Potassium cesium and

If flame emission is based on excitation of atoms formed by combustion in the flame, why does flame emission work well for sodium, potassium, cesium and some of the transition metals but not vanadium, molybdenum or the lanthanides ... 

Rubidium is a soft, silvery metal, ft is one of the most active chemical elements. Rubidium is a member of the alkali family. The alkali family consists of elements in Group 1 (lA) of the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. Other Group 1 (lA) elements include lithium, sodium, potassium, cesium, and francium. Rubidium was discovered in 1861 by German chemists Robert Bunsen (1811—1899) and Gustav Kirchhoff (1824-1887). 

Changing the metal carbonate also affected intramolecular cyclization to form the 10-membered macrocycle with three nitrogen atoms in the ring. Isolated yields were 0%, 21%, 75%, 75%, and 0% using lithium, sodium, potassium, cesium, and silver ions, respectively (Chavez and Sherry, 1989). This indicates that potassium and cesium carbonates are excellent bases for the deprotonation of the tosylamides in DMF and that a template effect is not the most important factor in this reaction. 

Raman studies have been carried out on the potassium, cesium and ammonium salts and on the [OsjOClio] " ion in acid solution resonance Raman enhancement was observed for the v, (symetric 6s—6—Os stretch) mode. IR data have also been reported. A molecular orbital scheme for the bonding in [OsjOCfo] " can be derived from that proposed by Dunitz and Orgel for the analogous [RU2OCI10] species. Such a scheme has been used to interpret the electronic and vibrational spectra of [OsjOCljJ ... 

Reactions with Metals. Liquid ammonia possesses a remarkable ability to dissolve some electropositive metals, mostly the alkali and the alkali earths metals such as lithium, sodium, potassium, cesium, and copper. It is therefore advisable not to store these chemicals together. For example, sodium dissolves in excess ammonia to produce sodamide, a white solid, while magnesium, when heated in ammonia, produces magnesium nitride. 

A variety of photoemissive surfaces are used in commercial phototubes. Typical examples are shown in Figure 7-30. From the user s standpoint, photoemissive surfaces fall into four categories highly sensitive, red sensitive, ultraviolet sensitive, and flat response. The most sensitive cathodes are bialkali types such as number 117 in Figure 7-30 they are made up of potassium, cesium, and antimony. Red-sensitive materials are multialkali types (for example, Na/K/Cs/Sb) or Ag/O/Cs formulations. The behavior of the Ag/O/Cs surface is shown as. S-11 in the figure. Compositions of Ga/In/As extend the red region up to about 1.1 pm. Most formulations are ultraviolet sensitive if the tube is equipped with UV-transparent windows. Relatively flat responses are obtained with Ga/As compositions such as that labeled 128 in Figure 7-30. 

Fig. 8.2 Flame colors they are lithium, sodium, potassium, cesium, and rubidium in the clockwise from the top left [from D. A. Mcquarrie and P. A. Rock, Descriptive Chemistry (W. Freeman and Co., 1985)]...

Various salts of 5-azidotetrazole can be prepared by treating it with relevant salts [78]. Preparation, crystallographic studies, and characterization of hydrazinium, ammonium, aminobiguanidinium, guanidinium, lithium, sodium, potassium, cesium and calcium salts of 5-azidotetrazole were described by Klapotke and Stierstorfer [83]. Some experimental data from this paper are summarized in Table 8.12. The guanidinium salt forms as a semihydrate, whereas the lithium and sodium salts of 5-azidotetrazole form hydrates. The structure of the calcium salt is more complicated as it forms a complex with the following formula [Ca(CN7)2(H20)io] [Ca(H20)6](CN7)2. 

Increased para selectivity has been reported by using potassium, cesium and ammonium hydroxide as bases instead of sodium hydroxide.The addition of 6-cyclodextrin (BCD) afforded 100% para selectivity due to formation of a preferentially para ternary molecular complex between the phenolate ion, BCD and the dichlorocarbene intermediate.Although the presence of BCD does not enhance the total aldehyde production, it reduces the proportion of other isomeric aldehydes formed in favour of the para-product. Recently Zhang et. reported the synthesis of p-... 

Graphite reacts with alkali metals - potassium, cesium and rubidium - to form lamellar compounds with different stoichiometries. The most widely known intercalate is the potassium-graphite which has the stoichiometry of CgK. In this intercalate the space between the graphite layers is occupied by K atoms. CgK functions as a reducing agent in various reactions such as reduction of double bonds in a,fl-unsaturated ketones [19], carboxylic acids and Schiff bases alkylation of nitriles [20], esters and imines [21] reductive cleavage of carbon-sulfur bonds in vinylic and allylic sulfones [22]. The detailed reaction mechanism of CgK is not known, and the special properties which are ascribed to the intercalate come either from the equilibrium between K+/K [23], or topochemical observations (the layer structure) [24]. 

Hydroxides All hydroxides (except lithium, sodium, potassium, cesium, rubidium, and am- ... 

Potassium, Pubidium, and Cesium idjdrides. Although all the other alkah metal hydrides have been synthesized and some of the properties measured, only potassium hydride [7693-26-7] is commercially available. KH is manufactured in small amounts and sold as a mineral oil dispersion. It is a stronger base than NaH and is used to make the strong reducing agent KBH(C2H )2 and the super bases RNHK and ROK (6). 

Iodine is only slightly soluble in water and no hydrates form upon dissolution. The solubiHty increases with temperature, as shown in Table 2 (36). Iodine is soluble in aqueous iodide solutions owing to the formation of polyiodide ions. For example, an equiHbrium solution of soHd iodine and KI H2O at 25°C is highly concentrated and contains 67.8% iodine, 25.6% potassium iodide, and 6.6% water. However, if large cations such as cesium, substituted ammonium, and iodonium are present, the increased solubiHty may be limited, owing to precipitation of sparingly soluble polyiodides. Iodine is also more... 

Liquid Metals. If operating temperatures rise above 250—300°C, where many organic fluids decompose and water exerts high vapor pressure, hquid metals have found some use, eg, mercury for limited appHcation in turbines sodium, especially its low melting eutectic with 23 wt % potassium, as a hydrauhc fluid and coolant in nuclear reactors and potassium, mbidium, cesium, and gallium in some special uses. 

Other Peroxohydrates. Potassium, mbidium, and cesium carbonates all form peroxohydrates having the general formula M2CO2 3H20. Crystal stmctures have not been estabflshed Raman spectra (31) confirm the presence of molecular hydrogen peroxide in the crystal. These compounds are unstable and have no commercial appHcation. 

Potassium Graphite. Potassium, mbidium, and cesium react with graphite and activated charcoal to form intercalation compounds CgM, C24M, C gM, C gM, and C qM (61,62). Potassium graphite [12081 -88-8] 8 P gold-colored flakes, is prepared by mixing molten potassium with graphite at 120—150°C. 

Potassium Superoxide. Potassium, mbidium, and cesium form superoxides, MO2, upon oxidation by oxygen or air. Sodium yields the peroxide, Na202 lithium yields the oxide, Li20, when oxidized under comparable conditions. Potassium superoxide [12030-88-5] KO2 liberates oxygen in contact with moisture and carbon dioxide (qv). This important property enables KO2 to serve as an oxygen source in self-contained breathing equipment. 

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. 

Eutectics melting at about —30, —47, and —40° C are formed in the binary systems, cesium—sodium at about 9% sodium, cesium—potassium at about 25% potassium, and cesium—mbidium at about 14% mbidium (34). A ternary eutectic with a melting point of about —72°C has the composition 73% cesium, 24% potassium, and 3% sodium. Cesium and lithium are essentially completely immiscible in all proportions. 

The performance of many metal-ion catalysts can be enhanced by doping with cesium compounds. This is a result both of the low ionization potential of cesium and its abiUty to stabilize high oxidation states of transition-metal oxo anions (50). Catalyst doping is one of the principal commercial uses of cesium. Cesium is a more powerflil oxidant than potassium, which it can replace. The amount of replacement is often a matter of economic benefit. Cesium-doped catalysts are used for the production of styrene monomer from ethyl benzene at metal oxide contacts or from toluene and methanol as Cs-exchanged zeofltes ethylene oxide ammonoxidation, acrolein (methacrolein) acryflc acid (methacrylic acid) methyl methacrylate monomer methanol phthahc anhydride anthraquinone various olefins chlorinations in low pressure ammonia synthesis and in the conversion of SO2 to SO in sulfuric acid production. 

The NIOSH recommended exposure limit for carcinogenic hexavalent chromium is 1 lg/m Cr(VI) as a 10-h TWA, and for noncarcinogenic Cr(VI) the 10-h TWA is 25 lg/m Cr(VI), including a 15-min maximum exposure of 50 lg/m Cr(VI). According to NIOSH, the noncarcinogenic Cr(VI) compounds are chromic acid and the chromates and dichromates of sodium, potassium, lithium, mbidium, cesium, and ammonia. NIOSH considers any hexavalent chromium compound that does not appear on the preceding Hst carcinogenic (145). 

The six elements adjacent to and following the six inert gases are lithium, sodium, potassium, rubidium, cesium, and francium. These elements have similar chemistries and are called the... 

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,... 

X-ray crystallography of potassium, rubidium, and cesium methyls shows completely ionic crystal lattices Weiss, E. Sauermann, G. Chem. Ben, 1970, 103, 265 Weiss, E. Koster, H. Chem. Ber., 1977, 110, 717. 

The ionic conductivity of complexes of the polymer VIII n=3 with potassium, sodium and cesium thiocyanates were also determined. The conductivity of the polymer complexed with CsSCN is in the order of 10" S cm" at 30 °C, and lO- Scm-i at 90 °C [616]. 

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.). 

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