Quantum mechanics - probability of finding an electron

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Discussion Overview

The discussion revolves around calculating the probability of finding an electron in various volumes around the nucleus of a hydrogen atom, using its wave function. The scope includes homework-related queries and mathematical reasoning regarding quantum mechanics concepts.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • Post 1 presents the wave function for an electron in the ground state of hydrogen and poses three specific probability questions regarding different volumes and distances from the nucleus.
  • Post 2 states that the probability of finding the electron in a volume element is given by the square of the wave function multiplied by the volume element, suggesting integration for the sphere's probability.
  • Post 3 expresses uncertainty about integration, mentioning that the teacher indicated it might not be necessary for the problem.
  • Post 4 also questions the need for integration, stating a method of evaluating the probability by substituting r=0 in the wave function, squaring it, and multiplying by a small volume, while seeking confirmation on this approach.

Areas of Agreement / Disagreement

Participants show uncertainty about the necessity of integration for solving the problem, with some suggesting it is needed while others believe it is not. There is no consensus on the correct approach to take.

Contextual Notes

Participants express limitations in their understanding of integration and its application in this context, with some relying on specific values and assumptions about the wave function.

Who May Find This Useful

Students studying quantum mechanics, particularly those working on problems related to wave functions and probability distributions in atomic physics.

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Homework Statement


The wave function of an electron in the lowest (that is, ground) state of the hydrogen atom is
\psi(r) = (\frac{1}{\pi a_0^3})^{1/2} exp(-\frac{r}{a_0})
a_0 = 0.529 \times 10^{-10} m
(a) What is the probability of finding the electron inside a sphere of volume 1.0 pm3, centered at the nucleus (1pm = 10-12m)?
(b) What is the probability of finding the electron in a volume of 1.0 pm3 at a distance of 52.9 pm from the nucleus, in a fixed but arbitrary direction?
(c) What is the probability of finding the electron in a spherical shell of 1.0 pm thickness, at a distance of 52.9 pm from the nucleus?

Homework Equations


|\psi(r)|^2

The Attempt at a Solution


(a) volume = 1.0 \times 10^{-36} m^3
using r = 0, the probability is 1.137 * 10-16.
(b), (c) What equations should I use here?
R^2|\psi(r)|^2 ?
4\pi r^2 R^2|\psi(r)|^2 ?
but I don't have R...
 
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a) The probability of finding the electron with a real wave function \psi in a small volume element d\tau is |\psi|^2 d\tau. To obtain the probability of finding the electron inside the sphere, you integrate. Can you take it from here?
 
I don't know how to integrate it, but my teacher said although the correct way is to integrate, we won't need to integrate...
 
I would like some help on the same problem too... I'm not sure if I'm doing it correctly. The probability of finding the electron is given by (\Psi)^{2}dV... Though I know how to integrate I don't think its necesssary (we're not supposed to use integration). I am solving it by setting r=0 in the wave function, then squaring it, and multiplying it by dV, which I am taking to be 1.0 pm^3. I'm not sure if this is the correct way of doing it. Any help appreciated.
 

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