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Water molecule?

  1. Jul 17, 2005 #1
    what's the bonding and forces that exist in a water molecule?is it ionic bond and van der waals force?
     
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  3. Jul 17, 2005 #2

    Gokul43201

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  4. Jul 18, 2005 #3
    Hydrogen bonds are not a kind of "dipole-dipole interaction caused by the polar nature" of the O-H bonds. Hydrogen bonds are of quantum origin, caused by superposition of hidrogen into two molecules at once.

    H-O·······H-O-H (quantum state 1)

    H-O-H·······O-H (quantum state 2)

    H-O·····H·····O-H (quantum superposition)
     
  5. Jul 18, 2005 #4

    Gokul43201

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    Thanks for the clarification. I shall look into it now. Meanwhile, if you have some references to suggest, I would be grateful.

    Nevertheless, MD simulations of hydrogen bonds (in water) as essentially classical electrostatic interactions have proven to be pretty accurate (Sciortino et al, Luzar & Chandler). So, I believe the classical view is not a terrible approximation.
     
    Last edited: Jul 18, 2005
  6. Jul 20, 2005 #5
    would read like
    ----------H
    -----------\
    H-O·····H·····O--H

    In the EV approach, one can study the different contributions of diferent wavefunctions to bond. Yes, the most important contribution (more than 90% energy) are ionic ones. Therefore you was right on the energetic ionic character of bond. This is the reason of sucess of classical siimulations. However, note that is not completely a classical picture, because one may study two posibilities of ionic breaking, it possesses some degree of orientational preference (pure electrostatic attraction is spheric), and can be shown to have some of the characteristics of a covalent bond.

    Reference:
    I used volume 2 of Diaz Peña on Química física. I think that many textboks on physical chemistry or quantum chemistry can help to you.

    I also find this
    http://www.sciencedaily.com/releases/1999/01/990121074852.htm

    Note: I verify some online resources (e.g. Wikipedia) and many do the same mistake.

    "hydrogen bond is a type of attractive intermolecular force"

    This is not true because there is also intramolecular hidrogen bonds.
     
    Last edited: Jul 20, 2005
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