Chlorine
From The School of Biomedical Sciences Wiki
Chlorine, or Cl2 is a diatomic halogen with the atomic number of 17.
In biological terms, chlorine is found as a Cl- ion, or chloride ion in cells.
Sodium Chloride (NaCl) is the compound in which chlorine is most frequently found in the body. Chloride concentration plays a vital role in epithelial tissues, and NaCl is the salt produced in the sweat glands.