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Can ions have dipoles?

  1. Nov 27, 2005 #1
    Can ions have dipoles?

    ive had a really long argument with a teacher who says ions cant have dipoles because ions are not compounds....

    can anyone clarify this for me please
     
  2. jcsd
  3. Nov 27, 2005 #2
    Ions can certainly have dipoles, since ions are not restricted to being monoatomic like the chloride anion or the lithium cation.

    Consider the acetate ion (see attached figure). The acetate ion consists of a methyl group directly connected to a carboxylate group.

    An oxygen atom in the carboxylate group contains an extra electron, which causes the carboxylate group to be negatively charged. Because the extra electron is localized on the carboxylate group, an electric gradient across the molecules is set up; which causes the dipole moment.

    Perhaps your teacher, for the sake of the class, wanted to emphasize that the ions you will be dealing with ions which are strictly monoatomic; and because of spherical symmetry, wouldn't have a dipole moment. :smile:
     

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  4. Nov 27, 2005 #3
    awsome
    i think shes just stupid....at one point she said NF3 had no dipole. and i specifically asked her why NO3- wouldnt have one and she gave me that BS reson (ions arent compounds...)
    thanks alot
     
    Last edited: Nov 27, 2005
  5. Nov 27, 2005 #4

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    Even monoatomic ions can have transient dipoles.
     
  6. Nov 27, 2005 #5
    really?

    never heard of those....in AP Chemistry in HS
     
  7. Nov 27, 2005 #6
    Never? I took AP Chemistry last year; transient dipoles are simply temporary imbalances of charge, which can exist among molecules or separate atoms.

    Recall this from the "(London) dispersion forces" section in the chapter on intermolecular forces. (though, I don't know what textbook you are using)

    Remind her of that common term, "polyatomic ions" :wink:
     
    Last edited: Nov 27, 2005
  8. Nov 28, 2005 #7
    ha

    im using Zumdahl, which my tacher warships like a god.

    thanks again
     
  9. Nov 28, 2005 #8

    maybe you havent learned about it yet...?

    i took that course last year and learned aboot them
     
  10. Nov 28, 2005 #9
    well if its what i think your talking about, we call them tomporary dipoles or induced dipoles

    :tongue:
     
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