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This is an accepted version of this page This is the latest accepted revision, reviewed on 12 December 2024. This article is about the chemical element. For other uses, see Iodine (disambiguation). Chemical element with atomic number 53 (I) Iodine, 53 I Iodine Pronunciation / ˈ aɪ ə d aɪ n, - d ɪ n, - d iː n / (EYE -ə-dyne, -din, -deen) Appearance lustrous metallic gray solid ...
Iodine, however, is minimally soluble in water (0.03 g/100 g water at 20 °C) and does not react with it. [26] However, iodine will form an aqueous solution in the presence of iodide ion, such as by addition of potassium iodide (KI), because the triiodide ion is formed.
The total amount of iodine in the human body is still controversial, and in 2001, M.T. Hays published in Thyroid that "it is surprising that the total iodine content of the human body remains uncertain after many years of interest in iodine metabolism. Only the iodine content of the thyroid gland has been measured accurately by fluorescent ...
Its formation explains why the solubility of iodine in water may be increased by the addition of potassium iodide solution: [11] I 2 + I − ⇌ I − 3 (K eq = ~700 at 20 °C) Many other polyiodides may be found when solutions containing iodine and iodide crystallise, such as I − 5, I − 9, I 2− 4, and I 2−
The main elements that comprise the human body (including water) can be summarized as CHNOPS. Element Symbol percent mass percent atoms Oxygen O 65.0 24.0 Carbon C 18.5 12.0 Hydrogen H 9.5 62.0 Nitrogen N 2.6 1.1 Calcium Ca 1.3 0.22 Phosphorus P 0.6 0.22 Sulfur S 0.3 0.038 Potassium K 0.2 0.03 Sodium Na 0.2 0.037 Chlorine Cl 0.2 0.024 Magnesium Mg
This supports a mechanism whereby I 2 first dissociates into 2 iodine atoms, which each attach themselves to a side of an H 2 molecule and break the H−H bond: [9] H 2 + I 2 + (578 nm radiation) → H 2 + 2I → I···H···H···I → 2HI. In the laboratory, another method involves hydrolysis of PI 3, the iodine analog of PBr 3.
Other chemical compounds with "triiodide" in their name may contain three iodide centers that are not bonded to each other as the triiodide ion, but exist instead as separate iodine atoms or iodide ions. Examples include nitrogen triiodide (NI 3) and phosphorus triiodide (PI 3), where individual iodine atoms are covalently bonded to a central atom.
Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability. [3]