbook :/

M.A.R.

O.O

You have mine?

SO IT WAS YOU

Chasing Bernard

Bernard Meurer

Dipole moment = Energy of Electron * Distance * %ionic character

@M.A.R. Lol, Chang is too expensive for me

M.A.R.

Who's Chang?

@BernardMeurer And how is percent ionic character measured?

Bernard Meurer

@M.A.R. Don't ask me hard questions, It's here on my periodic table

M.A.R.

8:59 PM

O.O

9-BBN

Show us

orthocresol

@M.A.R. gen chem textbook

M.A.R.

On the plus side, you now seem to have all the required data.

Bernard Meurer

drive.google.com/open?id=0Byf35sSROVGbOEd6eXRxbHVSbWM

Second page, table under the captions for the Fe example

M.A.R.

@BernardMeurer What the color

It looks 100 years old

And HOLY CRAP that's a lot of data in one cell.

Bernard Meurer

9:02 PM

@M.A.R. I quite like this table tbh, has a lot of data

my friend's one has electroafinity too, I wish I had that

M.A.R.

@BernardMeurer I think you can download similar tables from the interwebz

Bernard Meurer

@M.A.R. Yeah but I already bought this one, it cost me 45 cents it needs to last at least 5 years

orthocresol

Bernard Meurer

Did any of you understand what's on that little table I'm talking about?

M.A.R.

@BernardMeurer I couldn't read

@orthocresol Is this becoming a chat meme or what

Bernard Meurer

9:04 PM

Top row "Electronegativity Delta" Bottom row " Percentage of ionic characteristic"

orthocresol

Oh, ok. I see it.

So, what's your issue? You have EN values so you can calculate the difference, and from there you get the % ionic character.

You can look up the bond length somewhere, I suppose.

And lastly, I have no clue what energy of electron refers to, but you probably have something on it?

Bernard Meurer

Just checking if my formula is right or if I'm plain wrong

M.A.R.

@BernardMeurer Your formula is right in the exam if it's from your textbook, and wrong everywhere else.

orthocresol

I've never heard of such a formula, but if your text says so, then go with it.

Bernard Meurer

Jesus christ what am I learning?

M.A.R.

9:09 PM

@BernardMeurer Exam material.

9-BBN

It looks fun

Maybe a tanh in the "f" function

orthocresol

Why not just a sin?

M.A.R.

Sins are for sinners.

9-BBN

Because a sin is periodic

M.A.R.

No sins in this chat

@9-BBN And what if the whole diagram is part of one period?

9-BBN

9:17 PM

You cannot make a negative difference of electronegativity it doesn't make sense and you cannot make one more than the most electronegative - the less one with will be less than 3.98

which will be *

Bernard Meurer

"Determine the wavelength of the photoelectrons removed from a rhodium anion (Rh-) with a radiation of 488nm, knowing that the electroaffinity of Rh is 110,27 kJ/mol"

So, this one I can kind of make sense of

So for Rh to get an electron it must be charged with 110.27Kj/mol of energy, right?

So for Rh- to lose that electron it would need the same energy

It's the last step that I don't see how to do, do I need de-broglie?

orthocresol

That's very odd, normally questions ask about the kinetic energy of the photoelectron. To convert the energy to a wavelength, yes, you need the de Broglie relation.

Bernard Meurer

But what do I use the 488nm radiation for? Do I need to see how much energy that means with E = hv (v being frequency)

orthocresol

9:32 PM

You know how photoelectron effect works?

You shoot x amount of energy at something.

y amount of it is used for ionising the thing.

and you need to conserve energy, which means that there's (x-y) of energy remaining. This goes into kinetic energy of the electron.

Bernard Meurer

OH

So

the energy of that radiation is $h * 488$?