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This is an accepted version of this page This is the latest accepted revision, reviewed on 9 January 2025. 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, black ...
In 1802 the term "metalloids" was introduced for elements with the physical properties of metals but the chemical properties of non-metals. [194] However, in 1811, the Swedish chemist Berzelius used the term "metalloids" [ 195 ] to describe all nonmetallic elements, noting their ability to form negatively charged ions with oxygen in aqueous ...
Iodine is semiconductor in the direction of its planes, with a band gap of about 1.3 eV and a conductivity of 1.7 × 10 −8 S•cm −1 at room temperature. This is higher than selenium but lower than boron, the least electrically conducting of the recognised metalloids. Iodine is an insulator in the direction perpendicular to its planes.
The mildest of the halogens, iodine is the active ingredient in tincture of iodine, a disinfectant. This can be found in household medicine cabinets or emergency survival kits. Tincture of iodine will rapidly dissolve gold, [167] a task ordinarily requiring the use of aqua regia (a highly corrosive mixture of nitric and hydrochloric acids).
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−
These definitions are equivalent to stating that metals conduct electricity at absolute zero, as suggested by Nevill Francis Mott, [2]: 257 and the equivalent definition at other temperatures is also commonly used as in textbooks such as Chemistry of the Non-Metals by Ralf Steudel [3] and work on metal–insulator transitions. [4] [5]
The halogens (/ ˈ h æ l ə dʒ ə n, ˈ h eɪ-,-l oʊ-,-ˌ dʒ ɛ n / [1] [2] [3]) are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors [4] would exclude tennessine as its chemistry is unknown and is theoretically expected to ...
Studies indicate that iodine deficiency, either dietary or pharmacologic, can lead to breast atypia and increased incidence of malignancy in animal models, while iodine treatment can reverse dysplasia, [7] [62] [63] with elemental iodine (I 2) having been found to be more effective in reducing ductal hyperplasias and perilobular fibrosis in ...