In hobby terrns, we see chlorine as 1) the dissolved gas (CL2) - either as itself as a disinfectant in municipal watyer supplies, or as part of the chloramine complex, also a disinfectant in water supplies. Alternately we see it as 2) the chloride ion (Cl-) in solution from some chemical comound such as sodium chloride (NaCl) or potassium chloride (KCl) - such materials when dissolved appear as their component ions - i.e., NaCl in water gives a solution with Na+ and Cl- ions.
The biological impadts of the two forms - dissolved chlorine gas or chlotide ion - are quite different, two entirely separate materials.
HTH