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edexcel IAL - intermolecular forces and London forces watch

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    im quite confused with those intermolecular forces..
    among (1) permanent dipole-permanent dipole, (2) permanent dipole-induced dipole, (3) instantaneous dipole-induced dipole, (4) instantaneous dipole - instantaneous dipole interactions,

    Q1)
    which several of them actually exist?

    In my local secondary school public exam, only (1), (2), (3) are mentioned,
    but when i look into my IAL textbook as a private candidate, it mentions (1), (3), (4)

    i think (4) does really make sense.. if one molecule has a dipole instantaneously, it could induce another molecule to have a dipole.. so there should not be (4), but only (3) when molecules in a substance or mixture do not have permanent dipole

    Q2)
    the IAL textbook also says that wan der Waals forces equal London forces, and include (3) and (4), where(4) could be specifically called London dispersion force

    but in my local public exam syllabus , Van der Waals' forces include all intermolecular forces, i.e. (1), (2), (3), since we dont have (4) mentioned in the textbook or syllabus

    so.. which one of them are actually London forces?
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    The chance of (4) happening is vanishingly small and should be ignored.
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    so, could any one please tell me which few of them are London forces? :s
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    (Original post by kesun)
    so, could any one please tell me which few of them are London forces? :s
    London dispersion forces are instantaneous dipole-induced dipole interactions, although this is commonly just expressed as induced dipole-dipole interactions.
 
 
 
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