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Mesomer
In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or ''forms'', also variously known as ''resonance structures'' or ''canonical structures'') into a resonance hybrid (or ''hybrid structure'') in valence bond theory. It has particular value for analyzing delocalized electrons where the bonding cannot be expressed by one single Lewis structure. Overview Under the framework of valence bond theory, resonance is an extension of the idea that the bonding in a chemical species can be described by a Lewis structure. For many chemical species, a single Lewis structure, consisting of atoms obeying the octet rule, possibly bearing formal charges, and connected by bonds of positive integer order, is sufficient for describing the chemical bonding and rationalizing experimentally determined molecular properties like bond lengths, angles, and dipole moment. However ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonance (chemistry)
In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or ''forms'', also variously known as ''resonance structures'' or ''canonical structures'') into a resonance hybrid (or ''hybrid structure'') in valence bond theory. It has particular value for analyzing delocalized electrons where the bonding cannot be expressed by one single Lewis structure. Overview Under the framework of valence bond theory, resonance is an extension of the idea that the bonding in a chemical species can be described by a Lewis structure. For many chemical species, a single Lewis structure, consisting of atoms obeying the octet rule, possibly bearing formal charges, and connected by bonds of positive integer order, is sufficient for describing the chemical bonding and rationalizing experimentally determined molecular properties like bond lengths, angles, and dipole moment. Howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxylamine
Hydroxylamine is an inorganic compound with the formula . The material is a white crystalline, hygroscopic compound.Greenwood and Earnshaw. ''Chemistry of the Elements.'' 2nd Edition. Reed Educational and Professional Publishing Ltd. pp. 431–432. 1997. Hydroxylamine is almost always provided and used as an aqueous solution. It is consumed almost exclusively to produce Nylon-6. It is also an intermediate in biological nitrification. The oxidation of to hydroxylamine is a step in biological nitrification. History Hydroxylamine was first prepared as hydroxylammonium chloride in 1865 by the German chemist Wilhelm Clemens Lossen (1838-1906); he reacted tin and hydrochloric acid in the presence of ethyl nitrate. It was first prepared in pure form in 1891 by the Dutch chemist Lobry de Bruyn and by the French chemist Léon Maurice Crismer (1858-1944). The coordination complex , known as Crismer's salt, releases hydroxylamine upon heating. Production Hydroxylamine or its salts can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillating force is applied at a resonant frequency of a dynamic system, the system will oscillate at a higher amplitude than when the same force is applied at other, non-resonant frequencies. Frequencies at which the response amplitude is a relative maximum are also known as resonant frequencies or resonance frequencies of the system. Small periodic forces that are near a resonant frequency of the system have the ability to produce large amplitude oscillations in the system due to the storage of vibrational energy. Resonance phenomena occur with all types of vibrations or waves: there is mechanical resonance, orbital resonance, acoustic resonance, electromagnetic resonance, nuclear magnetic resonance (NMR), electron spin resonance (ESR) and reso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leviathan
Leviathan (; he, לִוְיָתָן, ) is a sea serpent noted in theology and mythology. It is referenced in several books of the Hebrew Bible, including Psalms, the Book of Job, the Book of Isaiah, the Book of Amos, and, according to some translations, in the Book of Jonah; it is also mentioned in the Book of Enoch. The Leviathan is often an embodiment of chaos and threatening to eat the damned after their life. In the end, it is annihilated. Christian theologians identified Leviathan with the demon of the deadly sin envy. According to Ophite diagrams, the Leviathan encapsulates the space of the material world. The Leviathan of the Book of Job is a reflection of the older Canaanite ''Lotan'', a primeval monster defeated by the god Baal Hadad. Parallels to the role of Mesopotamian Tiamat defeated by Marduk have long been drawn in comparative mythology, as have been wider comparisons to dragon and world serpent narratives such as Indra slaying Vrtra or Thor slaying Jörm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unicorn
The unicorn is a legendary creature that has been described since antiquity as a beast with a single large, pointed, spiraling horn projecting from its forehead. In European literature and art, the unicorn has for the last thousand years or so been depicted as a white horse-like or goat-like animal with a long straight horn with spiralling grooves, cloven hooves, and sometimes a goat's beard. In the Middle Ages and Renaissance, it was commonly described as an extremely wild woodland creature, a symbol of purity and grace, which could be captured only by a virgin. In encyclopedias, its horn was described as having the power to render poisoned water potable and to heal sickness. In medieval and Renaissance times, the tusk of the narwhal was sometimes sold as a unicorn horn. A bovine type of unicorn is thought by some scholars to have been depicted in seals of the Bronze Age Indus Valley civilization, the interpretation remaining controversial. An equine form of the unicorn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
