Arsenic, As, is a nonmetallic element that is a silver-gray, brittle, crystalline solid Mercury, Hg , is a liquid metallic element that is silvery in color and heavy. It is insoluble in water and has a specific gravity of 13.59, which is heavier than water. Bromine, 〖Br〗_2 , is a nonmetallic, fuming liquid element of the halogen on the periodic table. It is dark reddish-brown in color with irritating fumes. Bromine is slightly soluble in water and attacks most metals. The boiling point is 138 ℉ (58℃), and the specific gravity is 3.12, which is heavier than water. Bromine is toxic by ingestion and inhalation, and is a severe skin irritant. The is 0.1 ppm in air, and the IDLH is 10 ppm. The target organs are the respiratory system, the eyes, and the central nervous system. It is also a strong oxidizing agent and may ignite combustible materials on contact. The DOT lists it as a Class 8 corrosive; however, it carries the corrosive and poison label. The four-digit UN identification number for bromine is 1744. The NFPA 704 designation for bromine and bromine solutions 3, flammability 0, and reactivity 0. The white section at the bottom of the 704 diamond has the prefix “oxy” indicating an oxidizer. The primary uses are in antiknock compounds for gasoline, bleaching, water purification, as a solvent, and in pharmaceuticals.