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Home >> Chemistry Dictionary >>Beryllate Beta Decay
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Benzylamine (C6H5CH2NH2). A colourless liquid (b.p. 458k) having a characteristic ammonical odour resembling aliphatic amine. It gives benzoic acid with potassium permanganate.
Benzyl chloride. C7H7CI, PhCH2CI. Colourless liquid with a characteristic odour, b.p. 179˚C. It is slowly hydrolysed by boiling water, yielding benzyl alcohol.
It is prepared by the direct chlorination of toluene in the presence of PCI5. It is purified by fractionation from the unchanged toluene and the higher chlorinated products. It is used for benzylating amines and for preparing benzyl alcohol.
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Benzyne. A compound, C6H4 which is having a hexagonal ring of carbon atoms containing two double bonds and one triple bond. The compound is highly reactive and cannot be isolated.
Bergius process. A process which is used for making hydrocarbon mixtures from cool by heating powdered coal mixed with tar and iron oxide catalyst at 450˚C under Hydrogen at a pressure of about 200 atmospheres.
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Berkelium, Bk. At no. 97 m.p 986˚C, 249BK (314 days) is formed by the action of neutrons on 243Am; 247Bk (104 years) is much more stable but can only be produced in an accelerator. Bk is separated by ion exchange. The metal has been prepared by Li reduction of BkF3, it has a double hexagonal close-packed structure and is a typical electro-positive actinide.
Berthollide compound. Solid phases showing a range of composition
Beryllium hydroxide. A white crystalline compound, Be(OH)2, precipitated from solutions of beryllium salts by adding alkali. Like the oxide, it is amphoteric and dissolves in excess alkali to give beryllates.
Beryllium sulphate. BeSO4, 4H2O. A very soluble Be Salt (BeO plus H2SO4).
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Beryl. A hexagonal mineral form of beryllium aluminium silicate, Be3Al2 Si6O18, the chief ore if beryllium. It may be green, blue, yellow, or white and has long been used as a gemstone. Beryl occurs throughout the world in granite and pegmatites. Emerald, the green gem variety, occurs more rarely and is of great value. Important sources of beryl are found in Brazil, Madagascar, and the USA.
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Beryllate. A compound found in solution when beryllium metal, or the oxide or hydroxide, dissolves in strong alkali. The reaction (for the metal) is often written
Be + 2OH (aq) → BeO22-
(aq) + H2(g)
The ion BeO22- is the Beryllate ion. In fact, as with the aluminates, the ions present are probably are probably hydroxy ions of the type Be(OH)2-2 (the tetrahydroxoberyllate (II) ion) together with polymeric ions.
Beryllia beo. Beryllium oxide.
Bessemer process. A process for converting pig iron to steel by oxidation of the impurities (C, Si, P, Mn) by blowing air through the molten metal.
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Beryllium. Symbol Be. A gray metallic element of group II of the periodic table ; a.n. 4; r.a.m. 9.012; r.d. 1.85; m.p. 1285˚C; b.p 2970˚C. Beryllium occurs as beryl (3BeO. AI2O3. 6SiO2) and chrysoberyl (BeO.Al2O3). The metal is extracted from a fused mixture of BeF2/NaF by electrolysis or by magnesium reduction of BeF2. It is used to manufacture Be-Cu alloys, which are used in nuclear reactors as reflectors and moderators because of their low absorption cross section. Beryllium oxide is used in ceramics and in nuclear reactors. Beryllium and its compounds are toxic and can cause serious lung diseases and dermatitis. The metal is resistant to oxidation by air because of the formation of an oxide layer, but will react with dilute hydrochloric and sulphuric acids. Beryllium compounds show high covalent character.
Beta decay. A type of radioactive decay in which an unstable atomic nucleus changes into a nucleus of the same mass number but different proton number.
Betaines. A group of feebly basic substances, resembling betaine, which occur chiefly in plants. They are intramolecular salts (zwitterions) of e.g. quaternary ammonium compounds and include stachydrine, trigonelline and carnitine. Also the name given to the dipolar intermediates, X+ —C—C—O—assumed to be formed between ylids and a ketone or an aldehyde (X = R2S,R3PR3N).
Beta iron. An allotropic form of pure iron. It is stable between 786˚C and 910˚C and non-magnetic.
Beta particles. The electric, emitted from the nuclei of certain radioactive atoms.
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