2. Atomic Structure

[@petemiller2598]

I feel like when I was in high school and college, my brain wasn't developed enough yet to appreciate or be interested in this stuff. I saw these sorts of courses as "work" to suffer through. But now that I'm in my 30's, I finally have the attention span and the interest to learn these things. Unfortunately, I am no longer in college, and have a boring 9-5 job. Thank you MIT and KZbin for making this material available so I can at least enjoy it on nights and weekends!

[@gaudiumlex9929]

If u are enjoying it u must do a job related to it....U can do independent research or something....

[@Plexversal]

right?? Exactly the same here, we only appreciate the spectacular wonders of the universe when its too late.

[@IshaniRathore1205]

kzbin.info/www/bejne/rWfTi4dqm8xlbKs

[@nishantshade668]

@@gaudiumlex9929 jobs require you to have marks and skills. Your background plays a major role. Another thing is independent research requires a bit of funding. Changing fields ain't an easy task.

[@nijiasheng711]

Exactly so, we come to this world not to just learn and prepare for something related to our career, our routine life(like learn how to get higher score, learn how to be sophisticated, learn how to build our families), but to understand the universe, the world surrounding us. MIT OCW courses just provide us with these knowledge.

[@inversnone]

Just repeating the plain obvious, but can't express how glad I am that MIT offers this HQ material to independent learnears, like I am.

[@moncefgot3855]

Hello. I am an independent learner too . So you are an undergraduate physics student? Or you are just learning to learn for pleasure nd love of physics hahah?

[@__rikaisuru]

@@moncefgot3855 not op, but both

[@IshaniRathore1205]

kzbin.info/www/bejne/rWfTi4dqm8xlbKs

[@lilmoney100s]

Man I’ve watched this series like 4 times and feel like I haven’t learned anything things get cut out and what not

[@NazriB]

Lies again? App Store

[@JolieFleur0116]

I wish I had her as my chemistry professor. She explains things so clearly.

[@trenttagestad5282]

I've had the Rutherford experiment explained to me probably a dozen times, and this is the first time I feel I truly understood the methodology and Rutherford's headspace

[@schmetterling4477]

In order to understand that, you would have to read Rutherford's original paper. It's online.

[@foutokinata7624]

I'm now trying to get my 2nd bachelor, this time in chemical engineering, and my teachers do not explain this well. Thank you MIT for letting me understand what I'm studyin elsewhere

[@herambpatilofficial]

Please make a playlist on Organics chemistry, it'd be great help......................

[@Plexversal]

The fluent connections of how atomic matter were discovered in this lecture were portrayed amazingly

[@IshaniRathore1205]

Nice

[@--076]

This is so awesome that these lectures are posted. One of the finest institutions in the world, and I get to learn for free. Amazing.

[@IshaniRathore1205]

Ya

[@FreeCourseBLGX]

Thanks for the videos that we can learn Outside the University. thank you so much for your work

[@IshaniRathore1205]

🙄

[@IshaniRathore1205]

Respected sir, I want to inform Faculty of Chemistry

[@diegoarmandosalazarimpata6199]

37:21 That would occur if the electron were static, but it has a tangential velocity (classically speaking), that's why 'it is in a circular motion'. I think that there is a misunderstanding. The problem is not precisely newton's law but maxwell equations that says if a particle is acelerated like in this case, the electron, it should radiate and loose energy causing it to decay into the nucleus.

[@runakovacs4759]

I think she explicitly avoided the "orbital electrons" explanation as it would cause misunderstandings without benefit. It's better to consider the base problem without going down and hunting the red herring, than to waste time dancing with said red herring. After all, what would justify the electrons having tangential velocity? It would be introducing a concept without an experimental reason.

[@ofekgillon10]

@@runakovacs4759 This is like saying "why would the earth have tangential velocity (relative to the sun)". This is something that has to do with the initial conditions of how the earth formed, and then rises the question "so probably all of the atoms also formed in a similar way" and really almost any initial condition will do! (due to conservation of angular momentum it is easy to see that the electrons will orbit and not crash!). So before introducing a whole new theory which is maybe the weirdest theory the humankind ever discovered, one needs to explain really why this doesn't work. The answer "radiation friction" is not so bad, it can be said without too much explanation, and it really tells people what was wrong.

[@lds7614]

I was having the same idea

[@snoopdogofscience6873]

Marie Cuire was from Poland, she lived in France due to occupation of Poland

[@lsbrother]

13:00 Actually Rutherford was at the time of his illness a 'Lord' - not merely (!) a Knight. And it was Lords that were entitled to be treated - if they so wished - by a Knighted doctor. He was operated on in good time - by a Knight - but later there were complications and he died. i don't believe it's true to say he died because of waiting for a Knight!

[@paul_lewallen]

This lecture is a great supplement to my courses at community college.

[@byabdullahsahibzada]

1:10 the answer is none because this ammonia reaction is reversible and in reversible reactions there is no limiting and excess reagent

[@byabdullahsahibzada]

So now send me MIT t-shirt on my address .

[@brandoncrenshaw6813]

This is amazing. I'm an old dude going back to school to do/learn things that I regret blowing off when I was younger, and this video has made me feel even more the idiot for blowing off chemistry. (I skipped the majority of classes and didn't even bother dropping the course)... the questions answered in this one video... man!!!

[@piyushkumar4706]

Love to see your video lectures

[@piyushkumar4706]

From India

[@TaregtNeet2024]

In India all teacher osm u can easily understand and feels everything without any doubt and you people easily solve hardest hard question in short time Tricks are so osm

[@samikshamathe]

Which channel is best for chemistry?? l am preparing for NEET

[@TaregtNeet2024]

@@samikshamathe same here I'm also neet aspirant No one looks better on utube for chemistry offline krta hu ji Pankaj sir ka thik hai youtube pe u should try once....

[@TaregtNeet2024]

Elon yadav ...... Kanpur se

[@katel3479]

Wow, I never found Chemistry so fun and interesting!! As someone with honours degree 14:07 got me lol

[@IshaniRathore1205]

kzbin.info/www/bejne/rWfTi4dqm8xlbKs

[@IshaniRathore1205]

Unbiliv

[@richardchen2169]

7:23 ~ 8:00 I had the impression that cathode ray only contains electrons. Besides, the nuclei of hydrogen (positively charged particles) can only move from the anode to the cathode, which means we can't observe any positively charged particle behind the anode. Could someone explain for me?

[@chiklachikla7641]

It shown in the picture of the experiment that the cathode rays were hydrogen gas so there is positive and 'egative charge im pretty sure she explained it using the realtionship between deflection and mass hope that helps.

[@Shivam-sb8df]

Even I don't understand that part! It says in the lecture that when Thompson applied a very large potential difference, a slight deflection occurred towards the negative plate. But because cathode rays only consist of electrons, the statement about deflection towards the negative plate does not make sense!

[@thebestiarybell]

thank you for these! i was watching the older version (2009), when dr drennan and dr vogel-taylor were co-teaching. i reaaaaaally love it. now that it is 2021 i wonder, does it matter that these are so outdated? my guess is moooostly, no - but if anyone has information they want to share about any of these question, i send huge appreciation!: are there any/significant differences in the content taught in the 2009 version and this version? and/or has there been any science research which has rendered this version or the 2009 content obsolete/outdated? and/or does anyone know if there is/will be soon, an MIT OCW update available? (or non-MIT alternatives that are as amazingly taught?)

[@IshaniRathore1205]

I would be grateful for the same Thank you Faculty of Chemistry

[@mackenzieonyx7586]

THANKYOU THANKYOU THANKYOU! I can't express how grateful I am for this playlist/these lectures (both on your site and on yt).

[@nalarsehat456]

God bless you prof Catherine

[@neerajazad123]

Thank you so much for providing this i hope through chemistry I can make this world a better place

[@codeman9388]

8:51 what neutral normally ? Cathode Ray are negatively charged. how it was assumed that charge of electron is equal to charge of proton ?

[@anilsharma-ev2my]

Atomic Atamik Atma Atmospheric Automatic Authorities Automatically Atomizer Atomization Antim Antattogatwa

[@kimtiedits]

Thankyou very much for HQ free classes.I'm from India.

[@IshaniRathore1205]

I would be grateful for the same Faculty of Chemistry

[@sanfransardine]

So much better than podcasts about serial killers or other useless garbage

[@elcikay]

At 37:50, perhaps the problem is there is actually no distance r between the electron and nucleus. So my question, how did we know there is a distance r between them? I like the way she explained how everything was discovered, but it's a pity she didn't explain this. It's like a plot hole in an otherwise awesome mystery novel.

[@nhra7110]

Instructor makes me want to come back to school and get a Chemistry degree! She is awesome

[@computerlover9290]

Wow Americans really have a good and fun and easy approach to learning.here in Iran its very hard and boring and full of memorisation.not to mention the konkur entrance examination which gets harder each year

[@Unknowledgeable1]

0:38 limiting reactant? Synthesis? Moles? Reaction vessel? This wasn't covered in the wk1 lecture iirc, how do the people in the lecture know how to do this question? ❤2:05 discovery of the electron AND the nucleus; 2:24 2:37 2:44 how do you study something that is really small? ❤3:07; 3:19 3:29 dangerous, hubristic thinking that slows progress 3:43 what is the atomic theory of matter and Newtonian mechanics? What are their principles? 4:00 4:11 atomic theory of matter is updated when the electron was discovered? 4:22 4:29 JJ Thompson's experiment to discover the electron 4:37 cathode rays? You can see rays? Evacuated glass? You can apply current to gases? 4:58 negatively charged particles? Positively charged particles? Neutral charged particles? 5:06 you can actually see cathode rays get deflected? You can charge plates? 5:18; 5:27 voltage difference? 5:40; 5:49; 6:08 cathode rays contains negatively charged particles 6:15 negatively charged particles? 6:30 6:43 deflection of negatively charged particles - you can measure the magnitude of the charges of particles? (So some particles can be more negatively charged than other particles); 6:50 7:14 7:22 7:47 there is also a positively charged particle 8:21 10:32 10:47 10:53 11:20 11:28 11:45 11:54 12:05 13:30 radioactive material can emit alpha particles - idk what ions are 13:39 14:14 14:26 15:15 15:33 16:38 17:50 ❤18:02 Rutherford's discovery of the nucleus 18:09 18:38 18:55 how did he know the overall atom is going to be neutral? 19:37 25:47 26:32 28:31 31:23 31:53 34:55 35:15 35:29 37:49

[@Unknowledgeable1]

Further questions: - does particles means exactly the same thing as atoms?

[@bharatarora.]

@@Unknowledgeable1 Atoms contains electrons and protons which are defined as sub-atomic particle or just simply particles.

[@FinnA07]

The students in the class get reading assignments so they should know that

[@FinnA07]

18:55 he knew it was neutral because otherwise it would be Charged, either positive or negative, which it isn't

[@FinnA07]

Ions are part of salt so look into that to learn more about it, atoms become Ions in a chemical reaction with oxidation and reduction, for example the bonding between Sodium and Chlorid becoms a Sodium Ion and a Chlorid Ion which go together as typical salt from an everyday kitchen. But again the overall topic of salts is interesting and difficult to just explain in a comment, i encourage you to look into that

[@examinationguidance3038]

The Department of Basic Science and Humanities of Institute of Engineering & Management (IEM) takes pleasure to announce the FIRST ONLINE INTERNATIONAL OLYMPIAD OF PHYSICS - IEMOLYMPHYS 2021 on 24th July, 2021. The Olympiad is fully sponsored by IEM, in collaboration with IEM-AIP Society of Physics Students Chapter (SPS) and SMART SOCIETY, USA . IEM group is a global name and it is in fame due to its strong foundation in teaching and R&D. IEM has always aimed to serve the future generation through its commitment and unparalleled excellence. As a part of its commitment to serve the academic community in the national and international level, IEM is organizing this Olympiad. This Olympiad aims to provide a unique competitive platform to genius young minds and create a global talent pool. IEMOLYMPHYS 2021 will help young individuals to learn and practice new skills for today’s competitive world and help them to think beyond the conventional learning. With this note, we invite you to participate in IEMOLYMPHYS 2021 and request you to circulate our flyer to your friends/juniors/seniors of your school and college to participate in this Olympiad. Interested participants will need to fill in and submit the following Google form and follow the instructions provided in the form. forms.gle/9UkapuM53pa4CPFm9 Thanking you, IEMOLYMPHYS 2021 team [e-mail]

[@duraace6511]

The legend says they still cleaning up that mess.

[@IshaniRathore1205]

😁

[@allaboutstudystuff817]

Ok I could solve this problems and understand concept while I am just 15 it's not that tough as I thought it would be to be able to solve university problems. I would have I get that T-Shirt but the point is not in solving that question it is in solving it in MIT class.

[@AbhijeetSingh-lz2xc]

Actually it's class 9th thing . Its basic for class 9th student . You can understand these easily

[@Sakib.Shahriar]

27:51 You had the count of the total number of nuclei. But how was it done during Rutherford's time? Was there a way back then to get the number of atoms based on the area of the gold foil? That would require the radius of the atom itself. But from Rutherford's atomic model, we didn't get any idea about the radius of electron's orbit. That implies Rutherford had no idea about the radius of atom itself. How did he have the nucleus count then? If someone in the comment section have any proper idea about it, please share. That'll be highly helpful.

[@codeman9388]

37:10 how to integrate the double differentiation ?

[@AlejandroTaylorEscribano]

How can they know the number of nuclei in the gold foil ahead of the experiment?

[@anyoon1454]

alpha beta and lamda consist so called 'atom' , then is it possible to create 'atom' by colliding A B R ? how can we bring it back?

[@AnneSjahsam]

love this professor!

[@Speed4Runs]

If a cathode ray is by definition a stream of electrons, then how could the cathode ray have a positive charge? And why should only protons stream out instead of a linear combination of protons and electrons, so that the "net charge" could be assumed to be equal for both electrons stream's deflection and proton stream's? You apply more voltage difference, so there is definitely more energy in the ionized H_2 molecules' movement, and I suppose this could justify the additional presence of positive ions, but then, once they're out to reach the linear path, shouldn't they cancel out, if both are exiting at the same time? I mean ok, thermal noise is a random process, so even with a theoretical (averaged) voltage difference of 0 we can still have random fluctuations, both positive and negative, thus leading to, theoretically, a positive or negative net current - further justifying the presence of protons despite cathode rays being the main thing there. But this introduces another problem, that is even the amplitude of the random process is indeed a random variable. And since dV/dt is proportional to the current, which itself is dQ/dt, then the "amount" of charge Q itself, for a given time interval in which the experiment is observed, should be a random process as well. So... Since the ray is a "stream" of (electrons?), which I interpret as a varying and moving set of elementary particles, then the net charge at a given time should be a random variable. I must be missing something, so I wonder; how could the dude be so sure that whatever he saw had the same charge as the electrons, in absolute value? Like, from my pov, one could have a stream of positively charged particles that are fewer with respect to the negative ones previously found in the ray. Where's the proof they are equal? I don't think this experiment is as easy and trivial as it was presented. Could someone clarify, please? Also, it is unclear whether the "increased" voltage difference was applied on the plates or on the illustrated battery - that would change the whole thing even more, but still make no sense to me. Edit: after re-watching, I see that the voltage difference is meant to be \Delta V, which in the picture is the voltage drop between the two plates. Okay, so this could further change the problem; if the battery voltage is kept constant and the plates' is increased, then no stuff about ionization, at the first stage, should change - same amount of electrons exiting from the cathode, same number of protons, if any, exiting as well (at least on average). Now, since I still can't explain myself the flow of protons towards the low potential zone, I'm just assuming it's due to either the random nature of particles or by the fact that an increased V would produce a negative variation of the magnetic flux, to the point where a huge instantaneous variation can occur, giving rise to, after a very small time, a very negative magnetic field which is now the factor that dominates the Lorentz force (even though if this is the case, then simply waiting for longer time would give the same result even with lower voltage difference), thus producing a force parallel to the electric field, but in the opposite direction, making protons come out instead. This would justify how the increment in potential difference between the plates could lead to a "leak" of protons stream. But still, that would still be influenced by both thermal noise, thus variable impedance, and the Lorentz force's electric field factor. I don't really see how can a visual result imply such confidence in the "equal charge" statement. To me, it sounds like an equivalent statement to claiming that the charge at a given point of a circuit A is the same as the charge at the same point in a circuit B, completely identical to A, just because we see current in both circuits and because the charge of an electron is always the same. I mean, circuit A could be powered up by a 12V battery and circuit B by a 5V one, or circuit A could be exposed to higher temperatures than circuit B, leading to a different impedance and thus different currents. Ok, current != charge, fine, but from what I see in this experiment, one point of interest is chosen and then, for a given time interval, the flow is observed in that point. If charge builds up in that point, then this is equal to integrating the current, giving in fact the amount of charge which is dependent on the interval length, a further reason to add uncertainty in the statement that charges are equal. I am aware that thermal noise may be negligible since we're talking about 3 orders of magnitude in difference, but I still don't think that, visually, one can deduce whether the charge is approximately the same or not, especially when dealing with light, whose intensity after a threshold is not as influential/noticeable in luminosity as when you're within a middle interval of intensities. Dunno, maybe I'm misinterpreting the experiment in general. Also, I don't understand whether there is a common ground between plates and the cathode, and if the battery powers up both the cathode/anode H_2 circuit and the capacitor, or if they're two separate circuits.

[@JC19999]

The Professor seems to be glossing over some of the details for simplicity's sake. It was a separate experiment (also in 1897) where Thomson measured the deflection of H+ ions (i.e.: bare protons) and subsequently calculated the charge to mass ratio of H+. Essentially, he ionized H2 gas, accelerated the resultant hydrogen cations using an electric field, and then deflected this stream of protons with a pair of plates much like in the classic electron experiment.

[@Speed4Runs]

@@JC19999 thanks for sharing!

[@DrChrisB]

It was actually Maria Skłodowska (Curie) of Poland, but... who is counting?

[@anjaneyamohapatra9124]

I think I need one of those lectures for my NEET preparation...

[@studygupshup5491]

Right bro

[@shyamverma7552]

Hello mam and I am from India your lecture is superb how I get your all lecture

[@Roy-el7yf]

India 🇮🇳

[@lyingcat9022]

If anyone counted their ping pong ball hitting the string and not the balls. That would make the diameter appear larger in the calculation.

[@AlejandroTaylorEscribano]

How did they know the nucleus and electron even have a ‘r’ apart.

[@evania2854]

because r is the radius of the atom and nucleus is in the center of atom. cmiiw

[@Capellofficial]

The answer to the practice problem at the beginning of the lecture would be hydrogen which would produce 6.667 moles of NH3 right?

[@namastebharat9553]

Thanks mam, each single word was going directly into my brain🙏🙏🙏

[@aureliomaximinocarranzarod8492]

I loved miss Catt

[@alexmartian3972]

I decided to learn some chemistry trying to understand how galvanic battery works. And 4:46 first lecture of the series - electric current is taken for granted. I'm going in circles.

[@schmetterling4477]

You are welcome to go back to Galvani, Volta, Oersted, Ampere and Faraday and a few others, if you feel like learning about it in historical order.

[@hektor6766]

@@schmetterling4477 Electricity is the basis for chemical bonding. This course should address that.

[@priyamkaple7015]

Why positive particles in cathode rays go towards anode and not cathode

[@mohasahal1771]

10:21 I don't follow the logic there, would someone elaborate plz?

[@schmetterling4477]

It's a trivial result from classical scattering theory. You can estimate it with energy and momentum transfer alone, but Rutherford actually did the proper classical mechanics calculations in his paper, I believe.

[@KSUBSCRIBERINYEARCHALLENGE]

My dream is to learn there

[@IshaniRathore1205]

kzbin.info/www/bejne/rWfTi4dqm8xlbKs

[@Sen7channel]

Lol, the pingpong experiment was pretty funny !

[@tarloksingh6224]

you are always good in teaching...i hope i will become like you...your voice always removes my stress...👍👍👍👍👍

[@soumyarupchoudhury163]

Does MIT opencourseware have only undergraduate lectures?

[@mitocw]

MIT OpenCourseWare has undergraduate and graduate lectures. See our site for the full list of materials available at ocw.mit.edu/courses/find-by-topic/

[@greeshmareddy8876]

Will these lectures help in preparing for jee??

[@LeviKalki]

these are kindergarten stuff when its about JEE. indian coaching system is beyond PhD if you really wanna compare.

[@anilsharma-ev2my]

All the MIT consulting me for being liberating the essences of Knowledge that our karma are being hitting us as action and reaction are equally and opposition

[@IshaniRathore1205]

Ya

[@the.abdullah.nouman]

7126D

[@sushmadevi1463]

What are that positive particles?

[@addisonbiaggi2391]

Why is it that increasing the voltage of the plates resulted in a deflection in the opposite direction? Shouldn’t the deflection be in the same direction with greater magnitude if it’s a stream of electrons?

[@badrmahmoud4437]

Exactly my question.And unfortunately she didn't explain it thoroughly.

[@treasureofchemistry]

Great work

[@tonight_gamer_shiraj3413]

Wow!I am learning all these in my high school.

[@schmetterling4477]

Yes, doesn't it strike you as strange that a university professor teaches at the high school level?

[@hektor6766]

@@schmetterling4477 Welcome to American Academia. Why students transfer to here from other countries is a mystery to me, unless they're just looking for an impressive diploma easily obtained-and casual sex..

[@deborahrhoades7544]

I love this professor💞💞💞

[@gauravshrestha4465]

Helpful

[@d.mijanurrahmanajhari5368]

I'm Bangladeshi... Mam you are a great teacher...

[@ArunKumar-ni9lq]

nice lecture forevver

[@HotDogLA]

I love this professor so much. Thank you! Thank you! Thank you! When I make some money I will mosdef donate to this...

[@shuklaanany6]

So easy learned this in high school in india in 9th grade

[@TSBoncompte]

wait... in chemistry, division by zero *is* defined?

[@aaryeah603]

I'm in 9th grade and i understand this completely she's explaining so clearly!!❤️

[@schmetterling4477]

That is the problem. She is teaching at 9th or 10th grade level, but this is supposed to be an introductory class for university students. MIT charges $72k for this, and even after tuition students are paying an average of $16k. Why in the world would you pay for this level of teaching????

[@aaryeah603]

@@schmetterling4477 You yourself said this is an introductory class i guess they will gradually increase the difficulty level👀

[@bharatarora.]

How is the value of the charge of -ve particle is equal to the value of charge of +ve particle?

[@sajidrafique375]

That shirt could have gone to many contenders...LoL

[@jesusvaldes9957]

Solving Newton's second law for the electron at a distance of 0.5A (in the hydrogen atom), it gave me 0.01fs, no 0.1ns.

[@enzocaramella2617]

It's because you're wrong (maybe) Just kidding

[@deborahrhoades7544]

Is that the Japanese high quality chalk?

[@hektor6766]

Probably railroad chalk. Calcium sulfate not calcium carbonate, very soft and much cheaper than the Hagaromo. MIT math courses use it prodigiously.

[@anilsharma-ev2my]

Potential differences are the main cause of being different😀😀😃😃😃😃😃😀👽😃😃😃😃👽👽👽👽👽😃😀😀😃😃👽

[@melissarainchild]

Hmm, 50-plus girl here...I think...university will be fun :)

[@anewagewithd.u2907]

hey buddy

[@melissarainchild]

@@anewagewithd.u2907 Hi there...and...I'm a girl 🙂

[@HarunBd-zx5ws]

Here from Bangladesh

[@bipendrasingh2144]

How I joined

[@bollywood_movie694]

Omg.... She doesn't teach as clear as indian teachers..... Salute to our indian teachers... ♥️

[@ss-jz5xk]

35:00

[@karencrazy5106]

Why are university students in America learning this at 18 to 21 when kids in the uk are learning this in secondary school at the age of 14 to 15

[@guciochris5297]

Marie Curie was Polish , not French. She migrated to France at 24 and became Naturalized.

[@mmc5005]

Yes and her maiden name was Sklodowska.

[@KPraveen.369]

Here from India

[@wild_cub_times]

cool shirt :3

[@CarolinaVizcaino8]

Could you please share what book are they using??

[@mitocw]

The following textbook was used when this course was taught on the MIT campus: Atkins, Peter William, and Loretta Jones. Chemical Principles: The Quest for Insight. 5th ed. Macmillan, 2010. ISBN: 9781429239257. See the course on MIT OpenCourseWare for more info and materials at: ocw.mit.edu/5-111F14. Best wishes on your studies!

[@NitishRaj]

Which book to follow

[@mitocw]

The following textbook was used when this course was taught on the MIT campus: Atkins, Peter William, and Loretta Jones. Chemical Principles: The Quest for Insight. 5th ed. Macmillan, 2010. ISBN: 9781429239257. For more info and materials visit MIT OpenCourseWare at: ocw.mit.edu/5-111F14. Best wishes on your studies!

[@bymanshi]

9:02

[@fawzibriedj4441]

Seems to me the lecture is full of mistakes and misunderstanding... For example, there could be a force between the electron and the proton without a decrease in the distance between them. As the earth attracts the moon but the moon doesn't crash on us. It depends on the initial velocity

[@pradoprado9993]

Still that wouldn’t be possible since it would require electrons orbiting in a circular motion. We all know accelerated electrons would radiate energy, losing the KE to stay in orbit, therefore spiraling towards the nucleus. I don't see what was misleading in that. The circular orbit proposal was made by Rutherford and Bohr specifically to explain why electrons are not crashing towards the nucleus, in analogy to planets around a massive star. As said, there is a big problem with that proposal.

[@fawzibriedj4441]

​@@pradoprado9993 for me it's not "misleading", it's a mistake. And the mistake is when she applies Newton's 2nd Law, and replaces "dv/dt" by "d²r/dt²", r being the distance between the electron and the proton. There is nothing in what she did that is specific to the electron and proton. We could do the same calculation between the Earth and the Moon, and we would obtain that the Moon should crash rather quickly on Earth. And with this reasoning, she concludes that classical mechanics isn't working... (meaning she never understood why it didn't work at that scale)

[@Naveenbabuborugadda]

I didn't expected that MIT professor also dictate like Indian professors like seeing and writing on the board.

[@R0A1MN5Z9]

Long long ago i came to know this story. Tell me different story or new story only if you have one

[@jackchan6719]

learned

[@kagoActivities]

What kind of radiation does hot water radiates?

[@schmetterling4477]

Electromagnetic radiation. Also a very tiny bit of gravitational waves, but that would be completely unmeasurable. :-)

[@hektor6766]

Thermal.

[@CaptainCalculus]

The story about Rutherford's death is absolute horses---t. That has absolutely no basis in truth at all. Also, her claim that it was undergraduates moving the detectors around is also completely wrong--they built a circle of detectors all around the foil and studied the patterns.

[@hektor6766]

Her "facts" are wrong and display a snarky attitude with a fashionable bias. Her career in American academia is secure.

[@pratapseervi8127]

I think ur teacher forget one thing, which should to teach you. In india 2600 year ago maharshi kanada discover atom and he gave atomic theory

[@AbhijeetSingh-lz2xc]

But he didn't told about sub atomic particles

[@regulus8518]

if you didn't know the nucleus existed or its size of the gold atom, how would you count how many there were per unit area ??

[@fawzibriedj4441]

They knew gold atoms existed before, they just didn't know the atoms were mostly made of empty space with a nucleous in the center.

[@hektor6766]

They already knew the mass, the density, Avogadro's number, and solid geometry. (1 cm^3 X Molar mass for gold: 197 gm)/(density: 19.32gm/ cm^3 X Avogadro's number of atoms in a mole: 6.022 X 10^23) = experimental effective volume 1.693 X 10^ -23 cm^3. The Face Centered Cubic efficiency of a gold matrix is 74%. Radius R = ((4 X 0.74 X 1.693 X 10^ -23 cm^3) / 3 pi) ^ 1/3 = 1.44 pm (picometers) or .0144 Angstrom. So the diameter is 2.88 pm. 1cm / 2.88 pm = 34,722,222.22 gold atoms. One square centimeter contains 1,205,362,716,049,382 atoms of gold.

[@mrkakotube]

At the end of the lecture a question is presented to us: "Why doesn't the electron plummet into the nucleus if it is attracted by it?" It is explained that Newton laws fail and that another law is required. Well, following the same argument we could conclude that Newton´s laws are not applicable to the solar system because the earth doesn't fall into the Sun despite the fact that there is an attraction force between them.

[@diegoarmandosalazarimpata6199]

You're right. The electric force just play the role of the centripetal force, those are basic concepts of circular motion (it seems strange that a MIT proffesor doesn´t know that). The real reason why classical mechanics or to be precise, classical electrodynamics doesn't work at this point, it's because an acelerated charge particle must radiate and in this case causes to decay into the nucleus.

[@runakovacs4759]

I'm pretty sure the prof knows that. The problem is - based on the experiments so far explained, there is no justification for slapping "well, it just orbits the nucleus" as a justification for why it doesn't crash into the thing.

[@leecoates]

And you forgot to factor in that that earth has tangential inertial forces which counteract the weak gravity force. Newton's laws don't apply to quantum physics, this is completely wrong way of thinking although I do understand your rationale.

[@annafrebel2872]

14:02, dentist wanted

[@sanjeetkumar-rd4je]

i am chemistry teacher...but what's process joining teaching

[@dhruvraina8383]

It was a really easy question which was asked in the starting... Being a high school( medical ) student it was a piece of cake for me.

[@garrysekelli6776]

old school MIT videos from the 1950's are way better and actually do handson experiments

[@nuduw]

Garry Sekelli where can we get them?

[@grossly820]

a lot of new stuff has been discovered since then so it wouldn't ideal to study from outdated resources

[@garrysekelli6776]

@@nuduw search: PSSC

[@garrysekelli6776]

@@grossly820 lots of liberal Bull#$&_ has been discovered since then.

[@grossly820]

@@garrysekelli6776 ah so you're one of those braindead people. Welp, you do you and I'll do me