Intermolecular Forces Explained | A level Chemistry

Intermolecular Forces Explained.
A level Chemistry.
Shapes of Molecules Explained:
• Shapes of Molecules | ...
Intermolecular forces Question Walkthrough:
• Intermolecular forces ...
Bonding Question Walkthrough:
• Bonding | A level Chem...
Bonding Multiple Choice Question Walkthrough:
• Bonding, Shapes & Pola...
Electronegativity and Polarity Explained:
• Electronegativity & Po...
00:00 Intro
00:19 What are Intermolecular Forces?
01:35 Permanent dipole-dipole Forces
03:26 Proving Molecules are Polar
04:53 Hydrogen Bonding
07:06 van der Waal's Forces
08:48 Temporary dipole-induced dipole
10:12 Strength of vdW Forces
12:10 Polymers & Melting Point
12:44 Linear Vs Branched
13:38 Which has the highest Boiling Point?
15:12 Hydride Boiling Point
17:28 Hydrogen bonds per molecule
18:16 Proteins and DNA
19:23 Ice and Solubility
20:56 Hair Straighteners and Ironing

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[@chemistrytutor]

That's really lovely to hear that it's so useful! Helps to keep me going!

[@EvanPeterson.]

My college does flipped classroom learning -- and when I tell you Chem 125 is kicking my butt it truly is. I find the "textbook" & youtube videos my professor gives does NOTHING. I haven't been able to retain any info and I've felt no hope pursuing a chemistry degree. Your video really is so helpful. Thanks so much :)

[@chemistrytutor]

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[@kat-bh7zv]

Once again your explanations are perfectly clear and so helpful! Thank you so much!

[@chemistrytutor]

You're welcome. I appreciate your feedback 😊

[@gracechen2412]

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[@chemistrytutor]

Thanks 😀

[@grannynoobtopro]

This is so helpful thank you so much!!

[@chemistrytutor]

Great to know! Hopefully you'll find even more useful things 🙂 Here is a document that might be useful drive.google.com/file/d/1s3I5prjbJRR1U1lcKpXO9TQpQMaVoP66/view?usp=drivesdk

[@user-eb6px4ud8t]

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[@chemistrytutor]

Thanks for your feedback 😀

[@sparkles6396]

thank you this was so helpful, to revise for my exams on monday

[@chemistrytutor]

Good luck!

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[@chemistrytutor]

@HUM TUM EARLY thank you for the feedback 😀 Difficult to answer that one. The answer has to be yes... in theory. The break down of A level Chemistry is approximately 35% fact (AO1), 35% application (AO2) and 30% analysis and interpretation (AO3). Provided you also do lots of past paper practice along the videos and can do the, the answer should be yes

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[@chemistrytutor]

Thank you for your encouragement! 😁

[@marigeo24]

Idk if I asked this already but would an ionic bond between two polyatomic ions for example ammonium nitrate, be considered an ionic intermolecular force? Rather than an ionic intermolecular force? Or is the answer no, because the point about intermolecular forces is that they’re not actually bonds that join molecules, rather they’re just attractions between them

[@chemistrytutor]

The answer is no because the classification of molecular ion gives greatest importance to the ion. So the forces between the ions are electrostatic attractions. And we know they will be strong. Labelling something as an intermolecular forces carries unspoken information that these forces are weak and so we know a little about them by their name. They also arise through different means. As an extra, again for understanding not because you will be asked about it. Intermolecular forces are kind of the same as electrostatic attractions in their nature (delta + attracted to a delta - ) its just that they are significantly weaker and we recognise that by calling them something different. They have different names because the names implies addtional information, whilst also telling you about the nature of the substance (e.g. actually charged rather than partially)

[@whoknows2298]

Thanks for the great explanations you provided in this video but how does large surface area affect van der waal's force?

[@chemistrytutor]

Good question There are more opportunities for there to be a random arrangement of electrons. So, there more spaces for there to be a temporary dipole in a molecule. So each molecule can attract jts neighbour from more than one point. There is also the potential for the electron distribution to be more imbalanced the larger the molecule is. The good news is you just need to write in the exam: Larger molecule, so More van der Waals forces

[@whoknows2298]

@@chemistrytutor Oh, Ok thank you so much!

[@chemistrytutor]

@@whoknows2298 😀👌

[@pratyasha279]

Sir how do we identify the difference between whether a molecule is polar & whether it has polar bonds? thank you :)

[@chemistrytutor]

Great question... I made a video about this kzbin.info/www/bejne/bmKnd42Hial3aMk

[@MariamNuhu-fc9vz]

Hello sir , I wanted to ask you if you may know a way to easily identify if a molecule is a permanent dipole as I was confused as to why Cl2O would be a permanent dipole I would really appreciate if you explained !

[@chemistrytutor]

Two steps: 1) does it have polar bonds (electronegativity difference) If yes move on to 2. 2) is it symmetrical? If no, then pd-d forces If yes then vdw only.

[@chemistrytutor]

kzbin.info/www/bejne/bmKnd42Hial3aMkfeature=shared

[@MariamNuhu-fc9vz]

Thank you sir!@@chemistrytutor

[@marigeo24]

(1) what is the difference between a "permanent dipole" and a polar bond? (2) So, a molecule can have polar bonds but not necessarily "be polar"? Does this mean that a molecule can be polar but not necessarily have polar bonds? (3) I guess the implication is that van der Waals forces are inevitable between atoms, does this mean that all atoms and molecules experience some degree of van der Waals? (4) Is the presence or absence of hydrogen bonds and then less importantly van der Waals forces, basically the deciding factor on what makes a substance have a certain boiling/melting point? (5) Is a single hydrogen bond stronger than even the strongest van der Waals force? (6) If asked a question about why ice is less dense than water, can we say that there is stronger hydrogen bonding in ice and therefore more space between molecules? Or would it be incorrect to say that the hydrogen bonds in ice are "stronger", and that its not about strength, it's about the greater density of water due to the hydrogen bonds within it being "temporary" as the molecules move around constantly?

[@chemistrytutor]

1) they are the same 99% of the time. Except bonds can be temporarily polar due to induction (think electrophilic addition of Br2 to alkenes) 2) Yes. If they're symmetrical 3) yes they do. If a molecule has no hydrogen Bonding and is symmetrical the strongest IMF is van der waals forces 4) it can vary but generally the deciding factor between the MPt or BPt of 2 Substances is - which has the stronger type of IMF. The exception is if a huge molecule has stronger VdW forces due to being really large. This would likely be implied in the question... e.g. you'd be told X has the higher BPt and then you'd work out it didn't have anything other than VdW and deduce they must be very strong 5) 1 HB > 1 VdW but the issue here is not 1 vs 1. In larger Molecules there is the option for a huge number of separate vdw forces and those can add up all together to be stronger than 1 HB 6) you're right it's not due to stronger HBonding. It's more to do with your second idea. Due to tetrahedral aligmnent of the water molecules in ice the molecules are on average much further apart. At any given moment in water the molecules are far more randomly arranged with fewer than the optimum 2 that forms in ice and they're therefore closer

[@marigeo24]

@@chemistrytutor thank you, and so just clarify one more thing, hydrogen bonds are not attractions between oscillating electrons, they’re just attractions due to the polarity of a proton/H+ and a very electronegative atom. In other words, LACK of oscillating electrons and an abundance of them. Whereas in vdw, the two atoms could have the same number of electrons for example the diatomic molecules. Or, is it that a bonded hydrogen DOES have oscillating electrons, but it’s higher positive charge causes an attraction with neighboring electrons? Because in that sense, couldn’t hydrogen bonds also have vdws within them?

[@chemistrytutor]

@@marigeo24 almost. The electronegative atom has a lone pair of electrons, which is the slightly negative thing attracted to the slightly positive H

[@marigeo24]

@@chemistrytutor So a hydrogen bond is like a coordinate bond that doesn’t officially “bond”?

[@chemistrytutor]

@@marigeo24 kind of yes. But maybe 1/10 of the strength

[@dao6263]

hello, great video. i’m not sure you’ll see this comment but i’m still struggling to differentiate the difference between id-id and pd-pd bonds 😢

[@chemistrytutor]

They are really similar! The difference is that to have pd-pd Molecules need to a polar bond and be non-symmetrical Maybe seeing it discussed in an exam question example would help? kzbin.info/www/bejne/aqDXi2OYqsyLb80

[@dao6263]

@@chemistrytutor Thank you!