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Lanthanum(II) Iodide
Lanthanum diiodide is an iodide of lanthanum, with the chemical formula of LaI2. It is an electride, actually having a chemical formula of La3+[(I−)2e−]. Preparation Lanthanum diiodide can be obtained from the reduction of lanthanum(III) iodide with lanthanum metal under a vacuum at 800 to 900 °C: : It can also be obtained by reacting lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lantha ... and mercury(II) iodide: : It was first created by John D. Corbett in 1961. Properties Lanthanum diiodide is a blue-black solid with metallic lustre, which is easily hydrolyzed into the iodide oxide. It has a molybdenum disilicide, MoSi2-type structure, with the space group ''I''4/''mmm'' (No. 139). References [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerium Diiodide
Cerium diiodide is an iodide of cerium, with the chemical formula of CeI2. Preparation Cerium diiodide can be obtained from the reduction of cerium(III) iodide with metallic cerium under vacuum at 800 °C to 900 °C. : It can also be formed from the reaction of cerium and ammonium iodide in liquid ammonia at −78 °C. The reaction forms an ammonia complex of cerium diiodide, which decomposes to cerium diiodide under vacuum at 200 °C. : It was first created by John D. Corbett in 1961. Properties Cerium diiodide is an opaque dark solid with a metal-like appearance and properties. There is no cerium(II) in cerium diiodide, and its real structure is Ce3+(I−)2e−. It is easily hydrolyzed to form the corresponding iodide oxide. Like lanthanum diiodide and praseodymium diiodide, the cerium diiodide forms in the MoSi2-type structure, with space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Praseodymium Diiodide
Praseodymium diiodide is a chemical compound with the empirical formula of PrI2, consisting of praseodymium and iodine. It is an electride, with the ionic formula of Pr3+(I−)2e−, and therefore not a true praseodymium(II) compound. Preparation Praseodymium diiodide can be obtained by reacting praseodymium(III) iodide with metallic praseodymium at 800 °C to 900 °C in an inert atmosphere: :Pr + 2 PrI3 → 3 PrI2 It can also be obtained by reacting praseodymium with mercury(II) iodide where praseodymium displaces mercury: :Pr + HgI2 → PrI2 + Hg Praseodymium diiodide was first obtained by John D. Corbett in 1961. Properties Praseodymium diiodide is an opaque, bronze-coloured solid with a metallic lustre that is soluble in water. The lustre and very high conductivity can be explained by the formulation , with one electron per metal centre delocalised in a conduction band. The compound is extremely hygroscopic, and can only be stored and handled under carefull ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanthanum(III) Iodide
Lanthanum(III) iodide is an inorganic compound containing lanthanum and iodine with the chemical formula . Synthesis Lanthanum(III) iodide can be synthesised by the reaction of lanthanum metal with mercury(II) iodide: :2 La + 3 HgI2 → 2 LaI3 + 3 Hg It can also be prepared from the elements, that is by the reaction of metallic lanthanum with iodine: :2 La + 3 I2 → 2 LaI3 While lanthanum(III) iodide solutions can be generated by dissolving lanthanum oxide in hydroiodic acid, the product will hydrolyse and form polymeric hydroxy species: :La2O3 + 6 HI → 2 LaI3 + 3 H2O ''→ further reactions'' Structure Lanthanum(III) iodide adopts the same crystal structure as plutonium(III) bromide, with 8-coordinate metal centres arranged in layers. This orthorhombic structure is typical of the triiodides of the lighter lanthanides (La–Nd), whereas heavier lanthanides tend to adopt the hexagonal bismuth(III) iodide structure. Reactivity and applications Lanthanum(III) iodide is very ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodide
An iodide ion is the ion I−. 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. Structure and characteristics of inorganic iodides Iodide is one of the largest monatomic anions. It is assigned a radius of around 206 picometers. For comparison, the lighter halides are considerably smaller: bromide (196 pm), chloride (181 pm), and fluoride (133 pm). In part because of its size, iodide forms relatively weak bonds with most elements. Most iodide salts are soluble in water, but often less so than the related chlorides and bromides. Iodide, being large, is less hydrophilic compared to the smaller anions. One consequence of this is that sodium iodide is highly soluble in acetone, whereas sodium chloride is not. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanthanum
Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. Lanthanum is traditionally counted among the rare earth elements. Like most other rare earth elements, the usual oxidation state is +3. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity. Lanthanum usually occurs together with cerium and the other rare earth elements. Lanthanum was first found by the Swedish chemist Carl Gustaf Mosander in 1839 as an impurity in cerium nitrate – hence the name ''lanthanum'', from the Ancient Greek (), meaning 'to lie hidden'. Although it is classified as a rare earth element, lanthanum is the 28th most abund ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and ''plus'' (+) and ''minus'' (−) signs. These are limited to a single typographic line of symbols, which may include Subscript and superscript, subscripts and superscripts. A chemical formula is not a chemical nomenclature, chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulae can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than chemical names and structural formulae. The simplest types of chemical formulae are called ''empirical formulae'', which use letters and numbers ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electride
An electride is an ionic compound in which an electron is the anion. Solutions of alkali metals in ammonia are electride salts. In the case of sodium, these blue solutions consist of a(NH3)6sup>+ and solvated electrons: :Na + 6 NH3 → a(NH3)6sup>+ + e− The cation a(NH3)6sup>+ is an octahedral coordination complex. Solid salts Addition of a complexant like crown ether or -cryptand.html" ;"title="''2.2.2/nowiki>-cryptand">''2.2.2/nowiki>-cryptand to a solution of a(NH3)6sup>+e− affords a (crown ether)sup>+e− or a(2,2,2-crypt)sup>+e−. Evaporation of these solutions yields a blue-black paramagnetic solid with the formula a(2,2,2-crypt)sup>+e−. Most solid electride salts decompose above 240 K, although a24Al28O64sup>4+(e−)4 is stable at room temperature. In these salts, the electron is delocalized between the cations. Electrides are paramagnetic Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a ''perfect'' vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure. The Latin term ''in vacuo'' is used to describe an object that is surrounded by a vacuum. The ''quality'' of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. But hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury(II) Iodide
Mercury(II) iodide is a chemical compound with the molecular formula Hg I2. It is typically produced synthetically but can also be found in nature as the extremely rare mineral coccinite. Unlike the related mercury(II) chloride it is hardly soluble in water (<100 ppm). Production Mercury(II) iodide is produced by adding an aqueous solution of to an aqueous solution of with stirring; the precipitate is filtered off, washed and dried at 70 °C. : HgCl2 + 2 KI → HgI2 + 2 KClProperties Mercury(II) iodide displays |
John D
John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second Epistle of John, often shortened to 2 John * Third Epistle of John, often shortened to 3 John People * John the Baptist (died c. AD 30), regarded as a prophet and the forerunner of Jesus Christ * John the Apostle (lived c. AD 30), one of the twelve apostles of Jesus * John the Evangelist, assigned author of the Fourth Gospel, once identified with the Apostle * John of Patmos, also known as John the Divine or John the Revelator, the author of the Book of Revelation, once identified with the Apostle * John the Presbyter, a figure either identified with or distinguished from the Apostle, the Evangelist and John of Patmos Other people with the given name Religious figures * John, father of Andrew the Apostle and Saint Peter * Pope Jo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrolyzed
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g., sucrose being broken down into glucose and fructose), this is recognized as saccharification. Hydrolysis reactions can be the reverse of a condensation reaction in which two molecules join into a larger one and eject a water molecule. Thus hydrolysis adds water to break down, whereas condensation builds up by removing water. Types Usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both the substance and water molecule to split into two parts. In s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdenum Disilicide
Molybdenum disilicide (MoSi2, or molybdenum silicide), an intermetallic compound, a silicide of molybdenum, is a refractory ceramic with primary use in heating elements. It has moderate density, melting point 2030 °C, and is electrically conductive. At high temperatures it forms a passivation layer of silicon dioxide, protecting it from further oxidation. The thermal stability of MoSi2 alongside its high emissivity make this material, alongside WSi2 attractive for applications as a high emissivity coatings in heat shields for atmospheric entry. MoSi2 is a gray metallic-looking material with tetragonal crystal structure (alpha-modification); its beta-modification is hexagonal and unstable. It is insoluble in most acids but soluble in nitric acid and hydrofluoric acid. While MoSi2 has excellent resistance to oxidation and high Young's modulus at temperatures above 1000 °C, it is brittle in lower temperatures. Also, at above 1200 °C it loses creep resistance. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
