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 picture info Tin Dioxide Tin dioxide (tin(IV) oxide), also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin. With many other names, this oxide of tin is the most important raw material in tin chemistry [...More Info...]       [...Related Items...] picture info Reverberatory Furnace A reverberatory furnace is a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases [...More Info...]       [...Related Items...] picture info NFPA 704 "NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response" is a standard maintained by the U.S.-based National Fire Protection Association. First "tentatively adopted as a guide" in 1960, and revised several times since then, it defines the colloquial "fire diamond" or "safety square" used by emergency personnel to quickly and easily identify the risks posed by hazardous materials [...More Info...]       [...Related Items...] Pearson Symbol The letters A, B and C were formerly used instead of S. When the centred face cuts the X-axis, the Bravais lattice is called A-centred [...More Info...]       [...Related Items...] picture info Space Group In mathematics, physics and chemistry, a space group is the symmetry group of a configuration in space, usually in three dimensions. In three dimensions, there are 219 distinct types, or 230 if chiral copies are considered distinct. Space groups are also studied in dimensions other than 3 where they are sometimes called Bieberbach groups, and are discrete cocompact groups of isometries of an oriented Euclidean space. In crystallography, space groups are also called the crystallographic or Fedorov groups, and represent a description of the symmetry of the crystal [...More Info...]       [...Related Items...] picture info Molecular Symmetry Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain many of a molecule's chemical properties, such as its dipole moment and its allowed spectroscopic transitions. Many university level textbooks on physical chemistry, quantum chemistry, and inorganic chemistry devote a chapter to symmetry. The predominant framework for the study of molecular symmetry is group theory. Symmetry is useful in the study of molecular orbitals, with applications such as the Hückel method, ligand field theory, and the Woodward-Hoffmann rules [...More Info...]       [...Related Items...] picture info Lattice Constant The lattice constant, or lattice parameter, refers to the physical dimension of unit cells in a crystal lattice. Lattices in three dimensions generally have three lattice constants, referred to as a, b, and c. However, in the special case of cubic crystal structures, all of the constants are equal and we only refer to a. Similarly, in hexagonal crystal structures, the a and b constants are equal, and we only refer to the a and c constants. A group of lattice constants could be referred to as lattice parameters. However, the full set of lattice parameters consist of the three lattice constants and the three angles between them. For example, the lattice constant for diamond is a = 3.57 Å at 300 K. The structure is equilateral although its actual shape cannot be determined from only the lattice constant. Furthermore, in real applications, typically the average lattice constant is given [...More Info...]       [...Related Items...] picture info Coordination Geometry The term coordination geometry is used in a number of related fields of chemistry and solid state chemistry/physics. picture info Specific Heat Capacity Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to (or removed from) an object to the resulting temperature change. The unit of heat capacity is joule per kelvin ${\displaystyle \mathrm {\tfrac {J}{K}} }$[...More Info...]       [...Related Items...] Standard Molar Entropy In chemistry, the standard molar entropy is the entropy content of one mole of substance under a standard state (not STP). The standard molar entropy is usually given the symbol S°, and has units of joules per mole kelvin (J mol−1---> K−1--->). Unlike standard enthalpies of formation, the value of S° is absolute. That is, an element in its standard state has a definite, nonzero value of S at room temperature. The entropy of a pure crystalline structure can be 0 J mol−1---> K−1---> only at 0 K, according to the third law of thermodynamics. However, this presupposes that the material forms a 'perfect crystal' without any frozen in entropy (defects, dislocations), which is never completely true because crystals always grow at a finite temperature [...More Info...]       [...Related Items...] picture info Standard Enthalpy Change Of Formation The standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy during the formation of 1 mole of the substance from its constituent elements, with all substances in their standard states. The standard pressure value po---> = 105---> Pa (= 100 kPa = 1 bar) is recommended by IUPAC, although prior to 1982 the value 1.00 atm (101.325 kPa) was used. There is no standard temperature. Its symbol is ΔfH⊖--->. The superscript Plimsoll on this symbol indicates that the process has occurred under standard conditions at the specified temperature (usually 25 °C or 298.15 K) [...More Info...]       [...Related Items...] picture info Safety Data Sheet A safety data sheet (SDS), material safety data sheet (MSDS), or product safety data sheet (PSDS) is an important component of product stewardship, occupational safety and health, and spill-handling procedures. SDS formats can vary from source to source within a country depending on national requirements. SDSs are a widely used system for cataloging information on chemicals, chemical compounds, and chemical mixtures. SDS information may include instructions for the safe use and potential hazards associated with a particular material or product. The SDS should be available for reference in the area where the chemicals are being stored or in use. There is also a duty to properly label substances on the basis of physico-chemical, health or environmental risk [...More Info...]       [...Related Items...] picture info National Institute For Occupational Safety And Health The National Institute for Occupational Safety and Health (NIOSH, /ˈnaɪɒʃ/) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the Centers for Disease Control and Prevention (CDC) within the U.S. Department of Health and Human Services. NIOSH is headquartered in Washington, D.C., with research laboratories and offices in Cincinnati, Ohio; Morgantown, West Virginia; Pittsburgh, Pennsylvania; Denver, Colorado; Anchorage, Alaska; Spokane, Washington; and Atlanta, Georgia. NIOSH is a professionally diverse organization with a staff of 1,200 people representing a wide range of disciplines including epidemiology, medicine, industrial hygiene, safety, psychology, engineering, chemistry, and statistics [...More Info...]       [...Related Items...] picture info Crystal Structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter. The smallest group of particles in the material that constitutes the repeating pattern is the unit cell of the structure. The unit cell completely defines the symmetry and structure of the entire crystal lattice, which is built up by repetitive translation of the unit cell along its principal axes. The repeating patterns are said to be located at the points of the Bravais lattice. The lengths of the principal axes, or edges, of the unit cell and the angles between them are the lattice constants, also called lattice parameters [...More Info...]       [...Related Items...] Permissible Exposure Limit The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits are established by the Occupational Safety and Health Administration (OSHA). Most of OSHA’s PELs were issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970. For chemicals, the chemical regulation is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic meter (mg/m3--->). Units of measure for physical agents such as noise are specific to the agent. A PEL is usually given as a time-weighted average (TWA), although some are short-term exposure limits (STEL) or ceiling limits. A TWA is the average exposure over a specified period, usually a nominal eight hours [...More Info...]       [...Related Items...]