* Electronegativity: Nitrogen (N) is more electronegative than hydrogen (H). This means nitrogen attracts the shared electrons in the N-H bonds more strongly.

* Molecular Geometry: The ammonia molecule has a trigonal pyramidal shape. The lone pair of electrons on the nitrogen atom creates an uneven distribution of electron density, making one side of the molecule slightly negative and the other side slightly positive.

* Dipole Moment: The unequal sharing of electrons and the molecular shape result in a net dipole moment, indicating a permanent separation of charge within the molecule.

Therefore, the polar covalent bonds and the overall molecular shape make NH₃ a polar molecule.