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Homework Help: Radial wave function

  1. Jan 27, 2007 #1
    "(a) Use the radial wave function for the 3p orbital of a hydrogen atom (see Table 15.2) to calculate the value of r for which a node exists.
    (b) Find the values of r for which nodes exist for the 3s wave function of the hydrogen atom."

    For part a, I looked at Table 15.2 and found the equation R3p = 4/(81*square root of 6) * (Z/a0)^(3/2) * (6*sigma - sigma2) exp (-sigma/3)
    where sigma = Z*r/a0 and a0 = 0.529 * 10^-10m

    1. Does exp (-sigma/3) mean raise (6*sigma - sigma2) to the (-sigma/3) power?

    2. What exactly does the value of R3p represent?

    3. To solve this problem do I set R3p to 0 and solve for r?
  2. jcsd
  3. Jan 28, 2007 #2


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    First, if you need help with LaTeX, try https://www.physicsforums.com/showthread.php?t=8997&page=52".

    No. It means [tex] e^{-\sigma/3}[/tex]. So you'd have [tex] (6\sigma - \sigma^2)(e^{-\sigma/3})[/tex]

    While solving Schroedinger's equation with various approximations for the Hydrogen atom, you would have probably used the separation of variables technique, to separate the equation into a radial part, and an angular part.

    R3p is a solution to the radial wave equation, for certain values of n,l which signify the 3p orbital.

    To find the nodes, you need to find where the probability of finding the electron is zero. So, how would you solve it? Can you take it from here?
    Last edited by a moderator: Apr 22, 2017
  4. Jan 28, 2007 #3


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    I'm not sure if you're trying to make him think about this in a broader picture, but a radial node is simply where the radial function is equal to 0, as the OP said. It is true that there is 0 probability of finding the electron at this radius, but I feel that is additional information.
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