Aromatic Nitrogen Compounds

Step 1: Structure of NH .
Ammonia has a lone pair of electrons on nitrogen atom. Step 2: Lewis base behaviour.
Due to this lone pair, NH can donate electrons to electron-deficient species (protons or metal ions). Hence, it acts as a Lewis base. Step 3: Bronsted-Lowry base behaviour.
According to Bronsted-Lowry concept, a base is a proton acceptor. NH readily accepts a proton to form ammonium ion: Conclusion:
Ammonia is basic in nature because nitrogen atom has a lone pair which can accept protons, showing both Bronsted-Lowry and Lewis base properties.