Alkali metals Group properties

The niobium-arseitic compounds described here, with novel anionic structures, clearly demonstrate the many possibilities for stractural motifs in this system. Similarly high potential for diverse structures and properties should be expected for the heavier pitictides when combined with other transition metals and the alkali-metal group. 

Tetrahydroborates. The tetrahydroboranes constitute the most commercially important group of boron hydride compounds. Tetrahydroborates of most of the metals have been characterized and their preparations have been reviewed (46). The important commercial tetrahydroborates are those of the alkali metals. Some properties are given in Table 4. 

A column of the periodic table is called a family. Some families have special names. Group IA elements are called alkali metals, group IIA elements are called alkaline earth metals, group VIIA elements are called halogens, and group VIIIA elements are called the noble gases. The group B elements are called transition elements. Elements with atomic numbers from 58 to 71 are called lanthanides, and elements with atomic numbers from 90 to 103 are called actinides. Families have similar chemical and physical properties. For example, the alkali metals are soft metals at room temperature they are shiny, conduct... 

Due to its electron acceptor properties (Section 5.6), Ceo reacts with strong reducing agents (D)to yield salts of general formula [D] +[Ceo]" With the alkali metals (Group... 

According to Mott s rule the miscibility of metals in the liquid state depends on the ratios of atomic sizes, on the vapour pressures and on the electronegativity of the solutes and solvents. The properties last mentioned are close together in the alkali metal group. Differences in the atomic radii, however, cause incomplete miscibility of light and heavy alkali metals. 

Without the overlap of energy bands, the periodic properties of metals could not be explained. In the absence of the d- and p-bands, we would expect the s-band to be half-filled for the alkali metals (group lA) and completely filled for the alkaline-earth metals (group 2A). If that were true, metals like magnesium, calcium, and strontium would not be good electrical and thermal conductors, in disagreement with experimental observations. 

Classically, a base is a substance capable of liberating hydroxide ions, OH , in water solution. Hydroxides of the alkali metals (Group lA) and alkaline earth metals (Group 2A),suchasLiOH, NaOH, KOH, Ca(OH)2,and Ba(OH)2,are the most common inorganic bases. Water solutions of bases are cdlled alkaline solutions or basic solutions. Some of the characteristic properties commonly associated with bases include the following ... 

Section 7.7 The periodic properties of the elements can help us understand Ihe properties of groups of the representative elements. The alkali metals (group lA) are soft metals with low densities and low melting points. They have the lowest ionization energies of the elements. As a result, Ihey are very reactive toward nonmetals, easily losing Iheir outer s electron to form 1+ ions. The alkaline earth metals (group 2A) are harder and more dense and... 

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. 

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. 

The Group 1 elements are soft, low-melting metals which crystallize with bee lattices. All are silvery-white except caesium which is golden yellow "- in fact, caesium is one of only three metallic elements which are intensely coloured, the other two being copper and gold (see also pp. 112, 1177, 1232). Lithium is harder than sodium but softer than lead. Atomic properties are summarized in Table 4.1 and general physical properties are in Table 4.2. Further physical properties of the alkali metals, together with a review of the chemical properties and industrial applications of the metals in the molten state are in ref. 11. 

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