Chlorine Atoms - Cl, the seventeenth element in the periodic table of elements. It has a atomic weight of 35.453 grams per mole. It has 17 protons in its nucleus and 7 electrons in its outer shell and is a very effective catalyst in the reaction that breaks down ozone in the stratosphere over Antarctica (see chlorine monoxide).
[Science; v 264; pages 32-33; 1994.]
[Science; v 262; pages 1703-1706; 1993.] 
Atmospheric Chemistry Glossary