Polarity

[melissa_dis4K]

Can someone please explain why NO2 is polar? Is it just because they are the same atoms and have an unequal sharing of electrons? Do the dipole moments not cancel out? If not, is this because the molecule is bent due to the unpaired lone electron on the N atom? Thanks

[Danny Zhang 4L]

Just as you mentioned, NO2 is polar because of the bent shape of the atoms as it prevents the dipole moments from canceling out.

[Artin Allahverdian 2H]

The NO2 Lewis structure has a central N atom that is double bonded to one oxygen and single bonded to another oxygen. Since this molecule has an odd number of valence electrons (17), it is a free radical, in which N will have a lone, unpaired electron. This unpaired electron acts as a lone pair, pushing the N-O bonds away, forming a bent/angular formation. This bent formation prohibits the N-O dipoles from canceling out, thus making it a polar molecule.

[melissa_dis4K]

Thank you! Regarding the dipole moment is there only one from the N to the O without the double bond? And if so do the formal charges "give it" its partial charge. I'm basing this idea off from the worksheet posted for "ch3; Chemical Bonds"

[melissa_dis4K]

Nvm to that^ that makes sense thanks!

[Archana Biju 1G]

The bent shape of NO2- makes it a polar molecule. The dipole moments are moving away from the nitrogen in two different directions, so they don't cancel out - making it a polar molecule.