Chlorine is the 17th element in the Periodic Table and has Cl for the symbol. It is a non-metal and a halogen.
Chlorine has 17 protons and electrons in total, and it has a mass number of 35, meaning that it has 18 neutrons. Pure chlorine is used in small doses to cleanse swimming pools, but too much is poisonous.
One of the most common chlorine compounds is Hydrochloric acid (HCl), which is a solution of hydrochloride (also HCl) in water. It is highly acidic (pH 0) and corrosive. When it reacts with a base a chloride salt is made.
Chlorine has several compounds, the most common is Sodium Chloride, commonly known as table salt.