What is the chemical formula for ammonia?

The story behind the answer

NH3 is ammonia because one nitrogen (N) atom typically forms three bonds, each to a hydrogen (H) atom, giving NH3. Its shape is trigonal pyramidal due to a lone pair on nitrogen. By contrast, CH4 is methane (carbon makes four bonds), CO2 is carbon dioxide (one carbon and two oxygens), and NO3 usually refers to the nitrate ion (NO3−), not neutral ammonia.

Ammonia is a weak base that accepts a proton to form ammonium (NH4+), has a sharp, pungent smell, and is crucial for fertilizers—mass-produced by the Haber-Bosch process from nitrogen and hydrogen. Memory tip: “N needs 3” — nitrogen commonly makes three bonds,