Praseodymium electronic configuration

Although rare-earth ions are mosdy trivalent, lanthanides can exist in the divalent or tetravalent state when the electronic configuration is close to the stable empty, half-fUed, or completely fiUed sheUs. Thus samarium, europium, thuUum, and ytterbium can exist as divalent cations in certain environments. On the other hand, tetravalent cerium, praseodymium, and terbium are found, even as oxides where trivalent and tetravalent states often coexist. The stabili2ation of the different valence states for particular rare earths is sometimes used for separation from the other trivalent lanthanides. The chemicals properties of the di- and tetravalent ions are significantly different. 

Prandtl mixing length hypothesis, 11 779 Prandtl number, JJ 746, 809 13 246-247 Praseodymium (Pr), J4 631t, 634t electronic configuration, J 474t Praseodymium bromide, physical properties of, 4 329 Prater equation, 25 270, 299 Prater number, 25 299, 300-301, 303 effect on maximum dimensionless intrapellet temperature, 25 304, 309 effect on maximum intrapellet temperature, 25 306 Prato reaction, 12 244 Pratsinis aluminum nitride, 17 212 Pravachol, 5 143... 

Lanthanum, the first member of lanthanides has the configuration of 5d)6s2 and next member cerium, has 4fi6s2 while the next element praseodymium has the configuration 4f3 6s2. Although lanthanum itself does not possess any 4/electrons, it is customary to include this element in the series. The electronic configurations of the elements with fully filled (// and half-filled (f7)/-orbitals are relatively more stable. 

In solid solutions, rare earths impart colour to the solutions due to their electronic configurations. This property has been profitably used in the manufacture of ceramic pigments which are extensively used in colouring of wall and floor tiles, table-ware and sanitary-ware. Cerium and praseodymium are extensively used in ceramics pigments. The shades that result due to the use of cerium and praseodymium are yellow, orange and green. 

Lanthanide elements (referred to as Ln) have atomic numbers that range from 57 to 71. They are lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). With the inclusion of scandium (Sc) and yttrium (Y), which are in the same subgroup, this total of 17 elements are referred to as the rare earth elements (RE). They are similar in some aspects but very different in many others. Based on the electronic configuration of the rare earth elements, in this chapter we will discuss the lanthanide contraction phenomenon and the consequential effects on the chemical and physical properties of these elements. The coordination chemistry of lanthanide complexes containing small inorganic ligands is also briefly introduced here [1-5]. 

The lutetium hahdes (except the fluoride), together with the nitrates, perchlorates, and acetates, are soluble in water. The hydroxide oxide, carbonate, oxalate, and phosphate compotmds are insoluble. Lutetium compounds are all colorless in the solid state and in solution. Due to its closed electronic configuration (4f " ), lutetium has no absorption bands and does not emit radiation. For these reasons it does not have any magnetic or optical importance, see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Neodymium Praseodymium Promethium Samarium Terbium Ytterbium. 

Because the energies of the 4/and 5d orbitals are very close to each other, the electron configurations of some of the lanthanides involve 5d electrons. For example, the elements lanthanum (La), cerium (Ce), and praseodymium (Pr) have the following electron configurations ... 

In principle three valence configurations are possible in the final state reached by a 3d photoelectron. Note that we describe the photoemission final state again by the addition of one nuclear charge to the cerium ion thus producing a core configuration which is close to the one of praseodymium. This pulls the Ce valence electron configuration (and of course the other Ce electron levels above the 3d level) to lower energies and can lead to three different final states (Kotani and Jo 1986). One, which has no 4f occupancy, we call it 4f° >, one which has one 4f electron in... 

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