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Einsteinium Compounds
Einsteinium compounds are compounds that contain the element einsteinium (Es). These compounds largely have einsteinium in the +3 oxidation state, or in some cases in the +2 and +4 oxidation states. Although einsteinium is relatively stable, with half-lives ranging from 20 days upwards, these compounds have not been studied in great detail. Properties of einsteinium compounds Oxides Einsteinium(III) oxide (Es2O3) was obtained by burning einsteinium(III) nitrate. It forms colorless cubic crystals, which were first characterized from microgram samples sized about 30 nanometers.Greenwood, p. 1268 Two other phases, monoclinic and hexagonal, are known for this oxide. The formation of a certain Es2O3 phase depends on the preparation technique and sample history, and there is no clear phase diagram. Interconversions between the three phases can occur spontaneously, as a result of self-irradiation or self-heating. Haire, p. 1598 The hexagonal phase is isotypic with lanthanum oxide w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Einsteinium
Einsteinium is a synthetic element with the symbol Es and atomic number 99. Einsteinium is a member of the actinide series and it is the seventh transuranium element. It was named in honor of Albert Einstein. Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952. Its most common isotope, einsteinium-253 (half-life 20.47 days), is produced artificially from decay of californium-253 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year. The reactor synthesis is followed by a complex process of separating einsteinium-253 from other actinides and products of their decay. Other isotopes are synthesized in various laboratories, but in much smaller amounts, by bombarding heavy actinide elements with light ions. Owing to the small amounts of produced einsteinium and the short half-life of its most easily produced isotope, there are currently almost no practical applications for it outside bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenwood
Green wood is unseasoned wood. Greenwood or Green wood may also refer to: People * Greenwood (surname) Settlements Australia * Greenwood, Queensland, a locality in the Toowoomba Region * Greenwood, Western Australia, a suburb of Perth Canada * Greenwood, Calgary, Alberta, a neighbourhood * Greenwood, British Columbia, a city * Greenwood, Nova Scotia, a village * Greenwood, Halifax County, Nova Scotia, a community in the Halifax Regional Municipality * Greenwood, Durham Regional Municipality, Ontario * Greenwood, Renfrew County, Ontario United States * Greenwood, Arizona * Greenwood, Arkansas * Greenwood, El Dorado County, California * Greenwood, Glenn County, California * Greenwood, former name of Elk, Mendocino County, California * Greenwood Village, Colorado, a city * Greenwood, Delaware * Greenwood, Florida * Greenwood, Georgia * Greenwood, Idaho * Greenwood, Illinois * Mount Greenwood, Chicago, Illinois * Greenwood, Indiana * Greenwood, Wayne County, Indiana * Gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation Therapy
Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. A physician who practices in this subspecialty is a radiation oncologist. Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of cancerous tissue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.However, most of the universe's mass is not in the form of baryons or chemical elements. See dark matter and dark energy. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 ... [...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] |
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] |
Uranium(III) Chloride
Uranium(III) chloride, UCl3, is a water soluble salt of uranium. UCl3 is used mostly to reprocess spent nuclear fuel. Uranium(III) chloride is synthesized in various ways from uranium(IV) chloride; however, UCl3 is less stable than UCl4. Preparation There are two ways to synthesize uranium(III) chloride. The following processes describe how to produce uranium(III) chloride. (1) In a mixture of NaCl-KCl at 670–710 °C, add uranium tetrachloride with uranium metal. :3 UCl4 + U → 4UCl3 (2) Heat uranium(IV) chloride in hydrogen gas. :2 UCl4 + H2 → 2UCl3 + 2HCl Properties In solid uranium(III) chloride each uranium atom has nine chlorine atoms as near neighbours, at approximately the same distance, in a tricapped trigonal prismatic configuration. Uranium(III) chloride is a green crystalline solid at room temperature. UCl3 melts at 837 °C and boils at 1657 °C. Uranium(III) chloride has a density of 5500 kg/m3 or 5.500 g/cm3. Its composition by weig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexagonal Crystal Family
In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal system and the rhombohedral lattice system are not equivalent (see section crystal systems below). In particular, there are crystals that have trigonal symmetry but belong to the hexagonal lattice (such as α-quartz). The hexagonal crystal family consists of the 12 point groups such that at least one of their space groups has the hexagonal lattice as underlying lattice, and is the union of the hexagonal crystal system and the trigonal crystal system. There are 52 space groups associated with it, which are exactly those whose Bravais lattice is either hexagonal or rhombohedral. __TOC__ Lattice systems The hexagonal crystal family consists of two lattice systems: hexagonal and rhombohedral. Each lattice system consists of one Bravais la ... [...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] |
Chlorine Trifluoride
Chlorine trifluoride is an interhalogen compound with the formula ClF3. This colorless, poisonous, corrosive, and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temperature). The compound is primarily of interest in plasmaless cleaning and etching operations in the semiconductor industry, in nuclear reactor fuel processing, as a component in rocket fuels, and other industrial operations. Preparation, structure, and properties It was first reported in 1930 by Ruff and Krug who prepared it by fluorination of chlorine; this also produced ClF (chlorine monofluoride) and the mixture was separated by distillation. :3 F2 + Cl2 → 2 ClF3 The molecular geometry of ClF3 is approximately T-shaped, with one short bond (1.598 Å) and two long bonds (1.698 Å). This structure agrees with the prediction of VSEPR theory, which predicts lone pairs of electrons as occupying two equatorial positions o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluoride
Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin. Fluoride is the simplest fluorine anion. In terms of charge and size, the fluoride ion resembles the hydroxide ion. Fluoride ions occur on Earth in several minerals, particularly fluorite, but are present only in trace quantities in bodies of water in nature. Nomenclature Fluorides include compounds that contain ionic fluoride and those in which fluoride does not dissociate. The nom ... [...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] |
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