Atomic Structure - A Level Physics

Continuing the A Level Physics revision series looking at Atomic Structure, including the formula for the allowed energy levels for an electron in a Hydrogen atom and how this fits in the with observed spectral lines from Hydrogen.

[@DrPhysicsA]

The A-level playlist consists of videos on issues which are generally covered in the syllabus for the main A-level boards including AQA. I do not separate out the A2 and AS videos because they differ for different boards. These are revision videos so I hope people will be able to identify the appropriate videos for the material that they have covered in their course.

[@DrPhysicsA]

See my video on Nuclear Structure Physics. But you may also want to look at all the videos in my Nuclear Physics playlist.

[@DrPhysicsA]

When an electron falls from, say, -2eV to -5eV it gives off 3eV of energy which can be converted to EM radiation according to E=hf, A fall from level 6 to 2 releases more energy than a fall from 3 to 2.

[@DrPhysicsA]

The Compton effect or Compton scattering is basically where a photon scatters off a particle (eg an electron). In doing so it transfers some of its energy to the electron, and thus the scattered photon has a lower energy (ie lower frequency).

[@DrPhysicsA]

When we are looking at electrons jumping between energy levels then the photon gives all its energy to the electron. Compton scattering results in the electron being ejected from the atom, leaving an ionised atom.

[@DrPhysicsA]

The incoming photon is one which was generated earlier by an electron falling back to a lower energy level. So if photons generated by electrons falling to a lower level then hit another electron and cause that to fall to a lower level all the photons will be of the same energy (frequency) since they all come from the same transition.

[@diyarfalah9693]

I am from kurdistan- Iraq and I am a medical student but very interested in physics, I was hardly finding any good source to understand some goos physics and now I am extremely happy to know about these videos..they have helped me a lot..thank you...

[@DrPhysicsA]

Thanks. You are right that the strong nuclear force stops the protons in the nucleus from flying apart. But the treatment of electrons as waves rather than particles (as proposed by de Broglie) is what stops electrons spiraling into the nucleus.

[@DrPhysicsA]

But how would the 0.1ev KE be manifested given that the electron is still bound to the atom.

[@DrPhysicsA]

I am gradually working my way thro typical exam questions. Hope they help.

[@DrPhysicsA]

Thanks for kind comments.

[@karupparna3875]

As a. Teacher I liked the way yku explain it dear sir ..amazing .. I never knew many things you taught in every lecture .. greetings from India ..

[@proquimica]

Amazing, a real jewel of knowledge. No way to thank you enough.

[@annenna2354]

All these years and I never knew laser was an acronym. My entire life is a lie.

[@O0marO]

Your videos are really amazing. I like your voice and your accent and the way you explain things are understandable. You have a new subscriber :)

[@DrPhysicsA]

Well an alpha particle is about 8000 times more massive than an electron so the alpha particle isn't going to be diverted very much.

[@kan0o0]

THANKS! i really loved this explanation at last I understood the real working of the laser concept after so many years!!!!!!. I never understood it earlier because i thought the incoming photon would be absorbed by the electron then, although produced another one, didn't understand the "duplicity" but now I do thanks to your explanation in which the electron already had to be in an excited state previously. your work is AMAZING. thanks thanks thanks! going onto the next one!

[@aisha.s614]

Sir I love your explanation. Thanks for your efforts, it's really helpful for those who are studying physics. 👍

[@DrPhysicsA]

There are several ways to express the SE. I chose a simple approach in one dimension.

[@pigdog126]

I would like to discuss a little more about what happens 13.25 when a photon with 10.3ev interacts with the electron, Can the electron absorb 10.2ev and reflect 0.1ev? I thought that Compton scattering provides for that. Aside from that case, can’t the photon energy be absorbed in whole or part as heat/momentum? Thanks! Fantastic videos. Will watch all of them.

[@boddahboy]

Wonderful, clear and concise explanations.

[@DrPhysicsA]

SE is Schrodinger Equation

[@TAG2785]

i just wanted to say thanks you so much for the effort you put in to teach us!!

[@Laughbankrip]

If an electron of kinetic energy 0.92eV is scattered from a lithium atom which is initially in th -5.02 eV level, the scatterd electron can have only two possible kinetic energies what are the two possible kinetic energies

[@Houriaa]

Great video :D I enjoyed it all along :) but when u said in the rutherford model that some alpha particules go straight i guess they don't , they will deviate because of the electromagnetic field and when they will get closer to the nucleus the angle of deviation will become greater that they will go back and sort of reflect !

[@xXxBladeStormxXx]

At 13:24 you said that if you give it a 10.3eV of energy then it will do nothing as there it isn't a permitted energy level according to the Srchodinger equation but then what happens to that energy? Something must happen right?

[@DrPhysicsA]

If the photon cannot transfer its energy to the electron it just carries on as a photon.

[@ilhamwicaksono5802]

so, what video containing your explaination about the 2nd problem of rutherford model? thanks

[@Son96601]

what video do you cover the second poblem of the nuclear model?

[@randomdude79404]

Hi sir , I have a quick question do you teach the material off the AQA Exam Board and also could you please put your videos into a playlist for AS Physics with all the videos ? Thanks :)

[@chadjad1]

THANK YOU so much for this series,they are brilliant! I have a question though, at 16:31, you say that the energy difference between n=3 and n=2 gives to the frequency of a red line in the spectrum and the difference between the n=6 and n=2 gives the violet line. My question is, on the diagram in which the energy levels are drawn to scale, the difference between n=3 and n=2 is greater than the energy difference between n=6 and n=2, so shouldn't the n=3 to n=2 produce the violet line,not the red?

[@mathveeresh168]

Was it not Bohr ?? Who gave that formula and it is not based on wave nature Bohr derived it by particle point of view

[@hallojimmy]

hi in part 6:20 you have mentioned that the protons and the neutrons in the nucleus are in the stable state due to which is explained by the de brogie formula however I thought the strong nuclear force that is present in the nucleus which overcomes the electrostatic forces in the nucleus between alike charged particles is the reason for the nucleus to become stable? Great video by the way!!

[@uddeshyaupadhyay1136]

sir I'hv studied the derivation of E = -R(Z^2)/n^2 formula where bhoe's atomic model was used to write down the equations....which were similar to the equation we derive while studying gravitation for the energy of orbit...however formula came out to be exactly the same n as far as i knw bohr's atomic model didn't consider the wave nature of electron....so schrodinger's eqation really gives that simple result..becuz i hv seen it as equtn containin del operators....plzzz reply m confused..

[@uddeshyaupadhyay1136]

While u were explainin workin of LASER....u said that photon will hit an electron in an excited state n push it back to the ground state which would result in another photon emmision of the same frequency....but i cant understnd why the frequency of the 2 photons will match???frequency of second proton is unique and fixed while the external photon hittin the electron could be of any frequency...right??plzz correct me if m wrong somewhere...

[@StickSkits]

at 4:00 can't they be reflected not only by hitting the nucleus but also one of the electrons or is this impossible ?

[@dark24400]

hey man are you sure if the energy of the photon is 10.3, the electron will stay in ground state??? wont it go to level 2 and the 0.1ev will tranfer to kinetic energy??

[@joeldsouza5463]

What abt dat alpha particle which goes straight to nucleus i should come back by same path and at some point must have zero kinetic energy

[@Matey_Mate]

Thank you for uploading these, they are very helpful!

[@mahmoudm451]

Why when you have an electron at an elevated state and you hit it with a photon of specific energy you cause it to fall back downwards to the lower level? shouldn't it cause it to move to a higher energy level? that occurs at 19:48 mins through the video.

[@Luigiticano]

can you go through aqa exam questions!

[@Xchannelful]

If the photon transfers all of its energy to the electron to make it jump into the higher energy level, then why is that when that electron goes back into the lower energy level we get two photons? I mean, the photon that was used to promote the electron was used up, right? So why do we get two photons instead of just one?

[@keretaman]

+Hamza Siddiqui I'm thinking the same thing! Why!

[@keretaman]

+Hamza Siddiqui It looks like the photon just hits the electron but doesn't give its energy. If the photon gives its energy, the electron would go up instead of down. Looks like that..

[@kosiokoye2384]

Rizz first of all what is photon... it is light or fragments of light... it has energy and when it hits an electron, the electron absorbs all of the photons energy to be able to move to another energy level. so electrons giving of photons is basically electrons giving of radiation or light when they fall back to the ground state.... for electrons giving of two photons, this when an already excited electron is stimulated again and this will lead it to emitting two identical photons. hope this made sense although very late.....

[@Rockthegaspar]

Brilliant!

[@dark24400]

the electron does have kinetic energy even when its bind to the atom, remember it is spinning with a certain velocity. rt??

[@uddeshyaupadhyay1136]

sorry but what does SE stands for????

[@joeldsouza5463]

The visible hydrogen spectrum n=2 is called d balmer series i think

[@rajmohann.t252]

what is compton effect?

[@omsingharjit]

Yes yes This topic ❤❤❤❤

[@nasim5673]

DrPhysicsA If E = hf and hf = work function + kinetic energy then when an electron moves from the ground state to n = 2 state then what happens to the work function and the kinetic energy? According to the wave particle duality.

[@DrPhysicsA]

+Nasim 567 The work function remains the same value because that tells you the energy needed to get an electron out from its lowest energy state. But you would need less energy to remove an electron in a higher energy state. And if you used a photon of specific energy to knock an electron out of an atom then he residual KE of the emerging electron would be higher if it had been knocked out from a higher energy level (because less energy is needed to get it out of the atom).

[@nasim5673]

+DrPhysicsA Thank you very much sir!

[@joeldsouza5463]

Will d mirror absorb d photon in dat laser

[@rajmohann.t252]

can you do a video on antimatter

[@clotanoob]

Well and clear explaination thks

[@razamate]

Great video! Thank you

[@uddeshyaupadhyay1136]

oh yes....sir kindly answer my question about working of LASER...

[@nizachanda9929]

You're the best

[@mizmazqwerty7198]

Hey.buffering lma sngt

[@jad2805able]

Thank you :)

[@Cusnpbzn]

I thought I had birds in my house for a moment, or the dryer was squeaking again.

[@NerdNordic]

Awsome! :D

[@chadjad1]

actually, no, Im wrong, ignore this question. I understand now! sorry. But again thank you for this series

[@dark24400]

buit yeah ur rt, btw its a bit confusing