joð

Joð is a chemical element with the symbol I and atomic number 53. It is a member of the halogen group, consisting of the elements fluorine, chlorine, bromine, iodine, and astatine. Under standard conditions, iodine is a lustrous, purple-black non-metallic solid that sublimes readily into a gas of the same color. This property is unique among halogens. Iodine has relatively few naturally occurring isotopes, with only one stable isotope, iodine-127. It is the least abundant of the stable halogens.

Iodine is essential for life, playing a crucial role in the synthesis of thyroid hormones. These hormones regulate metabolism and are vital for growth and development, particularly in the brain. Iodine deficiency can lead to various health problems, including goiter and hypothyroidism. For this reason, iodized salt is commonly used to ensure adequate iodine intake in many populations.

The element was discovered in 1813 by the French chemist Bernard Courtois. It is found in sea salt, seawater, and certain minerals. Industrially, iodine is extracted from brines and seaweed. Its applications extend beyond nutrition to include disinfectants, catalysts, and reagents in chemical analysis.