Alkali metals compound formulas formed

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.). 

One of the most widely explored systems is derived from the interpolation of Li between the TiS2 layers in varying amounts to form nonstoichiometric phases with a general formula LivTiS2. Because the bonding between the layers is weak, this process is easily reversible. The open nature of the structure allows the Li atoms to move readily in and out of the crystals, and these compounds can act as convenient alkali metal reservoirs in batteries and other devices. A battery using lithium intercalated into TiS2 as the cathode was initially developed some 30 years ago. 

Bismuthides. Many intermetallic compounds of bismuth with alkali metals and alkaline earth metals have the expected formulas M3Bi and M3Bi2, respectively. These compounds are not salt ike but have high coordination numbers, interatomic distances similar to those found in metals, and metallic electrical conductivities. They dissolve to some extent in molten salts (eg, NaCl—Nal) to form solutions that have been interpreted from cryoscopic data as containing some Bi3 . Both the alkali and alkaline earth metals form another series of alloylike bismuth compounds that become superconducting at low temperatures (Table 1). The MBi compounds are particulady noteworthy as having extremely short bond distances between the alkali metal atoms. 

Bismuth trioxide may be prepared by the following methods (/) the oxidation of bismuth metal by oxygen at temperatures between 750 and 800°C (2) the thermal decomposition of compounds such as the basic carbonate, the carbonate, or the nitrate (700—800°C) (3) precipitation of hydrated bismuth trioxide upon addition of an alkali metal hydroxide to a solution of a bismuth salt and removal of the water by ignition. The gelatinous precipitate initially formed becomes crystalline on standing it has been represented by the formula Bi(OH)3 and called bismuth hydroxide [10361 -43-0]. However, no definite compound has been isolated. 

A mechanism has been proposed for the reactions in which Cp2NbH3 is formed from Cp2NbCl2 in the presence of hydridoaluminate reducing agents of general formula [MA1H2R2] where M is an alkali metal and R is H, Et, or (OCH2CH2OCH3) (143). To account for the production of Nb(V) compounds in such circumstances, it is postulated that the initial product is a Nb(IV) hydride, which disproportionates into Nb(V) and Nb(III) hydrides as follows ... 

Carbon disulfide is the dithio derivative of C02. It is only a weak electrophile. Actually, it is so unreactive that in many reactions it can be used as a solvent. Consequently, only good nucleophiles can add to the C—S double bond of carbon disulfide. For example, alkali metal alkoxides add to carbon disulfide forming alkali metal xan-thates A (Figure 7.4). If one were to protonate this compound this would provide compound B, which is a derivative of free dithiocarbonic acid. It is unstable in the condensed phase in pure form, just as free carbonic acid and the unsubstituted carbamic acid (Formula B in Figure 7.3) are unstable. Compound B would therefore decompose spontaneously into ROH and CS2. Stable derivatives of alkali metal xanthates A are their esters C. They are referred to as xanthic add esters or xanthates. They are obtained by an alkylation (almost always by a methylation) of the alkali metal xanthates A. You have already learned about synthesis applications of xanthic acid esters in Figures 1.32, 4.13, and 4.14. 

Silver iodide is only slightly soluble in ammonia, but dissolves in sodium thiosulphate, concentrated hydriodic acid, and saturated solutions of potassium iodide.7 It forms a series of double salts with silver bromide,8 with mercuric iodide, and with the iodides of the alkali-metals.10 Double compounds of silver iodide and ammonia of the formulae AgI,8NH3 (6-92) AgI,l NH3 (7-25) AgI,NHs (8-56) AgI,2NHs (7-05) and AgI, NH3 (11-59) have also been prepared,11 the figures in parentheses indicating the calculated heats of formation in large calories. 

Several double salts with alkali-metal nitrites have been described.10 Double compounds with ammonia of the formulae AgN02,NH8 AgNOa,2NH3 and AgN02,3NH3 have also been prepared.11 A double salt with caesium, AgCs(N02)2, is formed by the interaction of caesium nitrite and silver nitrite. It crystallizes in lemon-yellow needles.12... 

The chloride2 is a yellowish-white substance, soluble in aqueous alkali-metal chlorides 3 with formation of complex anions, the solutions soon decomposing with precipitation of metallic gold and the formation of complex auric derivatives. The transformation is more rapid in bromide solutions. At 110° to 120° C. aurous chloride and excess of phosphorus trichloride combine to form a double compound of the formula AuCl,PCl3, colourless prisms insoluble in water.4... 

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