The element for ammonia is nitrogen (N). Ammonia is a compound composed of one nitrogen atom and three hydrogen atoms (NH3). Nitrogen is the seventh element in the periodic table, and it belongs to Group 15, also known as the pnictogens. It is a colorless, odorless, and tasteless gas at room temperature and pressure. Nitrogen is the most abundant element in the Earth's atmosphere, making up about 78% of its volume.