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Surface tension forces

  1. Sep 7, 2007 #1
    i'm looking into the physics behind surface tension, and am a little confused about the intermolecular forces that act on the liquid. I understand that hydrogen bonding occurs because of the positive and negative atoms in a water molecule. However, i am unsure of exactly what other forces occur. i keep coming across things like intermolecular, van der waals, london dispersion and cohesive. What are all the forces exactly? thanks
  2. jcsd
  3. Sep 10, 2007 #2
    From what i know:

    Hydrogen bonding : Occurs between Hydrogen atoms and atoms of oxygen, fluorine and nitrogen. It is the strongest out of the three intermolecular forces listed here. Hydrogen bonds pull the molecules of water outwards, resulting in water being less dense when frozen than when in a liquid state.

    Dipole-dipole : This occurs between molecules with an uneven charge distrubtion. The opposite charges attract one another creating a bond.

    Van Der Waals : This is an induced dipole-dipole attraction which occurs when the distribution of electrons in an atom become unevenly spread, resulting in a uneven charge distribution. This results in neighboring atoms electrons to fluctuate. The uneven distribution of charge allows the opposite charges to attract. This is the weakest of the three.

    Van Der Waals occurs in all substances. Dipole-dipole occurs only in polar molecules. Hydrogen Bonding occurs only between hydrogen atoms in a molecule and the atoms of either oxygen, nitrogen or fluorine in another.
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