Halogen elements are found in salts present in sea water
There are three different halogens found in seawater. They are chlorine, bromine, and iodine. The other halogen elements are fluorine and astatine. Halogens are very reactive and are found in many minerals as well as seawater.
The term ‘halogen’ is derived from Greek origin hals (sea) and halos(salt). It means ‘salt producing’ since these elements are found in the salts present in seawater. The natural salt that we obtain from evaporation of seawater, is known as common salt or table salt. It is predominantly sodium chloride. It has small amounts of other chlorides and iodides (such as NaI, MgI2, MgCl2 etc.).
Iodized salt is a modern day commercially available salt‐which is NaCl mixed with NaI. Iodine is necessary, in trace amounts, for our thyroid glands to function properly; it regulates our growth and body temperature. Chlorine gas is used as a disinfectant and bleaching agent. In swimming pools mild chloric acid HOCl is mixed in water ‐ the nascent oxygen released is useful for killing bacteria in the water. This is the reason why swimming pools always smell of chlorine.