Series Rare-Earth Elements Period

The lanthanide series is composed of metallic elements with similar physical properties, chemical characteristics, and unique structures. These elements are found in period 6, starting at group 3 of the periodic table. The lanthanide series may also be thought of as an extension of the transition elements, but the lanthanide elements are presented in a separate row of period 6 at the bottom of the periodic table. 

The elements in the lanthanide series are also called rare-earth elements they are not scarce or rare, but at one time they were thought to be rare because they were very difficult to find and extract from their ores, difficult to separate from each other, and difficult to identify. Chemical elements that have similar physical and chemical properties tend to occur together in the same ores and minerals. 

The rare-earth metals are sometimes divided into two groups. The first group is called the yttrium group. It consists of Y, La, Ce, Pr, Nd, Pm, and Sm. The second group is call the dysprosium group and consists of Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. 

The lanthanide series can begin either with lanthanum (j La) or with cerium (jgCe) and continue through lutetium ( jLu). 

The element yttrium (jjY), located just above lanthanum in group 3, is sometimes included in this series because its physical properties and chemical characteristics are similar to those of other elements in the series. 

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Lanthanide Series (Rare-Earth Elements) Period 6... 

Krebs, Robert E. The history and use of our earth s chemical elements a reference guide. Westport (CT) Greenwood P, 1998. ix, 346p. ISBN 0-313-30123-9 A short history of chemistry — Atomic structure The periodic table of the chemical elements — Alkali metals and alkali earth metals - Transition elements metals to nonmetals — Metallics and metalloids - Metalloids and nonmetals — Halogens and noble gases - Lanthanide series (rare-earth elements) — Actinide, transuranic, and transactinide series... 

Period 5 (group 3 [IIIB] to group 12 [IIB]) is located in the second row of the transition elements and represents 10 of the transition metals to nonmetals found in the periodical table of chemical elements. This period is also known to include some of the so-called rare-earth elements. Most of the rare-earths are found in the lanthanide series, which follows barium (period 6, group 3). (Check the periodic table to locate the major rare-earth elements in the lanthanide series. These are addressed in a later section of the book.)... 

Yttrium is always found with the rare-earth elements, and in some ways it resembles them. Although it is sometimes classified as a rare-earth element, it is listed in the periodic table as the first element in the second row (period 5) of the transition metals. It is thus also classified as the lightest in atomic weight of all the rare-earths. (Note Yttrium is located in the periodic table just above the element lanthanum (group 3), which begins the lanthanide rare-earth series. 

LANTHANIDE SERIES. The chemical elements with atomic numbers 58 to 71 inclusive, commencing with cerium t.5K)and through lutetiuni 171) frequently ate termed collectively, the Lanthanide Scries. Lanthanum, the anchor element of the series, appears in group 3h of the periodic table. Some authorities eonsider lanthanum a part of the series. Members ol the series, along with lanthanum and yttrium, are described under Rare-Earth Elements and Metals. See also Actinide Series. 

RARE-EARTH ELEMENTS AND METALS. Sometimes referred to as the fraternal fifteen," because of similarities in physical and chemical properties, the rare-earth elements actually are not so rare. This is attested by Fig. 1, which shows a dry lake bed in California that alone contains well in excess of one million pounds of two of die elements, neodymium and praseodymium. The world s largest rare earth body and mine near Baotou, Inner Mongolia, China is shown in Fig. 2. It contains 25 million tons of rare earth oxides (about one quarter of the world s human reserves. The term rare arises from the fact that these elements were discovered in scarce materials. The term earth stems from die tact that the elements were first isolated from their ores in the chemical form of oxides and that the old chemical terminology for oxide is earth. The rare-earth elements, also termed Lanthanides, are similar in that they share a valence of 3 and are treated as a separate side branch of the periodic table, much like die Actinides. See also Actinide Contraction Chemical Elements Lanthanide Series and Periodic Table of the Elements. 

If in the first stage Mendeleev presumed the existence of a whole series of undiscovered rare-earfh elements on the basis of the periodic system, in the second stage of development a majority of these elements were actually discovered and they were generally bivalent. The problem about their position in the table was, therefore, unprecedentedly serious. If in the first stage Mendeleev was actively engaged in the problem of the position of rare-earth elements in the system, discussing different versions for the position of different elements, then in the second stage his views were characterized by maximum caution. 

The analytical chemistry of the transition elements see Transition Metals), that is, those with partly filled shells of d (see (f Configuration) or f electrons see f-Block Metals), should include that of the first transition period (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) and that of the second transition series (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, and Ag). The third transition series embraces Hf, Ta, W, Re, Os, Ir, Pt, and An, and although it formally begins with lanthanum, for historical reasons this element is usually included with the lanthanoids (rare-earth elements) see Scandium, Yttrium the Lanthanides Inorganic Coordination Chemistry Rare Earth Elements). The actinoid elements see Actinides Inorganic Coordination Chemistry) are all radioactive see Radioactive Decay) and those with atomic number see Atomic Number) greater than uranium (Z = 92) are artificial the analytical chemistry of these elements is too specialized to consider here. 

The lanthanides are a series of 14 metallic elements that appear at the bottom of the periodic table. Lanthanum, the element preceding the lanthanides in the periodic table, is usually also included in a discussion of the lanthanides since all 15 elements have very similar properties. When first discovered and isolated, the lanthanides were called the rare earth elements. Many uses have been found for these elements and their compounds despite their expense. 

Holmium occurs in Row 6 of the periodic table. The periodic table is a chart that shows how chemical elements are related to each other. Elements with atomic numbers 57 through 71 are known as the lanthanoids. The name comes from the first element in the series, lanthanum. The lanthanoids are also known as rare earth elements. Although lanthanoids are not especially rare, they were once very difficult to separate from each other. 

CAS 7440-54-2. Gd. A rare-earth element of the lanthanide series, atomic number 64, group IIIB of the periodic table, aw 157.25, valence of 3 seven natural isotopes. 

Note Though often loosely so used, the word group should not be applied to a number of elements of similar properties that are not actual groups in the periodic table the proper term for these is series, e.g., lanthanide series, rare-earth series, etc. 

The periodic table of the elements, showing three main groups of trace elements, which are often treated together in geochemistry because of their relative positions in the table. These are the elements of the first transition series, the platinum group elements and the rare earth elements. The elements which are shaded are also Important trace elements in geochemistry. 

Periodic table of the elements. The lanthanide series ( rare earths ), beginning with lanthanum (57), and the actinide series, which begins with actinium (89) and includes thorium (90) and uranium (92), are chemically similar. Other families of elements read vertically down the table—at the far right, for example, the noble gases helium, neon, argon, krypton, xenon, radon. 

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