Single-atom chemistry

The values of absolute hardness, shown in the Tables, are highly satisfactory when compared with the known chemical behaviour of the selected systems. The expected chemical behaviour is well reproduced when the valence shell electrons in the absolute hardness calculation are taken into account. As previously mentioned [3], single atom chemistry is not so significant in terms of Lewis acid-base... 

Before dealing with the ultimate case of single atom chemistry, one has to establish first, the thermodynamical relations with some tens or hundreds of atoms and then extrapolate these concepts to a single atom. Only the equations necessary for the basic understanding of the demonstration are presented in this paragraph. Details of the mathematical treatment can be found in Appendix 1. 

For the development of concepts of kinetics and of thermodynamics, considered in this chapter, the single atom was assumed to be stable. In fact, the probability for a unique atom to exist in specific specie can only be determined in a chemical experiment if the atom is radioactive. Therefore, if the atom is stable or has a large half-life, any radiochemical techniques can be used for single atom chemistry. 

The concept of one-atom-at-a-time chemistry is different from that of a single atom chemistry. The main difference is the time. An observable chemical reaction of a given radio nuclide can be defined with the following temporal quantities ... 

Conclusive Remarks on Fundamental Aspects of Single Atom Chemistry... 

Single atom chemistry is of particular importance if only single atoms are available for chemical studies, as in the case of the heaviest elements. The short-lived isotopes of these elements can only be produced at a rate of one atom at a time, and the investigation of their chemical properties requires special considerations. 

The equilibrium constant K of a chemical reaction A-l-B C-l-Dis given by K = (ac ao)/(aA Ub), where aA,aB,ac, and ao are the chemical activities. However, if only one atom is present, it cannot exist at the same time in fonn of A and C and aA or ac must be zero. Consequently, in single atom chemistry K is no longer defined. The same holds for AG = —RTlnK, the free enthalpy of the reaction. In order to overcome this problem, in single atom chemistry the probabilities of finding the single atom in form of A or C are introduced instead of the chemical activities or concentrations, respectively, and by use of these probabilities equilibrium constants and single particle free enthalpies can be defined. 

R. Guillaumont, J. P. Adloff, A. Peneloux, Kinetic and Thermodynamic Aspects of Tracer Scale and Single Atom Chemistry, Radiochim. Acta 46, 169 (1989)... 

In the literature, there sometimes occur inaccurate statements about the validity of Stirling s approximation in connection with the validity of single atom chemistry. 

Trubert D, Le Naour C (2003) Fundamental aspects of single atom chemistry. In Schadel M (ed) The chemistry of superheavy elements. Kluwer, Dordrecht, p.95... 

Guillaumont, R., Adloff, J.-P., and Peneloux, A. 1989. Kinetic and thermodynamic aspect of tracer-scale and single atom chemistry. Radiochim Acta 46, 169-176. 

Collaboration on an international level is essential in big science. These trends began with work centered at large facilities such as big accelerators but have also penetrated into areas of small science. Research on the chemistry of the heaviest elements concentrated at the few suitable heavy-ion accelerators is an obvious and successful example. Small groups take over at their home institutions a considerable part of the development of fast single-atom chemistry each element and each class of compounds requires a specific approach they test it in model experiments at smaller facilities. Eventually, the external groups and the in-house experimentalists join up at the heavy-ion accelerator to perform the major experiment. 

In this chapter, the special conditions of the synthesis and decay of the transactinides are considered followed by some remarks about performing chemistry with only one atom at a time (referred to therefore as one-atom-at-a-time chemistry or single-atom chemistry). The experimental techniques are outlined, and a description of theoretical predictions and experimental results on the chemistry of Rf, Db, Sg, Bh, Hs, and Cn is given and mutually compared. Perspectives to go beyond 112 are also briefly discussed. 

However, reactions between Ei and E2 can only be observed if the half-life of El is compatible with the time characteristics of the reaction under study. For instance, the time needed to achieve the equilibrium must be shorter than the lifetime of the involved radionuclide. Studies of the chemical properties of SHEs give rise not only to the concept of single-atom chemistry but also to one-atom-at-a-time chemistry. For that purpose, chemical processes with high reaction rates are required. 

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