Chlorine Chemical & Physical Properties – Chlorine liquid form will burn the skin, Chlorine has been used as a chemical warfare agent. Properties: Chlorine has a melting point of -100.98°C, boiling point of -34.6°C, density of 3.214 g/l, specific gravity of 1.56 (-33.6°C), with a valence of 1, 3, 5, or 7.