Reactivity of element

The chemistry of superheavy elements has made some considerable progress in the last decade [457]. As the recently synthesized elements with nuclear charge 112 (eka-Hg), 114 (eka-Pb) and 118 (eka-Rn) are predicted to be chemically quite inert [458], experiments on these elements focus on adsorption studies on metal surfaces like gold [459]. DFT calculations predict that the equilibrium adsorption temperature for element 112 is predicted 100 °C below that of Hg, and the reactivity of element 112 is expected to be somewhere between those of Hg and Rn [460, 461]. This is somewhat in contradiction to recent experiments [459], and DFT may not be able to simulate accurately the physisorption of element 112 on gold. More accurate wavefunction based methods are needed to clarify this situation. Similar experiments are planned for element 114. 

The lower reactivity of elemental tellurium has prevented the general exploitation of this approach for polytellurido complexes. 

For chalcogenide thin films it is possible to use elemental S, Se, Te as precursors provided that the other source is a volatile and reactive metal. ZnS deposition using elemental zinc and sulphur was the first ALD process developed [4]. Therefore for precursors other than metals, the reactivity of elemental chalcogens is not sufficient. For other precursor types, including halides, 6-diketonates and organometalHcs, simple hydrides, such as H2S, H2Se and H2Te, have typically been used as a second precursor. 

A very diversified art has been developed utilizing certain metal fluorides, inorganic fluorides, halogen fluoride, or electrochemical cells as media for fluorination. The more important approaches which have been developed to produce fluorocarbons and yet avoid the great reactivity of elemental fluorine are ... 

In group 18, noble gases become less inert with increasing Z. A relatively high reactivity of element 118 was foreseen by earlier considerations [154,12], Element 118 was predicted to be the most electropositive in the group and to be able to form a 118-C1 bond. 

Figure 5.5 The Reactivity Series chart is used to compare the reactivity of elements. Elements higher on the chart are more reactive than elements lower on the chart. For example, sodium is higher on the chart than lead because sodium is more reactive than lead.

Down the group, reactivity reflects the decrease in electronegativity, but the exceptional reactivity of elemental F2 is also related to the weakness of the F—F bond. The F—F bond is short, but F is so small that lone pairs on one atom repel those on the other, which weakens the bond (Figure 14.17). As a result, F2 reacts with every element (except He, Ne, and Ar), in many cases, explosively. 

Also included in Table 1 is an estimate of the average oceanic residence times for these elements. A shorter residence time indicates a more rapid removal from the oceans. Another way to estimate the relative reactivity of elements with crustal sources is to compare their sea water concentrations with their abundance in the Earth s crust. This is presented in Table 2 (with a normalization to aluminum) and is shown graphically in Figure 1. If variations in the composition of continental materials and differences in the solubility of the elements from these materials are not too great, then to a first approximation the... 

There have been a number of theories regarding the geochemical basis for the relative reactivity of elements, and the factors that control their sea water concentrations. One theory is that the differential reactivity of strongly hydrolyzed elements may be related to the charge of the hydroxide species that dominates. Those that exist in an anionic form may be less particle-reactive (i.e., they may be less likely... 

Despite the. similarities in the chemical reactivity of elements in the lanthanide series, their abundances in Earth s crust vary by two orders of magnitude. This graph shows the relative abundance as a function of atomic number. How do you explain the sawtooth variation across the series ... 

The comparatively low bond enthalpy of F2 (155 kj/mol) accounts in part for the extreme reactivity of elemental fluorine. Because of its high reactivity, F2 is difficult to work with. Certain metals, such as copper and nickel, can be used to contain F2 because their surfaces form a protective coating of metal fluoride. Chlorine and the heavier halogens are also reactive, although less so than fluorine. 

Group VI.—Sulphur general. The reactivity of elemental sulphur, in the forms Se, S7, Ss, and S12, has been probed by a study of its reaction with o-tolyldiphenylphosphine to give the sulphide S=PPh2(o-tolyl). These reactions, conducted in solution in carbon disulphide, are second-order. Rates and activation parameters were determined the highest activation enthalpy was for... 

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