Sampling #3

[David He]

When drawing nitrate ion, I assume the Lewis structure with two O=N and one O-N is more stable than a structure with one O=N and two O-N, but only the latter one is assessed as correct. Why is that?

[Charmaine Ng 2D]

While having two N=O bonds would make it more "stable" due to the lower formal charges, Nitrogen is only in period 2 of the periodic table, which means it cannot hold more than an octet. A structure with 2 N=O bonds and 1 N-O bond would mean that N is sharing 10 electrons, exceeding the octet, which it can't do. Hope this helps! :))

[Margaret Wang 2D]

If you have two double bonds and a single bond on a nitrogen, the nitrogen would then have 10 electrons. Nitrogen cannot have more than 8 electrons in its valence shell. Only Period 3 elements and down can do that.

[David He]

While having two N=O bonds would make it more "stable" due to the lower formal charges, Nitrogen is only in period 2 of the periodic table, which means it cannot hold more than an octet. A structure with 2 N=O bonds and 1 N-O bond would mean that N is sharing 10 electrons, exceeding the octet, which it can't do. Hope this helps! :))

Got it, thank you !

[David He]

If you have two double bonds and a single bond on a nitrogen, the nitrogen would then have 10 electrons. Nitrogen cannot have more than 8 electrons in its valence shell. Only Period 3 elements and down can do that.

That helps a lot, thanks!