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Q & A: electrons around protons

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Most recent answer: 10/22/2007
Q:
OK, thank you for your help. I get it now. I know my next question is not related to light, but what is the speed of electrons orbiting protons?
- Bill (age 16)
Vancouver, B.C., Canada
A:
Bill- that question doesn't have a definite answer, even if we were to specify that we mean single protons (hydrogen atoms) and electrons in the state of lowest energy, as they usually are found. The reason is that on a small scale objects do not actually have positions and velocities.  they exist as quantum states, which are spread out in position, like clouds, and also have a spread of velocities. They aren't really 'orbiting' at all, despite the toy pictures of fictional atoms which you often see.
Still, we can talk about the typical range of velocities of the electrons in a hydrogen atom. Roughly speaking, the typical speed is 2x108 cm/sec, a little less than 1% of the speed of light.

Mike W.

(published on 10/22/2007)

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