chlooratoom

Chlooratoom, or the chlorine atom, is the chemical element with symbol Cl and atomic number 17. It belongs to the halogen group in period 3 of the periodic table. The name derives from the Greek chloros, meaning greenish-yellow, a nod to the color of chlorine gas. In its neutral state, a chlorine atom is highly reactive and tends to gain one electron to form the chloride ion (Cl−).

Its electronic configuration is [Ne] 3s2 3p5, giving seven valence electrons and a strong tendency to gain or share electrons. In the elemental form, chlorine is found as diatomic molecules, Cl2, which at room temperature is a pale yellow-green gas. Its standard state is reactive and toxic, with a characteristic sharp, irritating odor.

Chlorine is abundant in nature mainly as chloride ions in seawater and rocks. It forms a wide range of compounds, including chlorides, chlorates, and perchlorates. The chlorine atom participates in many reactions, from simple salts such as sodium chloride to complex organochlorine compounds used in industry and agriculture.

Industrial production of chlorine is dominated by the chlor-alkali process, which electrolyzes molten sodium chloride to yield chlorine gas along with sodium hydroxide and hydrogen. Major applications include disinfection and water treatment, paper bleaching, and the production of plastics such as polyvinyl chloride (PVC). Chlorine chemistry also enables a large family of organic and inorganic chemicals.

Two stable isotopes occur in nature: Cl-35 and Cl-37, with abundances of about 75.8% and 24.2%, respectively. Safety considerations are important, as chlorine gas is highly reactive and toxic if inhaled or contacted.