-
Finished your HSC? Check out our University Discussion, Non-School forums or help out next year's HSC students! -
YOU can help the next generation of students in the community! Share your trial papers and notes on our Notes & Resources page
Orbiting electron (1 Viewer)
- Thread starter undalay
- Start date
me121
Premium Member
it wouldn't. it would only release energy if it moved to a lower shell, and then it would only be releasing while it was moving from one shell to another.
According to numerous sources it would.
Jacaranda.
"Rutherford knew that if the electrons were in orbit around the nucleu,s they would be accelerating. They would be expected to be emitting emr in accordance with the theories of Maxwell and, ofcourse, the atom would be unstable"
It's saying that if the orbit was circular it would EMR.
Why is this the case?
What are these "theories of maxwell"?
Jacaranda.
"Rutherford knew that if the electrons were in orbit around the nucleu,s they would be accelerating. They would be expected to be emitting emr in accordance with the theories of Maxwell and, ofcourse, the atom would be unstable"
It's saying that if the orbit was circular it would EMR.
Why is this the case?
What are these "theories of maxwell"?
tommykins
i am number -e^i*pi
- Joined
- Feb 18, 2007
- Messages
- 5,730
- Gender
- Male
- HSC
- 2008
回复: Re: Orbiting electron
Note that Rutherford's model had a few problems -
Rutherford’s model however, was not able to explain spectral lines of elements and that his model suggested radiation emission is a continuous spectrum. It also posed the problem that the electrons would be accelerating and the atom would be unstable.
Note that Rutherford's model had a few problems -
Rutherford’s model however, was not able to explain spectral lines of elements and that his model suggested radiation emission is a continuous spectrum. It also posed the problem that the electrons would be accelerating and the atom would be unstable.
I realse his model had problems.
I am just trying to understand why his model was flawed.
His model would collapse due to the electron spiraling into the nucleus, however I dont understand why the electron loses energy.
I am just trying to understand why his model was flawed.
His model would collapse due to the electron spiraling into the nucleus, however I dont understand why the electron loses energy.
Will Shakespear
mumbo magic
- Joined
- Mar 4, 2006
- Messages
- 1,186
- Gender
- Male
- HSC
- 2013
The point is that if, keyword if electrons were little balls orbiting a nucleus, then they would radiate EMR and spiral into the nucleus.
But they aren't.
And you already know why: an accelerating charge produces a changing electric field. This produces a changing magnetic field (remember in motors & generators?), which produces a changing electric field, which... etc.
That's what electromagnetic radiation (light etc.) are, changing electric & magnetic fields propagating through space at the speed of light. That's what Maxwell's laws say; they explain how EM waves are created by a changing electric or magnetic field.
Now the point is that Rutherford's model had electrons as little charged balls orbiting around a positive nucleus.
You also already know from year 11 that an object in circular (or it could be elliptical, the circle's not important) motion is undergoing constant acceleration because it's changing direction.
So since about year 9 you've been thinking of atoms as negatively charged particles (like little balls) orbiting a positively charged nucleus.
But the fact that any accelerating charge produces EMR makes this impossible; the accelerating (orbiting) electrons should just radiate EMR, and in so doing lose energy (since the energy for the EMR has to come from somewhere) and spiral down into the nucleus.
Remember before Rutherford was the "plumb pudding" model which had the electrons embedded int he nucleus. Rutherford's experiments with the alpha particles & gold foil showed that there was in fact a large nucleus in the centre. But as soon as he proposed his new model all the other physicists would have asked "are we supposed to believe that a charged electron is constantly accelerating and not radiating EMR?". His model wasn't very good, really.
That's why Bohr had to come and make a new (though still wrong) model of the atom.
But they aren't.
That's not true on both counts; only a charged object undergoing acceleration will emit EMR.
And you already know why: an accelerating charge produces a changing electric field. This produces a changing magnetic field (remember in motors & generators?), which produces a changing electric field, which... etc.
That's what electromagnetic radiation (light etc.) are, changing electric & magnetic fields propagating through space at the speed of light. That's what Maxwell's laws say; they explain how EM waves are created by a changing electric or magnetic field.
Now the point is that Rutherford's model had electrons as little charged balls orbiting around a positive nucleus.
You also already know from year 11 that an object in circular (or it could be elliptical, the circle's not important) motion is undergoing constant acceleration because it's changing direction.
So since about year 9 you've been thinking of atoms as negatively charged particles (like little balls) orbiting a positively charged nucleus.
But the fact that any accelerating charge produces EMR makes this impossible; the accelerating (orbiting) electrons should just radiate EMR, and in so doing lose energy (since the energy for the EMR has to come from somewhere) and spiral down into the nucleus.
Remember before Rutherford was the "plumb pudding" model which had the electrons embedded int he nucleus. Rutherford's experiments with the alpha particles & gold foil showed that there was in fact a large nucleus in the centre. But as soon as he proposed his new model all the other physicists would have asked "are we supposed to believe that a charged electron is constantly accelerating and not radiating EMR?". His model wasn't very good, really.
That's why Bohr had to come and make a new (though still wrong) model of the atom.
Last edited:
Will Shakespear
mumbo magic
- Joined
- Mar 4, 2006
- Messages
- 1,186
- Gender
- Male
- HSC
- 2013
James Maxell wrote down 4 equations that explain what EMR is and how it's created.
He was to electromagnetism what Newton was to mechanics. Underrated in the syllabus, but most of his equations are integrals which wouldn't mean much to you guys at this stage so you don't see them.
In terms of what the atom actually is... well, the electrons are actually waves, and when in orbit around a nucleus, the circumfrence of their orbit is an integer multiple of their wavelength, so they form a standing (i.e. essentially not moving) wave. The consequence is that they aren't just particles and you can't see the exact position of an electron as it orbits, only the probability that it's in one place or another.
The point is that knowing about Maxwell's equations and EMR immediately tells you that the "electrons orbiting as little negatively charged particles" model is impossible, since the electrons would just spiral into the nucleus and there'd be no atoms. But atoms exist!
He was to electromagnetism what Newton was to mechanics. Underrated in the syllabus, but most of his equations are integrals which wouldn't mean much to you guys at this stage so you don't see them.
In terms of what the atom actually is... well, the electrons are actually waves, and when in orbit around a nucleus, the circumfrence of their orbit is an integer multiple of their wavelength, so they form a standing (i.e. essentially not moving) wave. The consequence is that they aren't just particles and you can't see the exact position of an electron as it orbits, only the probability that it's in one place or another.
The point is that knowing about Maxwell's equations and EMR immediately tells you that the "electrons orbiting as little negatively charged particles" model is impossible, since the electrons would just spiral into the nucleus and there'd be no atoms. But atoms exist!
Will Shakespear already answered it, but just to make it clearer:
When charged speicies accelerate, they emit EMR. If electrons are "orbiting" a nuclei, it is accelerating, hence it will emit EMR. If it emit EMR, it will lose energy.
When charged speicies accelerate, they emit EMR. If electrons are "orbiting" a nuclei, it is accelerating, hence it will emit EMR. If it emit EMR, it will lose energy.
