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Bismuth Tribromide
Bismuth tribromide is an inorganic compound of bismuth and bromine with the chemical formula BiBr3. Preparation It may be formed by the reaction of bismuth oxide and hydrobromic acid. : Bismuth tribromide can also be produced by the direct oxidation of bismuth in bromine. : Structure Bismuth tribromide adopts two different structures in the solid state: a low-temperature polymorph α-BiBr3 that is stable below 158 °C and a high-temperature polymorph β-BiBr3 that is stable above this temperature. Both polymorphs are monoclinic but α-BiBr3 is in space group ''P''21/a whereas β-BiBr3 is in ''C''2/m. α-BiBr3 consists of pyramidal molecules whereas β-BiBr3 is polymeric and adopts the AlCl3 structure. BiBr3 is the only group 15 A pnictogen ( or ; from grc, πνῑ́γω "to choke" and -gen, "generator") is any of the chemical elements in group 15 of the periodic table. Group 15 is also known as the nitrogen group or nitrogen family. Group 15 consists of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diethyl Ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It is commonly used as a solvent in laboratories and as a starting fluid for some engines. It was formerly used as a general anesthetic, until non-flammable drugs were developed, such as halothane. It has been used as a recreational drug to cause intoxication. Production Most diethyl ether is produced as a byproduct of the vapor-phase hydration of ethylene to make ethanol. This process uses solid-supported phosphoric acid catalysts and can be adjusted to make more ether if the need arises. Vapor-phase dehydration of ethanol over some alumina catalysts can give diethyl ether yields of up to 95%. Diethyl ether can be prepared both in laboratories and on an industrial scale by the acid ether synthesis. Ethanol is mixed with a stro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig (in 1825) and Antoine Jérôme Balard (in 1826), its name was derived from the Ancient Greek (bromos) meaning "stench", referring to its sharp and pungent smell. Elemental bromine is very reactive and thus does not occur as a native element in nature but it occurs in colourless soluble crystalline mineral halide salts, analogous to table salt. In fact, bromine and all the halogens are so reactive that they form bonds in pairs—never in single atoms. While it is rather rare in the Earth's crust, the high solubility of the bromide ion (Br) has caused its accumulation in the oceans. Commercial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth Compounds
Bismuth compounds are compounds containing the element bismuth (Bi). Bismuth forms trivalent and pentavalent compounds, the trivalent ones being more common. Many of its chemical properties are similar to those of arsenic and antimony, although they are less toxic than derivatives of those lighter elements. Oxides and sulfides At elevated temperatures, the vapors of the metal combine rapidly with oxygen, forming the yellow trioxide, . Wiberg, p. 768. Greenwood, p. 553. When molten, at temperatures above 710 °C, this oxide corrodes any metal oxide and even platinum. Krüger, p. 185 On reaction with a base, it forms two series of oxyanions: , which is polymeric and forms linear chains, and . The anion in is a cubic octameric anion, , whereas the anion in is tetrameric. The dark red bismuth(V) oxide, , is unstable, liberating gas upon heating. The compound NaBiO3 is a strong oxidising agent. Greenwood, p. 578. Bismuth sulfide, , occurs naturally in bismuth ores. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct. For example, NH3 is a Lewis base, because it can donate its lone pair of electrons. Trimethylborane (Me3B) is a Lewis acid as it is capable of accepting a lone pair. In a Lewis adduct, the Lewis acid and base share an electron pair furnished by the Lewis base, forming a dative bond. In the context of a specific chemical reaction between NH3 and Me3B, a lone pair from NH3 will form a dative bond with the empty orbital of Me3B to form an adduct NH3•BMe3. The terminology refers to the contributions of Gilbert N. Lewis. From p. 142: "We are inclined to think of substances as po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pnictogen
A pnictogen ( or ; from grc, πνῑ́γω "to choke" and -gen, "generator") is any of the chemical elements in group 15 of the periodic table. Group 15 is also known as the nitrogen group or nitrogen family. Group 15 consists of the elements nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and moscovium (Mc). Since 1988, IUPAC calls it Group 15. Before that, in America it was called Group VA, owing to a text by H. C. Deming and the Sargent-Welch Scientific Company, while in Europe it was called Group VB and IUPAC recommended that in 1970. (Pronounced "group five A" and "group five B"; "V" is the Roman numeral 5). In semiconductor physics, it is still usually called Group V. The "five" ("V") in the historical names comes from the " pentavalency" of nitrogen, reflected by the stoichiometry of compounds such as N2O5. They have also been called the pentels. Characteristics Chemical Like other groups, the members of this family show similar patterns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium Chloride
Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contaminated with iron(III) chloride, giving a yellow color. The anhydrous material is important commercially. It has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large amounts are also used in other areas of the chemical industry. The compound is often cited as a Lewis acid. It is an example of an inorganic compound that reversibly changes from a polymer to a monomer at mild temperature. Structure Anhydrous adopts three structures, depending on the temperature and the state (solid, liquid, gas). Solid has a sheet-like layered structure with cubic close-packed chloride ions. In this framework, the Al centres exhibit octahedral coordination geometry. In contrast, has a more mol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonal Pyramidal Molecular Geometry
In chemistry, a trigonal pyramid is a molecular geometry with one atom at the apex and three atoms at the corners of a trigonal base, resembling a tetrahedron (not to be confused with the tetrahedral geometry). When all three atoms at the corners are identical, the molecule belongs to point group ''C3v''. Some molecules and ions with trigonal pyramidal geometry are the pnictogen hydrides (XH3), xenon trioxide (XeO3), the chlorate ion, , and the sulfite ion, . In organic chemistry, molecules which have a trigonal pyramidal geometry are sometimes described as sp3 hybridized. The AXE method for VSEPR theory states that the classification is AX3E1. Trigonal pyramidal geometry in ammonia The nitrogen in ammonia has 5 valence electrons and bonds with three hydrogen atoms to complete the octet. This would result in the geometry of a regular tetrahedron with each bond angle equal to cos−1(−) ≈ 109.5°. However, the three hydrogen atoms are repelled by the electron l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Group
In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchanged. In three dimensions, space groups are classified into 219 distinct types, or 230 types if chiral copies are considered distinct. Space groups are discrete cocompact groups of isometries of an oriented Euclidean space in any number of dimensions. In dimensions other than 3, they are sometimes called Bieberbach groups. In crystallography, space groups are also called the crystallographic or Fedorov groups, and represent a description of the symmetry of the crystal. A definitive source regarding 3-dimensional space groups is the ''International Tables for Crystallography'' . History Space groups in 2 dimensions are the 17 wallpaper groups which have been known for several centuries, though the proof that the list was complete was only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (materials Science)
In materials science, polymorphism describes the existence of a solid material in more than one form or crystal structure. Polymorphism is a form of isomerism. Any crystalline material can exhibit the phenomenon. Allotropy refers to polymorphism for chemical elements. Polymorphism is of practical relevance to pharmaceuticals, agrochemicals, pigments, dyestuffs, foods, and explosives. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure." According to McCrone, polymorphs are "different in crystal structure but identical in the liquid or vapor states." Materials with two polymorphs are called dimorphic, with three polymorphs, trimorphic, etc. Examples Many compounds exhibit polymorphism. It has been claimed that "every compound has different polymorphic forms, and that, in general, the n ... [...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] |
Bismuth
Bismuth is a chemical element with the Symbol (chemistry), symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs naturally, and its sulfide and oxide forms are important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery-white color when freshly produced. Passivation (chemistry), Surface oxidation generally gives samples of the metal a somewhat rosy cast. Further oxidation under heat can give bismuth a vividly Iridescence, iridescent appearance due to thin-film interference. Bismuth is both the most Diamagnetism, diamagnetic element and one of the least Thermal conductivity, thermally conductive metals known. Bismuth was long considered the element with the highest atomic mass whose nuclei do not spontaneously decay. However, in 2003 it was discovered to be extremely weakly radioactive. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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