الرئيسية » Simplified Chemistry (صفحه 3)

Simplified Chemistry

Banana bond

1. In strained-ring compounds the angles assumed on the basis of hybridization are often not equal to the angles obtained by joining the atomic centers. In these cases it is sometimes assumed that the bonding orbital is bent or banana-like in shape. Cyclopropane is an example, in which geometric considerations imply a bond angle of 60° while sp³ hybridization implies …

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Auger effect

Auger effect تأثير أوجيه Auger Effect An effect in which an excited ion decays by emission of an electron (rather than a photon). How Auger effect is happened? For example, if a substance is bombarded by high-energy electrons or gamma rays, an electron from an inner shell may be ejected. The result is a positive ion in an excited state. …

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Arrhenius equation

An equation relating the rate constant of a  chemical reaction and the temperature at which the reaction is taking place: k = Aexp(–Ea/RT) where A is a constant, k the rate constant, T the thermodynamic temperature in kelvins, R the gas constant, and Ea the activation energy of the reaction. Reactions proceed at different rates at different temperatures, i.e. the magnitude of the rate constant is temperature dependent. The …

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ثلاثي كلوريد الأنتيمون ( كلوريد الأنتيمون ) antimony(III) chloride – antimony trichloride

مادة صلبة بلورية عديمة اللون، استرطابية و تتبخر عند تعرضها للهواء و هي مادة سامة و كاوية، صيغتها الكيميائية SbCl3 و وزنها الجزيئي 228.13 جرام/مول، و درجة انصهارها 73 درجة سيليزية و درجة غليانها 223.5 درجة سيليزية و كثافتها 3.14 جرام/سم3 ، و هي قابلة للذوبان في الكحول و الأسيتون .يجب التعامل مع هذه المادة في جو نقي و غير …

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Annealing

A type of heat treatment applied to metals to change their physical properties. The metal is heated to, and held at, an appropriate temperature before being cooled at a suitable rate to produce the desired grain structure. Annealing is most commonly used to remove the stresses that have arisen during rolling, to increase the softness of the metal, and to …

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alkylbenzene

A type of organic hydrocarbon containing one or more alkyl groups substituted onto a benzene ring. Methylbenzene (C₆H₅CH₃) and 1,3-dimethylbenzene are simple examples. Alkylbenzenes can be made by a Friedel- Crafts reaction or by the Fittig reaction. Industrially, large quantities of methylbenzene are made by the hydroforming of crude oil. Substitution of alkylbenzenes can occur at the benzene ring. Substitution …

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alkali metals (group 1 elements)

alkali metals (group 1 elements) A group of soft reactive metals, each represent in the start of a new period in the periodic table and having an electronic configuration consisting of a rare-gas structure plus one outer electron. The alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They formerly were classified in …

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Aldol reaction

A reaction in which two molecules of aldehyde combine to give an aldol – i.e. a compound containing both aldehyde and alcohol functional groups. The reaction is base-catalyzed; the reaction of ethanal refluxed with sodium hydroxide gives: 2CH3CHO → CH3CH(OH)CH2CHO The mechanism is similar to that of the Claisen condensation: the first step is removal of a proton to give …

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Acidic Salt

Salt in which there is only partial replacement of the acidic hydrogen of an acid by metal or other cations. For polybasic acids the formulae are of the type NaHSO₄ (sodium hydrogensulfate) and Na₃H(CO₃)₂.2H₂O (sodium sesquicarbonate). For monobasic acids such as HF the acid salts are of the form KHF2 (potassium hydrogen fluoride). Although the latter were at one time …

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