The bond between N and H in amines is a polar bond due to the difference in electronegativity between nitrogen (N) and hydrogen (H).

Here's why:

* Electronegativity: Nitrogen is more electronegative than hydrogen. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.

* Electron Distribution: The higher electronegativity of nitrogen causes the shared electrons in the N-H bond to be pulled closer to the nitrogen atom. This creates a partial negative charge (δ-) on the nitrogen atom and a partial positive charge (δ+) on the hydrogen atom.

* Polarity: This uneven distribution of electron density results in a polar covalent bond. The bond has a dipole moment, with the positive end pointing towards the hydrogen atom and the negative end pointing towards the nitrogen atom.

This polarity of the N-H bond in amines contributes to the overall properties of amines, such as their ability to act as bases and form hydrogen bonds.