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Lanthanide Compounds
Lanthanide compounds are compounds formed by the 15 elements classed as lanthanides. The lanthanides are generally trivalent, although some, such as cerium and europium, are capable of forming compounds in other oxidation states. Hydrides Lanthanide metals react exothermically with hydrogen to form LnH2, dihydrides. With the exception of Eu and Yb, which resemble the Ba and Ca hydrides (non-conducting, transparent salt-like compounds),they form black pyrophoricity, pyrophoric, conducting compounds where the metal sub-lattice is face centred cubic and the H atoms occupy tetrahedral sites. Further hydrogenation produces a trihydride which is non-stoichiometric compound, non-stoichiometric, non-conducting, more salt like. The formation of trihydride is associated with and increase in 8–10% volume and this is linked to greater localization of charge on the hydrogen atoms which become more anionic (H− hydride anion) in character. Hydroxides All of the lanthanides form hyd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanthanide
The lanthanide () or lanthanoid () series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare-earth elements or rare-earth metals. The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell. There is some dispute on whether lanthanum or lutetium is a d-block element, but lutetium is usually considered so by those who study the matter; it is included due to its chemical similarities with the other 14. All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium. These elements are called lanthanides because the elements i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutetium
Lutetium is a chemical element with the symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among the rare earth elements. Lutetium is generally considered the first element of the 6th-period transition metals by those who study the matter, although there has been some dispute on this point. Lutetium was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James. All of these researchers found lutetium as an impurity in the mineral ytterbia, which was previously thought to consist entirely of ytterbium. The dispute on the priority of the discovery occurred shortly after, with Urbain and Welsbach accusing each other of publishing results influenced by the published research of the other; the naming honor went to Urbain, as he had publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terbium(IV) Fluoride
Terbium(IV) fluoride is an inorganic compound with a chemical formula TbF4. It is a white solid that is a strong oxidizer. It is also a strong fluorinating agent, emitting relatively pure atomic fluorine when heated, rather than the mixture of fluoride vapors emitted from cobalt(III) fluoride or cerium(IV) fluoride. It can be produced by the reaction between very pure terbium(III) fluoride and xenon difluoride, chlorine trifluoride or fluorine gas: : 2 TbF3 + F2 → 2 TbF4 Properties Terbium(IV) fluoride hydrolyzes quickly in hot water, producing terbium(III) fluoride and terbium oxyfluoride (TbOF). Heating terbium(IV) fluoride will cause it to decompose into terbium(III) fluoride and predominantly monatomic fluorine gas. : TbF4 → TbF3 + F•↑ The reaction will produce the mixed valence compound Tb(TbF5)3, which has the same crystal form as Ln(HfF5)3. Terbium(IV) fluoride can oxidize cobalt trifluoride into cobalt tetrafluoride: : TbF4 + CoF3 → TbF3 + CoF4↑ It can fluo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Praseodymium(IV) Fluoride
Praseodymium(IV) fluoride (also praseodymium tetrafluoride) is a binary inorganic compound, a highly oxidised metal salt of praseodymium and fluoride with the chemical formula PrF4. It forms light yellow crystals. Synthesis Praseodymium(IV) fluoride can be prepared by the effect of krypton difluoride on praseodymium(IV) oxide: ::\mathsf Praseodymium(IV) fluoride can also be made by the dissolution of sodium hexafluoropraseodymate(IV) in liquid hydrogen fluoride: ::\mathsf Properties Praseodymium(IV) fluoride forms light yellow crystals. The crystal structure is anticubic and isomorphic to that of uranium tetrafluoride UF4. Decomposes when heated: ::\mathsf Due to the high normal potential of the tetravalent praseodymium cations (Pr3+ / Pr4+: +3.2 V), praseodymium(IV) fluoride decomposes in water, releasing oxygen, O2. See also * Praseodymium(III) fluoride *Uranium tetrafluoride Uranium tetrafluoride is the inorganic compound with the formula UF4. It is a green solid with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerium(IV) Fluoride
Cerium(IV) fluoride is an inorganic compound with a chemical formula CeF4. It is a strong oxidant that appears as a white crystalline material. Cerium(IV) fluoride has an anhydrous form and a monohydrate form. Production and properties Cerium(IV) fluoride can be produced by fluorinating cerium(III) fluoride or cerium dioxide with fluorine gas at 500 °C Georg Brauer (Hrsg.), unter Mitarbeit von Marianne Baudler u. a.: Handbuch der Präparativen Anorganischen Chemie. 3., umgearbeitete Auflage. Band I, Ferdinand Enke, Stuttgart 1975, , S. 256. :\mathrm :\mathrm Its hydrated form (CeF4·xH2O, x≤1) can be produced by reacting 40% hydrofluoric acid and cerium(IV) sulfate solution at 90°C. Cerium(IV) fluoride can dissolve in DMSO Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula ( CH3)2. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds an ..., and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holleman
Holleman is a surname. Notable people with the surname include: *Boyce Holleman (1924–2003), American war veteran, attorney, politician, and actor * Frederik David Holleman (1887–1958), Dutch and South African professor, ethnologist, and legal scholar * Joel Holleman (1799–1844), American politician and lawyer from Virginia *Johan Frederik Holleman (1915–2001), Dutch and South African professor, ethnologist, legal scholar, and author * Kim Holleman (born 1973), mid-career contemporary artist with interdisciplinary approach *Mitch Holleman (born 1994), American child actor, plays ''Jake Hart'' on the TV sitcom ''Reba'' *Saskia Holleman (1945–2013), Dutch actress, lawyer and model See also * Holleman Elementary, school in Waller, Texas *Samuel Bartley Holleman House, historic home located in New Hill, North Carolina * Hallman (other) * Halman (other) *Hellman *Helman * Hileman (other) *Hillman * Holliman *Hollman * Hollmann *Holloman * Hollowm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates . The monohydrate crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students. Sodium hydroxide is used in many industries: in the manufacture of pulp and paper, textiles, drinking water, soaps and deterge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ytterbium(III) Hydroxide
Ytterbium is a chemical element with the symbol Yb and atomic number 70. It is a metal, the fourteenth and penultimate element in the lanthanide series, which is the basis of the relative stability of its +2 oxidation state. However, like the other lanthanides, its most common oxidation state is +3, as in its oxide, halides, and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble ytterbium compounds form complexes with nine water molecules. Because of its closed-shell electron configuration, its density and melting and boiling points differ significantly from those of most other lanthanides. In 1878, the Swiss chemist Jean Charles Galissard de Marignac separated from the rare earth "erbia" another independent component, which he called " ytterbia", for Ytterby, the village in Sweden near where he found the new component of erbium. He suspected that ytterbia was a compound of a new element that he called "ytterbium" (in total, four elements ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fajans' Rules
In inorganic chemistry, Fajans' rules, formulated by Kazimierz Fajans in 1923, are used to predict whether a chemical bond will be covalent or ionic, and depend on the charge on the cation and the relative sizes of the cation and anion. They can be summarized in the following table: : Thus sodium chloride (with a low positive charge (+1), a fairly large cation (~1 Å) and relatively small anion (0.2 Å) is ionic; but aluminium iodide (AlI3) (with a high positive charge (+3) and a large anion) is covalent. Polarization will be increased by: * high charge and small size of the cation **Ionic potential Å Z+/r+ (= polarizing power) *High charge and large size of the anion **The polarizability of an anion is related to the deformability of its electron cloud (i.e. its "softness") *An incomplete valence shell electron configuration **Noble gas configuration of the cation produces better shielding and less polarizing power ***e.g. Hg2+ (r+ = 102 pm) is more polarizing than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutetium(III) Hydroxide
Lutetium(III) hydroxide is an inorganic compound with the 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 symbol ... Lu(OH)3. Production Reacting lutetium chloride and alkalis will first produce Lu(OH)2Cl, then it will become Lu(OH)2.5Cl0.5. Finally, the reaction will produce Lu(OH)3.Aksel'rud, N. V.; Akhrameeva, T. I. Basic chlorides and hydroxide of lutetium. ''Zhurnal Neorganicheskoi Khimii'', 1962. 7. pp 1998-2001. . :LuCl3+2 NaOH→Lu(OH)2Cl+2 NaCl :Lu(OH)2Cl+0.5 NaOH→Lu(OH)2.5Cl0.5+0.5 NaCl :Lu(OH)2.5Cl0.5+0.5 NaOH→Lu(OH)3+0.5 NaCl Chemical properties Lutetium(III) hydroxide can react with acid and form lutetium(III) salts： : Lu(OH)3 + 3 H+ → Lu3+ + 3 H2O While heating lutetium(III) hydroxide, it will produce LuO(OH), continued heating could produce Lu2O3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-stoichiometric Compound
In chemistry, non-stoichiometric compounds are chemical compounds, almost always solid inorganic compounds, having elemental composition whose proportions cannot be represented by a ratio of small natural numbers (i.e. an empirical formula); most often, in such materials, some small percentage of atoms are missing or too many atoms are packed into an otherwise perfect lattice work. Contrary to earlier definitions, modern understanding of non-stoichiometric compounds view them as homogeneous, and not mixtures of stoichiometric chemical compounds. Since the solids are overall electrically neutral, the defect is compensated by a change in the charge of other atoms in the solid, either by changing their oxidation state, or by replacing them with atoms of different elements with a different charge. Many metal oxides and sulfides have non-stoichiometric examples; for example, stoichiometric iron(II) oxide, which is rare, has the formula , whereas the more common material is nonstoichi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrophoricity
A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolithium compounds and triethylborane. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of argon or (with a few exceptions) nitrogen. Class D fire extinguishers are designated for use in fires involving pyrophoric materials. A related concept is hypergolicity, in which two compounds spontaneously ignite when mixed. Uses The creation of sparks from metals is based on the pyrophoricity of small metal particles, and pyrophoric alloys are made for this purpose. The sparking mechanisms in lighters and various toys, using ferrocerium; starting fires without matches, using a firesteel; the flintlock mechanism in firearms; and spark testing ferrou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
