Here's why:
* Chlorine (Cl) is a highly reactive element. It exists as a yellow-green gas at room temperature and is extremely dangerous to breathe.
* Swimming pools use chlorine compounds. The chlorine you encounter in a pool is actually in the form of compounds like sodium hypochlorite (NaClO) or calcium hypochlorite (Ca(ClO)2). These compounds release chlorine gas (Cl2) when they dissolve in water, which then sanitizes the pool.
In summary: While chlorine is the basis for pool sanitizers, the element itself isn't found directly in a pool. It's present in the form of compounds that break down and release chlorine gas to kill bacteria and algae.
