Here's why:
* Covalent bond: Both nitrogen and oxygen are nonmetals, and they share electrons to form a covalent bond.
* Polar: The electronegativity difference between nitrogen and oxygen is small (0.1), but it's enough to create a slight imbalance in electron sharing. The oxygen atom will attract the shared electrons more strongly, resulting in a partial negative charge (δ-) on the oxygen atom and a partial positive charge (δ+) on the nitrogen atom.
In summary, while the electronegativity difference is small, it's enough to create a polar covalent bond with a slight separation of charge.
