Why nitrogen *often* forms three bonds:
* Electronic Configuration: Nitrogen has 5 electrons in its outer shell (2s² 2p³). It needs 3 more electrons to achieve a stable octet configuration.
* Sharing Electrons: Nitrogen achieves this by sharing its three valence electrons with other atoms, forming three covalent bonds.
* Common Examples: Ammonia (NH₃), Nitrite (NO₂⁻), and Nitrous Oxide (N₂O) are examples of molecules with nitrogen forming three bonds.
Why nitrogen *can* form four bonds:
* Formation of Cations: Nitrogen can lose its three valence electrons to form a N³⁺ cation. This cation then can form four bonds with four other atoms.
* Coordinate Covalent Bonds: In some cases, nitrogen can donate a lone pair of electrons to form a coordinate covalent bond, resulting in a total of four bonds. An example is the ammonium ion (NH₄⁺), where nitrogen forms four bonds with hydrogen atoms.
Key Point: Nitrogen's tendency to form three bonds is more common, but its ability to form four bonds in specific situations makes it a versatile element in various chemical compounds.
