Cesium metals

Cesium, first discovered by Bunsen and Kirchoff ia 1860 while examining spring water, was the first element discovered spectroscopically (1). The name, comes from the Latin caesius, sky blue, and refers to the characteristic blue spectral lines of the element. Cesium salts were not successfully reduced to metal until 1881. Electrolysis of the molten chloride did not yield cesium metal under the same conditions that led to the reduction of the other alkaU metal chlorides. 

There are three basic methods of converting poUucite to cesium metal or compounds direct reduction with metals decomposition with bases and acid digestion. In each case grinding of the ore to 75 p.m precedes conversion. 

Direct Reduction with Metals. PoUucite can be directly reduced by heating the ore in the presence of calcium to 950°C in a vacuum (20), or in the presence of either sodium or potassium to 750°C in an inert atmosphere (21). Extraction is not complete. Excessive amounts of the reducing metal is required and the resultant cesium metal is impure except when extensive distiUation purification is carried out. Engineering difficulties in this process are significant, hence, this method is not commerciaUy used. 

The primary producer of cesium metal in the United States is Cabot Corp. 

Magnesium is used to obtain cesium metal from cesium hydroxide [21351 -79-17, Cs(OH), cesium carbonate [534-17-8J, or cesium... 

Vacuum redistillation at low temperature is used for final purification of the cesium metal, if required. 

Thermal Decomposition. Cesium a2ide [22750-57-8] CsN, which is prepared by reacting aqueous solutions of cesium sulfate and barium a2ide, melts at 326°C and decomposes at 390°C to cesium metal (32) ... 

Most current appUcations require relatively smaU quantities of cesium, and hence aimual world production of cesium metal and compounds is estimated to be on the order of 250 t of cesium chloride equivalents. 

Cesium metal and cesium compounds are produced and marketed in a variety of grades, eg, from 99% for technical grades to as high as 99.999% for ultrapure compounds. 

The number of commercial uses of both cesium metal and its compounds has grown significantly since the early 1980s. 

Chemical Applications. Cesium metal is used in carbon dioxide purification as an adsorbent of impurities in ferrous and nonferrous metallurgy (qv) it can be used as a scavenger of gases and other impurities. 

Cesium metal is used for time standards based on the natural vibration of the Cs atom, which oscillates 9,192,631,770 times per second, and in high precision oscillators to synchronize fiber optic telecommunication. 

Cesium isotopes can be recovered from fission products by digestion in nitric acid, and after filtration of waste the radioactive cesium phosphotungstate is precipitated using phosphotungstic acid. This technique can be used to prepare radioactive cesium metal or compounds. Various processes for removal of Cs isotopes from radioactive waste have been developed including solvent extraction using macrocycHc polyethers (62) or crown ethers (63) and coprecipitation with sodium tetraphenylboron (64). 

C07-0053. Draw energy level diagrams that illustrate the difference in electron binding energy between cesium metal and chromium metal. Refer to Problems and. ... 

C07-0131. A hydrogen atom undergoes an electronic transition from the = 4 to the = 2 state. In the process the H atom emits a photon, which then strikes a cesium metal surface and ejects an electron. It takes 3.23 X 10 J to remove an electron from Cs metal. Calculate (a) the energy of the — 4 state of the H atom (b) the wavelength of the emitted photon (c) the energy of the ejected electron and (d) the wavelength of the ejected electron. 

Gomplexation of cesium at a tetracarbaborane cage was achieved in the reaction of [ / >-2,4,6,12-(SiMe3)4-2,4,6,12-C4B8H8] with an excess quantity of cesium metal in THF. In the polymeric structure of the cesium salt, one cesium atom occupies an apical position above an open six-membered C3B3 face 5.19... 

Alkali metals, especially potassium, rubidium, and cesium Metal amides (e.g., NaNH2)... 

Cesium chloride (CsCl) is produced by the reaction of cesium metal with chlorine gas (Ca + Cl —> CsCl). It is also used in the beer brewing industry, to coat fluorescent screens, and to improve the taste of mineral water. 

Cesium hydroxide (CsOH) is the strongest base (alkali) with the highest pH value of any chemical yet found. It is easy to produce by just placing cesium metal in water (which is very reactive). After the hydrogen escapes, cesium hydroxide remains in the water (2Cs + —>... 

Although cesium has many of the properties and characteristics of the other alkali metals, because of the large size of its atoms, cesium metal is much more reactive and dangerous to handle. Special precautions need to be taken to keep it away from air, water, and organic substances with which it can vigorously react. Its use should be restricted to laboratories and industries capable of using it safely. 

Cesium hydroxide is prepared hy electrolysis of cesium salts to obtain cesium metal, which then reacts with water to yield hydroxide. It also is prepared hy the action of harium hydroxide with an aqueous solution of cesium sulfate. 

This reaction has been used to make crystalline triphenylmethyl derivatives that have been characterized by X-ray structure determinations,22 and a technique has been developed for the reduction of hydrocarbons by liquid cesium activated by ultrasound irradiation in the presence of ethers such as diglyme.23 The blue solutions obtained when cesium metal is dissolved in THF in the presence of [18]-crown-6 have been used to metallate a series of 1,4- or 1,5-hexadienes. The organocesium compounds have not been isolated but they have been identified by derivatization by carbonation and trimethylsilylation.24 Substituted cyclopentadienyl derivatives of sodium have also been synthesized by this method.25... 

Similar structural principles are evident in compounds obtained by the metallation of l,2-bis(dimethylamino)-l,2-di-9-fluorenyldiborane (LH2) by MN(SiMe3)2 (M = Na or K) or by cesium metal in hexane-THF (lithium, calcium, and barium derivatives have also been made).93 The dianions were characterized by NMR spectroscopy, and the crystal structures of K2L.4THF, 53, and K2L.2DME, 54, were determined (Fig. 33). In each the... 

The muin source of cesium is camallite KCI MgCL 6H1O which contains a small percentage of cesium compounds. See also Camallite. Cesium also occurs in pollucile (cesium aluminosilicaie, 35% Cs 0) and lepidolite (lithium aluminosilicaie). See also Lepidolite and Pollucile. In early processes, cesium metal was obtained by the reduction of cesium salts, such as Ihe hydroxide or chloride. In current practice, the metal is produced by electrolyzing the cyanide. The latter compound usually is fused cesium barium cyanide mixture. 

Cesium metal is frequently used in photoelectric cells because the amount of energy necessary to eject electrons from a cesium surface is relatively small—only 206.5 kj/mol. What wavelength of light (in nanometers) does this correspond to ... 

Potassium, rubidium, and cesium metals are produced by chemical reduction rather than by electrolysis. Sodium is the reducing agent used in potassium production, and calcium is the reducing agent used for preparing rubidium and cesium. 

Describe the electron-sea model of the bonding in cesium metal. Cesium has a body-centered cubic structure. 

Cesium metal is very soft, and tungsten metal is very hard. Explain the difference using the electron-sea model. 

Cement, laboratory, 189 Cerium amalgam, 15 Cesium, metallic, 79 Chloroamine, 59 Chlorides, anhydrous, 28, 29 of silicon, 42 Chloroplumbic acid, 48 Chromi-oxalates, 37 Chromous acetate, 122 Chromous chloride, 124, 125 solution, 124 tetrahydrate, 126 trihydrate, 126 Cinnabar, 20 Cobalti-oxalates, 37... 

As already stated above, a cesium-metal surface, when exposed to oxygen at liquid-air temperatures, is spontaneously covered with a chemisorbed layer of oxygen. As the fully oxidized product which is formed by oxidation at higher temperatures proves to be cesium superoxide (Cs02), we may assume that the chemisorbed layer formed at — 180°C. also consists of chemisorbed 02 ions. As the work function of cesium has a low value, the difference in energy between levels A and D in Fig. 18 is rather small and, consequently, minimum E of the chemisorption curve will be appreciably lower than level A. 

Ignoring for the present ionization and contraction of the lattice, the structure of cesium chloride may be considered similar to that of cesium metal, but with the cesium atoms removed from the body centers and chloride ions inserted. In the diffraction pattern for cesium chloride, the 100 reflections, 111 reflections, and other reflections absent from the pattern for cesium metal are present but are weak. Wave interference similar to that occuring for cesium metal must occur, but here interference is not complete. The planes of chloride ions are not as strong reflectors or scatterers as the planes of cesium ions (the scattering power of an atom rises sharply with atomic number). Thus, interference in cesium... 

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