Why doesn't the electron fall on the proton? Every book

Its like how the earth doesnt fall to the sun. I just don't understand why when it reaches 0 Kelvin it doesn't fall to proton

It has to do with the strength of the EM field. If it were stronger then the electrom would orbit closer.

>>7973965
>implying there's such a thing as gravitational bremsstraluhng

>>7973953
>Why doesn't the electron fall on the proton?

Because it has energy. It's like a standing wave. "Falling onto the proton" would mean it's amplitude is zero.

>>7973965
>I just don't understand why when it reaches 0 Kelvin it doesn't fall to proton

It is a misconception that 0 Kelvin = 0 energy. It simply means it can't give off any more energy.

>>7973953
It's like a 4chan thread.

You know everyone here is an idiot yet you still stick around and think something exciting could come out of it.

>>7973953
>Why doesn't the electron fall on the proton?

Magnets and magic.

>>7973953
It does sometimes. I think it's called k-capture.

>>7973953
Thinking of electrons as orbiting particles is obsolete when asking questions like this and you really have to turn to some basic quantum theory -- as classical mechanics would describe the electron "falling" into the nucleus, like an orbiting planet.

Electron position is thought of as a probability rather than a posit. We have to use statistics to understand the likelihood of it manifesting itself in some part of space with respect to the nucleus. The reason the electron doesn't simply whiz away from the nuclear space or crash into it is a simple balance of kinetic vs. potential energy. As the electron moves towards the nucleus, its potential energy shoots to negative infinity and its kinetic energy shoots to positive infinity. This push and pull balances, according to theory, to a relationship in which potential energy is twice that of kinetic energy -- and the result is electron detection at an average distance from the nucleus which corresponds to the Bohr radius.

>>7973965
The earth doesn't fall into the sun because it has angular momentum.

An s-orbital electron has none.

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Its velocity overcomes the force of attraction to the proton.

>>7974093
>The earth doesn't fall into the sun because it has angular momentum.

False.

>>7974146
The issue with this classical picture is that accelerating charges should radiate from classical EM. That would mean there are no stable orbits, since it always radiates its energy away--eventually falling inward. The way around this is to impose certain favorable, stable orbits like Bohr did. This is a trick from the classical picture, but can be matched to the quantized energy levels observed.
>>7974093
Quantum mechanically, you have stable states (orbitals) with quantum number l=0, but this doesn't correspond to a classical picture. You've only got a probability density around the nucleus, in which it can exist--there's no corresponding classical picture ('where' is it, 'how' is it 'moving?') at this scale. What it's doing here is purely quantum mechanical, the 'orbit' picture is attached from classical intuition/ideas.

>>7974037
s-stammering?

>>7974172
You give no actual explanation. You just say "well, in QM this is how it works".

Even in QM the electron feels the attractive potential of the proton. If you claim they should never scatter on each other you better have something really good to back it up.

>>7974170
Fucking explain your statement

>>7974200

The fact that the Earth is spinning is not why it doesn't fall into the sun.

>>7973953
take your earphones and start spinning them
when the earbud is at the top why doesnt it fall on your hand?

>>7974216
Spinning around its own axis =/=angular momentum.
Angular momentum does stop the earth from falling into the sun

>>7973965
>reaches 0 kelvin
2nd law of thermodynamics says nope

>>7974039
damm man. can you refer me to the text where you read that? good stuff

>>7974237
Gotta love chemwiki.

Cheers

http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Quantum_Mechanics/09._The_Hydrogen_Atom/Atomic_Theory/Why_atoms_do_not_Collapse

doesn't the electron constantly accelerate when it is orbiting since the tangents are rotating? i thought accelerating charges had to give off energy.

>>7974253
>What are stationary states.

>>7974258
this isn't jeprodary. explain yourself.

>>7974261
The idea is the electron moves in stationary states, which are states with definite energy.

>>7974232

heisenberg uncertainy principle says no aswell

>>7974267
not knowing it's 0 with utmost certainty doesn't mean it's not 0.

>>7974262
what do you mean definite? the energy it releases is conserved?

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ayyy you guys are all fags lmao

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>>7973953

A free neutron will decay into a proton, an electron and a third "particle."

Maybe electrons can fall into protons and then the two become a neutron under the correct conditions.

>>7974274
Not really, if you look at stationary state you'll get an expression a bit like [eqn] | \Phi (t) \rangle = e^{ -iEt/ \hbar} | \Phi (0) \rangle [/eqn] Here [math] | \Phi (t) \rangle [/math] is the state at some given time, [math] e^{-iEt / \hbar } [/math] is a phase factor and [math] | \Psi (0) \rangle [/math] is the state at t=0. Now it looks like the phase factor means the state varies with time, right? But no, we take the square modulus of the state to get a measurable (often called an observable) quantity, when we do that what we get is [math] \left ( | \Phi (t) \rangle \right )^2 = \left ( | \Phi (0) \rangle \right )^2 [/math], which tells us that the stationary state stays constant in time. Which in turn means the electron should loose no energy as it moves around the nucleus. There's a bit more to it than that, but that's the basics of it.

>>7974297
DUDE WIKIPEDIA LMAO

>>7974231
>Angular momentum does stop the earth from falling into the sun

No it doesn't. That's not what an orbit is.

>>7973953
>Why doesn't the electron fall on the proton?
Confinement. If the electron were to fall onto the proton, I would have a rather good measure of its position and so I have a poor idea of its momentum according to the Heisenberg uncertainty relations. Thus, the electron's momentum may be huge [this isn't a problem for the proton because the proton weighs so much more than the electron] and the electron can escape again. So, an electron cannot fall onto the nucleus because it would be to spatially confined to actually stay there.

>>7974231
spinning around its own axis is angular velocity. the earth has mass. if it has mass and angular velocity is has angular momentum. that's not why it doesn't drop on the sun. it doesn't drop into the sun because it has more linear velocity than gravitational attraction to the sun, resulting in an eliptic orbit around the sun.

>>7974330
Angular momentum can be taken around ANY axis including one not inside the object.
Take a dynamics class

>>7974337
>hurr durr take a class

The system can have zero angular momentum and still orbit just fine.

>>7974330
not sure if trolling or

>>7974351
You could engineer a system that has total angular momentum zero and has objects which form closed orbits, but any individual orbiting object will have non-zero angular momentum. Look up a basic problem calculating the angular momentum of a mass on a string as the same basic principle applies here.

>>7974351
Not in a inertial frame.
It'd fall into the primary body.


We are still talking about gravity right?
Draw a FBD and see where the planet goes when it has zero tangential velocity

>>7974358
>but any individual orbiting object will have non-zero angular momentum.

Not true either.

>>7974253
Atomic orbitals are states in which orbital motion of a charge does not produce classical radiation. This is the important difference. So in the classical sense, yes it's changing directions and momentum, and so it would radiate. But this is not classical physics.

>>7974362
You could work in the orbiting bodies stationary frame, but then you are in a non-inertial frame and the orbit center picks up an angular momentum.

>>7973953
Why don't you fall on the sun?

>>7974362
Please provide a counterexample then

>>7974003
But if [math]KE=\frac{3}{2}kT[/math], then if the electron is at zero kelvin then it has no kinetic energy?

>>7974361
>>7974382
>>7974390
>planet revolves clockwise and rotates counterclockwise
>zero net angular momentum

Okay? Can we move on now?

>>7974417
Hahahahahaha, 10/10 post bro.

>>7974412

That equation is for a large group of particles in an ideal gas. It is not applicable in this case. A single particle doesn't have a temperature.

>>7973953

https://www.quora.com/What-is-the-average-distance-of-a-single-electron-in-the-first-orbital-of-a-hydrogen-atom-relative-to-the-size-of-the-nucleus

>>7973965
The earth is falling into the sun.

>>7974176
What is google

>>7974417
L = mvr

L will not be equal to zero in your example. The rotation about its own axis has nothing to do with angular momentum.

>>7974460
>The rotation about its own axis has nothing to do with angular momentum.

It has very much to do with it! The night side of the planet is farther away from the sun than the day side, and moving in an opposite direction with equal speed. (i.e., v1 = -v2 and r1 > r2) It's contribution to the angular momentum is therefore nonzero (which should have been intuitive, because it's spinning).

Since this contribution can be in either direction and can be arbitrarily increased by increasing the speed of rotation, it is simple to cancel out the angular momentum of revolution.

>>7974474
The equation assumes point masses. Point masses have no night/day side. Hence those parameters are not included in the equation.

To be clear:

m : mass
v : velocity vector
r : radius vector between the massive body M and the smaller body m

>>7974480
>>7974474
To add to that: If your claim that the angular momentum of individual celestial bodies can be zero is right, it would presume that either mass, velocity or distance was zero. None of these premises make sense.

>>7974509
Or you could use the more general equation and parallel axis theorem

>>7974516
Both are dissimilar concept.

>>7974253
There is no next lower energy state so the energy is never released

>>7974480
>The equation assumes point masses.

It really doesn't. But I guess you'll get to that later in the semester ;)

>Point masses have no night/day side

But planets do!

>>7974509
>If your claim that the angular momentum of individual celestial bodies can be zero is right, it would presume that either mass, velocity or distance was zero. None of these premises make sense.

No, it just presumes that the body can rotate.

>>7974559
You still haven't provided an equation for angular momentum which takes your assumptions into account. I believe you are fighting semantics here.

I repeat the fact: The rotation of a body around itself has nothing to do with the angular momentum of that body around a more massive body M.

The electron has a speed and moved within the orbital. It is attracted to the nucleus, which holds it in the orbital, but this attraction is not enough to overcome the momentum.

>>7974589
I didn't read the argument chain, but to clarify--even classically it's broken into spin and orbital angular momentum. Spin is about your rigid axis of rotation and orbital about the point chosen (i.e. origin for central force problems). QM has the same decomposition, total angular momentum J = S + L conserved and obvious quantum numbers. I hope that clears some things up.

By "lowest possible orbital" they mean that the orbitals are quantum in nature. They cannot go outside of discrete atomic "radii." I use radii loosely here, since electron distribution is more complicated than literal uniform circular motion

>>7973953
>wat is a lennard-jones potential

>>7973953
the electron doesn't exist until measured

>>7974589

Here, I drew you a picture.

The angular momentum of the planet about the sun is composed of both revolution (planet mass*SE*Vr) and rotation. For rotation you would have to integrate across the sphere of varying density (which I won't do), but I'm showing you just two points to illustrate the end result. Points A and B are moving in opposite directions with equal speed (Va=-Vb), have the same mass (since the planet is symmetrical), but different radii (SA vs SB). From this you can see that the components from the half of the planet that is farther away will be greater than the components from the closer half, because L=mvr. Since L increases as v increases and Va is independent of Vr, there is no reason you can't have the situation where L(rotation)= - L(revolution)

Understand?

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>>7974747

Shit, forgot picture.

>>7974747
>>7974748
There is no doubt in my mind that there are literal, actual retards on /sci/ that believe this.

>>7974747
>>7974748
> Points A and B are moving in opposite directions with equal speed (Va=-Vb)
What the fuck?
Did you just assume that the planet is stationary?

>>7974783

That believe what?

>>7974793
>Did you just assume that the planet is stationary?

No you doofus, I am dealing with rotation and revolution components sepatately. Which I can do because they are independent.

>>7974797
>>7974802

Just write down the Lagrangian for the system, it quickly becomes apparent that the generalised momentum is non-zero.

>>7974748
>Adding linear momentum when talking about angular momentum.

shiggidy.

>>7974802
>No you doofus, I am dealing with rotation and revolution components sepatately. Which I can do because they are independent.
No they aren't. Consider the case of a tidally locked planet.

>>7974828
>Consider the case of a tidally locked planet.

What about it?

>>7974803
>the generalised momentum is non-zero

Obviously it doesn't HAVE to be zero, but it CAN be zero.

>Adding linear momentum when talking about angular momentum

What linear momentum?

>>7974850
Lagrangian describes the general orbiting system, if it's generalised momentum is non-zero then the orbiting system will always have non-zero angular momentum. In fact [eqn] L = \frac { 1 } {2} \left ( \dot { r } ^2 + r^2 \dot { \phi } ^2 + I \dot { \theta } ^2 \right ) - V (r) [/eqn] Which gives us three components of momentum [math] p_r = \mu \dot { r } ~~ p_{ \phi } = \mu r^2 \dot { \phi } ~~ p_ { \theta } = \mu I \dot { \theta } [/math] Notice all three are non-zero, the only way to make them 0 is to have a planet at rest in space, which I'm not certain is physically permissible, I'm fairly sure that in a central force problem the system either enters into an orbit, or the smaller (in the gravitational problem) is ejected or collapses into the larger body, in this case it would collapse. Any way I have nothing more to say on this other than:
>[math] \textbb { YOU'RE } ~~ \textbb { WRONG } [/math]

>>7974748
>>7974747
Thank you for your drawing, but I disagree.

Unfortunately, despite you thinking otherwise, drawings are not equivalent to established equations. Unless you argue to redefine what angular momentum entails you fail to make a valid point.

Maybe you are talking about tidal forces? Which indeed is yet another concept different to angular momentum.

>>7974859

What I'm showing you is that the components can cancel out, not that the separate components are zero. So no, I'm not wrong. Please try to understand the explanation as presented instead of copypasting equations.

>>7974871

I assure you I'm using the same "established equations" you are, as I've already explained twice. Have you been reading the thread?

>>7974859
>>7974871

Here we go, an actual physical demonstration that you guys are wrong:

https://www.youtube.com/watch?v=5cRb0xvPJ2M

The planet here is the bicycle wheel. Observe how its rotation relates to its revolution about the axis of the chair. When he turns the wheel so that it is spinning clockwise, he begins to rotate counterclockwise, and vice versa. The net clockwise angular momentum remains zero, however.

>>7974231
The earth IS falling into the sun, its just going sideways so fast it constantly misses

>>7974967
Yes, but the distance between the earth and sun is decreasing over time. So the earth is literally slowly falling into the sun.

electron isn't a particle

>>7974176

noice

>>7973994
there is you retard

>>7974412

>hurr why doesn't my classical stat mech (actually chem101 shit) equation apply to quantum mech

CAN THE UNDERGRADS LEAVE ALREADY

>>7973953

>every book avoids the issue by telling me the answer

GET
OFF
MY
BOARD

friendly reminder that if you still think elementary particles and even atoms are pointlike or near-pointlike, solid 'spheres' or whatever bullshit they teach you in high school, you need to get off /sci/ and open a textbook

>>7975258

holy shit i just noticed after posting this that this thread has somehow devolved into a misinformed argument about planetary orbits and angular momentum

holy shit im done GAS THE KIKES OF /SCI/

>>7975038
reductive... yes, but also kind of the answer, and the reason why the regression into all this classical object talk has been off subject.
... best answer ...
>>7974621
... this.

Think of the orbit as a rubber band. Higher orbits are the band spinning so fast it stretches. Lowest possible orbit is kind of like the unstretched band... take all the energy you want out of it, its not getting any smaller. This is a shitty metaphor for understanding the orbiting electron as a whole, but its decent enough for generally understanding the limit that is its lowest orbit.

>>7974093
Spin.

>>7973953
Wow, it's actually shocking how under informed all the replies are here.
I thought /sci/ was a place for intellectuals

Basically, what you have right there is what is known as the "Bohr model" of an atom. It was constructed as a simplistic hypothesis for the way atoms worked, in order to understand the periodic table. In the modern world, we reject this model, I'm not even sure why it's taught in schools at all.

Generally, an electron (or any other particle's) position is defined by what we call a "wavefunction". Which is basically a probability amplitude with an imaginary component "i". In general, an electron can be thought of not as a particle, but as a "fuzz". It has a certain probability of being measured in a certain location. Perhaps right next to the proton, perhaps a thousand miles a way, perhaps on the moon.

Therefore at any given time, it is not in a specific location, but rather has a certain probability of being at a multitude of locations. When we make a measurement, the electron manifests itself in a specific location. But ONLY when it's measured

As you might have noticed, this makes absolutely no sense, but it's the current understanding. Quantum doesn't make sense. Either our universe is one kooky place, or modern physics is very misguided.

The radius at which the electron orbits in your diagram is simply the AVERAGE radius at which the electron is likely to appear. Sort of like if I flip 10 quarters 100 times, I will get on average 500 heads.

>>7975260
get a life bro xD

>>7975369
This
Bohr just said "lol I guess it doesn't make em radiation lmao"
They then used this wavefunction model and were able to derive the same expressions for angular momentum based on discrete shells that Bohr merely ad-hoc stated as fact.

You can't really think of quantum stuff classically; it's a whole new paradigm

>>7974243
thanks anon

>>7973953
The electron can only "fall" if its "orbiting", which it isn't.
If you're asking whether the electron can exist within the proton at a particular time the answer to that is surprisingly yes as the most complex calculations find a non-zero probability of this occurring.
Orbitals exist as probability density functions.

>>7974980
There are no stable orbits, you're either getting closer or drifting away. At any rate my point stands, the earth is falling into the sun

>>7975369
>I'm not even sure why it's taught in schools at all
Because that way you don't have to bother with teaching differential equations to highschoolers.

>>7973953
electron has negative charge while proton has a positive charge. they repell each other

>>7974897
Angular momentum is normal to the radius and direction of the spinning wheel. When he shifts that angular momentum 90 degrees to face upward, the direction changes too.

>The net clockwise angular momentum remains zero, however.
The entire point of the demonstration is that he CHANGED the angular momentum to face vertically when there was no vertical component previously

>>7975369
thanks, a couple of us were not misguided, but i don't blame you for skipping around. i think the problem is that quantum physics is still a fairly esoteric field, so the educated population is a fraction of what it would be on say, a computer science thread. Yet people are drawn to comment on it for reasons I only partially understand. There are people here that try in vain to apply classical physics like it was literally 1899, not realizing that classical physics fails on this scale... and that these failures are precisely what lead to the strange insights of quantum physics

>>7975565
>The entire point of the demonstration is that he CHANGED the angular momentum to face vertically when there was no vertical component previously

The entire point is that angular momentum is conserved, so that when he changed the wheel to align vertically, it forced an equal and opposite vertical component in the spinning chair such that the total remained zero.

Are van der waals forces involved?

This thread is what I'd imagine "Twitch plays pokemon" would look like if it was "Twitch learns quantum mechanics".

>>7975523
Weak bait

>>7973953
If it did, you'd know its position and its momentum. You can't.

>>7975815
You are confusing total energy vs angular momentum.

>>7975488
You literally didn't read my post carefully.

>>7975369
>the AVERAGE radius
So the semi major axis of an elliptical orbit

>>7974329

This is the only guy in this thread who knows his shit.