The Periodic Table

koolman

19:27

Thank you @Jan

Jan

19:38

Title of the day

Mithoron

@Jan Wow :D

Hexacoordinate-C

-3

Q: Why is the van der Waals radius of nitrogen greater than that of neon?

Neon is a noble gas. Therefore, its van der Waals radius should be highest in the respective period. But why has nitrogen has a greater van der Waals radius!

Why do people down vote ?

Mithoron

@Hexacoordinate-C You didn't see earlier title, which Jan linked? OP is well...

Hexacoordinate-C

Oh OK haha

He will wait then

And I'm not sure Neon has a greater VdW radius than Nitrogen

Mithoron

nitrogen is diatomic...

Hexacoordinate-C

19:52

And ?

Mithoron

@Hexacoordinate-C If it's radius for molecule that it's not strange it's bigger

Hexacoordinate-C

@Mithoron There are tables with VdW radius of all (most of all) elements including nitrogen.

physlab.lums.edu.pk/images/f/f6/Franck_ref2.pdf

orthocresol

groans

writing meta is difficult

Jan

Was that a meta-groan?

orthocresol

it is

it is a 1,3-groan

Hexacoordinate-C

20:03

Lol

Jan

An allylic groan?

orthocresol

My groans couple to each other with J ~ 2 Hz.

Hexacoordinate-C

In 1Groan NMR ?

gannex

@QuantumCAPUCCINO

I'm a 3rd year undergrad. My labs all take around the same amount of time to perform, but some take vastly different amounts of time to write-up. I' in pure-chemistry now but I used to be in biochem, and my biochem lab reports could be written in like 90 minutes, but now I have analytical, physical, and inorganic chem labs that can take up to 12 hours to write. My inorg labs take 4 hours to do, but I have to rush or I won't finish, and the reports take a long time mostly because I have to read & understand beforehand. Inorganic chem. is just the right level of complicated…

orthocresol

sounds about right

Hexacoordinate-C

20:08

@gannex studies ... :-)

pentavalentcarbon

@orthocresol oh god I finally get why it's called the 1,3 feed...

orthocresol

haha...

Jan

You know, @ortho, if you want to procrastinate from writing meta posts, you could draw up a scheme for the E2 elimination for me … O:)

gannex

@orthocresol Yeah, I think my university over-stresses lengthy lab reports. We have too little physics and math and too much boring writing. When I graduate, I'm going to write a letter to the admins and tell them they need to change stuff up a bit. My analytical labs are time-consuming because they take a huge amount of statistical analysis. The actual expt takes 30 min. but the report takes hours.

orthocresol

@Jan What kind of scheme do you want?

Jan

20:10

One that shows how the Zaitsev product can’t form in an E2 elimination.

(I’m being rea~lly lazy for not drawing it myself, I know O:))

orthocresol

@gannex I spend a lot of time on pre- and post-labs as well, but not quite as much as that. Perhaps 2-3 hours per lab. The lab itself is anywhere between 6-12 hours.

gannex

as for what you said about medicine/bio, I totally agree. That is one of the things I like about chem. We apply the same theories to many different specific situations, instead of the other way around.

orthocresol

@Jan Is it for that specific case? I wouldn't mind if it was a cyclohexane, but I'm lazy to draw cyclopentanes nicely..

gannex

you're an undergrad right @orthocresol ? You do 6-12 hour long labs for classes? I didn't know people did that. I have 4 hours for all my labs, but the writeups take a while.

Jan

It would be for the specific case.

I’ld be fine drawing it myself sometime later™ ^^

orthocresol

20:11

@gannex well, it depends on where you go to. Yeah, I'm a UK undergrad.

Hexacoordinate-C

@Jan has troubles to use ChemDraw haha

Jan

@Hexacoordinate-C Troubles called lazyness ;p

gannex

I like what I hear about UK schools chem programs. I wonder if I should apply to grad school there.

orthocresol

well, grad school is definitely shorter than in US

gannex

oh yeah? I thought Ms.c was two years for everyone.

but yeah, with RSC and places like nottingham, the UK seems like it's bossing out in chemistry. at least in proportion to its size, as a country.

orthocresol

20:13

Here a masters is usually 1 year and PhD's are 3-4 years.

gannex

oh wow. I wasn't planning on getting a PhD immediately. I ought to go get a masters in the UK.

Hexacoordinate-C

@Jan I have molecular models

pentavalentcarbon

Please don't forget that PhDs in the US are like MS + PhD from Europe, but no distinct MS diploma.

So the timeline is more similar.

orthocresol

Oh yeah, that's true.

I guess the other thing about doing a masters in UK is, not every university offers 1-year masters courses

Quite a number simply offer 4-year undergraduate courses leading to a MSc (or equivalent)

So your choices are (just slightly) limited.

Hexacoordinate-C

20:29

@Jan

Jan

@Hexa?

Hexacoordinate-C

We need to draw a non planar cyclopropane

Jan

Yeah, of course we do. Distortions are necessary.

orthocresol

how do you draw a non-planar cyclopropane o.o

Hexacoordinate-C

You can also show my beautifull pictures

beautiful

@orthocresol you can move bonds in ChemDraw

You can also you paint :P

Loong

20:35

@orthocresol It's like the non-linear H2 molecule.

Jan

I read cyclopentane there o.o'

Freudian misreading imho.

Why did you delete your @Loong answer? I wanted to upvote it =C

Hexacoordinate-C

Yeah cyclopentane sorry

lol

orthocresol

@Loong H2 undergoes a fifth-order Jahn-Teller distortion to a bent structure.

You need my molecular model set to prove that it works..

Hexacoordinate-C

Obviously

Jan

Tell Chuck and his hexagonic ozone structure =D

orthocresol

20:37

:D

Loong

@Jan I misread the question. I was thinking about how U-239 is made from uranium. But the question actually is about making U-235 from U-239.

Jan

Sounds so simple and reasonable o.o

gannex

since we're on the topic, does anyone know a version of Chemdraw where you can rotate things out of plane? I'm using ChemBiodraw 14.0, for example, and I need to use the orbital diagrams, but there is no easy way to draw dxz. You just have to use dyz and say you're changing the axes.

Jan

ChemDraw is terrible at 3D rotation, but it should feature a rotate-in-3D button.

gannex

@pentavalentcarbon I'm in Quebec where we have 2 year college (1 year shorter HS), 3 year Bsc, and 2 year Ms.c or 5 year Ph.d. Does it end up working out the same way?

Loong

20:41

@Jan U-238 -> U-239 -> Np-239 -> Pu-239 is also a nice experiment for students if you can have the course on multiple days of the week

gannex

maybe chembiodraw doesn't haev rotate in 3d?

Jan

It should; iirc it’s the same program whether you start it as ChemDraw or ChemBioDraw or SuperDuperUltraMegaOmegaChemBioPhysicsIncredibleDrawWhatnots.

Hexacoordinate-C

We can also use Neuman representation

@Jan Object -> Template -> Cycloalkanes

Jan

Are you telling me where to find things in ChemDraw? If so, that’s kinda cute =3

Loong

:-D

Hexacoordinate-C

20:49

Not that perfect but it's a begining

I should put my bromine in the opposite side

Loong

@Jan However, it took surprisingly long for me to find out how to draw a benzene with a circle instead of the Kekulé structure.

Hexacoordinate-C

@Loong and howdo you do ?

Loong

@Hexacoordinate-C hold CTRL while you place the benzene

Hexacoordinate-C

Thank's

@Jan sorry this is not Object but "view"

Loong

Hm, "Hexacoordinate-C" also sounds like a keyboard shortcut command: "Press Hexacoordinate-C to cancel."

Hexacoordinate-C

20:59

^^

But it exits

I don't know if I can say it exists. I would prefer say some people used something to measure a thing which looks like the molecules I have on my profil pics

Andrew Li

Are general chemistry questions welcome here?

Hexacoordinate-C

Yes

Everything about chemistry

gannex

@Jan oh ok so there is a rotate in 3D function, it just doesn't work for their pictures of orbitals. So how the hell does chemdraw want me to draw a dx2-y2 with the z axis in the plane of the paper?

@Andrew Li anything that will help me procrastinate

Hexacoordinate-C

@gannex ask Chuck Norris

This is not Chuck Norris who draws dx2-y2 this is the dx2-dy2 which appears for him :P

Andrew Li

Ok. So if I understand correctly Hydrogen-1 has no neutrons right? Just 1 proton and 1 electron

Jan

21:13

Chuck Norris keeps his electrons in his orbitals’ nodal planes.

@AndrewLi Correct.

gannex

@hex

@Hexacoordinate-C but I see people make diagrams of these orbitals that look like chemdraw style. there must be a way

Andrew Li

Helium-2 has 0 neutrons too because it has 2 as its mass number and helium has 2 protons/electrons (because that's the atomic number) right?

Or am I misunderstanding

Hexacoordinate-C

@AndrewLi no

Jan

It is correct.

orthocresol

yeah, but i'm not sure if it exists

Andrew Li

21:16

@Hexacoordinate-C Why not?

Hexacoordinate-C

Helium has two neutrons

Andrew Li

I thought so

orthocresol

Helium-4 has two neutrons

Jan

Helium-2 hasn’t been made yet according to webelements.com

Andrew Li

Hm. Wikipedia suggest that it exists

Loong

21:18

@orthocresol Its half-life probably corresponds to the time that it takes a photon to cross the diamater of the nucleus. ;-)

2

Hexacoordinate-C

Sorry I just see Helium

Jan

!!wiki/Helium

Chemobot

Helium

Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements. After hydrogen, helium is the second lightest and second most abundant element in the observable universe, being present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this figure in the Sun and in Jupiter. This is due to the very high nuclear binding energy...

Hexacoordinate-C

@gannex

Andrew Li

Isotopes of Helium

Wait. It says it may be possible that helium-2 has an even shorter half-life

Oh, so that means it hasn't been discovered?

Jan

21:20

Apparantly, scientists claim to have discovered it, but it undergoes beta decay to deuterium.

Andrew Li

Ok

Hexacoordinate-C

This might be a questin I would ask in PSE but when physicists measure what they call a "particule" what is the criterion to be accept as it and not as a wave ?

orthocresol

calling something a particle doesn't mean that it doesn't also exhibit wave-like behaviour

that double negative

._.

gannex

@Hexacoordinate-C there's no out of plane d orbital picture, and you can't rotate the in plane d orbital they give you in that menu

Loong

"Of these four forces, there's one we don't really understand." "Is it the weak force or the strong--" "It's gravity."

4

Andrew Li

21:24

Thanks :-)

Hexacoordinate-C

@gannex you can rotate on the plan with ctrl ^^

Jan

Loong, stop posting that many star-worthy comments =D

Loong

I was just too lazy to explain the Coulomb repulsion of a proton-proton nucleus.

Andrew Li

So if a nucleus becomes more and more unstable if the protons and neutrons are more and more unbalanced, why is Hydrogen-1 stable, and Helium-2 not?

Hexacoordinate-C

@orthocresol for me in my head measure a wave will looks like a sin(x) and measure a particule will look like a sin(x)/x in 0

Or better a dirac

with some fluctuation on the sides

orthocresol

21:29

yeah thats because your measurement collapses the wavefunction

to either a position eigenstate (dirac delta function) or a momentum eigenstate (a plane wave)

Hexacoordinate-C

hum

orthocresol

in position representation, that is

Loong

@AndrewLi H-1 has only one proton. Thus, there is no proton–proton repulsion.

Hexacoordinate-C

Ok I understand

Andrew Li

@Loong Oh, that makes sense! Thanks :-)

Loong

21:31

“To receive full credit all work must be shown”

Hexacoordinate-C

Yeah I was reading

He may be cheating ?

Did I saw "antilog" ?

0

Q: Effect of pH on Dilution of HCl Solution

Q. A solution of HCl has a pH of 5. If one ml is diluted to one litre. What is the pH of the resulting solution. Attempt- $$pH=-log[H^{+}]=5$$ $$[H^{+}]=antilog(-5)=10^{-5}$$ $$M_{1}V_1=M_{2}V_{2}$$ $$10^{-5}*10^{-3}=M_{2}*1$$ $$M_{2} = 10^{-8}$$ Thus, by common ion effect, $$[H^{+}]=10^{-7}[1...

homework ph

gannex

21:55

@Hexacoordinate-C doesn't work for me (ctrl is just right click on my mac) using ctrl or command.

pentavalentcarbon

@gannex Woah, that sounds very different though I think there's some terminology difference, college/university/BS/BA are the same thing; 4 years HS, 4 years college, 1-2 years MS or 4-7 years PhD

1,3-feeds

1

Q: A new policy of closure: November 2016

What's the current homework policy? The current HW policy is laid out in this post. In essence, only blatant homework copy-pastes should be closed. These often get closed unilaterally by moderators. Why do we need to do this? What's wrong with status quo? There have previously been disagreeme...

discussion featured close-reasons

orthocresol

@1,3-feeds you're really slow

:(

Loong

22:14

@orthocresol yes, the meta position is thermodynamically possible but kinetically inhibited

Jan

@hexa I was being nice to you, but remember to catch all instances where \ce or \mathrm are applicable ;)

Hexacoordinate-C

23:12

@Jan I do my best.

\ce for elements and \mathrm for fomulae. But I don't what is the main difference between them.

See*

Jan

Well, logics.

\ce logically wants to deal with an element, a compound, a formula, a reaction equation or something else that is ‘chemical’.

\mathrm is just meant for ‘we’re in maths mode but we need roman type.’

And then there’s \text which is basically ‘quickly escape from maths mode to insert a shot of text.’

Hello @Ringo and @Todd, how come you came in almost simultaneously? o/ Illuminati?

ringo

Our collective mind told us it was time for a chat

Todd Minehardt

hey @Jan - maybe it's something to do with how buses always arrive in pairs :)

either that or it's a slow day in ATX

hiya @Hexacoordinate-C

ringo

A nice day as well

Todd Minehardt

you have that right, sir - beautiful weather

Jan

23:22

I buses arrived in pairs at the stops I usually use, I would be doubly baffled because they’re only serviced by one bus line.

Or maybe you’re left sock and right sock? =D

Todd Minehardt

@Jan - could be. Something to do with traffic flow and delays (for real) and you get 2 or 3 buses at one stop all at once. Probably something to to with interrupting networks with scheduled events...

is the HW policy overview slated for today?

Loong

@Jan Maybe we should make the difference more clear here or here.

Todd Minehardt

hi @Loong, haven't chatted since the election - congratulations to you!

ringo

The homework policy issue seems to come up a lot without any resolution

Loong

@ToddMinehardt Hey y'all! Thank you. :-)

ringo

23:27

I've spent nearly my entire life in Texas, but I find I hardly ever say "y'all"

I certainly hear it a lot from those around me though

orthocresol

this is supposed to be the resolution

T_T

ringo

Well, there appears to be a good number of us here

By chance

Todd Minehardt

$\buildrel{\wr\wr\wr}\over{
\buildrel{\buildrel{\odot\;\odot}\over{\triangleright}}\over{\smile}}$

Jan

And the absolution!

pentavalentcarbon

waaahhhh, I don't want to do it now, I have to make dinner and hack on my stupid CV...

Jan

23:30

My TeXskills aren’t stronk enuff.

Todd Minehardt

@ringo - i like y'all, but use it infrequently. i'm a transplant from new jersey so i say "you guys." been here for almost 25 years though...

ringo

Texas all the way from New Jersey! Did you come here for school or a job?

I saw that you were a lecturer here at one point I thought

orthocresol

some hardcore nitrene chemistry going down here... chemistry.stackexchange.com/questions/62619/…

Todd Minehardt

i came for grad school - i started in Spring semester, 1992. got my master's in aqueous geochemistry/geology (Phil Bennett) in 1995, then was in Welch Hall from 1995-1999 getting my phd in theoretical chemical physics with Bob Wyatt (he's emeritus now). I did a couple of post-docs (UCSF, Princeton) and was a tenure-track prof at University of Colorado, Denver for 1.5 years (not a good fit). Came back to austin, lectured for one semester in 2004,

been bouncing around as basically a "scientific software developer" since then.

ringo

Very cool! What was the course you lectured in? You clearly have expertise in a few areas

Todd Minehardt

23:43

i taught second semester general chemistry for non-majors - i think it's CH 305, basement of Welch. i had 251 students. probably 10 of them wanted to be there :) I was between jobs and the guy who was supposed to teach that semester (Fall 2004) moved or left town, I forget which. So I got pinged at the last minute. It was fun. Presently trying to get back into it, St. Ed's or maybe ACC.

ringo

Well if you end up back here I'll be sure to take your course if I can :)

They've been renovating Welch as of late. I think they're due to finish renovations by next school year(?)

Todd Minehardt

ha that'd be wild - yeah, i think so - i get a newsletter from the chem dept once in a while. i was there for the last renovation due to one of Martin's guys setting a lab on fire

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