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Thread: polar or nonpolar

  1. #1 polar or nonpolar 
    Moderator Moderator AlexP's Avatar
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    Is there a point where the electronegativity difference between two atoms is so small that the bond is not considered polar? For example, in methane, the molecule is nonpolar due to its symmetry, but it still has polar bonds. But my question is, are they polar enough to be considered polar, when the EN difference is only .35?


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  3. #2  
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    Polarity is all relative.
    Since in methane is non-polar because each of the single C-H bonds is polar, but the four of them cancel each other out.
    You can't just look at a single bond, it is the molecule as a whole.


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    Forum Freshman César's Avatar
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    I would say that it is possible to talk about the polarity of a single bond in a particular molecule as the polarity of a particular bond would be the result of the electronegativity of the atoms implied and the influence of the other bonds these atoms are participating in.

    Is there a point where the electronegativity difference between two atoms is so small that the bond is not considered polar?
    Yes, it is called a pure covalent bond. It can be found in bonds between atoms of the same element: hydrogen, oxygen, etc. In general a polarity bellow 0.2 is considered enough to describe a bond as pure covalent.

    Best regards,

    César
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