Nitrogen can also bond with other
three atoms because of its outer shell (valence shell) that has three electrons.
This is the reason why organic molecules can be so large because of this
bonding. Suppose you have a compound of NH3. You know that hydrogen can only
share 1 electron because 7 of its electrons are filled. Also, in nitrogen, it can
only share 3 electrons because 5 of it are already filled. That is why nitrogen
needs three hydrogen to form NH3.