00:01
To predict the geometry of nitrogen or oxygen atoms, according to vsepr theory, we need to first understand how many bonds and how many unshared electrons the atoms have, and then whether there's any resonance delocalization or not.
00:22
So nitrogen has one pair of electrons, oxygen has two pairs of electrons, and in the case of the nitrogen atom, the electrons can be delocalized in an allylic resonance type of situation, which puts the electron pair on the carbon atom and leaves the nitrogen with a positive formal charge.
01:07
So when a lone pair can engage in resonance like that, it means it's in an unhybridized orbital or a p -orbital, and therefore the other three orbitals on the nitrogen are hybrid orbitals or sp2.
01:27
So this nitrogen is sp2 hybridized, and sp2 nitrogens have trigonal planar.
01:52
The oxygen has no resonance, so it's sp3, and sp3 oxygen has bent geometry.
02:10
If we look at the second example, the oxygens have two electron pairs apiece, and again we have a situation where on one of the oxygen atoms, the electrons can be delocalized through resonance and allylic, giving the oxygen a positive formal charge and the allylic carbon a negative formal charge.
03:14
So that means the oxygen with the delocalized electrons must be sp2 hybridized, but the shape or geometry is still bent because the oxygen has two attachments...