Alkali metals potassium, rubidium, sodium

The following supplements have been issued Volume 2, Supplement 1 (originally described as Supplement 2, part 1), The Halogens Supplement 2, The Alkali Metals Lithium, sodium Supplement 3, The Alkali Metals Potassium, rubidium, caesium, francium, and the radiochemistry of the alkali metals. References are given at the end of each section in numerical order according to their position in the text and bearing the CA reference. 

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,... 

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)... 

Sodium and potassium are among the alkali metals lithium, Li sodium, Na potassium, K rubidium, Rb and cesium, Cs. All these elements are metals and all react with water, explosively, with the exception of lithium. 

Group 1A—Alkali metals Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs) are shiny, soft metals. All react rapidly (often violently) with water to form products that are highly alkaline, or basic—hence the name alkali metals. Because of their high reactivity, the alkali metals are never found in nature in the pure state but only in combination with other elements. 

Octaethyl-l,l -biarsole/stibole 19 (E = As, Sb) can be reduced by alkali metals such as sodium, potassium, rubidium, and cesium in DME or TMEDA yielding metal arsolides 69 (E = As) or stibolides 69 (E = Sb) with corresponding counterion and solvents being bidentate co-ligands (Equation 11) <20040M3417>. 

Because of their metallic and alkaline properties, potassium and especially sodium are widely used in a variety of industrial processes both as metals and as compounds with various other elements. Lithium is rarely used, but does find application in lightweight alloys with magnesium. Rubidium and cesium are not commonly utilized industrially, except for some applications in electronics. Sodium and potassium are essential for life, sodium being the principal extracellular and potassium the major intracellular monovalent cations. The other alkali metals have no essential biological role, see ALSO Bunsen, Robert Cesium Davy, Humphry Francium Lithium Mendeleev, Dimitri Potassium Rubidium Sodium. 

The alkali metals include lithium, sodium, potassium, rubidium and caesium. 

Solubilities of transition metals in heavy alkali metals are of the same order as in sodium. Very few data exist on the liquid metals potassium, rubidium, and cesium. 

Alkali metals are principally similar in their ability to form compounds with non-metals and to dissolve these compounds. There are, however, some differences between light alkali metals, lithium and sodium, and their heavier homologues, potassium, rubidium, and cesium. The extreme position of lithium is due to its very high affinity to form salts and to its similarity to the alkaline earth metals. Lithium oxide and hydride are the alkali compounds of highest stability. Lithium nitride is the only stable compound of this class, and probably, lithium acetylide is also the only stable alkali carbon compound, which occurs in contact with excess alkali metal. 

Group I. The alkalis metals Lithium 7 Sodium 23, Potassium 39, Rubidium 85, Cesium 123, Thallium 204. The relationship between the equivalents of this group can be presented as in Table 1.3. 

The alkali metals are represented by the six chemical elements of group 1A(1) of Mendeleev s periodic chart. These six elements are, in order of increasing atomic number, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The name alkali metals comes from the fact that they form strong alkaline hydroxides (i.e., MOH, with M = Li, Na, K, etc.) when they combine with water (i.e., strong bases capable of neutralizing acids). The only members of the alkali metal family that are relatively abundant in the Earth s crust are sodium and potassium. Among the alkali metals only lithium, sodium, and, to a lesser extent, potassium are widely used in industrial applications. Hence, only these three metals will be reviewed in detail in this chapter. Nevertheless, a short description of the main properties and industrial uses of the last three alkali metals (i.e., Rb, Cs, and Fr) will be presented at the end of the section. Some physical, mechanical, thermal, electrical, and optical properties of the five chief alkali metals (except francium, which is radioactive with a short half-life) are listed in Table 4.1. 

The elements in group 1 are hydrogen and the alkali metals lithium li, sodium Na, potassium K, rubidium Rb, cesium Cs and francium Fr. The last one, francium, was discovered in 1939 by Marguerite Percy in Paris. It will be described in Chapter 52 The Radioactive Elements. The others wiU be treated in this and the following two chapters. 

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). 

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. 

Rubidium metal is commeicially available in essentially two grades, 99 + % and 99.9 + %. The main impurities ate other alkali metals. Rubidium compounds are available in a variety of grades from 99% to 99.99 + %. Manufacturers and suppliers of mbidium metal and mbidium compounds usually supply a complete certificate of analysis upon request. Analyses of metal impurities in mbidium compounds are determined by atomic absorption or inductive coupled plasma spectroscopy (icp). Other metallic impurities, such as sodium and potassium, are determined by atomic absorption or emission spectrograph. For analysis, mbidium metal is converted to a compound such as mbidium chloride. 

The alkali metals form a homogeneous group of extremely reactive elements which illustrate well the similarities and trends to be expected from the periodic classification, as discussed in Chapter 2. Their physical and chemical properties are readily interpreted in terms of their simple electronic configuration, ns, and for this reason they have been extensively studied by the full range of experimental and theoretical techniques. Compounds of sodium and potassium have been known from ancient times and both elements are essential for animal life. They are also major items of trade, commerce and chemical industry. Lithium was first recognized as a separate element at the beginning of the nineteenth eentury but did not assume major industrial importance until about 40 y ago. Rubidium and caesium are of considerable academic interest but so far have few industrial applications. Francium, the elusive element 87, has only fleeting existence in nature due to its very short radioactive half-life, and this delayed its discovery until 1939. 

Mercury forms amalgams with numerous metals. Usually, this conversion is very exothermic, therefore it can present risks the reaction can become violent if a metai is added too quickly into mercury. Accidents have been described with caicium (at 390°C), aluminium, alkali metals (lithium, sodium, potassium, rubidium) and cerium. Some of these alloys are very inflammable, in particular the Hg-Zn amalgam. 

Rubidium is a typical but very reactive member of the series of alkali metals.lt is appreciably more reactive than potassium, but less so than caesium, and so would be expected to react more violently with those materials that are hazardous with potassium or sodium. Rubidium ignites on exposure to air or dry oxygen, largely forming the oxide. 

The collected papers of a symposium at Dallas, April 1956, cover all aspects of the handling, use and hazards of lithium, sodium, potassium, their alloys, oxides and hydrides, in 19 chapters [1], Interaction of all 5 alkali metals with water under various circumstances has been discussed comparatively [2], In a monograph covering properties, preparation, handling and applications of the enhanced reactivity of metals dispersed finely in hydrocarbon diluents, the hazardous nature of potassium dispersions, and especially of rubidium and caesium dispersions is stressed [3], Alkaline-earth metal dispersions are of relatively low hazard. Safety practices for small-scale storage, handling, heating and reactions of lithium potassium and sodium with water are reviewed [4],... 

Stereospecific ketone reduction was also observed (Giordano et al. 1985) with potassium, rubidium, and cesium (but not with sodium) in tertiary alcohols (but not in secondary or primary alcohols). The undesirable dimerization probably proceeds more readily in the case of sodium. Tertiary alcohols are simply more acidic than primary or secondary alcohols. It is reasonable to point out that the ketone-to-alcohol reduction of 3a-hydroxy-7-oxo-5p-cholic acid by alkali metals is a key step in the industrial synthesis of 3a,7p-dihydroxy-5p-cholic acid. 

All of the alkali metals are electropositive and have an oxidation state of 1 and form cations (positively charged ions) by either giving up or sharing their single valence electron. The other elements of group 1 are lithium (jLi), sodium (jjNa), potassium (j K), rubidium (j Rb), cesium (jjCs), and francium (g Fr). Following are some characteristics of the group 1 alkali metals ... 

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