Question

Explain why NH$_3$ is basic in nature.

Hint:

The basic nature of NH$_3$ is due to the lone pair of nitrogen, which readily accepts protons to form NH$_4^+$.

Answer 1

Step 1: Structure of NH$_3$.
Ammonia has a lone pair of electrons on nitrogen atom. Step 2: Lewis base behaviour.
Due to this lone pair, NH$_3$ 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$_3$ readily accepts a proton to form ammonium ion: \[ NH_3 + H^+ \;\longrightarrow\; NH_4^+ \] 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.