Physics Help Forum Group 1 Metals

 Atomic and Solid State Physics Atomic and Solid State Physics Help Forum

 Oct 22nd 2009, 01:16 PM #1 Junior Member   Join Date: Oct 2009 Posts: 1 Group 1 Metals I know this question is fairly easy, but I'm completely flabbergasted by it. I'm sure it has to do with the Ionization energy, I'm just really confused by the negative values for the binding energies. Anyway here is the question. The absolute value of the binding energy of the outermost electron in the alkali atoms decreases with atomic size such as; Eb(Li)=-5.395eV Eb(Na)=-5.142eV Eb(K)=-4.34eV Eb(Rb)=-4.17eV Eb(Cs)=-3.90Ev (Eb just stands for binding energy) Provide an explanation for this series. (I figure that has to do with the ionization energy[This has to do with ionization energy, given the group1 metals has only one valence electron, the binding energy of that outermost electron must be equal to the ionization energy. I just don't know why the binding energy was given to me as a negative value.]) Describe how you could measure the binding energies experimentally and describe an ansatz to calculate them. (cant think of anything for this part) Last edited by Arcane; Oct 22nd 2009 at 01:21 PM. Reason: New information
 Oct 23rd 2009, 03:49 AM #2 Physics Team   Join Date: Feb 2009 Posts: 1,425 Look up the derivation of the total energy for the Hydrogen atom. The binding energy turns out to be -ve indicating a bound state. This is why we have to supply energy to ionize the atom.

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