[{"from": "human", "value": "Could you give me a brief overview of this molecule? [N]"}, {"from": "gpt", "value": "The molecule is a naturally-occurring compound with a chemical formula NH3 and structure of trigonal pyramidal geometry. It is a colorless gas with a pungent smell, and become NH4, or ammonium ion, when in water. Although ammonia is used as a food additive in the anhydrous form and serves as a starting material in pharmaceutical and commercial products, it is caustic and hazardous when concentrated. Ammonia gas has been used in the clinical setting as a respiratory stimulant to prevent fainting. The radiolabelled form of ammonia, ammonia N 13, is intravenously administered as a radioactive diagnostic agent for Positron Emission Tomography (PET) imaging of the myocardium to evaluate myocardial perfusion. Ammonia is a natural byproduct of biological and chemical reactions, including decomposition of organic matter, including plants, animals, and animal wastes. It is present in normally present in all tissues constituting a metabolic pool, where it is mostly taken up by glutamic acid and take part in transamination and other reactions, including the synthesis of protein by the Krebs-Hanseleit cycle in the liver. It is proposed that human adults produce about 1000 mmol of ammonia daily, most of which undergoes excretion in the urine."}]