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    I don't understand about electronegativity and finding difference between VDW and dipole-dipole forces
    I tried googling but all the results are "if electronegativity is below xxx above xxx then it is polar/non polar
    But how do you know the electronegativity?
    EG
    QUestion
    Which of the following substances only show VDW(Only showing 2 for clarity, imagine there are more choices in order to remove the "process of elimination")
    CH4
    NH3

    I know (just directly) that NH3 is dipole-dipole but how do I know if CH4 is dipole dipole or just VDW

    Any help is appreciated thanks
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    (Original post by SenseiChen)
    I don't understand about electronegativity and finding difference between VDW and dipole-dipole forces
    I tried googling but all the results are "if electronegativity is below xxx above xxx then it is polar/non polar
    But how do you know the electronegativity?
    EG
    QUestion
    Which of the following substances only show VDW(Only showing 2 for clarity, imagine there are more choices in order to remove the "process of elimination"
    CH4
    NH3

    I know (just directly) that NH3 is dipole-dipole but how do I know if CH4 is dipole dipole or just VDW

    Any help is appreciated thanks
    You need to learn the shapes produced by molecules in the process of minimising repulsion between electron pairs.

    Symmetrical molecules cancel out dipoles and become non-polar overall.
    linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral if the dipoles are all the same.

    All other shapes are polar.
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    (Original post by SenseiChen)
    I don't understand about electronegativity and finding difference between VDW and dipole-dipole forces
    I tried googling but all the results are "if electronegativity is below xxx above xxx then it is polar/non polar
    But how do you know the electronegativity?
    EG
    QUestion
    Which of the following substances only show VDW(Only showing 2 for clarity, imagine there are more choices in order to remove the "process of elimination"
    CH4
    NH3

    I know (just directly) that NH3 is dipole-dipole but how do I know if CH4 is dipole dipole or just VDW

    Any help is appreciated thanks
    Hey, I think NH3 is actually hydrogen bonding as it takes places between hydrogen and the highly electronegative elements( Oxygen, Fluorine and nitrogen), i do know that CH4 is van der waals because it has no permanent dipoles that are oppositely charged. Hope that helps
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    (Original post by charco)
    You need to learn the shapes produced by molecules in the process of minimising repulsion between electron pairs.

    Symmetrical molecules cancel out dipoles and become non-polar overall.
    linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral if the dipoles are all the same.

    All other shapes are polar.
    To summarise all non symmetrical molecules are dipole-dipole?
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    (Original post by SenseiChen)
    To summarise all non symmetrical molecules are dipole-dipole?
    yes, and don't forget resonance/delocalisation.
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    (Original post by charco)
    yes, and don't forget resonance/delocalisation.
    Thanks
 
 
 
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