Elements, compounds and experimental techniques

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. 

Analytical techniques used in troubleshooting and formulation experimentation available to the rubber compounder were reviewed [90]. Various textbooks deal with the analysis of rubber and rubber-like polymers [10,38,91]. Forrest [38] has illustrated the use of wet chemistry, spectroscopic, chromatographic, thermal, elemental and microscopy techniques in rubber analysis. 

A number of experimental techniques are carried out in organic chemistry to confirm that the correct compound has been synthesised during a reaction, or to identify unknown compounds. Some of these techniques are laboratory-based and are discussed in the Researching Chemistry section. Organic chemists rely heavily on a number of other techniques to identify compounds. These include elemental microanalysis, mass spectrometry, infrared spectrometry and NMR spectrometry. 

It is not possible to prescribe specific pretreatment procedures here because these can only be decided upon when the system and the purpose of the experiments has been properly defined. However, a wealth of information exist in various biochemical reference books on how to isolate various biological compounds. The recommended techniques and methods could be used as part of the trace element speciation protocol often after slight modification, taking into consideration the following points First, the trace element blank levels have to be low, less than 10% of the total concentration in the sample. Second, the regents used should not interfere with subsequent analytical determinations. Third, the experimental conditions should not deviate markedly from those found in vivo, especially the pH and ionic strength of the medium. 

Early on, gas-phase chemical separations played an important role in the investigation of the chemical properties of transactinide elements. The technique was pioneered by I. Zvara and co-workers at the Dubna laboratory and involved first chemical studies of volatile Rf, Db and Sg halides and/or oxyhalides [73,74,75] see Chapter 7 for a detailed discussion. The experimental set-ups and the techniques involved are presented in Section 4.2. A new technique, named OFGA (On-line Gas chromatography Apparatus), which allowed the a-spectrometric measurement of final products, developed by H.W. Gaggeler and co-workers was then successful in studying volatile transactinide compounds from Rf up to Bh [76,77,78,79], see Chapter 7 for a detailed discussion. In all these... 

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