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Endohedral Fullerenes
Endohedral fullerenes, also called endofullerenes, are fullerenes that have additional atoms, ions, or clusters enclosed within their inner spheres. The first lanthanum C60 complex called La@C60 was synthesized in 1985. The @ (at sign) in the name reflects the notion of a small molecule trapped inside a shell. Two types of endohedral complexes exist: endohedral metallofullerenes and non-metal doped fullerenes. Notation In a traditional chemical formula notation, a buckminsterfullerene (C60) with an atom (M) was simply represented as MC60 regardless of whether M was inside or outside the fullerene. In order to allow for more detailed discussions with minimal loss of information, a more explicit notation was proposed in 1991, where the atoms listed to the left of the @ sign are situated inside the network composed of the atoms listed to the right. The example above would then be denoted M@C60 if M were inside the carbon network. A more complex example is K2(K@C59B), which denotes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endohedral Fullerene
Endohedral fullerenes, also called endofullerenes, are fullerenes that have additional atoms, ions, or clusters enclosed within their inner spheres. The first lanthanum C60 complex called La@C60 was synthesized in 1985. The @ (at sign) in the name reflects the notion of a small molecule trapped inside a shell. Two types of endohedral complexes exist: endohedral metallofullerenes and non-metal doped fullerenes. Notation In a traditional chemical formula notation, a buckminsterfullerene (C60) with an atom (M) was simply represented as MC60 regardless of whether M was inside or outside the fullerene. In order to allow for more detailed discussions with minimal loss of information, a more explicit notation was proposed in 1991, where the atoms listed to the left of the @ sign are situated inside the network composed of the atoms listed to the right. The example above would then be denoted M@C60 if M were inside the carbon network. A more complex example is K2(K@C59B), which de ... [...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] |
Scandium(III) Oxide
Scandium(III) oxide or scandia is a inorganic compound with formula Sc2 O3. It is one of several oxides of rare earth elements with a high melting point. It is used in the preparation of other scandium compounds as well as in high-temperature systems (for its resistance to heat and thermal shock), electronic ceramics, and glass composition (as a helper material). Structure and physical properties Scandium(III) oxide adopts a cubic crystal structure (point group: tetrahedral (Th), space group: Ia) containing 6-coordinate metal centres. Powder diffraction analysis shows Sc−O bond distances of 2.159–2.071 Å. Scandium oxide is an insulator with a band gap of 6.0 eV. Production Scandium oxide is the primary form of refined scandium produced by the mining industry. Scandium-rich ores, such as thortveitite (Sc,Y)2(Si2O7) and kolbeckite ScPO4·2H2O are rare, however trace amounts of scandium are present in many other minerals. Scandium oxide is therefore predominantly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harry C
Harry may refer to: Television * ''Harry'' (American TV series), 1987 comedy series starring Alan Arkin * ''Harry'' (British TV series), 1993 BBC drama that ran for two seasons * ''Harry'' (New Zealand TV series), 2013 crime drama starring Oscar Kightley * ''Harry'' (talk show), 2016 American daytime talk show hosted by Harry Connick Jr. People and fictional characters *Harry (given name), a list of people and fictional characters with the given name, including **Prince Harry, Duke of Sussex (born 1984) *Harry (surname), a list of people with the surname Other uses *"Harry", the tunnel used in the Stalag Luft III escape Stalag Luft III (; literally "Main Camp, Air, III"; SL III) was a ''Luftwaffe''-run German prisoner-of-war camps in World War II, prisoner-of-war (POW) camp during the Second World War, which held captured Allies of World War II, Western Allied ... ("The Great Escape") of World War II * ''Harry'' (album), a 1969 album by Harry Nilsson * Harry (derogatory term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metallofullerenes
In chemistry, a metallofullerene is a molecule composed of a metal atom trapped inside a fullerene cage. Simple metallofullerenes consist of a fullerene cage, typically , with one or two metal atoms trapped inside. Recently, research has produced metallofullerenes that enclose small clusters of atoms, such as , , and . The '@' symbol in the formula indicates that the atom(s) are encapsulated inside the cage, rather than being chemically bonded to it. Fullerenes in a variety of sizes have been found to encapsulate metal atoms in this way. Medical applications One particular metallofullerene with gadolinium at its core is up to 40 times better as a contrast agent in magnetic resonance imaging scans for diagnostic imaging. Metallofullerenes may also provide ways to carry therapeutic radioactive ions to cancerous tissue. See also *Endohedral fullerene Endohedral fullerenes, also called endofullerenes, are fullerenes that have additional atoms, ions, or clusters enclosed withi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hafnium
Hafnium is a chemical element; it has symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1922, by Dirk Coster and George de Hevesy. Hafnium is named after , the Latin name for Copenhagen, where it was discovered. Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nanometers and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten. Hafnium's large neutron capture cross section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium
Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyish-white color that closely resembles hafnium and, to a lesser extent, titanium. It is solid at room temperature, Ductility, ductile, malleable and corrosion-resistant. The name ''zirconium'' is derived from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian Language, Persian ''Jargoon, zargun'' (zircon; ''zar-gun'', "gold-like" or "as gold"). Besides zircon, zirconium occurs in over 140 other minerals, including baddeleyite and eudialyte; most zirconium is produced as a byproduct of minerals mined for titanium and tin. Zirconium forms a variety of inorganic chemistry, inorganic compounds, such as zirconium dioxide, and organometallic compounds, such as zirconocene dichloride. Five isotope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium
Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactive decay, radioactively decays, usually by emitting an alpha particle. The half-life of this decay varies between 159,200 and 4.5 billion years for different isotopes of uranium, isotopes, making them useful for dating the age of the Earth. The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99% of uranium on Earth) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordial nuclide, primordially occurring elements. Its density is about 70% higher than that of lead and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few Parts-per notation#Parts-per expressions, parts per million in soil, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetravalent
In chemistry, the valence (US spelling) or valency (British spelling) of an atom is a measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Valence is generally understood to be the number of chemical bonds that each atom of a given chemical element typically forms. Double bonds are considered to be two bonds, triple bonds to be three, quadruple bonds to be four, quintuple bonds to be five and sextuple bonds to be six. In most compounds, the valence of hydrogen is 1, of oxygen is 2, of nitrogen is 3, and of carbon is 4. Valence is not to be confused with the related concepts of the coordination number, the oxidation state, or the number of valence electrons for a given atom. Description The valence is the combining capacity of an atom of a given element, determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in ammonia, nitrogen has a valence of 3; in water, oxygen has a valence of 2; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkali Metal
The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names for the elements in some languages, such as German and Russian. rubidium (Rb), caesium (Cs), and francium (Fr). Together with hydrogen they constitute Group (periodic table)#Group names, group 1, which lies in the s-block of the periodic table. All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Indeed, the alkali metals provide the best example of periodic trends, group trends in properties in the periodic table, with elements exhibiting well-characterised Homologous series, homologous behaviour. This family of elements is also known as the lithium family after its leading element. The alkali metals are all shiny, hardness, sof ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strontium
Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal, it is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to air. Strontium has physical and chemical properties similar to those of its two vertical neighbors in the periodic table, calcium and barium. It occurs naturally mainly in the minerals celestine and strontianite, and is mostly mined from these. Both strontium and strontianite are named after Strontian, a village in Scotland near which the mineral was discovered in 1790 by Adair Crawford and William Cruickshank; it was identified as a new element the next year from its crimson-red flame test color. Strontium was first isolated as a metal in 1808 by Humphry Davy using the then newly discovered process of electrolysis. During the 19th century, strontium was mostly used in the production of sugar from sugar beets (see strontian proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium
Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. The most common minerals of barium are barite ( barium sulfate, BaSO4) and witherite ( barium carbonate, BaCO3). The name ''barium'' originates from the alchemical derivative "baryta", from Greek (), meaning 'heavy'. ''Baric'' is the adjectival form of barium. Barium was identified as a new element in 1772, but not reduced to a metal until 1808 with the advent of electrolysis. Barium has few industrial applications. Historically, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes. It is a component of YBCO (high-temperature superconductors) and electroceramics, and is added to steel and cast iron to reduce the size of carbon grains within the microstructure. Barium compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
