Lanthanide elements abundance

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 earth s crust is again a good source of lanthanides. Although the name rare earths is still used to denote the lanthanide elements, and scandium and yttrium, in the strictest sense of the word rare they are more plentiful than many of our common elements. It comes as a surprise to many people when a comparison of the relative abundance of the lanthanides and other elements in the earth s crust is made. Table 4... 

The lanthanide elements were once known as the rare earths. Lanthanides, however, are not particularly rare. Holmium, one of the less common lanthanides, is still 20 times more abundant than silver on Earth. The rare earth name comes instead from how difficult it was for early chemists to separate all of the lanthanides from one another. Because these elements add electrons to an inner shell, they all show the same face to other elements. This makes them all react very similarly with other elements, and it can be tricky to tell them apart. 

As a prelude to this section, intrinsic properties of the Ln-OR moiety will be passed in review. Alkoxide ligands are put into the category of hard ligands according the Pearson terminology and therefore optimally match the electropositive requirements of the hard lanthanide cations. The natural abundance of the lanthanide elements is the force behind the hard-soft relationship. The strongly electropositive and oxophilic character is expressed in high forma-... 

The actinides (U, Th, Pu), alkaline earths (Be, Mg, Ca, Sr, Ba), lanthanides (elements La - Lu), Al, and the elements in groups 3b (Sc, Y), 4b (Ti, Zr, Hf), and 5b (V, Nb, Ta) of the periodic table are refractory lithophile elements. The refractory lithophiles are 5% of the total mass of the rock in solar composition material. Aluminum Al, calcium Ca, and titanium Ti are the three most abundant refractory lithophiles, and they form minerals that are the host phases for most of the less abundant refractory lithophile elements such as the actinides, lanthanides, and transition elements in group 5b of the periodic table. Some of the less abundant refractory lithophiles - the group 4b elements Zr, Hf, and the group 3b elements Y and Sc - condense as oxides before any Ca, Al, Ti-bearing minerals form [9], But the rest condense into the more abundant host phases. 

Cerium is the most abundant member of the lanthanide, or rare earth, elements. It has two stable valence states, Ce (cerous) and Ce " (ceric). It is found as a trace element in several minerals, but only two, bastnasite, LnFCOs, and monazite, (Ln, Th)P04 (where Ln = a lanthanide element, such as lanthanum, praseodymium, neodymium, or cerium), which are approximately 30 percent and 22 to 25 percent cerium, respectively, are the principal sources of this element. 

The lanthanide elements were originally known as the Rare Earths from their occurrence in oxide (or, in old usage, earth) mixtures. They are not rare elements, and the absolute abundances in the lithosphere are relatively high. 

Many elements such as tin, copper, zinc, lead, mercury, silver, platinum, antimony, arsenic, and gold, which are so essential to our needs and civilization, are among some of the rarest elements in the earth s crust. These are made available to us only by the processes of concentration in ore bodies. Some of the so-called rare-earth elements have been found to be much more plentiful than originally thought and are about as abundant as uranium, mercury, lead, or bismuth. The least abundant rare-earth or lanthanide element, thulium, is now believed to be more plentiful on earth than silver, cadmium, gold, or iodine, for example. Rubidium, the 16th most abundant element, is more plentiful than chlorine while its compounds are little known in chemistry and commerce. 

Masuda A.,-1962, Regularities in variation of relative abundances of lanthanide elements and an attempt to analyse separation-index patterns of some minerals. J. Earth Set. Nagoya f/nm, 10, 173-187. 

Anodier stone that has found wide cultural use as a carving medium in many early societies is steatite or soapstone, a very soft metamorphic rock related to chlorite and talc. In this laboratory, steatite (actually chlorite) from quarries near Tepe Yahya (Iran) was characterized by observation of the ratios of the relative intensities of basal-plane x-ray diffraction peaks after it was found that NAA-determined trace element concentrations varied wildly within a given specimen. Another technique that has been used involves the determination by NAA of a number of lanthanide elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb and Lu) and the taxonomy of their abundances relative to each other — in other words, true pattern recognition , when plotted as ratios to the levels of the same elements in a standard reference chondrite Although this technique found successful provenience application... 

Alpha radioactivity has been observed for all the elements above lead in the periodic table, as well as for a few nuclei as light as the lanthanide elements. In a decay the a-particles have discrete energies. The a-particles emitted from decay has the 4.18 and 4.13 MeV kinetic energy with abundance of 77 and 23%, respectively, a-particles usually have between 3 and 9 MeV of kinetic energy but, since they are relatively massive and doubly charged, they do not penetrate very far into matter. A thick sheet of paper is sufficient to completely stop a particles emitted in radioactive decay. 

Of all the materials sampled in the laboratory, the class of meteorites called chondrites is believed to come the closest to retaining the nonvolatile elements of the solar system in their primitive relative abundances. If the processes that formed those meteorites did not appreciably fractionate the nonvolatile elements, then surely they did not separate yttrium and the members of the lanthanide series from each other. Thus, from analyses of chondritic meteorites, the relative elemental abundances of Y and the lanthanides in the solar system are known to a high degree of confidence. 

Levinson (1966) has discussed the problems of nomenclature. The mineralogists propensity for sticking names on complex natural chemical phases (minerals) that give no clue whatsoever as to the nature of those phases runs amuck with lanthanide minerals. In those, a simple shift in lanthanide relative abundances changes the phase from that of mainly one chemical element to that of mainly another, with irresistible possibilities for a new and unrelated mineral name. 

Lanthanides is the name given collectively to the fifteen elements, also called the elements, ranging from lanthanum. La, atomic number 57, to lutetium, Lu, atomic number 71. The rare earths comprise lanthanides, yttrium, Y, atomic number 39, and scandium. Sc, atomic number 21. The most abundant member of the rare earths is cerium, Ce, atomic number 58 (see Ceriumand cerium compounds). 

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. 

Apart from the unstable (half-life 2.623 y) of which traces occur in uranium ores, the lanthanides are actually not rare. Cerium (66 ppm in the earth s crust) is the twenty-sixth most abundant of all elements, being half as abundant as Cl and 5 times as abundant as Pb. Even Tm (0.5 ppm), the rarest after Pm, is rather more abundant in the earth s crust than is iodine. 

Cerium, an element in the lanthanide series, has a number of radioactive isotopes. Several of these are produced in abundance in nuclear fission reactions associated with nuclear industry operations or detonation of nuclear devices. This report summarizes our present knowledge of the relevant physical, chemical, and biological properties of radiocerium as a basis for establishing radiation protection guidelines. 

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