Question

Is hyponitrite polar or nonpolar?

Answer 1

...Both (but not at the same time).

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The hyponitrite ion, `"N"_2"O"_2^(2-)`, has a trans major resonance structure that looks like this:

But it also has a cis major resonance structure that looks like this:

Either way, oxygen is more electronegative than nitrogen, so there are two dipole moment vectors whose components will add to form a net dipole.

• Here, the two dipole moment vectors cancel out in the horizontal direction (along the `"N"="N"` bond), but add in the vertical direction (perpendicular to the `"N"="N"` bond), giving a nonzero net dipole.

  

• Here, the two dipole moment vectors cancel out in both the horizontal (along the `"N"="N"` bond) and vertical (perpendicular to the `"N"="N"` bond) directions, giving no net dipole.

  

Therefore, the cis isomer is polar, and the trans isomer is nonpolar.