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Lutetium Nitride
Lutetium is a chemical element; it has 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; it can also be classified as the first element of the 6th-period transition metals. 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 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 published his results earlier. He chose the name ''lutecium'' for the new element, but in 1949 the spelling was changed to ''lutetium''. In 1909, the priority was fina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Element
A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen atom has 8 protons in its atomic nucleus, nucleus. Atoms of the same element can have different numbers of neutrons in their nuclei, known as isotopes of the element. Two or more atoms can combine to form molecules. Some elements form Homonuclear molecule, molecules of atoms of said element only: e.g. atoms of hydrogen (H) form Diatomic molecule, diatomic molecules (H). Chemical compounds are substances made of atoms of different elements; they can have molecular or non-molecular structure. Mixtures are materials containing different chemical substances; that means (in case of molecular substances) that they contain different types of molecules. Atoms of one element can be transformed into atoms of a different element in nuclear reactions, which change an atom's at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalyst
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the noncatalyzed mechanism. However the noncatalyzed mechanism does remain possible, so that the total rate (catalyzed plus noncatalyzed) can only increase in the presence of the catalyst and never decrease. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halides
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. A halide ion is a halogen atom bearing a negative charge. The common halide anions are fluoride (), chloride (), bromide (), and iodide (). Such ions are present in many ionic halide salts. Halide minerals contain halides. All these halide anions are colorless. Halides also form covalent bonds, examples being colorless TiF4, colorless TiCl4, orange TiBr4, and brown TiI4. The heavier members TiCl4, TiBr4, TiI4 c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at normally-encountered concentrations it is odorless. As the source of carbon in the carbon cycle, atmospheric is the primary carbon source for life on Earth. In the air, carbon dioxide is transparent to visible light but absorbs infrared, infrared radiation, acting as a greenhouse gas. Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, and seawater. It is a trace gas Carbon dioxide in Earth's atmosphere, in Earth's atmosphere at 421 parts per million (ppm), or about 0.042% (as of May 2022) having risen from pre-industrial levels of 280 ppm or about 0.028%. Burning fossil fuels is the main cause of these increased concentrations, which are the primary cause of climate change.IPCC (2022Summary for pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalate
Oxalate (systematic IUPAC name: ethanedioate) is an anion with the chemical formula . This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (), and several esters such as dimethyl oxalate (). It is a conjugate base of oxalic acid. At neutral pH in aqueous solution, oxalic acid converts completely to oxalate. Relationship to oxalic acid The dissociation of protons from oxalic acid proceeds in a determined order; as for other polyprotic acids, loss of a single proton results in the monovalent hydrogenoxalate anion . A salt with this anion is sometimes called an acid oxalate, monobasic oxalate, or hydrogen oxalate. The equilibrium constant ( ''K''a) for loss of the first proton is ( p''K''a = 1.27). The loss of the second proton, which yields the oxalate ion, has an equilibrium constant of (p''K''a = 4.28). These values imply, in solutions with neutral pH, no oxalic acid and only t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutetium(III) Oxide
Lutetium(III) oxide, a white solid, is a cubic compound of lutetium sometimes used in the preparation of specialty glasses. It is also called lutecia. It is a lanthanide oxide, also known as a rare earth.Lutetium Oxide. 1997-2007. Metall Rare Earth Limited. http://www.metall.com.cn/luo.htm History In 1879, Swiss chemist Jean Charles Galissard de Marignac (1817–1894) claimed to have discovered ytterbium, but he had found a mixture of elements. In 1907, French chemist Georges Urbain (1872–1938) reported that ytterbium was a mixture of two new elements and was not a single element. Two other chemists, Carl Auer von Welsbach (1858–1929) and Charles James (1880–1926) also extracted lutetium(III) oxide around the same time. All three scientists successfully separated Marignac's ytterbia into oxides of two elements which were eventually named ytterbium and lutetium Lutetium is a chemical element; it has symbol Lu and atomic number 71. It is a silvery white metal, which resists c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scandium
Scandium is a chemical element; it has Symbol (chemistry), symbol Sc and atomic number 21. It is a silvery-white metallic d-block, d-block element. Historically, it has been classified as a rare-earth element, together with yttrium and the lanthanides. It was discovered in 1879 by spectral analysis of the minerals euxenite and gadolinite from Scandinavia. Scandium is present in most of the deposits of rare-earth and uranium compounds, but it is extracted from these ores in only a few mines worldwide. Because of the low availability and difficulties in the preparation of metallic scandium, which was first done in 1937, applications for scandium were not developed until the 1970s, when the positive effects of scandium on aluminium alloys were discovered. Its use in such alloys remains its only major application. The global trade of scandium oxide is 15–20 tonnes per year. The properties of scandium compounds are intermediate between those of aluminium and yttrium. A diagonal rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanthanide Contraction
The lanthanide contraction is the greater-than-expected decrease in atomic radii and ionic radii of the elements in the lanthanide series, from left to right. It is caused by the poor shielding effect of nuclear charge by the 4f electrons along with the expected periodic trend of increasing electronegativity and nuclear charge on moving from left to right. About 10% of the lanthanide contraction has been attributed to relativistic effects. A decrease in atomic radii can be observed across the 4f elements from atomic number 57, lanthanum, to 70, ytterbium. This results in smaller than otherwise expected atomic radii and ionic radii for the subsequent d-block elements starting with 71, lutetium. Jolly, William L. ''Modern Inorganic Chemistry'', McGraw-Hill 1984, p. 22 This effect causes the radii of transition metals of group 5 and 6 to become unusually similar, as the expected increase in radius going down a period is nearly cancelled out by the f-block insertion, and has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenon
Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized. Xenon is used in flash lamps and arc lamps, and as a general anesthetic. The first excimer laser design used a xenon dimer molecule (Xe2) as the lasing medium, and the earliest laser designs used xenon flash lamps as pumps. Xenon is also used to search for hypothetical weakly interacting massive particles and as a propellant for ion thrusters in spacecraft. Naturally occurring xenon consists of seven stable isotopes and two long-lived radioactive isotopes. More than 40 unstable xenon isotopes undergo radioactive decay, and the isotope ratios of xenon are an important tool for studying the early history of the Solar System. Radioactive xe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Configuration
In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon atom is , meaning that the 1s, 2s, and 2p subshells are occupied by two, two, and six electrons, respectively. Electronic configurations describe each electron as moving independently in an orbital, in an average field created by the nuclei and all the other electrons. Mathematically, configurations are described by Slater determinants or configuration state functions. According to the laws of quantum mechanics, a level of energy is associated with each electron configuration. In certain conditions, electrons are able to move from one configuration to another by the emission or absorption of a quantum of energy, in the form of a photon. Knowledge of the electron configuration of different atoms is useful in understanding the structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pascal (unit)
The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m2). It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar, and the kilopascal (1 kPa = 1000 Pa), which is equal to one centibar. The unit of measurement called '' standard atmosphere (atm)'' is defined as . Meteorological observations typically report atmospheric pressure in hectopascals per the recommendation of the World Meteorological Organization, thus a standard atmosphere (atm) or typical sea-level air pressure is about 1013 hPa. Reports in the United States typically use inches of mercury or millibars (hectopascals). In Cana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brinell Scale
The Brinell hardness test (pronounced /brəˈnɛl/) measures the indentation hardness of materials. It determines hardness through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science. The hardness scale is expressed in terms of a Brinell hardness value, sometimes referred to as the Brinell hardness number but formally expressed as HBW (Hardness Brinell Wolfram – Wolfram being an alternative name for the tungsten carbide ball indenter used during the test). The test was named after Johan August Brinell (1849-1925) who developed the method at the end of the 19th century. History Premiered by Swedish engineer Johan August Brinell at the 1900 Paris Exposition, it was the first widely used and standardised hardness test in engineering and metallurgy. The large size of indentation and thus possible damage to test-pieces limits its usefulness. However, it also had the useful feature that the h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
