cl what is
Chlorine is a chemical element with symbol Cl and atomic number 17. It also has a relative atomic mass of 35.5. Chlorine is in the halogen group (17) and is the second lightest halogen following fluorine.The element is a yellow-green gas under standard conditions, where it forms diatomic molecules.6 Cl is produced in the atmosphere by spallation of 36 Ar by interactions with cosmic ray protons. In the subsurface environment, 36 Cl is generated primarily as a result of neutron capture by 35 Cl or muon capture by 40 Ca. 36 Cl decays to 36 S and to 36 Ar, with a combined half-life of 308,000 years.