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Berkelium Compounds
Berkelium forms a number of chemical compounds, where it normally exists in an Oxidation number, oxidation state of +3 or +4, and behaves similarly to its lanthanide analogue, terbium. Like all actinides, berkelium easily dissolves in various aqueous solution, aqueous inorganic acids, liberating gaseous hydrogen and converting into the trivalent oxidation state. This trivalent state is the most stable, especially in aqueous solutions, but tetravalent berkelium compounds are also known. The existence of divalent berkelium salts is uncertain and has only been reported in mixed lanthanum chloride-strontium chloride melts. Aqueous solutions of Bk3+ ions are green in most acids. The color of the Bk4+ ions is yellow in hydrochloric acid and orange-yellow in sulfuric acid.Peterson, p. 55Holleman, p. 1956 Berkelium does not react rapidly with oxygen at room temperature, possibly due to the formation of a protective oxide surface layer; however, it reacts with molten metals, hydrogen, halog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkelium(IV) Oxide
Berkelium(IV) oxide, also known as berkelium dioxide, is a chemical compound with the formula BkO2. This compound slowly decays to californium(IV) oxide. It can be converted to berkelium(III) oxide by hydrogen reduction at 600 °C. :2BkO2 + H2 → Bk2O3 + H2O Production Berkelium(IV) oxide is produced by burning berkelium metal in air at 1200 °C. It can also be produced by reacting berkelium(III) oxide with oxygen at 600 °C. References {{Oxides Berkelium compounds Oxides Fluorite crystal structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordination Number
In chemistry, crystallography, and materials science, the coordination number, also called ligancy, of a central atom in a molecule or crystal is the number of atoms, molecules or ions bonded to it. The ion/molecule/atom surrounding the central ion/molecule/atom is called a ligand. This number is determined somewhat differently for molecules than for crystals. For molecules and polyatomic ions the coordination number of an atom is determined by simply counting the other atoms to which it is bonded (by either single or multiple bonds). For example, r(NH3)2Cl2Br2sup>− has Cr3+ as its central cation, which has a coordination number of 6 and is described as ''hexacoordinate''. The common coordination numbers are 4, 6 and 8. Molecules, polyatomic ions and coordination complexes In chemistry, coordination number, defined originally in 1893 by Alfred Werner, is the total number of neighbors of a central atom in a molecule or ion. The concept is most commonly applied to coordin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monoclinic Crystal System
In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a parallelogram prism. Hence two pairs of vectors are perpendicular (meet at right angles), while the third pair makes an angle other than 90°. Bravais lattices Two monoclinic Bravais lattices exist: the primitive monoclinic and the base-centered monoclinic. For the base-centered monoclinic lattice, the primitive cell has the shape of an oblique rhombic prism;See , row mC, column Primitive, where the cell parameters are given as a1 = a2, α = β it can be constructed because the two-dimensional centered rectangular base layer can also be described with primitive rhombic axes. Note that the length a of the primitive cell below equals \frac \sqrt of the conventional cell above. Crystal classes The table below organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkelium(III) Iodide
Berkelium(III) iodide is a binary inorganic compound of berkelium and iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ... with the chemical formula . Synthesis Synthesis of berkelium(III) iodide is by action of hydrogen iodine on berkelium oxide at 650 °C. Physical properties Berkelium triiodide forms a yellow solid of the trigonal crystal system, space group R3 (No. 148), lattice parameters a = 758.4 pm and c = 2087 pm. Its crystal structure is the same as that of bismuth triiodide. References Iodides Berkelium compounds Iodine compounds Actinide halides {{inorganic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkelium(III) Bromide
Berkelium bromide is a bromide of berkelium, with the chemical formula BkBr3. Structure Berkelium bromide has a PuBr3 structure at low temperature and is in the orthorhombic crystal system, with lattice parameters a = 403 pm, b = 1271 pm and c = 912 pm. At high temperature, berkelium bromide has an AlCl3 structure and a monoclinic crystal system In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic sy ... with lattice parameters a = 723 pm, b = 1253 pm, c = 683 pm and β = 110.6°. References External reading * {{Actinide halides Berkelium compounds Bromides Actinide halides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkelium(III) Chloride
Berkelium(III) chloride also known as berkelium trichloride, is a chemical compound with the formula BkCl3. It is a water-soluble green salt with a melting point of 603 °C. This compound forms the hexahydrate, BkCl3·6H2O. Preparation and reactions This compound was first prepared in 1970 by reacting hydrogen chloride gas and berkelium(IV) oxide or berkelium(III) oxide at 520 °C: :Bk2O3 + 6HCl → 2BkCl3 + 3H2O Berkelium(III) chloride reacts with beryllocene to produce berkelocene(Bk(C5H5)3). It also reacts with oxalic acid to produce berkelium oxalate. This reaction is used to purify this compound, by reacting the oxalate with hydrochloric acid. Structure Anhydrous berkelium(III) chloride has a hexagonal crystal structure, is isostructural to uranium trichloride, and has the person symbol hP6. When heated it its melting point, it converts to an orthorhombic phase. However, the hexahydrate has a monoclinic crystal structure and is isostructural to americium trichlor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkelium(III) Fluoride
Berkelium(III) fluoride is a binary inorganic compound of berkelium and fluorine with the chemical formula . Synthesis The compound can be prepared by treating with a gaseous mixture of and HF at 600 °C. Physical properties Berkelium trifluoride forms a yellow-green solid with two structures. At low temperature, it is orthorhombic ( structure), with lattice parameters a = 670 pm, b = 709 pm, and c = 441 pm. At high temperature, it is trigonal ( structure), with lattice parameters a = 697 pm and c = 714 pm. The transition temperature of is between 350 and 600 °C. Chemical properties Berkelium trifluoride is reduced by lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ... to obtain metallic berkelium: :: References {{Actinide halides Fluorides Berkeli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkelium(IV) Fluoride
Berkelium tetrafluoride is a binary inorganic compound of berkelium and fluorine with the chemical formula . Synthesis Berkelium tetrafluoride may be formed by the fluorination of berkelium trioxide, dioxide, or trifluoride with elemental fluorine at elevated temperatures: :: :: Physical properties Berkelium(IV) fluoride forms light brown crystals of monoclinic crystal structure of uranium tetrafluoride type. Cell parameters: a = 1.2396 nm, b = 1.0466 nm, c = 0.8118 nm, angle β = 126.33°. Chemical properties Berkelium tetrafluoride is reduced by lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ... at elevated temperatures to metallic berkelium: :: References {{Actinide halides Fluorides Berkelium compounds Actinide halides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octahedral Molecular Geometry
In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The octahedron has eight faces, hence the prefix ''octa''. The octahedron is one of the Platonic solids, although octahedral molecules typically have an atom in their centre and no bonds between the ligand atoms. A perfect octahedron belongs to the point group Oh. Examples of octahedral compounds are sulfur hexafluoride SF6 and molybdenum hexacarbonyl Mo(CO)6. The term "octahedral" is used somewhat loosely by chemists, focusing on the geometry of the bonds to the central atom and not considering differences among the ligands themselves. For example, , which is not octahedral in the mathematical sense due to the orientation of the bonds, is referred to as octahedral. The concept of octahedral coordination geometry was developed by Alfred Wern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halide
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluoride, chloride, bromide, iodide, astatide, or theoretically tennesside compound. The alkali metals combine directly with halogens under appropriate conditions forming halides of the general formula, MX (X = F, Cl, Br or I). Many salts are halides; the ''hal-'' syllable in ''halide'' and ''halite'' reflects this correlation. All Group 1 metals form halides that are white solids at room temperature. A halide ion is a halogen atom bearing a negative charge. The halide anions are fluoride (), chloride (), bromide (), iodide () and astatide (). Such ions are present in all ionic halide salts. Halide minerals contain halides. All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation. Test ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cubic Crystal System
In crystallography, the cubic (or isometric) crystal system is a crystal system where the Crystal_structure#Unit_cell, unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of these crystals: *Primitive cubic (abbreviated ''cP'' and alternatively called simple cubic) *Body-centered cubic (abbreviated ''cI'' or bcc) *Face-centered cubic (abbreviated ''cF'' or fcc, and alternatively called Close-packing_of_equal_spheres, ''cubic close-packed'' or ccp) Each is subdivided into other variants listed below. Although the ''unit cells'' in these crystals are conventionally taken to be cubes, the primitive_cell, primitive unit cells often are not. Bravais lattices The three Bravais lattices in the cubic crystal system are: The primitive cubic lattice (cP) consists of one Lattice_(group), lattice point on each corner of the cube; this means each simple cubic unit cell has in total one latt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sesquioxide
A sesquioxide is an oxide of an element (or radical), where the ratio between the number of atoms of that element and the number of atoms of oxygen is 2:3. For example, aluminium oxide and phosphorus(III) oxide are sesquioxides. Many sesquioxides contain a metal in the +3 oxidation state and the oxide ion , e.g., aluminium oxide , lanthanum(III) oxide and iron(III) oxide . Sesquioxides of iron and aluminium are found in soil. The alkali metal sesquioxides are exceptions because they contain both peroxide and superoxide ions, e.g., rubidium sesquioxide is formulated . Sesquioxides of metalloids and nonmetals are exceptions too, e.g. boron trioxide , dinitrogen trioxide and phosphorus(III) oxide . Many transition metal oxides crystallize in the corundum structure type, with space group Rc. Sesquioxides of rare earth elements crystalize into one or more of three crystal structures: hexagonal (type A, space group Pm1), monoclinic (type B, space group C2/m), or body-centered cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
