Symbol

Cl

Atomic Number

17

Atomic Mass

35.453

Family

Group 17 (Viia) Halogen Pronunciation

CLOR-een

Overview

Chlorine ranks among the top 10 chemicals produced in the United States. In 1992, about 10.5 billion kilograms (23 billion pounds) of the element were produced in the United States. Chlorine, in one form or another, is added to most swimming pools, spas, and public water supplies because it kills bacteria that cause disease. Many people also use chlorine to bleach their clothes. Large paper and pulp mills use chlorine to bleach their products.

Chlorine is a greenish-yellow poisonous gas. It was discovered in 1774 by Swedish chemist Carl Wilhelm Scheele (1742-86). Scheele knew that chlorine was a new element, but thought it contained oxygen as well.

Chlorine is a member of the halogen family. Halogens are the elements that make up Group 17 (VIIA) of the periodic table, a chart that shows how elements are related to one another. They...