3rd group metals

The 3rd group metals a summary of their atomic and physical properties 5.5.5.1 The rare earth metals. A summary of the main atomic and physical properties of the rare earth metals has been collected in Tables 5.11-5.13. To complete the information and the presentation of the entire series of lanthanides the data relevant to Eu and Yb have been included in these tables. However, the same data are reported also in Table 5.7 in comparison with those of the other typical divalent metals (the alkaline earth metals). As for the properties of liquid rare earth metals and alloys see Van Zytveld (1989). 

The 3rd group metals remarks about their general chemical properties and reactivity... 

R-Me andAn-Me alloys. A summary of the alloying behaviour of the 3rd group metals with special attention to the compound formation capability is shown in Fig. 5.14. For the lanthanides two examples are shown La and Gd, the behaviour of which may be considered to give a reasonable first approximation description of the general intermetallic reactivity pattern of the lanthanides. For the actinides the reactivity schemes are shown for Th, U and Pu for the alloys of the other metals of this series, only a few data are available. 

Figure 5.14. Compound formation capability in the binary alloys of Sc, Y, light trivalent lanthanides (as exemplified by La), heavy trivalent lanthanides (exemplified by Gd) and of the actinides (exemplified by Th, U and Pu). The different partners of the 3rd group metals are identified by their position in the Periodic Table. Notice that a sharper subdivision between compound-forming and not forming metals will result from a shifting of Be and Mg from their position in the 2nd group towards the 12th group (see 5.12.3). The behaviour of the divalent lanthanides Eu and Yb is shown in Fig. 5.7 where it is compared with that of the alkaline earth metals.

As a conclusive remark about this topic we underline that the trend of the inter-metallic reactivity described for the 3rd group metals and the phase stability scheme shown may be considered an example of a systematic alloying behaviour generally presented by several metals of the first groups of the Periodic Table. The reader may indeed compare the patterns here reported in Fig. 5.14 with those previously presented for the 2nd group metals and with those shown in the next paragraphs for the metals of the 4th group. 

Remarks on the crystal chemistry of the alloys of the 3rd group metals. A large number of intermediate phases have been identified in the binary alloys formed by the rare earth metals and actinides with several elements. A short illustrative list is shown in Tables 5.19 and 5.20. Compounds of a few selected rare earth metals and actinides have been considered in order to show some frequent stoichiometries and crystal structure types. The existence of a number of analogies among the different metals considered and the formation of some isostructural series of compounds may be noticed. 

Amundsen, A. R. Stern, E. W. Platinum-group metals, compounds. In Kirk-Othmer Encyclopedia Chem. Technol., 3rd ed. Grayson, M., Eckroth, D., Eds. Wiley New York, 1982 Vol. 18, p 254. 

The 3rd group of the Periodic Table (the 1st column within the block of the transition elements) contains the metals scandium, yttrium, lanthanum, and actinium. Lanthanum (atomic number 57) may be considered the earliest member of the family of metals, called lanthanides (general symbol Ln), forming, inside the principal transition series, an inner transition series (up to atomic number 71). Scandium and yttrium together with the lanthanides are also called rare earth metals (general symbol R). 

Further remarks on the actinide alloys. Among the different alloys of the actinides especially those formed by Th, U and Pu are well known. The compound formation patterns of these metals are shown in Fig. 5.14 where a comparison is made with the behaviour of the other metals of the 3rd group, that is, the rare earth metals (Sc, Y, lanthanides). It is worth presenting here a few more details about the alloying behaviour of these actinides. 

A. Fumagalli, R. Della Pergola, L. Garlaschelli, and A. Sironi, 3rd International Conference on the Chemistry of the Platinum Group Metals, Sheffield, July 12-17, 1987. 

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