12:00 AM
Yes, I didn't say otherwise

If I like plots and interactive stuff, then I might think Python is a PITA

Well, that's a good point, Mathematica is better for animation and some interactive things

Source: have used matplotlib.

For plots in general, I much prefer matplotlib

I was just trying to think of programs that might be of assistance.

12:02 AM
@DavidZ yes well, you think in code.

@DanielSank, I was able to get the Arduino IDE installed =D

@heather YES!
o/

@DanielSank I ended up having to ask a question on arduino.SE, but it's installed
\o/

\o/
Got a project?

i was gonna make LEDs blink and line them up so they said merry christmas
nothing big
i just wanted to do it

12:19 AM
@heather check out my new hat
I have a beard now too

very nice @Kenshin

ty:)

2 hours later…
1:58 AM
Hi, everybody.

@DanielSank hi!

Woohoo! I got a cool hat!

@DanielSank iam also getting in 2 days,i n MSE
:D

2:35 AM
@Ramanujan What is this screenshot telling me?

@DanielSank see my fanatic batch it's 98/100
Only 2 days left to get gold batch😍
@Kaumudi.H hi,good morning

user228700
G'morning :-)

user228700
I've a quick question. This is what the Wiki page about Dipole-dipole interactions says:

user228700
> "Often molecules contain dipolar groups, but have no overall dipole moment."

user228700
What are "dipolar groups"?

user228700
2:43 AM

@Kaumudi.H di means 2 ,polar means having electrical or magnetically polarity,groups means just .a group
@koolman good morning :)

Good morning @Ramanujan

user228700
@Ramanujan That...is extremely unhelpful. I'm thinking about how there may be sections of a compound that are polarized but that the dipole moments of these "sections" cancel out.

user228700
> "This occurs if there is symmetry within the molecule that causes the dipoles to cancel each other out. "

@Ramanujan cool. It's "badge" by the way.

2:57 AM

user228700
Can anybody confirm if what I said is correct..?

user228700
@heather: Ello, almost Merry Christmas! :-)

indeed

user228700
No, that was me wishing you :-P

@Kaumudi.H, oh, thank you
Merry Christmas to you too
gtg now, good night all

user228700
3:10 AM
Thanks :-) G'night.

3:54 AM
From the "Comments not posted" file:
> You've been involved with this site for more than a year. You should probably put a little time into learning the editing tools and markup sometime soon.

4:08 AM
Is the allowed frequency of photons discrete or continuous?

@DHMO Depends on the system, of course.

@dmckee so it can be continuous?
I thought they are quantized lol

@DHMO As a general rule, quantization comes from boundary conditions. In the case of many open system you don't need to apply any beyond normalization so the spectrum is continuous.

@dmckee then I've been having a misconception for a long time lol

Of course (in a flat space-time) the number of photons is quantized, but that doesn't effect their spectrum.
@DHMO Many students come with it. I blame the popularity of "quantum leap" for that.

4:12 AM
no that isn't where i got it from
I got it from the ultraviolet catastrophe lol
> The ultraviolet catastrophe, also called the Rayleigh–Jeans catastrophe, was the prediction of late 19th century/early 20th century classical physics that an ideal black body at thermal equilibrium will emit radiation in all frequency ranges
so the natural negation is that it cannot emit in all frequency ranges?
@dmckee

@DHMO SO the ultraviolet catastrophe is resolved by quantizing the photon number. But (in the large size limit) they are allowed to take on any energy per photon.

so I was misled by that sentence lol

What changes between classical and quantum regime is the minimum amount of energy you can put into a band. There is no lower limit in the classical regime, but in the quantum regime it must be in units of $\hbar \omega = hf$.
With that established stat. mech. tells you that high frequency emissions are rare.

@DHMO It's hard to write clearly about. I have a supplementary note on the subject I'm preparing for my students, but I keep ending up unhappy with it. So I've been "preparing" it on and off for about nine months now.

4:28 AM
Hi guys.

@SwapnilDas hi!

5:08 AM
Hey, Ramanujan :)

user228700
Where the heck is @Kenshin when you need him? >.<

Lol.

user228700
@DanielSank: Very nice hat, that :-)

That rhymes!

user228700
Yep! Can anybody to help me to understand the subtleties b/w the different kinds of intermolecular forces?

user228700
5:20 AM
I'm referring to this:

user228700
Intermolecular forces (IMFs) are the forces which mediate interaction between molecules. They also include forces of attraction or repulsion which act between molecules and other types of neighboring particles (e.g., atoms or ions). They are weak compared to the intramolecular forces – the forces which keep a molecule together. For example the covalent bond, involving the sharing of electron pairs between atoms, is much stronger than the forces present between neighboring molecules. Both sets of forces are essential parts of force fields frequently used in molecular mechanics. The investigation...

user228700
And I cannot stress how confusing it is.

Howdy

user228700
Hey, @SirC :-)

5:49 AM
@Kaumudi.H which forces in particular?
If I explained every force it would be as long as the article

user228700
@DHMO All of 'em are pretty confusing.

@Kaumudi.H which do you want first?

user228700
brb

@Kaumudi.H there aren't that many different kinds of intermolecular force ...

user228700
I'm back!

user228700
6:03 AM
The information provided on the Wiki page doesn't match with what my textbook says, and my textbook doesn't match with what some YouTube videos have taught me.

user228700
Also, @JohnRennie: Morning :-)

How's the new computer working?

Morning :-)

Note that all intermolecular forces are electrostatic in origin. Assigning them to specific categories is always going to be a bit vague.

user228700
6:05 AM
Well, one of the major problems that I have found is that they've classified "Dipole-dipole" and "Van der Waals" into different categories.

user228700
@Pissedofflayman It's perfect, thanks :-)

user228700
While Van der Waals forces are caused due to induced, temporary dipole moments (according to my textbook), this isn't what Wiki says.

user228700
Also, let me submit that I have spent the past few hours, trying to figure this out so forgive me for being so sketchy. I dunno what I know and what I don't, at this point.

@Kaumudi.H Isn't it? That's how I've always understood VdW forces.

user228700
6:10 AM
@JohnRennie Me as well, but the Wiki page is effed up.

There is a possible ambiguity. The induced dipole fores are more properly dispersion forces
London dispersion forces (LDF, also known as dispersion forces, London forces, instantaneous dipole–induced dipole forces, or loosely van der Waals forces) are a type of force acting between atoms and molecules. They are part of the van der Waals forces. The LDF is named after the German-American physicist Fritz London. The LDF is a weak intermolecular force arising from quantum-induced instantaneous polarization multipoles in molecules. They can therefore act between molecules without permanent multipole moments. London forces are exhibited by non-polar molecules because of the correlated movements...

user228700
They are part of VdW forces..?

Some people like to define VdW forces as broader than this i.e. the dispersion force is just a part of the VdW forces.

user228700
Okay, what else does the superset contain, then?

Ah, I see that's what Wikipedia does. It's treating VdW force as basically the same as intermolecular force
So defined that way the term VdW force includes all the forces between molecules.

user228700
6:15 AM
Aha, many YouTube educators also used this definition!

user228700
Hang on, even hydrogen "bonds"?

user228700
Okay, so from what I understand, VdW forces ~ ?*All* intermolecular forces and these are:

user228700
1) Dipole-dipole (which, yes, includes hydrogen bonding)

9

Is a hydrogen bond considered to be a Van der Waals force?

user228700
2) Ion-dipole

user228700
6:18 AM
3) Dipole-induced dipole

user228700

user228700

user228700
> "The way I think of it is: van der Waals forces are anything that make a gas non-ideal, since that's how they were originally discovered and defined."

user228700
I guess that does make sense.

user228700
But many sources also include ion-dipole forces...

6:21 AM
Ion-dipole would be included as well.
I wouldn't place too much significance on exactly what each and every source mentions in their definition.

user228700
But the O.P doesn't seem to have included those in his answer...

user228700
> " The term includes: dipole–dipole, dipole-induced dipole and London (instantaneous induced dipole-induced dipole) forces."

That's quoting from the IUPAC site.
As I said, I wouldn't attach too much significance to the fact that ion-dipole forces aren't specifically mentioned.
The VdW force basically means everything that isn't intramolecular

user228700
Hmm, okay. Say, with reference to this, does it make sense to say:

user228700
Van der Waals force of attraction $\propto$ Molecular weight/Atomic weight

6:25 AM
The proportional symbol is \propto $\propto$

user228700
Thanks :-)

@Kaumudi.H I'd be surprised if any sweeping statements about VdW forces were useful, because the types of interaction included are so varied.

user228700
Okay, I guess it doesn't make sense to say that when talking about like, heteroatomic molecules.

user228700
But for inert gases, that seems to be true, no? I googled it and what I found is that for inert gases, these forces largely depend on the polarizability of the atoms and polarizability increases with increase in the number of electrons in the valence shell, which also increases with atomic weight.

For dispersion forces polarisibility is important because the greater the polarisibility the easier it is to induce dipoles.

user228700
6:29 AM
And when u say dispersion forces, you mean those temporary dipoles, yeah?

Yes
But even for atoms I don't think there are simple rules. e.g. I bet Fluorine is less polarisible than carbon because it's smaller.
(I haven't actually Googled to check ...)

user228700

user228700
> "A bigger cloud is more polarizable."

Ha, just Googled and fluorine is less polarisable than carbon.

user228700
But...

6:35 AM
But what?

user228700
Hm, okay, this correlation with the number of electrons/mass or whatever seems to work only going down a group in a periodic table.

You said (and I agree):
> A bigger cloud is more polarizable
But fluorine is smaller than carbon. So that fits.

user228700
(Since more electrons ~ smaller cloud when going across a period)

Yes. The effective nuclear charge increases as an orbital is filled so the electrons get pulled in tighter

user228700
Yeah. So ultimately, polarizability depends on size, not the number of electrons. It's just that size $\propto$ number of electrons when going down a group (but not when going across a period)

6:37 AM
Yes, though the link to size is an indirect one.

user228700
Huh? Isn't the link to the number of electrons the indirect one?

Polarisability is a complicated phenomenon that you need to calculate using a proper QM calculation.
It is roughly correlated to the size, but will be dependent on the exact electronic configuration.

user228700
Ohhh. ::Takes feet off the table, puts on shoes and starts running in the opposite direction::

As I recall (and it has been a long time) $d$ and $f$ orbitals tend to be highly polarisible. $p$ orbitals less so and $s$ orbitals even less so.
But do you need to know this level of detail?

user228700
@JohnRennie About the orbitals? Yeah, definitely. And what you said makes sense. The s orbitals are closest to the nucleus so good luck polarizing the electrons over there (:-P) and then as we keep going higher up (p, d, f...) the inner electrons do a good job of shielding the outer electrons from the nuclear charge so I think the effective nuclear charge decreases quite a bit.

user228700
6:43 AM
Does that make sense?

Yes, that matches what I remember.

user228700
Wokay! Sigh, I should've just waited for you to come online. I've been struggling with this crap for the past 4 hours and 45 minutes :'-(

Though with complications e.g. filling the 2p orbital going from B to Ne pulls the $p$ orbitals inwards and decreases the polarisability.
@Kaumudi.H I think you sometimes worry about the exact meaning of terms that are actually somewhat vague.

user228700
@JohnRennie Yeeah, but the problem is that I was sort of drowning in a pool of information and didn't know what the heck to do to sort anything out. This is probably where having a study partner helps.

A lot of the terms we use originated a hundred years ago when the subject was poorly understood, and as a result they aren't as precise as they could be.

user228700
6:46 AM
Hmm, yeah :-/

user228700
Anyhoo, thanks ever so much for saving the day again! :-) I can finally move on now :-P

Sigh. Yesterday exciting new laptop. Today back to revision :-)

user228700
Haha, yes :-P

Have you found the films?

user228700
I'm sorry I told u that I'd send a mail and then I...didn't :-/ I completely forgot.

6:48 AM
Did you?

user228700
@JohnRennie No, not yet. I'll ping you when I do. I'll do it today, for sure.

user228700
@JohnRennie Yep! That's one of the first things I did after getting it-check for the films :-P

@Kaumudi.H cool. The customs didn't delete them then :-)

user228700
Nope. Not even one :-) I wonder what they did tho-they used up 16% of the charge!

That's only an hour or so. They probably turned it on then went for a tea break.

user228700
6:51 AM
:-P Yeah. But this thing charges super fast! I'm sort of in awe at how amazingly fast, beautiful, etc. etc. this is because I haven't worked on anything that can compare before.

I do like those Dell laptops. They're four years old now but I still think they are an excellent design.

user228700
Of course you like 'em! Aren't all the laptops u own of this kind?

The good thing is that lots of companies bought them, and companies dispose of laptops after three years for accounting reasons. So there are lots of cheap Dell laptops around at the moment.

user228700
@JohnRennie Oh, wow, that's crazy.

user228700
Dyou know where mine is originally from..?

user228700
6:54 AM
(No, not the factory :-P)

I don't. The label on the top probably said which company owned it originally but it had been partially torn off by the time I got it.

user228700
Oh, okay, so it was a company.

Yes. I got it through my work place. It was returned to them for disposal.
So my work place probably supplied the laptop in the first place, and we only deal with comapnies not individuals.

user228700
The company you work for does disposing of electronic goods?

No. We're an IT support company.

user228700
6:57 AM
Oh, cool! :-)

And supplying laptops and computers is part of the service.

user228700
I see.

The laptop was returned because it was broken, but it rarely makes sense to try and repair laptops for a company as it's cheaper to buy a new one.

user228700
Ah, right.

It makes sense for me because I have the spare time to waste messing around with the broken laptops.

user228700
6:58 AM
Ooh, ooh, you had chole last night/afternoon?

Ah, you've seen the picture :-)

user228700
Yes, just now :-) Was it good?

See! I do eat vegetables sometimes :-)
It was really nice.
I love the way the intense flavour of the chole really brings out the flavour of the rice and vegetables.

HEllo

user228700
Tell me the next time you eat veggies again and then I can ascertain whether sometimes is really that often or not .

7:00 AM
@Kenshin Morning :-)

user228700
@Kenshin: Hey :-)

@Kaumudi.H I have that scheduled in for spring 2017

user228700
So that was a "risotto"?

user228700
@JohnRennie ::facepalm::

:-)
@Kaumudi.H sort of. An Italian chef would probably disagree.

user228700
7:02 AM
I don't know what a risotto is, so no worries :-P

I just put rice, stock and everything else ina pan and cook it for 15 minutes. A lazy man's risotto!

what did you need me for @Kaumudi.H

user228700
@JohnRennie Stock?

Risotto /rᵻˈzɒtɒ/ (Italian: [riˈzɔtto] or [riˈsɔtto]) is a northern Italian rice dish cooked in a broth to a creamy consistency. The broth can be derived from meat, fish, or vegetables. Many types of risotto contain butter, wine, and onion. It is one of the most common ways of cooking rice in Italy. Risotto in Italy is normally a primo (first course), served on its own before the main course, but risotto alla milanese, (pronounced [riˈzɔtto alla milaˈneːze]), is often served together with ossobuco alla milanese. == Rice varieties == A high-starch (amylopectin), low-amylose round medium- or short...

@Kaumudi.H @JohnRennie can you see my new hat?

7:03 AM
@Kaumudi.H Vegetable stock in this case!

user228700
@Kenshin JR came to the rescue! :-)

awwq

user228700
@Kenshin Yep. It's nice :-)

good ay

Ooh I just got a new hat

user228700
7:04 AM
@JohnRennie Oh, I see. Where did u get the Chole, from?

@Kaumudi.H u like a big hairy beard?

user228700
@Kenshin On real people? Not really. Have u seen Patrick Rothfuss's face? It's terrifying :-P

user228700
@JohnRennie So can't u like, get Indian sweets from wherever you got the chole?

wow that beard is crazy
just like my hat
@Kaumudi.H r u enjoying the new laptop?

user228700
7:06 AM
@Kenshin :-P Yuh huh.

or bored of it now?

user228700
@Kenshin Totally!

user228700
@Kenshin Nope. It's still amazing af :-)

wtf is that hat and how did you get it

user228700
7:08 AM
@JohnRennie I see.

user228700
Why do I feel like that hat makes u look a little bit like an old, erm, woman? (:-P)

I can buy gulab jaman in the UK but they are expensive.

how much

@Kenshin It's a secret hat so I don't know how I got it. It just appeared. It's probably just for taking some action of Christmas Eve.

r u at ur mum's house John?

user228700
7:09 AM
@JohnRennie Yeah :-/ I'll go to England one day and I'll bring a bunch of sweets with me. Then I can meet u (if u want) and then give them all to you! :-)

There's a Christmas eve hat? I can't see it, your picture is too small :-/

@Kaumudi.H AUstralia is better than England

user228700
@Kenshin I soooo wanna visit Scotland one day, so...

but y?

user228700
7:11 AM
@Kenshin It's really really really beautiful, that's why.

1 Brittish pound per sweet

user228700
@JohnRennie Oof, that is too much.

that's like $2 per sweet WTF @Kenshin they're a special treat so the price isn't terrible. yeah but who is going to eat 12 user228700 7:12 AM @JohnR: I just checked out the enlarged version of ur avatar with the hat and yep, it certainly makes u look like an old women :-P user228700 @Kenshin I will. oh lol user228700 Not all at once tho. I can do 5 at a time :-P You couldn't eat 12 gulab jamun at once. Not even I could do that! 5 per gob full? 7:13 AM Hii , can anybody help me in this physics.qandaexchange.com/?qa=649/… . user228700 @JohnRennie Hey, don't challenge me :-P I could totally pull that off! @Kaumudi.H do they have this cake in your country: I am getting the answer as (5/2)$\omega$$_0 but the answer given as (5/7)$$\omega_0$@DavidZ I think they did a Christmas Eve hat last year ... 7:14 AM @JohnRennie Yeah, it makes sense that they would. I don't pay attention to the hats nearly enough. user228700 @Kenshin By "do they have", dyou mean if I can eat that here? yeah user228700 I dunno, maybe. I haven't really tasted those many cakes. this is an australian/new zealand cake user228700 Actually, all I've tasted are the little pastries that I get in the little bakery nearby. user228700 7:15 AM @Kenshin I see. What's it called? Pavlova user228700 Ooh, why have I heard that name before? cos u've heard of pavlov's dog from psychology, it's difeferent tho user228700 Ah, yes. user228700 I was also thinking of "Elena Produnova" :-P user228700 7:17 AM Wokay, I'm off for a bit! user228700 Ooh, before I go, @Kenshin, I settled (okay, I wouldn't call it "settling") for this wallpaper: user228700 lol typical not bad tho user228700 -__- Why? coldplay u love coldplay user228700 7:19 AM Oh, u know about that? :-P Okay. yea ur last wall paper was coldplay user228700 Yeah, but that was very grainy. yea this one is betta laterz al all user228700 Bye :-) @JohnRennie could you help me in this physics.qandaexchange.com/?qa=649/… @Kenshin you too Or anyone else Or the answer given is just a misprint @JohnRennie @Kenshin 7:33 AM @koolman Mechanics problems isn't really my thing. Sorry. @JohnRennie ohk user228700 7:52 AM Quick question. Are the electrons in the same shell as the one in question also taken into consideration in the shielding effect? Yes. user228700 Wokay, thanks! :-) The electrons in the same shell overlap with each other, so they shield each other. user228700 Right... That's why He ($1s^2$) is smaller than hydrogen ($1s^1)$, but not half the size. user228700 7:55 AM Oh, yeah, that makes a lot of sense! Or would be a quarter the size for a$Z=21s^1$ion? Can't remember ... user228700 It's okay. The confusion is gone. Thanks very much! user228700 I just awarded 50 points for a bounty on CSE. How about I ask this question: Why isn't Helium half the size of Hydrogen? And then answer it myself? Would u mind? :-P Half the size. I couldn't resist checking :-) @Kaumudi.H here on the PSE you mean? user228700 No, on CSE... (:-|) 8:02 AM I don't care what you do on the CSE :-) user228700 Cool, thanks :-P You might want to check what their view is on canonical questions user228700 Ooh, okay :-| 9:47 AM [Division by zero, rambles]$a^2=0ca=1\forall x,y ,x+y=y\forall x, 1x=x1=x\forall x, 0+x=xa+c=0a^2+ca=0a0+1=0a1=0aca^2=c0a=c0a^2+ac=0+aca(a+c)=aca0=ac0=c!!!$[Divisible zero divisors] START=$\mathbb{Z}$and usual axioms Input$22=002=20=2$--->$4=2+204=02+0204=2+204=402=0(1+1)=0+0=0!!!\$