The chemical element with the symbol "Cl" is chlorine. Chlorine is a yellow-green gas at room temperature and is highly reactive, belonging to the halogen group in the periodic table. It is primarily used in a variety of applications, including disinfection, water purification, and as a precursor in the production of various chemicals and plastics. Chlorine’s reactive nature allows it to form compounds with most elements, contributing to its importance in chemical synthesis and industry. However, it must be handled with care due to its toxic and corrosive properties.