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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 ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 4 February 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 ...
An alternative in metallurgy is to consider various malleable alloys such as steel, aluminium alloys and similar as metals, and other materials as nonmetals; [20] fabricating metals is termed metalworking, [21] but there is no corresponding term for nonmetals. A loose definition such as this is often the common usage, but can also be inaccurate.
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).
The role of iodine in mammary tissue is related to fetal and neonatal development, but its role in the other tissues is not well known. [8] It has been shown to act as an antioxidant [8] and antiproliferant [9] in various tissues that can uptake iodine. Molecular iodine (I 2) has been shown to have a suppressive effect on benign and cancerous ...
Most metal iodides with the metal in low oxidation states (+1 to +3) are ionic. Nonmetals tend to form covalent molecular iodides, as do metals in high oxidation states from +3 and above. Both ionic and covalent iodides are known for metals in oxidation state +3 (e.g. scandium iodide is mostly ionic, but aluminium iodide is not).
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.
At slightly elevated temperatures, the halogens bromine (Br 2) and iodine (I 2) also form diatomic gases. [3] All halogens have been observed as diatomic molecules, except for astatine and tennessine, which are uncertain. Other elements form diatomic molecules when evaporated, but these diatomic species repolymerize when cooled.