Lanthanide elements oxides

Table 30.1 The discovery of the oxides of Group 3 and the lanthanide elements ...

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... 

The most important minerals of the lanthanide elements are monazite (phosphates of La, Ce, Pr, Nd and Sm, as well as thorium oxide) plus cerite and gadolinite (silicates of these elements). Separation is difficult because of the chemical similarity of the lanthanides. Fractional crystallization, complex formation, and selective adsorption and elution using an ion exchange resin (chromatography) are the most successful methods. 

Lanthanide elements, 411, 389 contraction, 413 electron configurations, 415 occurrence and preparation, 413 oxidation numbers, 414 properties, 412 Lanthanum... 

Unusual oxidation states of some actinide and lanthanide elements. L. B. Asprey and B. B. Cunningham, Prog. Inorg. Chem., 1960, 2, 267-302 (245). 

Recent advances in the chemistry of the less common oxidation states of the lanthanide elements. D. A. Johnson, Adv. Inorg. Chem. Radiochem., 1977, 20, 1-133 (599). 

Recent Advances in the Chemistry of the Less-Common Oxidation States of the Lanthanide Elements D. A. Johnson... 

A predominant feature of the atomic structure of the lanthanide group is the sequential addition of 14 electrons to the 4f subshell (Table 1). The /"electrons do not participate in bond formation and in ordinary aqueous solutions all of the lanthanides exhibit a principal (III) state. The common (III) state confers a similarity in chemical properties to all lanthanide elements. Some of the lanthanides can also exist in the (II) state (Nd, Sm, Eu, Tm, Yh) or in the (IV) state (Ce, Pr, Nd, Tb, Dy). Except for Ce(IV), Eu(II), and Yb(II), these unusual lanthanide oxidation states can only be prepared under drastic redox pressure and temperature conditions, and they are not stable in aqueous solutions. Cerium (IV) is a strong oxidizing agent... 

Table 1—Oxidation states, electronic configurations, and radii of the (III) ion of the lanthanide elements and yttrium...

Asprey, L. B. and Cunningham, B. B., Unusual Oxidation States of Some Actinide and Lanthanide Elements. 2 267... 

Americium may be separated from other elements, particularly from the lanthanides or other actinide elements, by techniques involving oxidation, ion exchange and solvent extraction. One oxidation method involves precipitation of the metal in its trivalent state as oxalate (controlled precipitation). Alternatively, it may be separated by precipitating out lanthanide elements as fluorosilicates leaving americium in the solution. Americium may also he oxidized from trivalent to pentavalent state by hypochlorite in potassium carbonate solution. The product potassium americium (V) carbonate precipitates out. Curium and rare earth metals remain in the solution. An alternative approach is to oxidize Am3+ to Am022+ in dilute acid using peroxydisulfate. Am02 is soluble in fluoride solution, while trivalent curium and lanthanides are insoluble. 

Symbol Nd atomic number 60 atomic weight 144.24 a rare earth lanthanide element a hght rare earth metal of cerium group an inner transition metal characterized by partially filled 4/ subshell electron configuration [Xe]4/35di6s2 most common valence state -i-3 other oxidation state +2 standard electrode potential, Nd + -i- 3e -2.323 V atomic radius 1.821 A (for CN 12) ionic radius, Nd + 0.995A atomic volume 20.60 cc/mol ionization potential 6.31 eV seven stable isotopes Nd-142 (27.13%), Nd-143 (12.20%), Nd-144 (23.87%), Nd-145 (8.29%), Nd-146 (17.18%), Nd-148 (5.72%), Nd-150 (5.60%) twenty-three radioisotopes are known in the mass range 127-141, 147, 149, 151-156. 

Samarium ore usually is digested with concentrated sulfuric or hydrochloric acid. The extraction process is similar to other lanthanide elements. Recovery of the metal generally consists of three basic steps. These are (1) opening the ore, (2) separation of rare earths first to various fractions and finally to their individual compounds, usually oxides or halides, and (3) reduc-... 

Thulium was discovered in 1879 by Cleve and named after Thule, the earliest name for Scandinavia. Its oxide thulia was isolated by James in 1911. Thulium is one of the least abundant lanthanide elements and is found in very small amounts with other rare earths. It occurs in the yttrium-rich minerals xenotime, euxenite, samarskite, gadolinite, loparite, fergusonite, and yttroparisite. Also, it occurs in trace quantities in minerals monazite and... 

The preparation of samarium sulphide, SmS, is of interest because it contains samarium (a lanthanide element) In an unusual oxidation state +2 instead of the more common state +3. Samarium metal In powder form and powdered sulfur are... 

The oxidation states of the lanthanide elements are given in Table 8.2. 

Table 8.2 Oxidation states of the lanthanide elements those in red are the most stable states in aqueous solution...

The ilillerent ranges of oxidation stales of the actinides in aqueous solution were described, discussed and compared with the much narrower ranges displayed by the lanthanide elements. 

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