Caesium

ELEfTRONir fONElCL RAIIONS Of THE ELEMENTS CAESIUM TO LAWRENflUM... 

The table contains vertical groups of elements each member of a group having the same number of electrons in the outermost quantum level. For example, the element immediately before each noble gas, with seven electrons in the outermost quantum level, is always a halogen. The element immediately following a noble gas, with one electron in a new quantum level, is an alkali metal (lithium, sodium, potassium, rubidium, caesium, francium). 

Taking francium as an example, it was assumed that the minute traces of francium ion Fr could be separated from other ions in solution by co-precipitation with insoluble caesium chlorate (VII) (perchlorate) because francium lies next to caesium in Group lA. This assumption proved to be correct and francium was separated by this method. Similarly, separation of astatine as the astatide ion At was achieved by co-precipitation on silver iodide because silver astatide AgAt was also expected to be insoluble. 

Rock salt Rutile Caesium chloride Fluorite... 

Lithium, sodium, potassium, rubidium, caesium beryllium, magnesium, calcium, strontium, barium)... 

All the cations of Group I produce a characteristic colour in a flame (lithium, red sodium, yellow potassium, violet rubidium, dark red caesium, blue). The test may be applied quantitatively by atomising an aqueous solution containing Group I cations into a flame and determining the intensities of emission over the visible spectrum with a spectrophotometer Jlame photometry). 

The chemical identities of the fission products determine their subsequent redistribution, those elements which are in the gaseous state at the temperature of the operation migrating to the cooler exterior of the fuel rods, and die less voltile elements undergoing incorporation in the fuel rod in solid solution. Thus caesium and iodine migrate to the gas fill which sunounds the fuel rod, and elements such as the rare earths and zirconium are accommodated in solid solution in UO2 without significant migration along the fuel rod radius. Strontium and barium oxidize to form separate islands which can be seen under the microscope. 

A number of attempts to produce tire refractory metals, such as titanium and zirconium, by molten chloride electrolysis have not met widr success with two exceptions. The electrolysis of caesium salts such as Cs2ZrCl6 and CsTaCle, and of the fluorides Na2ZrF6 and NaTaFg have produced satisfactoty products on the laboratory scale (Flengas and Pint, 1969) but other systems have produced merely metallic dusts aird dendritic deposits. These observations suggest tlrat, as in tire case of metal deposition from aqueous electrolytes, e.g. Ag from Ag(CN)/ instead of from AgNOj, tire formation of stable metal complexes in tire liquid electrolyte is the key to success. 

Thermodynamic data show that the stabilities of the caesium chloride-metal chloride complexes are greater than the conesponding sodium and potassium compounds, and tire fluorides form complexes more readily tlrair the chlorides, in the solid state. It would seem that tire stabilities of these compounds would transfer into tire liquid state. In fact, it has been possible to account for the heats of formation of molten salt mixtures by the assumption that molten complex salts contain complex as well as simple anions, so tlrat tire heat of formation of the liquid mixtures is tire mole fraction weighted product of the pure components and the complex. For example, in the CsCl-ZrCU system the heat of formation is given on each side of tire complex compound composition, the mole fraction of the compound... 

Aluminium caesium sulfate (I2H2O) [7784-17-0 (lIHjO), 14284-36-7] M 568.2. Crystd from hot water (3mL/g). 

Cadmium sulphide pigments, respirable dust, as Cd Caesium hydroxide... 

Potassium ozonide Caesium ozonide Ammonium ozonide... 

Dicaesium acetylide Copper(ll) acetylide Dicopper(l) acetylide Silver acetylide Caesium acetylide Potassium acetylide Lithium acetylide Sodium acetylide Rubidium acetylide Lithium acetylide-ammonia Dipotassium acetylide Dilithium acetylide Disodium acetylide Dirubidium acetylide Strontium acetylide Silver trifluoromethylacetylide Sodium methoxyacetylide Sodium ethoxyacetylide... 

Range of application and spectral sensitivity The photomultiphers most frequently employed in scanners possess antimony-caesium cathodes. These alloy cathodes are primarily sensitive to the short-wavelength part of visible light (Tab. 4). 

I. S. Barnes, S. T. Hyde, B. W. Ninham. The caesium chloride zero potential surface is not the Schwarz P-surface. J Physique Colloque 51 C7 19-24, 1990. 

AlLiiiiiiilLim Antimony Argon. . Arsenic barium Berylliu m Bismuth boron. . bromine. Cadmium Caesium, Calcium Carbon ( erium ( hloriiie. Cliromium L obait. . Copper. . Muorine. ... 

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