The Nuclear Shell Model: An Introduction

A basic introduction to the shell model to explain magic numbers in nuclei.

[@DrPhysicsA]

Well thank you for your kind words. Alas I can't always make a video every week due to other commitments. But I am currently working on a video on standing waves (by request) and I will try to get that up next week.

[@lapertica8258]

GREAT. If I had seen your videos earlier I should not have been confused as I was. Thank you and congratulations

[@bondjish]

Great video. We appreciate the effort you put into it.

[@ReviewSquadron]

Massive thanks for this. I may just get this degree after all thanks to you!

[@mvuyisimbabane583]

omg you have no idea of how much this video helped me. i read a couple of books but could not understand, now i get it

[@nuhanoor763]

This video was really really helpful. I was reading NMR but couldn't grasp the concept of nuclear spin. You explained it amazingly. Thank you!!

[@paulg444]

He is simply the gift that keeps giving !

[@Samuntiedekanava]

Very inspiring and clear explanation! Thanks!

[@golsson94]

Thank you for the clear exlpanation, it helped me alot!

[@Higgsinophysics]

What a brilliant explanation - thank you

[@evebannon7223]

Found this so helpful! thank you so much

[@herrzyklon]

Bob, I'd just like to say that you are a legend.

[@stokhosursus]

I apologize for my previous comment. It came out much harsher than I’d intended. What I really should have said is that I would love to see DrPhysicsA tackle some of these old topics again since it’s been some time and a lot has changed in video production since this video first came out. It’s a great video!

[@kamerl1]

he described it better than any text I've read, THANK YOU

[@zecarlosparahyba7498]

Great job, Dr. Physics.

[@JK-yj8oy]

Thank you so much. It is really helpful and found it very useful.

[@jimdogma9890]

Another awe-inspiring video Doc, thanks. I look forward to these weekly videos more than the weekly Breaking Bad episodes! Couple questions. 1) what happened to the saxon-woods-saxon model? I got geared up for that and it was gone? Also, you mentioned something about either the protons OR the neutrons acheiving the magic number. Does that mean there's a seperate shell arrangement for each, or can we combine nucleons to achieve these magic numbers. Thanks Doc.

[@awaisamjadmughal7256]

thank you so much sir, i like the way you made this clear. (A cold breath after watching this video)

[@ahmedashraf-1458]

Thank you very much. Very well explained.

[@akashashen]

Excellent 100th video. Congratulations and thanks for creating and sharing. Sincerely, Like #7

[@valmormn]

What a great explanation!

[@nishugoyal2365]

hello..!! it was literally a nice and very informative lecture, i am a master student in france ,working in nuclear physics domain, i was looking for some nice explanation about shape coexistence in exotic nuclei. could you please make a video on that too..

[@climbeverest]

This is an incredible lecture

[@enmanuelpadilla1801]

Thanks a lot, for this explanation..!

[@dacilrodriguez4693]

Soooo helpful!! Thank youu!!!!

[@debiprasad008]

very good explanation, was really instructive and fun to learn the physics

[@vinayanand6056]

Thank you sir for sharing your knowledge.

[@leazeslad]

great video, thank you!!!

[@venkataramireddyappireddyg8104]

Thanks a lot. I used your videos to teach my students

[@DrPhysicsA]

The shape of electron orbitals is really just a consequence of the wave function (which depends on the electromagnetic potential between the electron and nucleus - and other electrons) and indicates the probability of finding an electron at any given point. There will be a similar effect for protons and neutrons within the nucleus altho of course they are subject to a much stronger nuclear force which makes them more constrained. There will still be a prob of finding them cos subject to Pauli.

[@DrPhysicsA]

I didn't dwell on the WS potential in what was intended to be an overview of the shell model. The magic numbers apply to protons and neutrons separately. So if for example both the number of protons and neutrons in a nucleus are magic numbers (eg Calcium 40) it means both proton and neutron shells are full.

[@Dowstairs07]

Very good explaination in this video, helps a lot to understand basic physics! 1 Thing: in a sqare well potential, shouldn't there be E~n² instead of n?

[@seonaxus]

For the quantum numbers at ~ 20:00 should it not be ms is +/- 1/2 as s is always the same for a given particle.

[@EliottDucarme]

Good explanation plus cool accent make for a really good vid !

[@abigailmolusi6483]

it makes things much clearer

[@ronistiawan1130]

Thank you so much !

[@samapanbhadury6228]

@DrPhysicsA Sorry, but how can square potential wells have equally spaced energy level? it varies as square of n. LHO has equally spaced energy levels.

[@rishichandrawawhal3274]

Amazing!

[@tomaskadavy]

Thank you very much.

[@antoinegar.638]

Many thanks!

[@nourajchhetri7387]

I love physics. Thank you sir..

[@red-baitingswine8816]

Great explanation - a lot of exactly what I was looking for. How can the protons and neutrons form separate "shells"? Don't the strong forces act between all nucleons equally?

[@red-baitingswine8816]

@@TriNguyen-he7xk Thank you.

[@jimdogma9890]

Are the quantum numbers and orbital energies for the nucleus products of the shrodinger equation (SE) as they are for the electron orbitals? If so, the SE solutions for the electron orbitals specify a shape for those orbitals. Does the maths that determine the nuclear energy states specify shapes for their orbitals-shells?

[@loistownsend3710]

Thank you, great video! If you had to add in parity into these for the excited state configurations how would you go around doing that?

[@enchis1269]

is there any rule for the arrangement on binding energy levels? i got curious because the 2s(½) is appeared when the value of n is 3

[@muhammadtalhaanwar6649]

Great lecture.

[@samking4707]

Really helpful video, hopefully this will get me to pass my exam in 2 days!

[@michaelbenn5062]

i hope you failed

[@vicpinas7877]

Hi Sir great video, still I need to ask something I was calculating the energies for some nuclei but using the Dunlap equation chapter 5, I face a great deal of problems and my answers does not match the answers given by Dunlap . Pleasecan you help here Thank you Vic

[@michaelt9266]

Thank you so much, you did a better job than my university lecturer in a shorter amount of time

[@DrPhysicsA]

I suppose the key thing is that whatever theory is developed has to accord with experimental observations. The standard model is generally regarded as the best fit with what we actually observe.

[@syuhada9627]

thankyou so much!

[@MisterTutor2010]

In the graph @6:36 would the low points be occupied by the group 1 alkali metals?

[@nosirovabdurahmon5964]

Please continue with isospin model and cluster model.

[@MsSris2011]

Thank u so much

[@FelipeZucchetti]

Sorry, it may look a stupid question, but do have the ammount of nucleons a role on the electrons stability around the atom?? I mean, in order to be stable, do the atoms need a particular ammount of electrons around them?? By the way, thanks for your videos...i watch your channel since your begginings and i've learn a lot with you...

[@MarkRLeach]

Hi, love your stuff! Somewhat pedantically, there is a minor error at 6:32 and again at 6:37. You add two elements to the ionisation energy chart, but these should have been added _before_ the noble gas element(s), not after. There are no elements on the 'down slope' (as I know you know). Keep up the good work. Mark Leach (Dr.)

[@TheImpressionable]

What happens to the notation once you get past l=26?

[@earldcosta9785]

Thanks

[@nikoskoutsilieris1624]

you are fucking amazing!

[@rajkumardutta5452]

In atomic structure we do not have 1p level or 1 d level etc. But in nuclear structure we have 1p, 1 d, 1g etc. Why? Can we really refer 1 here as principal quantum number?

[@azharulislam4293]

what is the success and limitation of magic number?

[@samwelimathias1192]

Thanks much Dr l got light

[@kayodeajulo8377]

i like this tutor

[@BretVarcados]

~ Please tell me if I'm wrong, but: I would theorize that the attraction between the protons and neurons, and the strong force is regulated by the electrons cumulative amplitude of energy, which are held in orbit to the nucleus due to the laws of completing electric currents, and their need to ground before changing polarity. Protons being the point of force against electrons, and the neutrons are a force of attraction, which is defined as the Culon force. Thus the interactions between protons and nucleons are minimal other than giving polarity and mass to an energetic particle, because the laws of magnetism would be forcing the protons and neutrons to settle in relatively equally spaced and alternating positions, which form a circular shape and space thanks to the cymantics of sound, substance, time and space. ~ What do ya think??

[@jordanfox840]

Such a formulation would fail to explain basically all of nuclear physics. For example, nuclei can be dissociated from their electron cloud in a plasma, yet the nuclei do not dissolve themselves. Nuclei have energy levels, as seen in this video. Nuclei can transition those energy levels, in part, through radioactive decay. Interactions between protons and neutrons are not minimal - they give rise to a breadth of phenomena that do not depend *at all* on the electron cloud being there.

[@ritzch7632]

Thnks sir

[@sajateacher]

Does the Heisenberg Uncertainty Principle play into this somehow in terms of the size and interactions of the nucleus?

[@jordanfox840]

The HUP should not be involved with the form of the nuclear interaction. Uncertainty principles are not physical things, but rather it is a result of the mathematics used in the model. Depending on your physical system, you might have a different looking uncertainty principle. Quantum is done in infinite dimensional Hilbert space where "measurements" are made by applying self-adjoint operators to wavefunctions. It turns out the uncertainty principle for that space is the HUP. That also doesn't mean the HUP is not a *real* thing - it is - but it manifests in the experimental process and not in fundamental physics.

[@qewqeqeqwew3977]

Energy levels in a square well are not equally spaced.

[@Waranger5]

correct, that would be the harmonic potential. I think you need Woods-Saxon because neither harmonic nor infinite well gives you the observed magic numbers, even when accounting for spin-orbit

[@quarksarranged]

@@Waranger5 Woods saxon would only work if you account for spin orbit.

[@jimdogma9890]

Doc, where's the next video in the series? We look to you for our weekly harbinger of hope to sail us through this turbulent Dirac pool of life.

[@RR-yx5ux]

I was told that the number in front of the letter is only the shell for the atomic notation, and that for the nuclear shell it's just a way of ordering the levels.

[@brendawilliams8062]

Thankyou

[@kingmerkulov1754]

good video i finally managed to understand the enery levels thing

[@t4k3none]

Thankyou. Seems a very esoteric subject, but it is exaclty what I was looking for.

[@sarikasingla1144]

Thankuuu...so sir...really u r amazing....

[@rohitjha8978]

Now that is an understandable introduction! Finally a great video on you-tube! So when is the next video lesson on Shell model coming out?? Thank you for the lesson!

[@steliosgeorgiou9234]

DRPHYSICS YOU ARE A GOD

[@jaguaroar]

+Stelios Georgiou you're a loser

[@steliosgeorgiou9234]

you are a dweeb and probably filthy bieber fan

[@jaguaroar]

is it too late now to say sorry?

[@muhammadsohailkhan8947]

Sir how a nucleus have a spin of 3/2, 5/2, 7/2 etc

[@bedahfisika]

That's not spin, that's a new quantum number which describe how much proton can occupy in the state

[@kousoulides]

But what is the standard model nowadays, the string theory says elementary particles are one dimensional objects other say they are 0 dimensional.. The reason I am asking is because I was wondering lately if a black hole emits positively charged particles, and shrinks down. why can't it be shrinked to a theoretical stable point that it only holds a few particles into orbit. (atom) why does it have to evaporate. I guess I better start doing equations and see for my self why.. right?

[@mongoika3898]

Excuse me, isn't the principal quantum number in the lowest energy n=0 in the case of nuclei, and if so, why isn't the orbital called 0s?

[@DrPhysicsA]

No. The first principal quantum number is 1.

[@DrPhysicsA]

***** Yes you are right. And that is what I was trying to convey (tho I agree it isn't as clear as it could be). I'll add an annotation to clarify. Thanks for spotting it.

[@okotray4577]

Like this

[@kousoulides]

it seems to me that all these forces inside an atom exist on the assumption that elementary particles do not have substructures. If all that there is is those particles then you need to have forces. But why can't an atom be a collapsed spot and the elementary particles interpreted like.. hawking radiation into orbit of that spot ..I mean they do behave like they pop in and out of existence, they do entanglement similar to the radiation.. why not?

[@federico-bayarea]

Great video! I have a question about the Pauli exclusion in electrons and the concept of spin. When we say that two electrons cannot have the same quantum numbers, and for instance in the first shell one must be spin up and the other spin down. What spin axis x, y or z are we talking about? Is it on any axis we choose or a fixed axis that depends on the atom? Basically, why could not an electron be in x axis and another on the y axis? Not possible, but I would like to understand it. Many thanks!

[@jordanfox840]

This is a good question, but the answer might not be very satisfying. When you say electron spin could *be* on a x-axis or y-axis or z-axis, the quantum founding fathers start twitching in their graves. The process of measuring the components simultaneously is impeded by the uncertainty principle. For a single-particle wavefunction, a single component of spin can be known simultaneously with the *magnitude* of spin, but no two components can be known simultaneously. In practice, experiments measure components either in a transverse (z) or perpendicular (xy plane) directions, but it depends what you are doing. In the end, the restriction that a wavefunction has a good quantum number is a restriction on the result of a measurement, and due to uncertainty that measurement cannot give us the whole story.

[@luisbielmillan8467]

wow

[@marina4919]

Do we know magic numbers because we know where the gaps are, or do we know where the gaps are because we know magic numbers?

[@DrPhysicsA]

I fear so. You have to make the maths work. And its jolly hard.

[@DrPhysicsA]

Thanks for kind comment. I'm not aware that atomic stability is determined by number of electrons. It's much more determined by nature of nucleus (eg atom becomes unstable if more than 92 protons). Complete electron shells produce inert gases.

[@elinope4745]

protons, much like everything else, cannot be monopolar. They do not have a positive magnetic charge, they have a magnetic charge that is on average positive. But there is a north and south to it's charge, it is not universally positive. For exactly the same reasons not all electrons are negatively charged, although they may be on average negatively charged. The negative and positive of the charge only comes up for the field and not the individual hadrons/leptons.

[@pressaltf4forfreevbucks179]

Finally a non indian video

[@kousoulides]

I am not a physicist by the way I am a computer programmer .. here download my game on the iphone: puzzle flights! :P its free (it's for kids though but hey)

[@chaganarshiya6282]

😥😥 tomorrow is my exam and vdo is too long eeeeee