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Tellurite Fluoride
A tellurite fluoride is a mixed anion compound containing tellurite and fluoride ions. They have also been called oxyfluorotellurate(IV) where IV is the oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ... of tellurium in tellurite. Comparable compounds are sulfite fluorides or selenite fluorides. List References {{Fluorides Fluorides Tellurites Mixed anion compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mixed Anion Compound
Mixed anion compounds, heteroanionic materials or mixed anion materials are chemical compounds containing cations and more than one kind of anion. The compounds contain a single phase, rather than just a mixture. Use in materials science By having more than one anion, many more compounds can be made, and properties tuned to desirable values. In terms of optics, properties include laser damage threshold, refractive index, birefringence, absorption particularly in the ultraviolet or near infrared, non-linearity. Mechanical properties can include ability to grow a large crystal, ability to form a thin layer, strength, or brittleness. Thermal properties can include melting point, thermal stability, phase transition temperatures, Thermal expansion coefficient. For electrical properties, electric conductivity, band gap, superconducting transition temperature piezoelectricity, pyroelectricity, ferromagnetism, dielectric constant, charge-density wave transition can be adjusted. Pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tellurite (ion)
The tellurite ion is . A tellurite (compound), for example sodium tellurite, is a compound that contains this ion. They are typically colorless or white salts, which in some ways are comparable to sulfite. A mineral with the formula TeO2 is called tellurite. Structure and reactions Tellurite dianion is pyramidal, like selenite and sulfite. The anion has C3v symmetry. Tellurites can be reduced to elemental tellurium by electrolysis or a strong reducing agent. When fused with nitrate salts, tellurite salts oxidize to tellurates (). Upon acidification of aqueous solutions of tellurite salts, solid hydrated tellurium dioxide (TeO2) precipitates. This reaction allows the separation of tellurium from selenium since selenous acid remains soluble at low pH. The intermediate in the protonation occurs at oxygen to give eO2(OH)sup>−. Uses Potassium tellurite (K2TeO3) is used together with agar as part of a selective medium for growth of some bacteria (Clauberg medium). Coryneba ... [...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] |
Oxidation State
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state may be positive, negative or zero. While fully ionic bonds are not found in nature, many bonds exhibit strong ionicity, making oxidation state a useful predictor of charge. The oxidation state of an atom does not represent the "real" formal charge on that atom, or any other actual atomic property. This is particularly true of high oxidation states, where the ionization energy required to produce a multiply positive ion is far greater than the energies available in chemical reactions. Additionally, the oxidation states of atoms in a given compound may vary depending on the choice of electronegativity scale used in their calculation. Thus, the oxidation state of an atom in a compound is purely a formalism. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfite Fluoride
Sulfites or sulphites are compounds that contain the sulfite ion (or the sulfate(IV) ion, from its correct systematic name), . The sulfite ion is the conjugate base of bisulfite. Although its acid (sulfurous acid) is elusive, its salts are widely used. Sulfites are substances that naturally occur in some foods and the human body. They are also used as regulated food additives. When in food or drink, sulfites are often lumped together with sulfur dioxide.SeREGULATION (EU) No 1169/2011 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL/ref> Structure The structure of the sulfite anion can be described with three equivalent resonance structures. In each resonance structure, the sulfur atom is double-bonded to one oxygen atom with a formal charge of zero (neutral), and sulfur is singly bonded to the other two oxygen atoms, which each carry a formal charge of −1, together accounting for the −2 charge on the anion. There is also a non-bonded lone pair on the sulfur, so the structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenite Fluoride
A selenite fluoride is a chemical compound or salt that contains fluoride and selenite anions ( and ). These are mixed anion compounds. Some have third anions, including nitrate (), molybdate (), oxalate (), selenate (), silicate () and tellurate (). Naming A selenite fluoride compound may also be called a fluoride oxoselenate(IV) using IUPAC naming for inorganic compounds. Production Rare earth selenite fluorides can be produced by dissolving the rare earth selenate into molten lithium fluoride at over 800°C, whereupon the selenate loses oxygen to become selenite, and crystals of the selenite fluoride can form. Another similar method involves heating the rare earth oxide, with a rare earth fluoride and selenium dioxide with a caesium bromide flux. If glass or silica containers are used, they are eaten away by the molten flux and silicates are formed some of which may be fluoride selenite silicate compounds. Related Related to these are the selenite chlorides and se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Weight
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not consi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Group
In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchanged. In three dimensions, space groups are classified into 219 distinct types, or 230 types if chiral copies are considered distinct. Space groups are discrete cocompact groups of isometries of an oriented Euclidean space in any number of dimensions. In dimensions other than 3, they are sometimes called Bieberbach groups. In crystallography, space groups are also called the crystallographic or Fedorov groups, and represent a description of the symmetry of the crystal. A definitive source regarding 3-dimensional space groups is the ''International Tables for Crystallography'' . History Space groups in 2 dimensions are the 17 wallpaper groups which have been known for several centuries, though the proof that the list was complete was only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birefringence
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefringence is often quantified as the maximum difference between refractive indices exhibited by the material. Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress. Birefringence is responsible for the phenomenon of double refraction whereby a ray of light, when incident upon a birefringent material, is split by polarization into two rays taking slightly different paths. This effect was first described by Danish scientist Rasmus Bartholin in 1669, who observed it in calcite, a crystal having one of the strongest birefringences. In the 19th century Augustin-Jean Fresnel described the phenomenon in terms of polarization, understanding light as a wave with field components in transverse polariz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorides
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 nomenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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