What Quantum Numbers Define a Hydrogen Atom's State with No Angular Dependence?

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Homework Help Overview

The discussion centers around identifying the quantum numbers that define the state of a hydrogen atom, specifically focusing on a wavefunction that exhibits no angular dependence. Participants explore the implications of this condition on the angular momentum quantum numbers.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the quantum numbers n, l, and m, noting their roles in defining the energy level and angular momentum. There is a focus on the spherical harmonics and the specific case of the wavefunction lacking angular dependence, leading to the conclusion that l and m must be zero. Some participants express uncertainty regarding the terminology used, particularly the phrase "spatial part" of the wavefunction.

Discussion Status

The discussion is active, with participants confirming each other's reasoning about the quantum numbers. There is acknowledgment of potential nuances regarding the definition of n in relation to angular momentum, indicating a productive exploration of the topic without reaching a definitive consensus.

Contextual Notes

Participants note that the exercise may not require consideration of spin, which could influence the interpretation of the quantum numbers involved. There is also a mention of the gross structure of hydrogen, which typically excludes spin effects.

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Homework Statement



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What quantum numbers are used to define state of hydrogen? The wavefunction has no angular dependence. Find the values of all the angular momentum quantum numbers for the electron.

Homework Equations


The Attempt at a Solution



The numbers are n, l and m.

n: Energy level
l(l+1): Eigenvalues of total orbital angular momentum
m: z component of orbital angular momentum

The complete wavefunction is given by: ##\psi = u_n^l Y_l^m##.

Thus the only spherical harmonic that doesn't have angular dependence is ##Y_0^0 = \sqrt{\frac{1}{4\pi}}##.

Thus the wavefunctions are ##\sqrt{\frac{1}{4\pi}}u_n^0##.

Thus n = any integer, l = 0, m = 0.

I'm slightly bothered by the term 'spatial part' of the wavefunction.
 
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"Spatial part" as opposed to "spin part". The exercise probably doesn't want you to worry about spin (my guess -- change that if you just finished a chapter on spin...)
 
BvU said:
"Spatial part" as opposed to "spin part". The exercise probably doesn't want you to worry about spin (my guess -- change that if you just finished a chapter on spin...)

We learn about the gross structure of Hydrogen, which ignores spin as the Hamiltonian is the KE of the nucleus and electron, and the potential energy.

Are my answers right then?
 
I would say yes. A nitpicker would argue n isn't a quantum number for angular momentum. In that case the answer is: l = 0 and m = 0
 
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