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Homework Help: Energy liberation in ionic bonding

  1. Feb 8, 2010 #1
    1. The problem statement, all variables and given/known data
    If removing electrons from atoms requires energy, and adding electrons to atoms usually liberates energy, then why is energy liberated when the ionic compound NaCl forms from the elements sodium and chlorine?

    2. Relevant equations

    3. The attempt at a solution
    My solutions manual says: "Once Na+ and Cl- have been made, the attraction between them is very strong, resulting in the liberation of energy."

    I do not understand why the strong attraction between the ions would liberate energy. My book relates it to the emission of a photon when electrons move from higher to lower energy levels, but this just confuses me even more.
  2. jcsd
  3. Feb 9, 2010 #2


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    First thing is to look up the energy needed for liberating a e from Na.
    And the energy that Cl gives after taking an electron.

    Secondly what happens when two charged ions get closer to each other? Meaning that they are attracted by a force over a distance. (HINT E=F*x)

    If ultimately they stop what happens to that energy? Where does it all go?

    Energy will be conserved no matter what!!!
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