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When one say that the electron goes from 1 orbit , say 2S, to another (higher) orbital, say 5P, it mean that the electron is excited to that orbit by some mean. In doing so it also it will also cross the nodes of 2P etc. But doing so does the electron actually cross the node or what? Cause doing so the, there is probability, although very less, of finding electron in node for a very short time.

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    $\begingroup$ My understanding is that the electron instantly jumps from one energy level to another. Since it isn't a discrete object the idea of it moving through space across the node is meaningless. However, I will wait for someone else to provide a more detailed answer than me. $\endgroup$ – bon May 30 '15 at 17:09
  • $\begingroup$ @bon, one better says that electrons "jump" from one quantum state to another. Besides, an electron transition does not happen instantly, but rather in a course of a few nanoseconds (or less). $\endgroup$ – Wildcat May 30 '15 at 18:00
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    $\begingroup$ @Wildcat I suspect electron excitation must take at most a few hundred femtoseconds in order to explain, for example, ultrafast photoexcited electron transfer in systems with fullerenes. The duration of an electronic transition is probably given by a number close to the inverse of the absorbed photon frequency (e.g., $\mathrm{400\ nm \rightarrow 750\ THz \rightarrow 1.333\ fs}$). $\endgroup$ – Nicolau Saker Neto May 30 '15 at 18:13
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    $\begingroup$ @NicolauSakerNeto, picture it in the following way. Say, for the case of spontaneous emission, the emitted light of some frequency can be thought of as a result of electron "oscillations" at this frequency. To produce the wave an electron "oscillates" back and forth many times (say, few million times at average) which is why transition time is nowhere close to the inverse of the frequency. $\endgroup$ – Wildcat May 30 '15 at 19:20
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    $\begingroup$ with regard to the question I found this very helpful: antoine.frostburg.edu/chem/senese/101/electrons/faq/… $\endgroup$ – Jan Jensen May 31 '15 at 8:57
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When one say that the electron goes from 1 orbit , say 2S, to another (higher) orbital, say 5P, it mean that the electron is excited to that orbit by some mean.

First off, there are no orbits. Electrons do not circle the nucleus. Rather they are in particular quantum states, or, in other words, they "occupy" particular orbitals. Note that when we say that an electron "occupies" an orbital, we just mean that it is in a particular quantum state. There is no spatial occupation in a classical sense out there: eletrons do not "sit" or "circle" anywhere, they are just in their quanatum states.

Consequently, when we say that electron "goes" from one orbital to another, what we actually mean is that the quantum state of the electrons changes. And again, an electron transition is not a mechanical motion, thus, electrons upon transitions do not "move" through nodes.

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  • $\begingroup$ Can you please explain what this image says en.wikipedia.org/wiki/Electron#/media/… $\endgroup$ – Chinmay Chandak May 31 '15 at 6:00
  • $\begingroup$ @ChinmayChandak, different quantum states of an electron feature (among other things) different patterns of spatial probabilities (probabilities of finding the electron in different regions of space). Upon electron transition this probability pattern changes from one which correspondes to the initial quantum state to one which corresponds to the final quantum state. $\endgroup$ – Wildcat May 31 '15 at 9:35

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