Hydrogen

[Little Bang]

Can anyone tell me what keeps the electron from spiraling into the proton of a hydrogen atom? Please.

[Jay-qu]

its not just hydrogen, all atoms exibit this, it is the energy of the electron, it moves rather fast around the nucleus.

[Qfwfq]

Actually, it isn't quite as simple as that:

it is the energy of the electron, it moves rather fast around the nucleus.

Classically, this would be an accelerated motion of the electrically charged electron, implying radiation at the expense of kinetic energy. This was a great puzzle, as soon as Rutherford's experiment had shown the mass to be mostly concentrated in a positive nucleus, suggesting the "tiny solar system" model. Solving it was one of the main things that brought on quantum mechanics!

 

Little Bang, you might like to read the history from the Thomson model of the atom to the Bohr model. Even better, start with the blackbody spectrum and the photoelectric effect. There are some great books such as Eisberg-Resnick for example.

[CraigD]

Can anyone tell me what keeps the electron from spiraling into the proton of a hydrogen atom? Please.

it is the energy of the electron, it moves rather fast around the nucleus.

Actually, it isn't quite as simple as that …

Qfwfq is, as usual, correct, and his advice for further study good. However, as I get the impression LB is looking for a quick, slightly fast-and-loose answer, I’ll attempt one:

 

Electrons don’t spiral into atomic nuclei because the distance they travel must be an even multiple of a distance related to their energy. For this reason, electons can’t smoothly spiral between “orbits”, or spiral into nuclei the way a macroscopic particle can under the influence of a magnetic or gravitational field – they have to “jump”, leading to all sorts of quantum weirdness, including that an electron has a minimum “orbital circumference”, less than which it can’t “descend”.

 

For a less fast-and-lose explanation, try the wikipedia article "Atomic orbital"

[UncleAl]

An electron in an s-orbital has an antinode at the nucleus. Leptons are unaffected by the nuclear Strong Force. The classical, Bohr, and quantum field theory n=1 orbital is the energy minimum of the system. Nuclear and electron spins paired is lower in energy than parallel spins by 1.4204 GHz.

 

Muonic heavy atoms have the muon orbiting inside the nucleus. Respect selection rules.

[Little Bang]

Thanks for the help.

[Jay-qu]

I see, what level are you at LB? I wasnt sure whether to bring in the concept of deBroglie wavelength or not because like craig said it looks like you where after a quick solution.

[sebbysteiny]

I'm sorry to be the know it all, but you are all wrong.

 

In all your models, you have correctly stated that electrons can only have a cirtain quantum of energy, and the ground state is the very lowest energy that there can be. But this is only part of the answer since, even if this were true, any -ve charge moving in the vecinity of a +ve charge will emit energy which will cause the electron to collapse into the centre of the nucleus. This was the problem Bohr was trying to answer.

 

The solution is that particles are also waves (or wave functions). The wave function is the probability that the electron can be in one place at one time.

 

When an electron is in a hydrogen atom orbit, although the electron could be anywhere in the orbit, IT'S WAVEFUNCTION IS A STANDING WAVE and so is stationary. Thus, as it doesn't actually move, no energy is ommitted and it doesn't come crashing into the proton.

[Qfwfq]

Are you sure Sebbysteiny that we are all wrong? That isn't the way we like to discuss things here, so please respect other members.

 

You might notice that most replies have been mentioning the type of things you say, but trying to keep it simple and yet perhaps saying it at least as well as you have. Before presuming to be better than everyone else, you should at least have specified that the wave function is a standing wave for eigenvalues of energy, because otherwise it isn't a standing wave at all.

[sebbysteiny]

Hey Qfwfq,

 

Your right that calling you all 'wrong' was perhaps not very diplomatic, and I did appologise in advance for it.

 

But I am sure that all the other posts didn't answer the question (I've reread them just to be sure). Although the quantum of energy (which all the other posts talked about) is important in understanding hydrogen, the real problem causing electrons to colapse into the hydrogen atom both classically and in quantum mechanics is any movement whatsoever of the electron around the hydrogen.

 

In short, the only answer to this is the stationary nature of the electron wavefunction in an (energy eigenfunction) orbital.

 

But to keep this simple for those not fluent in Quantum mechanics, the election, in wave form, is a stationary wave.

 

No other posts talked of this, with some even going so far to say that the electron moves very quickly around the atom, which must be wrong or the electron would collapse into the hydrogen and, erm, oops, I think we've gone round full circle.

[sebbysteiny]

oh, except your post, which gave a good link with the answer on it.

[CraigD]

I'm sorry to be the know it all, but you are all wrong.

 

I wasn’t wrong! I was “fast-and-loose”!

 

Besides, I put quotes around all my macroscopic analogy words. Nothing’s wrong, if you put quotes around it

;)

 

Good criticisms, though, sebbysteiny – you can’t be to picky with these dreadfull, smeared-out, quantumy [math]\Psi[/math]s!

 

- CraigD, 1983 Batchelor of Math with 8 hours of Quantum Physics (and proud of it, damnit!), mind-numb corporate IT drone since 1985.

[InfiniteNow]

I wasn’t wrong! I was “fast-and-loose”!

 

I've heard that about you CraigD. Just be sure to keep an ample supply of penecilin handy, and you'll be A-Okay... :)

[Little Bang]

Thanks to everyone. The electron being a standing wave in it's energy level makes a lot of sense and explains why it does not collapse.