Some Transition Elements

Table 8.3 Stoichiometries of some transition element carbides...

Selective extraction experiments were then performed to see transference of some transition elements (Cu ", Ni ", Co ", and Fe " ) from the aqueous phase to the organic phase by the synthesized polymeric calixarenes. Phase-transfer studies in water-chloroform confirmed that polymer 2b and 3b were Fe ion-selective as was its monomer (1). Extraction of Fe " cation with 2b and 3b was observed to be maximum at pH 5.4. Only trace amounts of other metal cations such as Cu, Ni ", and Co " were transferred from the aqueous to the organic phase (Table 3). Furthermore, the extracted quantities of these cations remained unaffected with increasing pH. The effect of pH on the extraction of 3b was lower and 56% extraction was accomplished even at pH 2.2. The extraction experiments were also performed with calix[4]arene (1) the ratio was 8.4% at pH 2.2. The polymeric calix[4]arenes were selective to extract Fe " from an aqueous solution, which contained Cu +, Ni, Co ", and Fe " cations, and it was observed that the... 

This statement applies to the representative elements. Multiple bonding is also important for some transition elements. For a review of metal-metal multiple bonds, see Cotton, F.A. J. Chem. Educ., 1983, 60, 713. 

The Borides of Some Transition Elements. Acta chem. scand. 4, 209 (1950). 

Hoins, U. Charlet, L. Sticher, H. (1993) Ligand effect on the adsorption of heavy metals. The sulphate-cadmium goethite case. Water, Air, Soil Pollution 68 241-255 Holm, G. (1985) Substitution selectivity of some transition elements (Cr, Mn, Co, Ni, Cu, Zn) during formation of P-FeOOH. Geologiska Foreningsi Stockholm Forhandlingar 107 297-300... 

Enthalpies of Hydration of Some Transition Element Cations... 

Table 7.4 Standard Gibbs energies of formation and standard enthalpies of formation of some transition element monatomic cations and that of Ga3+ at 298 K (in kJ mol 1) ...

Soft metallic elements such as Al, In, Pb, Hg, Sn, Zn, Tl, Ga, Cd, V and Nb are type I superconductors. Alloys and chemical compounds such as Nb3Sn, V3Ga, and lZa3In, and some transition elements, are type II superconductors. Type II substances generally have a higher Tc than do type I superconductors. The recently discovered transition metal oxide superconductors have generated intense interest because they are type II superconductors with very high transition temperatures. Table 13.1 summarizes Tc for selected superconductors. 

The first chapter will start with a discussion of the methods being employed to elucidate the chemical and structural possibilities of metal nucleic acid interactions. This will be followed by specific reactions of some transition elements with the free bases, the nucleosides, the nucleotides and finally the polymer nucleotides. 

The X-ray fluorescence method normally affords adequate sensitivity for most elements of interest. However, overlapping X-ray emission lines may limit the use of this method. For instance, a lead line seriously interferes in the analysis of arsenic, and some transition elements may have overlapping spectra. Because of difficulties in calibration for thick samples, particle deposits on filters must be kept to minimal values of mass per unit area. For urban atmospheres, sampling is limited to about a one to six-hour period by the combination of detection limit and sample loading requirements. The elimination of sample preparation makes this method attractive despite relatively high capital costs. Sample mass loading limitations are even more severe for X-ray methods using particle excitation, such as with protons, than with the photon excitation fluorescence technique. 

Table 3.1 Electron Orbital Assignments for Some Transition Elements...

Physical properties of some transition element nuclei... 

The high affinity of 1 for some transition elements suggests the possibility of using it for selective removal of toxic heavy metals from contaminated environmental systems and biological liquors. This point is illustrated by the uptake of Pb, Cu ", Cd " and Hg ions in groundwater simulant (Fig. 7a) and Cu and Cd ions uptake in the Ringer solution (Fig. 7b). 

Table 5.4 shows the chemical names of some transition element ions. When you do Practice Problems 5 and 6, you will become familiar with these names. Note in the photos accompanying the table that the different ions of a transition element often form compounds of different colors. 

You ve learned that some transition elements are important in the production of steel because they impart particular properties to the steel. In addition, most of the transition elements, because of their individual properties, have a variety of uses in the production of the infrastructure and consumer products of the modern world. 

Bonatti, E., Fisher, D. E., Joensuu, O., and Rydell, H. S. (1971). Postdepositional mobility of some transition elements, phosphorous, uranium and thorium in deep sea sediments. Geochim. Cosmochim. Acta 35, 189-201. 

Some transition elements are important in biochemical reactions. 

The solubility of some transition elements in liquid lithium is found to be influenced by the nitrogen content of the alkali metal. Solubilities of elements can only be measured in very pure lithium. Nitrogen contents of >50 wppm increase the saturation concentrations. The presence of nitrogen, however, does not evidently change the values of the free enthalpy of solution. 

FIGURE 8.10 Configurations of some transition elements, extracted from more complete tables of configurations. J.D. Main Smith, Chemistry and Atomic Structure, Ernest Benn Ltd., London, 1924, p. 196. 

The d area of the periodic table contains the transition elements (Figure 3.10) in which the distinguishing electron is found in a subshell. Some transition elements are used for everyday applications (I Figure 3.11). Inner-transition elements are those in the/area of the periodic table, and the distinguishing electron is found in an/subsheU. 

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