Why is the s state spherically symmetric?

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Discussion Overview

The discussion revolves around the nature of the s state in quantum mechanics, particularly its spherical symmetry as derived from the Schrödinger equation for the hydrogen atom. Participants explore the implications of quantum numbers, specifically the principal quantum number and angular momentum, in defining the shape of s orbitals.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant notes that for the s state with quantum number ##\ell=0##, the shape is described as a "completely flattened ellipse" that goes through the nucleus, leading to confusion about its spherical symmetry.
  • Another participant questions the reference that describes the s state as an ellipse and affirms that s orbitals are indeed spherically symmetric.
  • A later reply corrects the initial reference, indicating that the document states the flattened ellipse description but also acknowledges that s orbitals are spherical.
  • One participant mentions that the elliptical orbits are remnants of the Bohr-Sommerfeld model, contrasting with the spherical representation of s orbitals in modern quantum mechanics.
  • Another participant explains that classically, an orbit with ##l=0## corresponds to the electron falling through the nucleus, while quantum mechanically, this orientation becomes undetermined.
  • It is stated that quantum mechanically, ##l=0## implies that the wave function and probability distribution for the particle's position is spherically symmetric.

Areas of Agreement / Disagreement

Participants express confusion regarding the transition from the description of the s state as an ellipse to its spherical symmetry. While some affirm the spherical nature of s orbitals, there is no consensus on the interpretation of the initial elliptical description.

Contextual Notes

The discussion highlights potential limitations in the clarity of the reference material and the historical context of orbital models, which may affect participants' understanding of the current quantum mechanical framework.

KFC
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Hi there,
I am reading something about quantum numbers, there the author introduce the quantum number by solving Schrödinger equation for Hydrogen atom. It gives me an example when the principal quantum number n=4, there are four different sub-level ##s, p, d, f##. It also depicts the sublevel for them. It is said that for s state which ##\ell=0##, the shape is something like a completely flattened ellipse going through the nucleus. But since ##\ell=0##, there is no angular momentum, the electron is not "orbiting" anything; hence, it must be totally radially so s state is spherically symmetric.

It is quite confusing for me. Since it is said at the beginning it is flatten ellipse but later becomes spherically symmetric.

reference: http://web.pdx.edu/~pmoeck/lectures/312/chapter 7 part 3.doc
page 3 and page 8
 
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KFC said:
It is said that for s state which ##\ell=0##, the shape is something like a completely flattened ellipse going through the nucleus.
Where does your reference say that?
KFC said:
But since ##\ell=0##, there is no angular momentum, the electron is not "orbiting" anything; hence, it must be totally radially so s state is spherically symmetric.
Right. s orbitals are spherically symmetric.
 
Doc Al said:
Where does your reference say that?

Right. s orbitals are spherically symmetric.

Sorry that I give the wrong reference. I just get it corrected. And in the document given by the link, in page 3, note below the caption of FIGURE 7.3, it is said that "for l=0 we have a completely flattened ellipse that goes through the nucleus, this will be later called an s state."
 
Those elliptical orbits are remnants of the Bohr-Sommerfeld model of the atom. (Old stuff!) Note the diagram on page 20 of your reference, which shows the s orbitals as spherical.
 
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Thanks a lot.
 
KFC said:
Hi there,
I am reading something about quantum numbers, there the author introduce the quantum number by solving Schrödinger equation for Hydrogen atom. It gives me an example when the principal quantum number n=4, there are four different sub-level ##s, p, d, f##. It also depicts the sublevel for them. It is said that for s state which ##\ell=0##, the shape is something like a completely flattened ellipse going through the nucleus. But since ##\ell=0##, there is no angular momentum, the electron is not "orbiting" anything; hence, it must be totally radially so s state is spherically symmetric.

It is quite confusing for me. Since it is said at the beginning it is flatten ellipse but later becomes spherically symmetric.

reference: http://web.pdx.edu/~pmoeck/lectures/312/chapter 7 part 3.doc
page 3 and page 8
According to my prejudices, I always warn against physics manuscripts written with Word. This one cements my prejudice. SCNR.
 
Classically, an orbit with l=0 corresponds to the electron falling straight on or through the nucleus. Quantum mechanically, the orientation of this line becomes completely undetermined.
 
Quantum mechanically ##l=0## means that your wave function and thus the probability distribution for the particle's position (and momentum) is spherically symmetric.
 

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