London dispersion force Puns

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Is it possible but just unlikely? Or is it not possible at all?

This is my first time using reddit I hope I did it right. Thank you so much in advanced

I have an exam in a few weeks and seem to be getting conflicting information from different sources on this question.

In the Kaplan Chemistry book it says that LDF’s don’t extend over long distances and are only significant in molecules that are close in proximity. But then they say that noble gases are only made up of London forces, but how would this be the case when gas particles have a larger distance between them?

I know that generally, dipole-dipole bonds are much stronger than LDFs. However, LDFs do grow in strength as the electron cloud/ molecule grows larger. Is there a tipping point where a large non-polar molecule would have stronger IMFs than a polar, smaller one? Would something like octane have stronger IMFs than ethanol? And is there any way to tell?

Also, I've read on the AP Chem syllabus that LDFs are not synonymous with Van der Waal's forces, but it never clarified what the difference was.

Why is CH4 a LDF but NH3 a hydrogen bond? Whats distinct about each 3?

Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c00190

https://ift.tt/32SjnkQ

Can anyone help me understand how we know that LDFs exist? How can we be certain of this minuscule IMF?

I am a sophomore in high school taking chemistry for the first time, and my teacher has explained the Dispersion forces before, but I am still extremely confused; any help?

I think all the forces mentioned in the title are the same but my book had this weird idea of 'instantaneous dipole-instantaneous dipole forces' which I don't get at all.

I don't think those forces exist, I think there's only 'instantaneous dipole-induced dipole forces'.

I also think that 'instantaneous dipole-instantaneous dipole forces', 'london forces', 'van der waals forces' and 'london dispersion forces' are more or less the same exact thing.

Here's the page in my book talking about all of this: https://imgur.com/a/nFv2Tib

Edit: Could 'instantaneous dipole-instantaneous dipole forces'/'london dispersion forces' be in-between molecules (Cl2-Cl2) and 'instantaneous dipole-induced dipole forces'/'london forces'/'van der waals forces' be in-between the two atoms in a molecule (Cl-Cl)?

More London Dispersion Forces -> higher boiling point

more "compact" non-polar molecules -> more LDFs

So does more "compact" non-polar molecules -> higher bp?
Also, do larger molecules have greater LDFs and thus higher bps?

In a molecule like H2O where the dominant force is hydrogen bonding is it still fair to say that it has dipole-dipole forces since there is a dipole movement toward the oxygens?

Also with a molecule like acetone that has dipole-dipole forces but no hydrogen bonding is it fair to say it has London Dispersion?

Need to get this cleared up because I have gotten conflicting answers.

To disperse means to spread, so why are attractive forces named after something that seems to be opposite to what they do?

This is something that none of my resources have really answered for me yet - London Dispersion IMF are generally presented as "instantaneous dipoles can occur in any molecule, and when it happens to be aligned such that opposite charges are near, there is a net attraction leading to cohesion." Why shouldn't the inverse also be true? Why is there a net cohesive effect (seen in the elevation of boiling/melting temperatures etc.)?

I'm doing an assignment where I have to compare experimentally derived London dispersion energies in dimers to ones that I've calculated using computational chemistry. To compare the two i need to work out the experimental values and ive been given the ionization energies and the atomic radii of the substituents molecules and I have to plug them into the equation: 𝑉(𝑅) = −𝐶6/ 𝑅6

The question I have is that im not sure where im supposed to get the R6 value from. Can anyone help? Thanks in advance

PS: Sorry if this worded poorly :)

LDF's make atoms dipolar because more atoms are on one side of an atom for a short amount of time. That much I know. But what I'm interested in is to how uneven an atom can really be, what is the max, if there is one, on how many electrons can possibly be on one side at a single given time?

I'd also like to make sure my title was factual and I'm not wrong. That may be a reason for my confusion.

I typically teach that a molecule that has more intermolecular forces (e.g. London disperson, dipole-dipole, hydrogen bonding) will have stronger IMF and will therefore have a higher boiling point than a molecule with just London dispersion forces. But then I look at dichloromethane (polar molecule) that has a higher vapor pressure than carbon tetrachloride (nonpolar molecule) which suggests that although dichloromethane has London dispersion AND dipole-dipole forces of attraction it is still weaker than carbon tetrachloride's London dispersion force because of all of the electrons!

I know it's not cut and dry but how do YOU determine when to use number of IMF (more IMF means stronger IMF) versus relative strength of London dispersion?

They are both easily pushed to one side and can take a negative charge.

Why do some people call them London forces, Dispersion forces, London Dispersion forces, van der Waals forces? Is there a difference, or some sort of history behind the name?

-Prospective Chem Major, Gen Chem II

Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c09976

Cary R. Stennett, Markus Bursch, James C. Fettinger, Stefan Grimme, and Philip P. Power

https://ift.tt/3scV2Vz

Are van der Waals forces more of an umbrella term with London dispersion forces being more specific?