Caesium physical properties

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. 

Caesium is a metal in Group I of the Periodic Table, a State two physical properties of caesium. [2]... 

Physical Properties.—Lithium is a white metal with silver-like lustre. It remains untarnished in dry air,12 but a freshly cut surface develops a yellow tinge if moisture is present. In extremely thin layers it is translucent, the transmitted light having a dark, reddish-browm colour.13 It is harder than caesium, rubidium, sodium, or potassium, but softer than lead, the degree of hardness on Rydberg s14 scale being 0 6. In ductility it resembles lead, and can be drawn into wire or rolled into thin... 

Physical Properties.—Rubidium is a silver-like metal of lustrous appearance, but rapidly tarnishes through atmospheric oxidation. It is the softest metal, except caesium, its hardness on Rydberg s scale being... 

One of the reasons why physical properties of rare-earth mixtures sometimes looked confusing was that some measured quantities are not at aU proportional to the concentration of the individual constituents. Sir William Crookes was a most extraordinary scientist, who also discovered thallium by flame emission spectra (as Bunsen and Kirchhoff did in the case of rubidium and caesium), but for our purposes Iris main... 

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. 

Considering adsorption as the first step in catalysis, both physical and chemical adsorption has been observed with intercalates. Watanabe et a/. have shown that selective adsorption based on molecular size occurs with potassium-, rubidium-, and caesium-graphite. The molecular sieve properties are not as distinctive as in zeolites, as a result of the comparatively easy expandability of the layers. Once the gas enters the layers, both chemisorption and chemical reaction is possible. Therefore, for example, adsorption... 

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