This video covers the sub-topic of Intermolecular Forces from the main topic of Bonding. Beginning with the forces and then details about each, it ends up looking at some past exam questions.
Hey, I am a human from the future. That is not how it actually works. You see, different situations, environments, and some other stuff contribute to what will ensure the most efficient teaching and learning. In a classroom environment, this teacher could have difficulty sharing the exact same information within the same time frame, with the same voice tone, and with no package loss. haha. Due to it being a video there are no other students to provide distractions and thus increase the duration of the lesson and package LOSS!!!!! dun dun dun. Indeed my friend, sitting alone watching a video and taking notes is not comparable to being in a class with other people. In the same way, you can not compare flashcards with just reading the notes. Both work well, but to what extent, and for who? WHO WHOO .... this reminds me did you know, owls hunt other owls? Maybe we should alert the parliament of owls. haha, owl puns are fun. Do you know what else is fun? Finding out whether we live in a simulation and to find out why our miserable souls have been placed on to the earth, why we are not who we think we are, Why we exist!!!!! AND Why I will never be able to finish all of the game theory and vsauce videos in time for tonight's anime marathon.
Keep doing past exam questions please, I find it unbelievably helpful when you go over them identifying where the marks lie! Thanks for all your videos, amazing work!
You are currently saving me from being failing AS Chemistry all together. I come home after a lesson and just switch your videos on straight away because my teacher teaches me nothing (He thinks he is a million times better at teaching than he actually is). I am constantly getting told I shouldn't be doing Chemistry, but thanks to you I am actually understanding all the content, because I am actually learning and being taught it. I sit on a evening playing you videos with my textbook open as if it was a lesson. (Because I am clearing gathering nothing from my actual lessons.)
+Sophie .Jayne That all sounds like a right hassle. But I'm glad you're coping and finding ways to deal with things. Let me know if there's anything I can help with and keep working hard!
I wish my Chemistry teacher was half as good as you, everyone in my class uses your videos for revision/learning. Thank you for all the effort you put into them
this is video is very good, had trouble with intermolecular from months. This helped to understand a lot and also had qns discussed . Thanks sir for the video
I'm so lucky I have a friend who recommended you to me, I've got two weeks to sort out my grades before my mocks and I might actually do it with these videos, I'm understanding chem so much more already
Seriously thank you so much for these videos, I have been basically teaching myself Chem and I have learned more from your videos in one day then the entire month and a half I have been in school! Thank you!
so easy to understand when you explain chemistry, I cant seem to take it in with my current chemistry teacher you're a great help thank you. I will watch you all the way through my A levels :)
Amazing video thank you!! Btw it is soooo helpful when you go through the relevant exam questions at the end it really made me fill the gaps in my knowledge!!
Just a quick observation. In question 1c) I’m pretty sure the strongest intermolecular force would be van fer waals. This is because the molecule will adopt a tetrahedral shape in which the dipoles will cancel out and it won’t be a polar molecule.
Thank you soooo much for your videos. I didnt do so well in my previous exams but for the first time...just looking at your videos I am finally understanding the subject. Thank you very very much :D
Thank you! This was really tough to read about as it requires lots of thought. I tried the exam questions at the end before you give the answers and I got them all right apart from the last one. I mentioned that "Hydrogen bonding only takes place between molecules with partially negative Oxygen, Nitrogen and Fluorine atoms attracted to molecules with partially positive hydrogen atoms" I didn't mention the phosphorus's negativity :s
than you sooo so too much for your amazing videos I missed a lot of school because I had a lot of tournaments last term but I'm catching up because of your videos... I won the chemistry prize last year and I will credit it to your help as well as my brilliant teacher who unfortunately left our school last term.... thank you so ,much
Your videos are absolutely amazing! I'm understanding chemistry so much more with your explanations.... thank you so much! Also, I was wondering what you mean by the titles of these videos "NEW & OLD SPEC", are you referring to the new 2016 SPEC or does "NEW" mean the 2015 spec? I'm asking because I've realised this video was uploaded on Feb 2015.
Haha, it's funny how my AS Chem qualified (somehow) teacher learns from your videos too. He doesn't even know why cinemas have staggered seating. He's probably reading this whilst he's teaching...his mouth how to consume crisps. Nice to see you continuing your videos, keep up the good work.
What a coincidence, just been doing a bit of revision on this exact topic as vdw came up in a u1 exam and I was getting a bit confused, good video as always!
only started my as levels and your videos are great for me, I have fun and learn whilst watching them, only wish that there were these videos for biology aha, thanks very much.
Did you make a video on electronegativity?? Since you knew straight away the differences between electronegativity when predicting the hydrogen bonds.. Also for the last question could you have wrote there isn't lone pairs in phosphine or is that wrong? Many thanks.
sorry im still a bit confused. as in how do you know CCl2F2 had dipole dipole but CH4 is just van der waals. like how can you tell which one does and doenst
+campervan20 I'm not the uploader but hopefully I can help :) What I do is draw out the molecule and then label where the electrons are being most attracted using an arrow. I always go positive to negative. When I'm done, I look at opposite ends of the molecule and if they have separate charges, there is a dipole and hence dipole dipole forces. If not, there's just VdW's.
Hi, can you do exam questions at the end of every video please as they are really helpful and can you make a video on electronegativity and which parts of the spec it links to?
Just to make sure, do the examiners allow the use of the three dots for a shorter way to say therefore? By the way these videos are really helping me out thanks a lot for your effort.
Sir, when we are finding out the electronegative difference for dipole-dipole ......what is the range for the big difference in electronegativity??? 35:54
i was having a hard time learning this as I'm currently a GCSE student studying a levels independently and your videos are bangin'! thanks for making this channel!
Eliot Rintoul I would absolutely love it if you were to do so. Even if you didn’t want to do every topic, just covering some of the harder AS topics like ‘The Immune System,’ ‘Oxyhemoglobin dissociation curves’ ‘Digestion of Lipids’ and ‘The Sodium Potassium Pump’ it would really help a lot of students! :)
one question- why does the electronegativity change in iodine molecule ..resulting in induced dipole? what causes this difference in one side of the bond being more positive and the other more negative??
If unsaturated fats are liquid at room temperature due to their shape causing them to have weaker VDW forces, then where does the part about double bonds come in? Wouldn't it make more sense if they were solids at room temp because breaking double bonds requires more energy than single bonds? How do they have double bonds if the VDW are weaker and the bonds are easier to break than saturated single bonded fats?
I am really stuck on this aspect of dipole dipole molecules. Basically, our teacher said that sometimes the delta postitve and delta negative bonds can cancel each other out, and so even if a molecule has permanent dipole bonds, it may not be a polar molecule overall, and will have no charge. Such as C02. I don't understand when these charges cancel each other out?! And I don't think you covered that in this video. The first exam question you did, you said the strongest force was the dipole dipole force, but wouldn't the charges just cancel each other out on that molecule. Sorry for the long question, and if I sound stupid but I would really appreciate it if you could help me out. Thanks
+Amy Yeah, I just had this very conversation with my Lower 6th group the other day. The video isn't as heavy on polarity and electronegativity as it maybe should be, but I am going to be making changes to the videos over the next little while to break them down into more manageable chunks! The way I explained it was that in some molecules, we have polar bonds. In a molecule such as HCl, the bond is polar. This molecule is also polar and therefore has a permanent dipole. Whereas, in a molecule such as CCl4 (methane with each hydrogen replaced by a chlorine atom), the C-Cl bonds are all polar, but basically the partial charges are balanced throughout the molecule and therefore cancel each other, leading to no permanent dipole. If you look at the shapes of the CCl4 molecule, you will see that it has some kind of symmetry and no matter which way you turn it, it is basically the same molecule. I should say at this point that a permanent dipole comes from an uneven balance in a molecule (or what I described as the molecule being wonky). Using the CCl4 example, but swapping one of the chlorine atoms for a hydrogen to go CHCl3, we still have 3 polar C-Cl bonds, but because of the introduction of the hydrogen atom, we find that the over molecule is now not balanced in terms of its charge. This is because the C-H bond is NOT polar and so the whole thing becomes wonky and as such, we DO have a permanent dipole. Has that helped at all?!
E Rintoul Yes, this is really helpful thank you, I totally get why molecules can and can't be polar. So wouldn't that mean in the CCl2F2 in the first exam question you did, due to all the negative charges around the outside, wouldn't the charges cancel and so there would be no dipole-diple intermolecular forces? And so the strongest would be VDW?
Amy That's a little bit more of a tricky example as the chlorine and fluorine atoms have different electronegativities which would cause the bonds between them and the carbon to be different in terms of their polarity!
+Vanessa Costello Yep. What I've written is 100% correct. The reason is due to the bonding being simple molecular. In this bonding the weak VdW forces play a key role.
hi, recently I discovered ur channel and I must say that I am loving it. but I find it difficult to watch a full 30 to 40 minute videos so would it be possible for u to cut it down in sub topics?? thanks once again 😁😁
+Krupali Parikh I've cut some down into smaller topics. I am aiming to cut others down, but I don't know when I'll get around to it. My advice would be to just watch a small portion at a time!
You are an amazing teacher!!! I wish you were my chemistry teacher at school!! I understood everything except for the phosphine one. Why can't H-bonding take place with Cl? Chlorine is more electronegative, right? I would be grateful if u could clarify it in the comments
Yo Mr Rintoul, One thing that tripped me up was the H2S, H2Se, H2Te graph. These molecules have permanent dipoles and hence dipole-dipole forces right? So why do we have to talk about the VDW forces?? Thanks in advance
***** Alright, chap? Nope, no permanent dipoles there. You're best to think of permanent dipoles occurring only where we have halogens involved. That help?
For question 1 (c) - I thought the dipoles would cancel because the shape is tetrahedral (four delta negative halides are surrounding the carbon atom? And therefore van der Waals are the only intermolecular forces present? I could be completely wrong though.
Thank you for this video I feel I understand however there are definitely gaps in my knowledge.. 1) how do you know if a molecule is electronegative and which one is more than another? and 2) how do you know how many lone pairs a molecule contains?
Thanks, You're videos are amazing but i was just wondering about a few things. at 26:30 do HI, HBr and HCl have dipole-dipole bonding? Also at 31:36 would you talk about bonding (i.e. covalent bonding) because the question says in terms of bonding or can this also mean hydrogen bonding?
Hi, I was just wondering, when at 30:11 in the video, how you identified that there were three lone pairs? Is there a set number of lone pairs for a Fluorine (and Oxygen and Nitrogen) atom or did you use the method from the shapes of molecules video? Or am I wrong in both of those suggestions? Sorry if I'm just being stupid! Thanks in advance, your videos are great!
Matt Grigg Just by looking at the electron configuration for fluorine - using the GCSE model, we can see that there are 7 outer-shell electrons. One of these has to be used for the bonding, leaving 6 which are all lonely. That help?
One thing on that very last question (why no H-bonds in phosphine). There is a lone pair present, so you might reasonably expect an H-bond. But as you say, despite that, the P-H bond has so little electronegativity (compared, say, to N-H in NH3) that it outweighs everything else. Only 1 mark, I know. But in light of your earlier description of the importance of the lone pair in H-bonding, perhaps worth pointing out here.
As well as an adjacent hydrogen, you also need a highly electronegative atom with a lone pair: oxygen, nitrogen or fluorine. Phosphorus isn't electronegative enough. A little late, but hope that helps! 🙂
Are dipole-dipole considered Van Der Waals too? The revision assistance guide (wjec) is treating both dipole-dipole and induced dipole as van Der Waals forces.
at 21:65, in the HF example wouldn't there have been 3 lone pairs of bonding electrons around F. And also in H bonding, is the delta -ve delta +ve attraction the reason of H bonding or is it the attraction between delta +ve and the negatively charged bonding electrons? Thanks!
Just outta curiosity do you reckon you can give a link in the description of AQA exam past questions specific to the video? E.g in this case a question on Intermolecular Forces? :) Your vids are really helpful btw
34:10 - surely the increased size in the iodine atom leads to more/stronger VdW forces between molecules which needs a larger amount of energy to break the bond? I don't understand why you mentioned electrons?
couldn't get the part where you said the reason for no h-bonding with phosphine molecule and the hydrogen molecules.... I'd be grateful if you help me with that part....
34:26 can you say that iodine has a bigger atomic radius than fluorine and therefore has more electrons and so requires more energy to break vdW’s forces ? Rather than saying that iodine is bigger ? Does it mean the same thing and will it get you the marks ?
I wanted to ask, in the questions about fluorine and hydrogen fluoride, why did you assume to talk about intermolecular forces rather than the bonding because it did ask about bonding?
in the last question which u showed at the end can we add there "therefore no partial charge are present on either of the molecules so hydrogen bonding cannot take place"
