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Q & A: visualizing electron waves in atoms

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Most recent answer: 02/02/2011
Q:
Hi I am reading some popular quantum physics books and have a question about how electrons are visualised (and knowing this is dodgy ground). Some books show an electron in an atom as a standing wave in orbit around the nucleus and use the standing wave idea to illustrate quantum jumps in terms of allowed wavelengths. Other books use the idea of an isolated wave packet made up of multiple wavelengths. Multiple wavelengths could not be used in the standing wave orbit approach. Is the difference in representation simply that both are equally "wrong"? Thanks
- Simon (age 42)
Turkey
A:
Simon-

You're right. They're both equally wrong. About the only way that those pictures of either little wave packets or complete wave-like orbits could even come close to representing the electron state would be if the electron is in some superposition of a large number of high-energy energy eigenstates. That gives enough flexibility to make nearly localized states in 3-D (for the little packets) or in 2-D (for the orbits).  Such states are very close to not being bound. The 2-D orbit pictures would involve states with a fixed absolute value of the angular momentum around some axis, but with a range of values for the other quantum numbers. The packets have a spread in that quantum number also. The electrons in the usual low-energy states that are occupied in atoms are highly spread out.

Mike W.

(published on 02/02/2011)

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