When paired with itself, nitrogen has three bonding pairs and one lone pair, so to covalently bond, it forms a triple bond.
Carbon has no lone pairs and 4 bonding pairs if it were to be covalently bonded to itself. So why does it not form quadruple bonds?
In: Chemistry
To put it very simply, electrons repel each other so they don’t like to be together in a large group. A triple bond has 3 pairs of electrons “close together” and that’s the most they’re willing to squeeze.
A quadruple bond will need 4 pairs of electrons “close together” and they go “nah that’s too much man I ain’t squeezing with so many others”.
As for the reason why the threshold is 3, u/Chromotron gave a bit more elaboration.
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