AQA A-Level Chemistry - Shapes of Molecules

This video looks at how to name and draw molecules as mentioned as part of the Bonding topic in the Physical side of the Chemistry A-Level.

[@PassPharmacy]

shoutout e rintoul u living legend man is making moves out here coz of you, no understatement but you make chemistry a level so easy maybe even easier than btec science hahahhaha, large up E RINTOUL, jazakallah bruda, watch a roley coming thru ur post in due time!

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You are seriously a life-saver. Why can't I have the same teacher with the same teaching qualities? :( Best Chemistry teacher in this Universe, seriously! Thank you so much for your amazing videos! I don't know how much I've thanked you xD Probably a hundred. :)

[@MrERintoul]

***** Haha, I'm not sure you'd say the same if I was actually your teacher... But thank you!

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I’ve got him in my school and his a Great teacher

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​@@addiburke910 what school he teach

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@@addiburke910no way tell him to finish the amount of substance series!!! Hes the only one i can properly learn from

[@TheCommandModule]

E Rintoul. Saving young chemists for years. And hopefully will continue to do so for years to come.

[@amandasmusic628]

His voice is perfect for ASMR😂Chemistry has never been more relaxing

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Hannah Louise same here 😂

[@ace1879]

Hannah Louise hey this comment is from 7 months,what was your grade? sorry in advance(Incase you didn't pass) 😬

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what did u get

[@GamingUbered]

fr I wanna know whether to watch these videos

[@sciencewithraihankhan3839]

@@GamingUbered they actually all fail.Watch mine then you can understand the topics clearly.

[@BlueTomatoe8]

This video is fantastic, I watched it just to revise over a few topics I didn't quite grasp in lesson and the subject of shapes of molecules finally makes complete sense now! :D

[@MrERintoul]

+Munya Muswizu I'm really glad :)

[@Pimpmymushroom]

Please do more AS videos, especially on unit 2, they're really helpful, thank you

[@meganedwards9294]

you make chemistry a level so easy to understand, you're better than both of my chemistry teachers and you move at such an understandable pace, it's coz of you if I get an A in chemistry thank you so much

[@elliemay7559]

did u get an A?

[@kwl6251]

These videos are life savers. You're excellent at explaining everything we need to know. Don't ever stop making these videos I beg if you. Without you I have no hope of at least B in chemistry. Thank you. You're way better than probably all of the other chemistry A Level teachers out there. You go over exam style questions which is really important. And the way you explain the theory side of the spec us brilliant. 👌

[@MrERintoul]

DS_2808 Only just saw this comment, but thank you so much for your lovely words!

[@AnotherGamerGurl]

Your videos are really helpful! I'm busy revising for a test next week and I'm finding a lot of it is sinking in with your help. :)

[@bobieawuah5879]

god bless you for these videos, saving lives ahaha.

[@MrERintoul]

+Bobie Awuah No problem :)

[@as-samaamedia1480]

+E Rintoul hi- could I use these videos if I am doing OCR A the new spec? thanks

[@MrERintoul]

As-Samaa Media I would say yes...

[@as-samaamedia1480]

Thanks bro- you are a kind person. Well done

[@ariellebresloff8786]

A tip: for figuring out how to draw it E.g NH3 1. Number of electrons on outer shell of centre atom (N has 5) 2. Number of bonded pairs (3 A’s it’s bonded to 3H) 3. 5-3=2 4. 2/2=1 5. So you have 3 boned pairs and one lone pair

[@ihsan2837]

So you divide by 2 every single time?

[@axelgenesis6937]

​@@ihsan2837 I might be a bit late, but yes. Or you can just see the 2 and figure out that it means 2 lone electrons, which is 1 lone pair.

[@ryanbower2005]

I love you E rintoul !

[@MrERintoul]

Ryan Bower Big words, Ryan. Do you really love me, or are you just saying it because you saw my video?

[@ryanbower2005]

The love is real man x

[@theoneh5249]

Still watching his vids in 2021 👌 What a legend! Thank u sir

[@zm7782]

such a legend!

[@MrERintoul]

+zakariya mohamed Thanks!

[@halftimelordwizard]

Your 5 step method is really useful thank you!! All your videos are great, really concise and informative :) :)

[@MrERintoul]

Afrah Hyder I'm glad it helped!

[@jennifergaskarth]

This was so helpful! I'm very glad I've found them before my exams

[@MrERintoul]

Not a problem!

[@adaezeschannel]

chemistry alevel is killing me and you've saved my life! thank you so much! only thing is, please make your cursor more visible because sometimes I cant see what you're pointing to

[@princess_naadirah9900]

ohmadaeze what grade did ya get

[@huquaver]

At 17:33 why does the F4 only account for 4 electrons? Fluorine is in group 7 so why doesn't it donate 7x4 electrons (ie 28) I understand that I am wrong in thinking this but I would like an explanation as to why the fluorine is only accounted for 1 electron. Thanks

[@blobar1231]

+Jason Bourne I think he means how many other bonds are there going to be, rather than electrons. So when he did it for H3 he did 3x1, so for F4 it was just 4x1.

[@MrERintoul]

+Jason Bourne I see what you are saying, but in a covalent bond, fluorine never shares 7 electrons. Instead it shares one and has one shared with it as a result, giving it that lovely full outer shell. In this case, each one of the four fluorine atoms shares one, hence four! That help?

[@MrERintoul]

+Vanessa Costello Nice.

[@huquaver]

+E Rintoul Most definitely, thank you very much! I felt like it was a silly question but always best to make sure I leave no gaps in my knowledge

[@MrERintoul]

Jason Bourne No question is ever silly if it is targeting something you aren't quite sure about!

[@nishisharma4096]

The 5 step method was exactly what I was looking for, perfect video. Can't thank u enough

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If you still need help with your A Levels, check out Alt Academy, we have a LOAD of resources that you can use for your exam prep. Video Lessons, Flash Cards, Handwritten solved past papers with explanations, Live Yearly Past Paper solutions, revision guides, 24/7 academic support and SO MANY more things. You'll ace your exams!

[@applee6335]

Extremely good stuff for a levels, many thanks 🙏

[@mariahkhan9172]

Hi. I've tried using the method you explained for working out the shape of SO3 but I got lost and I can't work it out. Would you mind explaining this to me? Thanks.

[@srinathravi8444]

u r dumb

[@asaphhere]

Lmao 5 years ago, hows life ?

[@Hey_haylei]

Still no reply?

[@hassanmohamed3272]

I just started doing this today during my summer holiday😁

[@MrERintoul]

Hassan Mohamed Yeahhhh! Get working hard!

[@tasneemrahman5844]

I'm just a little confused about this. So as you said 4 bonding pairs= a tetrahedral shape, for example CH4, 109.5 degrees. However with Ammonia, there are only 3 bp and 1 lp so why is it not based off of 120 degrees

[@Rtfsilky]

bro im legit cramming for my mock tomorrow all the topics i have to learn all over again today so cheers lad, wish me the best of luck

[@daaragoodluck]

Damn. How’d it go?

[@scholschol-g8e]

It may be best to not memorize any formulas, and instead just go through a logical process. F B requires 1 of the (3 + 1) electrons of F where + 1 is due to the extra negative charge of F^-1, next F B requires another, again, again, resulting in 4 F B bonds and no spares.

[@rohimabegum9146]

Thank you soooo much

[@sadiqchoudhury8475]

Thank you your method was SUPER helpful and easy to understand

[@maryamsiddiqui5974]

How do you know that CH4 is 3D and so the bonds aren't in the same plane? Couldn't you just draw the bonds as a square - how do you know not to do this? Thanks!

[@12horsea]

I know this is a long time after you uploaded this (!) but I'm just wondering for the very last bit, how you knew flourine was only bringing 1 electron? When I tried to work it out I said 7 because that's how many are in its outer shell, then I ended up with 16 bonding pairs!! (which is obviously wrong lol)

[@kellygarside]

Thank You so much! My teacher made the whole topic seem so confusing but you have literally just saved my life with this :) Thank you

[@Oguz2100]

Why is water V-Shaped and not completely linear? You said yourself that lone pairs repel each other as much as possible, surely they would therefore try and be as far apart as possible and be on different sides of the oxygen atom as opposed to being on the same side next to each other? Also, in the video you calculated the bond angle in water by 109.5-2.5-2.5 which gave you 104.5; but earlier you said that we only used 109.5 in three-dimensional molecules whereas water is in one plane I thought? btw the video was really good and well explained, I'm just struggling with understanding water Thanks

[@MrERintoul]

+Oguz2100 The way to look at situations that involve lone pairs is to imagine firstly that we start with a tetrahedral molecule and then swap bonding pairs for lone pairs. The reason tetrahedral is the starting place is that it is the most stable structure. This is also the reason for the 104.5 - start with it being tetrahedral and then subtract 2.5 for each lone pair that comes in. Bingo. That make any sense?

[@Oguz2100]

Thanks very much! This has cleared up a lot of confusion :p I have a feeling this channel will save my skin quite a lot of times in the next two years aha

[@ZALI7811]

Hi year 12, it’s me Zain Ali your number one superhero and hi Mrs C. 👋🏼 or Mr R. Whoever is going to teach me this

[@fatleo963]

Hi, how can P atom bond with 5 Cl atoms? Isn't it supposed to be only with 3 in order for P to be stable? Hmm..

[@MrsMathsGeek123]

bit late lol but it's because in its valence shell Phosphorus has a s-subshell (2 e-), p-subshell (6 e-) and also a d-subshell (10 e-) meaning it actually has space for 18 electrons in its outer shell. It's called an expanded octet. Anyone feel free to correct if im wrong though

[@hilfe7536]

Thank you so much for the videos,,,,they are too good !!! Would you be able to do a video on how to draw lewis dot structures for complicated molecules like HNO3....and how to calculate formal charges...

[@MrERintoul]

Hilfe! Hi! What do you mean by calculating formal charges...? To be honest, there's little need for lewis dot structures at all at AS, and certainly not for annoying molecules! Let me know if there's something I can help you with though!

[@camile1497]

is there a way to remember all the shapes? including those with lone pairs. im struggling remember the names of the shapes. i don't have a probably woking it out but usually on the exam, they always ask for the bond angle or the name of the shape

[@camile1497]

problem working*

[@toasticide816]

+camile1497 the bond angles you would have to remember as it is, but do note that for coordination pair 2 it's 180 degrees (360/2) and for 3 it's 120 degrees (360/3). the rest of the angles i have trouble with as i can't simply remember them as 360 divided by the pair number so i can't help with the rest. The names on the other hand do have a slight pattern. think of linear shapes forming a straight line and straight lines are linear (if you study maths a level you learn linear lines in great detail). co ordination pair 3 is trigonal planar, think of tri meaning 3. Tetrahedral is tetra (4). trigonal bipyramid has tri and bi (3+2=5) so coordination 5. octahedral.... i don't know sorry :s hope i've helped at least a little i also found this topic a great struggle before watching this video

[@MrERintoul]

+camile1497 Get them all written out. Draw them. Rinse and repeat. It's just a grind. Although the names do kind of suggest the shape that is formed.

[@MrERintoul]

+Louis Moore I'm glad the video helped! And thank you for your comment to Camile.

[@Alie800M]

thank you so much, you have no idea how confused I was in class today lmfao I cannot pay attention to my teacher for more than 4 minutes =/

[@kurdman12345678]

so lone pairs of electrons repel more than the electron in the covalent bond, leading to a reduced bond angle. a i correct? nice video by the way ;)

[@MrERintoul]

Yeah, you're spot on. And as I said in the video, the new bond angle is calculated based on a tetrahedral shape that has had the bonding pairs replaced with lone pairs, each one causing 2.5 degrees of constriction.

[@max25i67]

Holy ducking shit you are such an amazing teacher you make it seem so easy. God bless for putting you on this earth

[@aaina_lt]

BEST TEACHER EVER NGL! CLEARED ALL MY CONFUSIONS, APPRECIATED 🙌🏼🙌🏼🙌🏼

[@annagate3059]

Hi, can you please tell me how you use the 5 step method to draw ions?! Such as Cl3+ By the way your videos help me so much!!! . . . so THANKYOU!!!

[@MrERintoul]

Anna Gate Do you mean a single chloride ion with a charge of 3+ or a Cl3 molecule with a charge of +? In either case, could you tell me where you've found such a question please... But thank you for the kind words!

[@annagate4681]

E Rintoul Hi, its okay! It was just in a booklet full of past exam questions, so i couldn't tell you the year- sorry! Yep, a Cl3 molecule with a +1 charge, sorry for the confusion :)

[@MrERintoul]

Anna Gate Ah I see. Well I would still say to follow the same rules as in the video... I'm run you through it, but it's perhaps worth checking that you understand the rules if my explanation seems confusing! - Treat 1 chlorine as the central atom, and the other 2 as being bonded to it. - The central chlorine has 7 outer-shell electrons, and each chlorine that bonds will contribute 1. This means that we are at 9 electrons. - Minus 1 electron because it's a positive ion with 1+. - That leaves 8. Those 8 will exist as 4 pairs. - 2 pairs are used to bond the chlorines. The other 2 must be lone. - That means that it has a shape like water, a bent-linear shape. If asked, the bond angle would be 104 degrees. Has that helped at all?!

[@kiarashseddighi2847]

Thank you soo much for you're helpful video. But my question is what if there is no central atom. For instance CH3OH where C and O are in the middle and H are around them. How do we do that?

[@xriahlouise]

I don't get it... Question on a past paper asks for Shape of TiCl2+ ion.. Going by the video wouldn't it be 12 in the outer shell for Ti, 14 in the outer shell for the Cl2, added will be 26, lost one electron so it would become 25, then when this is divided it's 12.5... How would this work??? I'm honestly lost

[@MrERintoul]

riahlouise You need to give me paper references or I can't see the questions and all the detail that is being given. In a question like this, I'm pretty sure there's a piece of information that you're missing...

[@batoolwzaidi6676]

What about calculating the shapes of molecules with double/triple covalent bonds? I found that the same method doesn’t really work

[@physchemwithliz5879]

You can call them 'bonding regions' e.g. in phosgene COCl2, we say 3 bonding regions, 0 lone pairs, therefore trigonal planar 🙂

[@0riginalFIR3]

thanks a lot!! i missed the lesson on this and so this has really helped!! thanks :)

[@MrERintoul]

+0riginalFIR3 No worries :)

[@sALah1550]

what us molarity of 1.06g of h2so4 in 250cm3 of solution. could you help me here please. the mention of solution just throws me off

[@sALah1550]

oh of course. thanks alot.

[@bc5269]

12:08 smiley face with moustache

[@bc5269]

God this is why I can't learn anything

[@rumanaarulezs1575]

Have you done a video on bonding?

[@OT-tn7ci]

you are simply an amazing teacher.. pls dont stop making good videos like this . thank you so much

[@kwl6251]

On the Jun 13 paper, a Q asked to draw the shape of the TlCl2 ion. I worked out there was 2 bond pairs and 2 lone pairs. Am I right. If im wrong can u go through it from step 1-5??

[@MrERintoul]

DS_2808 That is wrong, but I can certainly show you what to do! They've used thallium to make it all seem much more difficult than it is. The fact that they talk about aluminium is a give-away - thallium has 3 electrons in its outer-shell, just like aluminium (you can also see this from them both being in the same group - group 3). So the thallium has 3 outer electrons. Following my method, each chlorine brings one. This brings our total now to 5. A positive charge means that one electron has been lost, bringing our total to 4. Dividing by 2 give 2 pairs. There are 2 chlorines bonded, each requiring a pair of electrons. Therefore the 2 pairs anre bonding pairs with no lone pairs present. This means that the shape is just linear. Does that help at all?

[@anmolmawai6865]

in the last diagram, BF4-, will the bond angle remain 109.5 degrees? since there is no lone pair to cause the 2.5 degree reduction in the angle

[@louisacowell4243]

Thank you so much for this!!

[@getochild13]

I need a reason why they are these shapes everyone just takes all info in and accepts it its just as easily forgotten unless theres a reason why they form bipyramidal instead of trigoal planar?

[@MrERintoul]

+ghetto child The reason is called the valence shell electron pair repulsion theory. Basically, the electrons (whether they be in bonding pairs or lone pairs) repel each other and as such, shapes are made. Get it?

[@a.Bader97]

sir, What happens when your atoms have double bonds, don't we treat them as single bonds which will change the shape totally? Should we see whether the central atoms share double bonds before we start to do anything? thanks a lot! p.s i am having trouble doing SO3, it's a trigonal planar (3 bond pairs), but can you please tell me why?

[@MrERintoul]

Rangahatimuhmon I wouldn't worry about double bonds. Concentrate on single bonds (besides CO2) and make sure you have their shapes down. SO3 is a difficult one. I've seen conflicting points about it so I think it's best to ignore it!!

[@a.Bader97]

E Rintoul So, would it be safe to assume that they wouldn't ask you to draw any molecules with double bonds (apart from CO2) in the exam?

[@a.Bader97]

Rangahatimuhmon ??

[@MrERintoul]

Rangahatimuhmon Sorry for not replying, KZbin doesn't do a great job at making it easy to see replies! It's pretty safe to say that you'll be dealing with single bonds!

[@a.Bader97]

E Rintoul Ok thank you!

[@GYM2012x]

Are trigonal pyramidal and trigonal bipyramidal the same thing? Thanks great vid btw !! X

[@MrERintoul]

In a word, no! The names are a give-away to the shape - the trigonal pyramid is a triangle-based pyramid and the bipyramid is similar, but there are two pyramids! The best way to see this is to look at diagrams of molecules that exhibit these shapes. This link will show you ammonia (ts2.mm.bing.net/th?id=HN.608039276177525953&pid=15.1) and this will show you phosphorous pentachloride (upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Phosphorus-pentachloride-3D-balls.png/540px-Phosphorus-pentachloride-3D-balls.png). The ammonia molecule has a trigonal pyramid shape (imagine joining the bottom three atoms together - you'd see a triangle). The phosphorous pentachloride has a trigonal bipyramid shape, though. If you look, you'll see that the top atom and the three in the middle make the same trigonal pyramid as before (ignore the very central atom in this case), then the bottom atom and the middle three atoms make another trigonal pyramid. Hence the BI in the name! Has that helped?

[@LilyGray]

youve saved my life.

[@B-LineOfficial]

Rintoul isn’t there more shapes we need to know about on the new spec?

[@mayA-ku4qn]

Hi thanks this was helpful! Please can you tell me what software you used to make this video ?

[@MrERintoul]

+smallbridgeto2 I use all sorts. Which part?

[@muheed11]

is trigonal pyramidal a variation of tetrahedral, in a sense that a bonding atom is replaced by a lone pair of electrons?

[@MrERintoul]

GTAV FRANKLIN Strong name. However I think I prefer Trevor. As for your question, kind of yes and kind of no. It's best to think of the shape as it is... the central atom with the 3 bonded atoms e.g. NH3. You are correct though that the bonding pair of electrons has just been replaced with a lone pair and that's particularly helpful when it comes to calculating the bond angle. Normally a tetrahedral molecule would have a bond angle of 109.5 but with the bonding pair replaced by a lone pair, there is more constriction on the remaining bonding pairs and so they get squished down by 2.5 degrees, resulting in that delightful 107 degree bond angle! That helped?

[@2ezeshaanmahmood994]

Amazing work!

[@hizzerramzan1474]

thank you so much! Got an exam tomorrow for Unit 1 and this is one of the things i've never understood. I do now, thank you!

[@MrERintoul]

Really glad to hear that you're feeling about the shapes part of the Bonding topic!

[@ryanbower2005]

When would you get a triangular pyramid?

[@MrERintoul]

Ryan Bower Ammonia should form a trigonal pyramid - basically any shape where you have a lone-pair and 3 bonding pairs.

[@ryanbower2005]

thank you!

[@oskarnowak6321]

E Rintoul You mean tetrahedral, ammonia is a tetrahedral.

[@MrERintoul]

Oskar Nowak Nope. If it was tetrahedral I would have used the word "tetrahedral." But I didn't. Ammonia is definitely trigonal pyramid shape. It only has 3 bonding pairs, not the fourth (like methane for example) which would give it the tetrahedral shape.

[@oskarnowak6321]

E Rintoul I get it now, so it's a tetrahedral shape, but a trigonal planar in name... confusing as fuck

[@nidhunaannna5121]

How come in NH3 the shape is trigonal pyramid, shouldn't it be trigonal planer because there is three bonding pairs, or I am getting confused!:)

[@MrERintoul]

+Nidhuna Annna Have you taken into account the lone pair too...! Start by pretending it's tetrahedral, then replace one bonding pair with a lone pair. Boom.

[@Coolpersony7]

shouldn't it actually be tetrahedral? initially it's trigonal planar and then with the lone pair it becomes tetrahedral??

[@edmcsteve2156]

At 17:35 , how come fluorine only brings 1 electron when it has 7 outer shell electrons?

[@xriahlouise]

I am confused on how you incorporate the lone pairs in aswell... Is there a rule that concerns what shape something should be depending on how many lone pairs there are... Eg with BrF3 I could work out there were 3 bonding pairs and 2 lone pairs but cannot figure out how you would draw this?

[@MrERintoul]

riahlouise There are 2 ways to draw this; the first is as Reece has said, and the other is a twist on the trigonal planar shape. You need to think about the fact that all the pairs of electrons, lone or bonding, will repel one another. In this, the lone-pairs will repel more than the bonding pairs. I find it easiest to think of the lone-pairs shifting to be completely opposite, with the bonding pairs in the same plane in the middle of the molecule. In this case, the bond angle is 120 degrees. That helped at all?

[@MrERintoul]

Reece Johnson Yeah, good job. The other option is the lone-pairs being completely opposite to one another with the 3 bonding pairs in the middle in a trigonal planar set-up. This would give a bond angle of 120 degrees.

[@prisila888]

hey rintoul dont u have a video on as level chemistry states of matter??

[@MrERintoul]

+M.D.L TM No because I hate that topic. Joking. Double joke. I do hate that topic. What can I help you with?

[@Smellyflowa]

Is this all relevant to the edexcel spec? btw great explanation!!

[@MrERintoul]

Mahrukh Hassan Honestly I have no idea! My gut feeling would be that there is some cross over, but without looking I honestly wouldn't know!

[@jessicbowater1770]

I am still so lost, I’ve tried to follow the steps for BCl3 but it makes no sense. The central atom provides 3, the bonding atoms provide a total of 21, giving 24. 24/2 = 12 electron pairs? But the molecule only has 3 bonding pairs, so where does the 12 fit in?

[@requiem165]

Cheers

[@TheVetema]

So According to the chart water should have been linear but if each lone pair of electrons reduce the angle by 2.5 degree, then should the angle of water be (180-5) degree? (I know it is 104.5 degree but it doesn't make sense to me, would be really grateful if you kindly explain it). Thanks

[@orageux101]

+TheVetema Water (H2O) would have a co-ordination number of 4 as it has 4 electron pairs (2 are bonded and 2 are lone pairs). Therefore the co-ordination number of 4 corresponds to a 109.5 degrees bond angle. 109.5 - (2*2.5) = 104.5

[@TheVetema]

+Riaz-Ahmed Patel My qus is why the bond angle would be reduced from 109.5 degrees? Why isn't it reduced from 180 degree. Shouldn't water molecule have a linear shape if the lone pair of electrons were not present?

[@MrERintoul]

+TheVetema Start with a tetrahedral and replace bonding pairs with lone pairs.

[@Smellyflowa]

at 12:32 you drew the lone pairs on the same end in the H2O molecule but wouldn't they repel each other by positioning themselves on opposite sides? as 2 lone pairs have a greater repulsion than 1 bond and 1 lone pair and greater than 2 bond pairs

[@MrERintoul]

Mahrukh Hassan Nope. I like your thinking but they stick on the one side. As I think I say in the video, it's best to think of it as a tetrahedral shape where 2 bonds have been removed and replaced with lone pairs. That helped?

[@Smellyflowa]

oh i see, thanks!

[@TomS1413]

Thanks for this

[@MrERintoul]

No problem!

[@Theo.31]

I don’t understand step 2, why is it always 4 x 1 for BF4? Why isn’t it 4 x 7? Because Fluorine is in group 7

[@maishan3589]

thats what i thought !

[@aamirpatel8507]

flourine is in group 7 so needs to gain 1 electron to have a full outershell, so it shairs 1 electron with bromine to gain an electron, and there are 4 electron pairs so bromine gains 4 electrons.

[@Theo.31]

Aamir Patel Cheers Aamir! I understood it after going over it a few times, makes sense

[@aamirpatel8507]

@@Theo.31 No problem! happy to help.

[@elzika739]

@@aamirpatel8507 why would Bromine want to gain 4 e- though? surely it would need 5 to get 10e- and have full outer shell? thanks

[@moneyhoneyhoney9047]

And lastly what would you do if you had more than one central atom

[@MrERintoul]

moneyhoneyhoney You wouldn't have that situation at A-Level!

[@haniakhakwani]

i am using your video playlists to prepare and recap for my upcoming cie exam in 20 days or so! hopefully there's not much difference in AQA and CIE chemistry :)

[@physchemwithliz5879]

Hi there 🙂 Hope your revision is going well. I have a free AS revision course playlist with resources here: kzbin.info/aero/PLaD6fcqFKTWjj4-QnOs4kQJQcym1EHsRo Best of luck with your exams.👍

[@haniakhakwani]

@@physchemwithliz5879 thanks a lot i'll check it out!

[@physchemwithliz5879]

@@haniakhakwani you're welcome! 😊

[@supersimple1686]

hi eliot, you know at 12:58, why is it 104.5 degrees, if conventional linear has 180 degrees, -5 degrees for 2 lone pairs = 175 degrees? this is so confusing

[@moneyhoneyhoney9047]

Why do you have to divide by two is it a fixed number you divide all molecules by? Secondly when drawing the tetrahedral molecule do you have to show the different lines going towards the page etc.

[@robbiebenson97]

moneyhoneyhoney divide by 2 because there are 2 electrons in each bond

[@MrERintoul]

moneyhoneyhoney Yeah, it's always 2 as no matter whether it is a bonding pair or a lone pair, there are 2 electrons in it! The division by 2 tells us the number of pairs that we have. Having looked at mark schemes recently, they don't seem too fussed with the 3D arrows, but I always tell my students to use those arrows.

[@MrERintoul]

Robbie Benson Spot on, Robbie!

[@danyalbeliani2221]

i'm slightly confused you stated that the bonding angle for NH3 would be 107 degrees but because it has got three bonds doesn't that mean its a trigonnal planner and not a tetrahedral?

[@MrERintoul]

Hi, Danyal. Yep, the bond angle between the H-N-H would be 107 degrees due to the extra repulsion from the lone pair. The only way that a trigonal planar shape would arise would be if there were 3 bonding pairs but no lone pairs e.g. BF3. However, with NH3, the 1 lone pair on the nitrogen causes the 3 bonding pairs to be forced down, resulting in that trigonal pyramid shape. Does that make sense?

[@danyalbeliani2221]

E Rintoul so if there is a lone pair on an original trigonnal planner shape is it taken as a tetrahedral then?

[@MrERintoul]

***** No, the shape is defined by the bonding pairs of electrons. However, they are affected by the lone pairs present. Methane would be tetrahedral - upload.wikimedia.org/wikipedia/commons/thumb/9/92/Methane-2D-stereo.svg/512px-Methane-2D-stereo.svg.png Whereas ammonia is a trigonal pyramid - 2.bp.blogspot.com/-1wp0M63YBLI/UBgoqN6EozI/AAAAAAAAABM/IIYQi-Vgjq4/s400/Ammonia.jpg Does that clear things up? When I mentioned tetrahedral before ammonia, it was only to say that when you work out the bond angle, imagine it is tetrahedral and then the bonding pairs are replaced with lone pairs, each causing that 2.5 degree constriction. The molecule is not actually tetrahedral.

[@nikilam8962]

Hey im so confused with the shapes of ions (that contain double bonds) as my teacher was on about the shape of nitrate ion this morning...and I apparently I didnt manage to understand it, so i did some research at home. And I dont know why it says ions like SO4, CO3 and NO3 only have their charges on the oxygen atoms; not the central atoms...and the charges are not included in the calculation lol I thought all charges are included in the bonds:( im so bad at this

[@nikilam8962]

Additionally, the shapes only have some double bonds with oxygen and some are just left with a single bond due to the negative charge on them...

[@MrERintoul]

+Niki Lam I never bother looking at the shapes of molecules with double bonds - besides maybe SO2 and CO2. Worry about the single bond examples and working out the shapes of them. With regard to the charges that you're talking about, no it isn't always the central atom that has a charge and when it comes to working out the shape of double bond shapes, the method I showed doesn't work!

[@nikilam8962]

+E Rintoul okay that makes sense now😳 so are we not required to know the shapes of molecules with double bonds in the new spec?

[@MrERintoul]

Niki Lam I've not taught my kids it! The specification doesn't make it clear whether they are needed or not so I've stuck with the single bond examples!

[@ahmedk2831]

Do we need to know about c-saw and T-SHAPED

[@akshykdowlut8439]

Where can i get Explanation on Hybridization Explanation video

[@rowank445]

When working out the shape, how do you know if the bonds are double or not? Like obviously C02 has double bonds but if you didn't know this wouldn't you be inclined to draw it as a trigonal planar with one lone pair?

[@retooluvyuhx5569]

sir you are amazing thank you for all your great work and your time ,you really are saving my life, my book doesn't isn't providing me with all these details while the teacher is explaining them in class and I was completely lost until I watched this video today. thank you very much really God bless you . may God also shower you with happiness where ever you go! imma cry your videos are just so amazing!!! Thank youu! you are very kind for uploading all these helpful videos.

[@commando1776]

EVERYONE according to the JAN2010 CHEM1 MS bent-linear is a contradiction so it would not be credited. They gave you credit for the following: 1) Bent 2)V shape (as sir suggested in the video) 3) Non-linear 3) triangular 4) Angular This was for the ClF2+ ion but I think its the same principle for water as well ( if not please correct me!)

[@MrERintoul]

commando1776 Good find! I shall amend...

[@commando1776]

E Rintoul Hir sir i am confused about q1bi and bii on : filestore.aqa.org.uk/subjects/AQA-CHEM1-QP-JAN12.PDF ok so i got the structure correct for both but for the bond angle in bi) i put 104.5 as there are 2 lone pairs, however the MS says 120. I understand that the shape is trigonal planar, but since lone pairs have greater repulsion shouldn't the bond angles be lower than 120? thanks

[@MrERintoul]

commando1776 I can see what you're saying. You are correct that the lone pairs repel more. And this forces them to opposite sides of the central atom. The remaining atoms form a trigonal planar shape, hence the 120 degrees. Does that make sense?

[@commando1776]

E Rintoul ok so basically if the molecule still has a trigonal planar shape the bond angles will be 120 regardless whether or not the central atom has lone pairs ? 1 more question, will all molecules with 4 bonds and 2 lone pairs have a square planar shape with bond angles of 90? thanks!

[@MrERintoul]

commando1776 Yes and no. If it had the 3 bonding pairs but one lone-pair, it would be a trigonal pyramid. By having the 2 lone-pairs, their repulsion means that they push as far away as possible, squeezing the others into the central plane. And yeah, 90 degrees in that case!

[@saeeda4353]

This guy is better than my chemistry teacher

[@omarhossain8905]

Would these videos work for Cambridge A Levels too?

[@ivanbliminse4325]

Doesn't F bring 7 electrons Cus it's in group 7. If H brings 1 than F should bring 7

[@Nomadic_soul99]

A level BioChem OCR in a covalent bond only 1 electron comes from the F not all 7. so there are 4 covalent bonds which means 4 electrons form F in total. do you get it now?

[@ibrahimshafi2064]

What about when there are 3 lone pairs?

[@japminiman]

Is there any exception to the 5 rules? I'm pretty sure the exam board is going to screw us over this year.

[@MrERintoul]

Hayato Murata Haha I like your confidence. If you start looking at double bonds, it goes wrong. But I honestly wouldn't worry. They aren't going to be THAT mean!

[@japminiman]

Like for CO2? That has a double bond. Would you do the same thing till step four, but consider the double bonds as two bonds? So for CO2 1) 4 2) 4+2+2=8 3) 8-0=8 4) 8/2=4 5) 4=2x2double bond

[@MrERintoul]

Hayato Murata Yeah, but you wouldn't know they were double bonds! For that reason, I can only see them asking about the single bond shapes and then maybe CO2 as a named example along with possibly SO2.

[@ivanbliminse4325]

Or do you look at how many they need

[@haniyabatool7978]

co2 is making 4 bonds so why isn't it's considered as tetrahedral ?

[@andyc5714]

Thanks for this great video, it kind of makes sense now :) So are all the shapes and names outlined in this video all we need to know? I recall my teacher saying things like "see saw" and other confusing names, is there a list of all the names for the shapes we need to know for the exam? Thanks in advance.

[@markrosenberg4369]

Great video but what is repelling from what, please?

[@tasfihaislam3673]

thank you very much

[@yoiki2897]

Question on the last BF4- The shape - why isn't this at 90 degree angles my friend

[@sazanrai6210]

I had no words to describe your work.You are just brilliant.Thank you ,Thank you so much !

[@maisamaskari8774]

wouldve been more helpful if u showed 3d diagrams.

[@minesh5583]

Wheres isomerism at!!?

[@MrERintoul]

Alias DMG It's not at anywhere. But it's coming...

[@zahramohamad1643]

Literally had no idea on what this topic was.. thank you so much !!!!!!

[@aadharshram4975]

This guy is really good at this, he could become a great teacher! Seriously though, you are a great teacher