The Alkali Metals and Their Compounds

The electrostatic valence rule states that the most stable structures of crystals and molecules are those in which the sum of the strengths of the bonds reaching each anion is Just equal to its negative charge. 

For example, in the AIF j crystal each F is held to AF by two bonds with strength i, and in the SiF molecule it is held to Si by one bond with strength I in each case the sum of the bond strengths equals the negative charge of the fluoride ion.  

Many of the properties of substances can be explained by the consideration of the relative sizes of ions or atoms, as illustrated above. Structural inorganic chemistry is, however, a new subject, and as yet far from precise. You may find it worth while to attempt to explain in terms of structure some of the properties of substances mentioned in later sections of this chapter and in the following chapter, but you must not become discouraged if you are unsuccessful. The fault may lie not with you but with the chemists of the present generation and earlier generations, who have not yet succeeded in the task of developing a really powerful theory of structural inorganic chemistry. If you become a chemist, you yourself may make a major contribution to the solution of this problem. 

The elements of the first group —lithium, sodium, potassium, rubidium, and cesiumt—are soft, silvery-white metals with great chemical reactivity. These metals are excellent conductors of electricity. Some of their physical properties are given in Table 18-1. It can be seen from the table that they melt at low temperatures—four of the five metals melt below the boiling point of water. Lithium, sodium, and potassium are lighter than water. The vapors of the alkali metals are mainly monatomic, with a small concentration of diatomic molecules, such as LL, in which the two atoms are held together by a covalent bond. 

The alkali metals are made by electrolysis of the molten hydroxides or chlorides (Chapter 11). Because of their reactivity, the metals must be kept in an inert atmosphere or under oil. The metals are useful chemical reagents in the laboratory, and they find industrial use (especially sodium) in the manufacture of organic chemicals, dyestuffs, and lead tetraethyl (a. constituent of ethyl gasoline ). Sodium is used in sodium-vapor lamps, and, because of its large heat conductivity, in the stems of valves of 

---

Group I, the alkali metals The alkali metals, lithium, sodium, potassium, rubidium, cesium, and francium, are light metals which are very reactive chemically. Many of their compounds have important uses in industry and in life. The alkali metals and their compounds are discussed in Chapter 9. 

Major uses of the alkali metals and their compounds... 

Write a brief account of the uses of the alkali metals and their compounds, with reference to relevant industrial... 

Other practical applications of the alkali metals and their compounds include sodium and potassium in living systems, lithium as treatment for bipolar disorder (manic depression), elemental sodium and lithium as reducing agents, lithium in a new generation of batteries, cesium in photoelectric devices, potassium-argon dating, and lithium as a source of tritium to fuel the hydrogen economy. 

This process is thermodynamically favorable. It has a Mt of-98.2 kJ-mol and a ACT of-119.2 kJ mor and a AS of 70.5 TmoP -K . The rate of decomposition is dependent on the temperature and concentration of the peroxide, as well as the pH and the presence of impurities and stabilizers. Hydrogen peroxide is incompatible with many substances that catalyse its decomposition, including most of the transition metals and their compounds. Common catalysts include manganese dioxide, silver, and platinum. The same reaction is catalysed by the enzyme catalase, found in the liver, whose main function in the body is the removal of toxic byproducts of metabolism and the reduction of oxidative stress. The decomposition occurs more rapidly in alkali, so acid is often added as a stabilizer. 

Among the alkali metals, Li, Na, K, Rb, and Cs and their alloys have been used as exohedral dopants for Cgo [25, 26], with one electron typically transferred per alkali metal dopant. Although the metal atom diffusion rates appear to be considerably lower, some success has also been achieved with the intercalation of alkaline earth dopants, such as Ca, Sr, and Ba [27, 28, 29], where two electrons per metal atom M are transferred to the Cgo molecules for low concentrations of metal atoms, and less than two electrons per alkaline earth ion for high metal atom concentrations. Since the alkaline earth ions are smaller than the corresponding alkali metals in the same row of the periodic table, the crystal structures formed with alkaline earth doping are often different from those for the alkali metal dopants. Except for the alkali metal and alkaline earth intercalation compounds, few intercalation compounds have been investigated for their physical properties. 

Although the elements tantalum and niobium were discovered more than 200 years ago in the form of oxides, the true beginning of the chemistry of tantalum and niobium was the discovery and investigation of complex fluorotantalates and fluoroniobates of alkali metals. Application of complex fluoride compounds enabled the separation of tantalum and niobium and in fact initiated the development of the industrial production of the metals and their compounds. 

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.). 

Replacement of ethers by thioethers in crown compounds [see, for example (178)] also reduces their affinity for the alkali metals and again leads to a tendency to complex heavy metals such as Ag(i) more strongly (Pedersen, 1971 Frensdorff, 1971). 

The main emphasis was laid, in this initial work, on Haber s catalysts, e.g., osmium and uranium compounds, as well as on a series of iron catalysts. Some other metals and their compounds which we tested are, as we know today, less accessibble to an activation by added substances than iron. Therefore, they showed no improvement or only small positive effects if used in the form of multicomponent catalysts. Finally, the substances which we added to the metal catalysts in this early stage of our work were mostly of the same type as those which had proved to favor the nitride formation, e.g., the flux promoting chlorides, sulfates, and fluorides of the alkali and alkaline earth metals. Again, we know today that just these compounds do not promote, but rather impair the activity of ammonia catalysts. 

The microstructure of the polymer varies little with changing reaction conditions 68,104). The effect of temperature is generally small and the alkali metals or their alkyls normally give the same product. Significant differences in microstructure have been noted between potassium and its alkyls (104) and between two different cesium compounds 88) but these effects are not general and their cause is obscure. A more difficult problem exists in that there is poor agreement between the microstructures reported by different authors for a particular initiator and solvent. Tables 3 and 4 include some of the data given for polyisoprene and polybutadiene. Standard infra-red methods were used for the analysis except... 

The alkaline earth metals are divalent their hydroxides, M(OH)2, are less soluble than those of the alkali metals, but are nevertheless very strongly basic. The compounds of these metals are not so generally soluble as those of the alkali metals, and in particular the carbonates, sulphates, and phosphates are mostly insoluble. 

With the radical controversy solved, Bailey and others set about the detailed investigation of anionic cyclisation as a synthetic method for the formation of five-membered carbocyclic rings, and we shall divide the remainder of this section, which covers work published between 1987 and 2000, into the main classes of compounds produced by the cyclisation cyclopentanes, furans, pyrrolidines, and polycyclic products. It turns out that organolithiums are unique among the alkali metals in their ability to undergo anionic cyclisation to give cyclopentanes, particularly where primary organometallics are concerned.121... 

It has been shown that it is possible to effectively reduce the flammability of many polymeric materials by using metal compounds in very low concentrations. Metals and their compounds may be included in the polymeric macrochains, either coordi-natively bonded to functional groups of the polymer or used as additives. For example optically transparent, low-flammability polycarbonates have been obtained by adding as little as 0.001 to 2 % by weight of alkali or alkaline earth metal sulfonates... 

The sharp distinction between ionic and covalent solids is maintained in a rearrangement of the periodic table of elements made by Pantelides and Harrison (1975). In this table, the alkali metals and some of their neighbors are transferred to the right (see Fig. 2-7). The elements of the carbon column (column 4) and compounds made from elements to either side of that column (such as GaAs or CdS) are covalent solids with tetrahedral structures. Compounds made from elements to either side of the helium column of rare gases (such as KCl or CaO) are ionic compounds with characteristic ionic structures. A few ionic and covalent compounds do not fit this correlation notably, MgO, AgF, AgCl, and AgBr are... 

The preferred alkaline compounds for carrying out my invention are the alkali metal and alkaline earth metal oxides, hydroxides and carbonates, and these compounds are utilized in just sufficient amount to displace the desired amine or amines. It is obvious, of course, that if the mixture of amine salts also contains free mineral acid or an ammonium salt, an additional amoimt of alkali stoichiometrically equivalent to these substances must be added. I have also found that as alkaline reagents for accomplishing this separation it is possible to use other alkylamines or methylamines of different basicity. These amines may be used for displacement together with or in place of the alkalies above mentioned. For example, dimethylamine being more basic than trim-ethylamine may be utilized to displace triethylamine from its hydrohalide salts, when utilized in stoichiometrical proportions. Similarly, diethylamine may be utilized to displace mono and triethylamine from their hydrohalide combinations. 

---