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Vor 3 Tagen · Platinum–iridium bar at melting point of ice (1st CGPM) 1889 0.2–0.1 μm: 10 −7: Platinum–iridium bar at melting point of ice, atmospheric pressure, supported by two rollers (7th CGPM) 1927 n.a. n.a. Hyperfine atomic transition; 1 650 763.73 wavelengths of light from a specified transition in krypton-86 (11th CGPM) 1960 4 nm: 4 × 10 −9
27. Mai 2024 · Chemical element, symbol I and atomic number 53 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/violet liquid, violet gas Standard atomic weight A r °(I) 126.904 47 ± 0.000 03 126.90 ± 0.01 (abridged) Iodine in the periodic table Hydrogen Helium Lithium Beryllium Boron Carbon ...
Vor 4 Tagen · Wikipedia [ ˌvɪkiˈpeːdia] ( anhören ⓘ /?) ist ein gemeinnütziges Projekt zur Erstellung einer freien Enzyklopädie auf Basis des sogenannten Wiki-Prinzips . Die Inhalte der Wikipedia werden von freiwilligen Autoren erstellt und gepflegt, dafür erhalten sie keine finanzielle Entschädigung.
Vor 3 Tagen · Gallium is a chemical element; it has symbol Ga and atomic number 31. Discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875, [10] gallium is in group 13 of the periodic table and is similar to the other metals of the group ( aluminium, indium, and thallium ). Elemental gallium is a relatively soft, silvery metal at standard ...
23. Mai 2024 · Yttrium. hexagonal close-packed (hcp) ( hP2) Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". [7]
Vor 3 Tagen · Instead, iridium is more common in comets and asteroids. Because of this, the Alvarez team suggested that an asteroid struck the Earth at the time of the K–Pg boundary. [12] There were earlier speculations on the possibility of an impact event , [159] but this was the first hard evidence, [12] and since then, studies have continued to demonstrate elevated iridium levels in association with ...
Iridium-NEXT. Iridium-NEXT is a low-orbiting communications satellite system operated by Iridium Communications Inc. as the company’s second generation global communications system for satellite calls and data transfer. Comprised of 66 active satellites in orbit, Iridium-NEXT delivers full global coverage on a 24/7 basis and, through a unique ...
