Jodider

Jodider is the term used in several languages, including Danish, Norwegian, and Swedish, to refer to iodide compounds. It designates the iodide ion (I−) and the salts formed when iodide combines with positively charged ions. In English, the corresponding term is iodide; jodider appears in plural form when discussing iodide salts collectively.

Chemistry and properties: The iodide ion is the reduced form of iodine and is common in many salts. Sodium iodide (NaI) and potassium iodide (KI) are highly soluble in water and have uses in medicine, photography, and laboratory chemistry. Iodide can be oxidized to elemental iodine (I2) or to higher oxidation states; reactions with oxidizing agents yield I2, which can give brown coloration in solution or form various iodine-containing species. Silver iodide (AgI) forms a pale-yellow precipitate and is notable for its historical use in cloud seeding; lead iodide (PbI2) forms a bright yellow solid that is sensitive to light.

Occurrence and production: Iodide is present in seawater and many minerals. Dietary iodine is primarily consumed as iodide and is essential for human health. Industrial production of iodide salts typically involves neutralizing hydroiodic acid with alkali metal hydroxides, yielding salts such as NaI and KI, or by reduction of iodine in solution to the iodide form.

Biological and practical role: Iodide is essential for the synthesis of thyroid hormones (thyroxine, T4, and triiodothyronine, T3) in humans and other vertebrates. Iodine deficiency can cause goiter and impaired development; iodized salt is a common public health measure to prevent deficiency. Medicinally, potassium iodide is used as a supplement and in certain radiation-protection applications; iodide-containing contrast agents are employed in medical imaging.

Safety: Iodide salts are generally handled as low-to-moderate hazards; excessive iodide intake can disrupt thyroid function and may irritate skin or eyes.