A gaseous organic compound that is best known for its use in preservative solutions has the chemical formula HCHO (read: H - C - H CHEM-92; Short Answer: Give me the name and atomic number of the element I am thinking about. It occupies the same column in the periodic table as selenium. Under standard conditions of temperature and pressure this element is a clear, odorless gas. This element is one of the essential ingredients in the burning process.