Chemical separation Single atom chemistry

In recent years predominantly continuous isothermal chromatography has been applied in gas chemical studies of transactinides. This technique offers the possibility to combine a continuous separation of volatile species with an in-situ detection of the products on the basis of single atom counting. To reach this ambitious goal, novel devices have been developed such as the On- Line Gas chemistry Apparatus (OLGA) [10] or, in a modified version, the Heavy Element Volatility Instrument (HEVI) [11] see also Chapter 4. 

The chemistry of superheavy elements always faces a one-atom-at-a-time situation - performing separations and characterizations of an element with single, short-lived atoms establishes one of the most extreme limits in chemistry. While large numbers of atoms and molecules are deeply inherent in the statistical approach to understanding chemical reactions as dynamic, reversible processes Chapter 3 discusses specific aspects how the behavior of single atoms mirrors properties of macro amounts. 

Abstract In this chapter, the chemical properties of the man-made transactinide elements rutherfordium, Rf (element 104), dubnium, Db (element 105), seaborgium, Sg (element 106), bohrium, Bh (element 107), hassium, Hs (element 108), and copernicium, Cn (element 112) are reviewed, and prospects for chemical characterizations of even heavier elements are discussed. The experimental methods to perform rapid chemical separations on the time scale of seconds are presented and comments are given on the special situation with the transactmides where chemistry has to be studied with single atoms. It follows a description of theoretical predictions and selected experimental results on the chemistry of elements 104 through 108, and element 112. 

Repetition Since the moment in time at which a single transactinide atom is synthesized can currently not be determined and chemical procedures often work discontinuously, the chemical separation has to be repeated with a high repetition rate. Thus, thousands of experiments have to be performed. This inevitably led to the construction of highly automated chemistry set-ups. Due to the fact, that the studied transactinide elements as well as the interfering contaminants are radioactive and decay with a certain half-life, also continuously operating chromatography systems were developed. 

Due to the extremely low production rates of transactinides in nuclear fusion reactions, all chemical characterizations are carried out at the single atom level (see chapter Fundamental and Experimental Aspects of Single Atom-at-a-Time Chemistry ). The chemical reaction products are characterized on the basis of their behavior in the separation process or, to be exact, in the gas-phase-adsorption chromatographic process (see Part I of this chapter). In this process the formation probability of defined stable chemical states of transactinides and the subsequent interaction of the formed species with a solid state surface are studied. 

However, Pauli s Nobel Prize-winning work did not provide a solution to the question which I shall call the closing of the periods —that is why the periods end, in the sense of achieving a full-shell configuration, at atomic numbers 2,10, 18, 36, 54, and so forth. This is a separate question from the closing of the shells. For example, if the shells were to fill sequentially, Pauli s scheme would predict that the second period should end with element number 28 or nickel, which of course it does not. Now, this feature is important in chemical education since it implies that quantum mechanics cannot strictly predict where chemical properties recur in the periodic table. It would seem that quantum mechanics does not fully explain the single most important aspect of the periodic table as far as general chemistry is concerned. 

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