Lanthanide elements from

The very slight differences that do exist among these elements are due to small changes in size brought about by increase of nuclear charge. The separation of the lanthanide elements from each other is based upon clever exploitation of these slight differences in properties. Table 23-1 shows a comparison of some of the properties of the various lanthanide elements. As can be seen, +3 is the common oxidation number and is most characteristic of the chemistry of these elements. Another thing to note is the steady decrease in... 

SANEX [Selective ActiNide Extraction] A process for removing lanthanide elements from actinides in the Purex process. Not yet fully developed. The name is used also for a range of toiletries. 

In the sixth period, the filling of the Af orbitals (and the generation of the -block elements) begins as the rare-earth (lanthanide) elements from lanthanum to ytterbium are reached. The configurations determined from calculations and experiment can be recalled as needed by assuming that the orbitals are filled in the sequence Is— 2s—— 3s— 3p— 4s — 3d— Ap— Ss— Ad— Sp— hs— Af—ySd— Gp— Is Sf Gd. The energies of the 4f, 5d, and 6s orbitals are comparable over much of the sixth period, and thus their order of filling is erratic. 

Feber and Herrick have used experimental, and in some instances predicted, energy-level data for the calculation of the free energy and enthalpy functions , entropy, and heat capacity of the gaseous monatomic lanthanide elements from cerium to lutetium and the gaseous monatomic actinide elements from thorium to curium over the temperature range 100 to 6000 K. 

The only transplutonium sulfate complex elucidated thus far is Am2(S04,)3-8H20 [433]. Since the Am " ion is about the same size as the Th " and ions, it is not surprising that it has the same eight-fold coordination as the hydrated and basic sulfates discussed above (Fig. 20.13). In this compound the Am ion is coordinated by four sulfate oxygen atoms and four water molecules. The same structure exists for a range of lanthanide elements from Pr to Sm. A different structure, involving nine-fold coordination of the metal, is... 

Figure 5 4f5d 6s -> 4f+ 6s excitation energies of the lanthanide elements from nonrelativistic Hartree-Fock (nrel) and scalar-relativistic Wood-Boring (rel) calculations in comparison with experimental data (exp) ... 

Reference has been made already to the existence of a set of inner transition elements, following lanthanum, in which the quantum level being filled is neither the outer quantum level nor the penultimate level, but the next inner. These elements, together with yttrium (a transition metal), were called the rare earths , since they occurred in uncommon mixtures of what were believed to be earths or oxides. With the recognition of their special structure, the elements from lanthanum to lutetium were re-named the lanthanons or lanthanides. They resemble one another very closely, so much so that their separation presented a major problem, since all their compounds are very much alike. They exhibit oxidation state -i-3 and show in this state predominantly ionic characteristics—the ions. 

It is easy to reduce anhydrous rare-earth hatides to the metal by reaction of mote electropositive metals such as calcium, lithium, sodium, potassium, and aluminum. Electrolytic reduction is an alternative in the production of the light lanthanide metals, including didymium, a Nd—Pt mixture. The rare-earth metals have a great affinity for oxygen, sulfur, nitrogen, carbon, silicon, boron, phosphoms, and hydrogen at elevated temperature and remove these elements from most other metals. 

Cerium [7440-45-17, Ce, at no. 58, is the most abundant member of the series of elements known as lanthanides. Lanthanide (Ln) is a collective name for the fifteen elements from at no. 57 (La) to 71 (Lu), also called the 4f elements. Rare-earth (RE) metal is the collective name for elements 21 (Sc), 39 (Y), plus 57 (La) to 71 (Lu). The label /, /is used herein for elements having atomic numbers from 57 to and the label heavj for numbers - 64 to 71. 

The actinides ( actinons or actinoids ) are the fourteen elements from thorium to lawren-cium inclusive, which follow actinium in the periodic table. They are analogous to the lanthanides and result from the filling of the 5f orbitals, as the lanthanides result from the filling of the 4f. The position of actinium, like that of lanthanum, is somewhat equivocal and, although not itself an actinide, it is often included with them for comparative purposes. 

Lanthanides Elements 57 (La) through 70 (Yb) in the periodic table, 146 Lanthanum, 147 Laser fusion, 528 Lattices in ionic crystals, 249 Lavoisier, Antoine, 14 Law of conservation of energy A natural law stating that energy can neither be created nor destroyed it can only be converted from one form to another, 214... 

A remarkable variety of compounds in the Ca-(B,C,N) system has opened a window for research in related fields. With the elements boron, carbon and nitrogen, substance classes such as borocarbides, boronitrides, and carbonitrides can be considered to contain anionic derivatives of binary compounds B4C, BN, and C3N4. Until now, most compounds in these substance classes have been considered to contain alkali, alkaline-earth, or lanthanide elements. Lanthanide borocarbides are known from the work of Bauer [1]. Lanthanide boronitrides represent a younger family of compounds, also assigned as nitridoborates [2] following the nomenclature of oxoborates. 

As nitridoborates are known as A3(BN2) for alkaline elements (A = Li, Na) and as AE3(BN2)2 for alkaline-earth elements (AE = Ca, Sr, Ba) it would be interesting to find methods for the synthesis of nitridoborates of transition or lanthanide elements. Can they be made straightforward Hke Ii3(BN2) and AE3(BN2)2 from metal nitrides and layer-like a-BN, or do they require new preparative strategies - if they can be made at all ... 

The rare earth elements (R) are those from atomic numbers 57-71, emanating as a particular series from the parent element lanthanum (atomic no. 57). The set of 14 elements from cerium (58) through lutetium (71) inclusive are commonly known as the lanthanoid (or lanthanide Ln) series. The rare earths form a bridge at the... 

Quaternary chalcogenides of the type A Ln M X, containing three metal elements from different blocks of the Periodic Table (A is an alkali or alkaline earth metal, Ln is an /-block lanthanide or scandium, M is a p-block main group or a r/-block transition metal, and X is S or Se) are also known [65]. 

The curves in Figure 10 were drawn from a composite of many observations made in the course of metabolic studies including radioisotopes of yttrium and the 14 lanthanide elements administered as chlorides. These experiments were performed at the Crocker Laboratory, University of California, in the years 1943 to 1957 under the general direction of J. G. Hamilton, K. G. Scott, and P. W. Durbin. Some of the information was presented in Laboratory Progress Reports, but much is unpublished. 

---