Alkali metals cesium

Like the other alkali metals, cesium is a soft-solid silvery metal, but much softer than the others. It is the least electronegative and most reactive of the Earth metals. Cesium has an oxidation state of +1, and because its atoms are larger than Li, Na, and K atoms, it readily gives up its single outer valence electron. The single electron in the P shell is weakly attached to its nucleus and thus available to combine with many other elements. It is much too reactive to be found in its metallic state on Earth. 

Some alkali metals—cesium, potassium, and sodium—react violently with water to produce hydrogen gas that bums. 

Kennedy, J. J. The Alkali Metal Cesium and Some of Its Saits. Chem. Reviews. 23, 159 (1938),... 

As for their stable analogs, the adsorption of radionuclides may depend on experimental conditions. Any variation results from the chemistry of the element, not form its radioactive nature. For example, the adsorption of the alkali metal cesium is largely independent of pH, whereas pH dependence is to be expected for oxyanions (Chapter 5, this volume) such as selenite and selenate and for transition metals such as nickel, silver, and palladium. 

Like the other alkali metals, cesium is a soft, silvery metal, but it appears golden if it has been exposed to small amounts of oxygen. It is not found in its metallic state in nature it is obtained as a byproduct of lithium processing of the mineral lepidolite. Its most significant ore is pollucite, and the world s largest pollucite deposit is found in Bernic Lake, Manitoba, Canada. Cesium s average crustal abundance is about 3 parts per million. Cesium is the most electropositive stable element and will ignite if exposed to air. Cesium burns blue in the flame test. 

Like the rest of the alkali metals, cesium is silvery white when in purified form. It is commonly found in the mineral pollucite, a compound containing silicon, oxygen, and aluminum as well. Cesium is the softest metal known and melts at 29°C. When held, it will melt at body temperature, 37°C (98.6°F), like a chocolate candy in your hand. Only mercury has a lower melting point. 

With other alkali metals cesium forms alloys with very low melting points, which can be used in certain applications. Cesium with 9% sodium melts at -30°C. 

Cesium, an alkali metal, occurs in lepidolite, pollucte (a hydrated silicate of aluminum and cesium), and in other sources. One of the world s richest sources of cesium is located at Bernic Lake, Manitoba. The deposits are estimated to contain 300,000 tons of pollucite, averaging 20% cesium. 

Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group and is the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet. Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineral oil or in a vacuum or inert atmosphere. 

AMP-1 4.0 Microcrystalline ammonium molybdo-phosphate with cation exchange capacity of 1.2 mequiv/g. Selectively adsorbs larger alkali metal ions from smaller alkali metal ions, particularly cesium. 

Xenates and Perxenates. Alkali metal xenates of composition MHXe04-1.5H20, where M is sodium, potassium, mbidium, or cesium, have been prepared by free2e-dryiQg mixtures of xenon trioxide and the corresponding metal hydroxides ia 1 1 molar ratios. The xenates are unstable, explosive solids. 

Rubidium [7440-17-7] Rb, is an alkali metal, ie, ia Group 1 (lA) of the Periodic Table. Its chemical and physical properties generally He between those of potassium (qv) and cesium (see Cesiumand cesium compounds Potassium compounds). Rubidium is the sixteenth most prevalent element ia the earth s cmst (1). Despite its abundance, it is usually widely dispersed and not found as a principal constituent ia any mineral. Rather it is usually associated with cesium. Most mbidium is obtained from lepidoHte [1317-64-2] an ore containing 2—4% mbidium oxide [18088-11-4]. LepidoHte is found ia Zimbabwe and at Bernic Lake, Canada. 

Barium titanate thin films can be deposited on various substances by treating with an aqueous solution containing barium salts and an alkanolamine-modifted titanate such as TYZOR TE (151). In a similar fashion, reaction of a tetraalkyl titanate with an alkah metal hydroxide, such as potassium hydroxide, gives oxyalkoxide derivatives (KTi O(OR) ), which can be further processed to give alkali metal titanate powders, films, and fibers (152—155). The fibers can be used as adsorbents for radioactive metals such as cesium, strontium, and uranium (156). 

Cesium [7440-46-2] Cs, is a member of the Group 1 alkali metals. It resembles potassium and mbidium ia the metallic state, and the chemistry of cesium is more like that of these two elements than like that of the lighter alkaU metals. 

More general procedures for additions of halogen fluorides to highly fluori-nated olefins involve reactions with a source of nucleophilic fluoride ion, such as an alkali metal fluoride, in the presence of aposttive halogen donor [62 107, lOff, 109, 110, 111] (equations 11 and 12) These processes are likely to occur by the generation and capture of perfluorocarbamonic intermediates Tertiary fluormated carbanions can be isolated as cesium [112], silver [113], or tns(dimethylamino)sul-... 

The use of cesium fluoride is limited because of its cost and its availability as a truly anhydrous reagent. Its use with 18-crown-6 shows a 5 times higher rate for the formation of benzyl fluoride from benzyl bromide when compared with cesium fluonde or potassium fluoride supported on calcium fluoride [21] Either cesium fluoride or potassium fluoride supported on calcium fluoride (Procedures 5a and 5b, p 194) provides about a twofold improvement over either unsupported alkali metal fluoride [55, 69], Cesium fluoride and Aliquat 336 convert benzyl bromide to the fluoride in 94% yield. Using tetrabuty lammonium fluoride in place of Aliquat... 

Interaction between niobium oxide and fluorides, chlorides or carbonates of alkali metals in an ammonium hydrofluoride melt, yielded monooxyfluoroniobates with different compositions, MxNbOF3+x, where they were subsequently investigated [123-127]. According to DTA patterns of the Nb205 - 6NFL HF2 - 2MF system, (Fig. 18) a rich variety of endothermic effects result from the formation of ammonium monooxyfluoroniobate, its thermal decomposition and its interaction with alkali metal fluorides. The number of effects decreases and separation of ammonium ceases at lower temperatures and when going from lithium to cesium in the sequence of alkali metal fluorides. 

It is important to note that the number of different compounds found in such systems increases significantly when moving along the sequence of alkali metals, from lithium to cesium, as does their thermal stability. This phenomenon is related to the systematic increase of both ionic radii and polarity of alkali metals ions when moving from lithium to cesium. 

A slight but systematic decrease in the wave number of the complexes bond vibrations, observed when moving from sodium to cesium, corresponds to the increase in the covalency of the inner-sphere bonds. Taking into account that the ionic radii of rubidium and cesium are greater than that of fluorine, it can be assumed that the covalent bond share results not only from the polarization of the complex ion but from that of the outer-sphere cation as well. This mechanism could explain the main differences between fluoride ions and oxides. For instance, melts of alkali metal nitrates display a similar influence of the alkali metal on the vibration frequency, but covalent interactions are affected mostly by the polarization of nitrate ions in the field of the outer-sphere alkali metal cations [359]. 

The atomic volumes of the alkali metals increase with atomic number, as do those of the inert gases. Notice, however, that the volume occupied by an alkali atom is somewhat larger than that of the adjacent inert gas (with the exception of the lithium and helium—helium is the cause of this anomaly). The sodium atom in sodium metal occupies 30% more volume than does neon. Cesium occupies close to twice the volume of xenon. 

Whereas technique (4) works for all alkali metals, lithium and sodium behave differently from potassium, rubidium, and cesium with respect to graphite on direct combination. The last three react facilely with graphite, to form compounds CgM (first stage) and Ci2 M (stage n > 1), but lithium reacts only under more extreme conditions of temperature or pressure, or both, to form compounds of formula CenLi (G3,... 

The first column of the periodic table, Group 1, contains elements that are soft, shiny solids. These alkali metals include lithium, sodium, potassium, mbidium, and cesium. At the other end of the table, fluorine, chlorine, bromine, iodine, and astatine appear in the next-to-last column. These are the halogens, or Group 17 elements. These four elements exist as diatomic molecules, so their formulas have the form X2 A sample of chlorine appears in Figure EV. Each alkali metal combines with any of the halogens in a 1 1 ratio to form a white crystalline solid. The general formula of these compounds s, AX, where A represents the alkali metal and X represents the halogen A X = N a C 1, LiBr, CsBr, KI, etc.). 

Flow boiling of other alkali metals CHF data for other alkali metals were reported by Fisher et al. (1964, 1965), who tested rubidium and cesium in axial and swirl flow and potassium in swirl flow. The data were correlated by postulating a mist or fog flow model for the hydrodynamic situation in the heated section in which CHF occurs. These investigations were motivated by the potential use of alkali metals as Rankine cycle working media in space applications and have not been pursued further, because there is no longer interest in such concepts. 

Bonilla, C. F., D. L. Sawhuey, and N. M. Makansi, 1962, Vapor Pressure of Alkali Metals III, Rubidium, Cesium, and Sodium-Potassium alloy up to 100 psia, Proc. 1962 High Temperature Liquid MetaI Heat Transfer Tech. Meeting, BNL-756, Brookhaven, NY. (3)... 

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