The Lanthanide and Actinide Elements

The characteristic oxidation state of the lanthanide elements is 4-3. The universal preference for this oxidation stale together with the notable similarity in size led to great difficulties in the separation of these elements prior to the development of 

Oxidation states higher than + 3 are exhibited by Ce, Pr, and Tb, but only Ce is stable (kinetically) in water. It is a very strong oxidizing agent in aqueous solution ( ° = 1.74 V) and is used as a volumetric standard in redox titrations. Some of its salts (e.g., cerium(lV) ammonium nitrate, eerium(IV) sulfate] find application in 

Corbett. J. D. In ScUd Suue Cfcemino - A Contempora y Overview Hok, S. L. Mislein. J. B. Robbins. M.. Eds. Advances in Chenistry 186 American Chemical Soddy WMhinglon DC, 1990 Cluyiter 18. 

The aqueous chemistry of the -t-3 and 4-4 actinide ions b complicated by their tendency to hydrolyze and polymerize. Higher oxidation states are represented by stable actinyl ions (e ., MOf. MO. and MOj ). 

The Lanthanide A.s a consequence of the poor shielding of the and 5/ electrons, there is a steady 

The ability of mercury lo form an Hg—Hgbond (cadmium to a much less extent) plus a greater tendency to form coordination compounds compared to the other members of the group increases the complexity of its Latimer diagram somewhat, but not much. Its electrochemistry is straightforward, with both mercuryil) and mer-cury(ll) being stable in aqueous solution. 

This section includes the chemistry of the elements La to Lu. and Ac to Lr. In addition, some speculations are made concerning heavier elements that may be synthesized in the future. 

In many ways the chemical properties of the lanthanides are repeated by the actinides. Much use of litis similarity was made during the early work on the chemistry of the synthetic actinides. Given that these elements were often handled in very small quantities and are radioactive, prediction of their propenies by analogy lo the lanthanide series proved very helpful. )u the other hand, it should not be thought that the actinide series is merely a replay of the lanthanides. There arc several significant differences between the two scries related principally lo the differences between the 4/ and 3/ orbitals. 

37 Compare the discussion of a simitar problem id versus s urhiialsi in transition metals. Chapter 2. 

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There is no single best form of the periodic table since the choice depends on the purpose for which the table is used. Some forms emphasize chemical relations and valence, whereas others stress the electronic configuration of the elements or the dependence of the periods on the shells and subshells of the atomic structure. The most convenient form for our purpose is the so-called long form with separate panels for the lanthanide and actinide elements (see inside front cover). There has been a lively debate during the past decade as to the best numbering system to be used for the individual... 

Unsubstituted bisphthalocyanines 2 are formed in the presence of several elements which exist in a stable oxidation state of + III or +IV such as titanium, zirconium, hafnium, indium and most of the lanthanide and actinide elements. 

F. T. Edelmann, Scandium, yttrium and the lanthanide and actinide elements, excluding their zero oxidation state complexes in Comprehensive Organometallic Chemistry II (eds. E. W. Abel, EG. A. Stone and G. Wilkinson), Elsevier, Oxford, 1995, vol. 4 (ed.M.F. Lappert), ch. 2. 

The lower half of most modern periodic tables contains two rows that seem to float apart from the rest of the elements. These two rows are the lanthanides and actinides. By atomic number, they should fall into Periods 6 and 7 of the table. Some extra-long tables do squeeze them into these periods. But the lanthanide and actinide elements have a few special features that truly set them apart from the rest of the transition metals. 

The lanthanide and actinide elements are located at the bottom of the periodic table in two rows separate from the rest of the elements. By atomic number, they should be located in Periods 6 and 7, but they have special properties that distinguish them from elements in those periods. Lanthanides are very similar to each other and have some industrial uses. Many of the actinides were discovered as part of the first atomic bomb experiments. They are highly radioactive and have few uses. The transuranium elements were mostly created in the laboratory and are very short-lived. 

Most ionic halides dissolve in water to give hydrated metal ions and halide ions. However, the lanthanide and actinide elements in the +3 and +4 oxidation states form fluorides insoluble in water. Fluorides of Li, Ca, Sr, and Ba also are sparingly soluble, the lithium compound being precipitated by ammonium fluoride. Lead gives a sparingly soluble salt PbCIF, which can be used for gravimetric determination of F . The chlorides, bromides, and iodides of Ag1, Cu1, Hg1, and Pbn are also quite insoluble. The solubility through a series of mainly ionic halides of a... 

There have been no reports of SO2 insertion into a metal-carbon bond of the lanthanide and actinide elements. 

F. T. Edelmann, Scandium, Yttrium, and the Lanthanide and Actinide Elements, Excluding their Zero Oxidation State Complexes, in Comprehensive Organometallic Chemistry IF, eds. F. G. A. Stone, G. Wilkinson, and E. W. Abel, Pergamon Press, Oxford, 1995, Vol. 4, Chap. 2 p. 11. 

The Chemistry of the Heavier Transition Metals 587 Oxidation States and EMFs of Groups ]-12 588 The Lanthanide and Actinide Elements 599 Coordination Chemistry 608 The Transactinide Elements 613... 

How do the electron configurations of the lanthanide and actinide elements differ from the electron configurations of the other transition metals ... 

If we consider the vertical columns instead of the horizontal rows, we find elements with similar chemical properties listed one below the other. Group I, for example, includes hydrogen and the alkali metals like lithium and sodium. Group III includes scandium, yttrium and all the lanthanide and actinide elements. 

Most of the lanthanide and actinide elements, as well as the group III transition metals, combine with nitrogen to form hard materials with the roeksalt structure, although some of them are slightly nitrogen deficient [217. 218, 219. 220 j. Their magnetic behavior has been studied extensively, for example by neutron diffraction [221]. Brooks has calculated the electronic structures of the actinides with the roeksalt structure [222], In addition, most lanthanides and actinides form oxynitrides [223, 224], and their ferromagnetic transition temperatures can thus be tailored [225, 226],... 

The representative elements The transition elements The lanthanide and actinide elements ... 

The lanthanide and actinide elements are omitted. For these elements see table 2.04... 

An alternative and in some respects more convenient form of the Periodic Table, from which the lanthanide and actinide elements have been omitted, is given in table 2.05. 

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