Scandium physical properties

It turned out that the dodecylsulfate surfactants Co(DS)i Ni(DS)2, Cu(DS)2 and Zn(DS)2 containing catalytically active counterions are extremely potent catalysts for the Diels-Alder reaction between 5.1 and 5.2 (see Scheme 5.1). The physical properties of these micelles have been described in the literature and a small number of catalytic studies have been reported. The influence of Cu(DS)2 micelles on the kinetics of quenching of a photoexcited species has been investigated. Interestingly, Kobayashi recently employed surfactants in scandium triflate catalysed aldol reactions". Robinson et al. have demonshuted that the interaction between metal ions and ligand at the surface of dodecylsulfate micelles can be extremely efficient. ... 

Table 16.1 summarizes the physical properties of the elements from scandium through nickel. Notice the similarities in their melting and boiling points, but the gradual increase in density. 

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 elements with atomic numbers from 57 (l thanum) to 71 (lutetium) are referred to as the lanthanide elements. These elements and two others, scandium and yttrium, exhibit chemical and physical properties very similar to lanthanum. They are known as the rare earth elements or rare earths (RE). Such similarity of the RE elements is due to the configuration of their outer electron shells. It is well known that the chemical and physical properties of an element depend primarily on the structure of its outermost electron shells. For RE elements with increasing atomic number, the first electron orbit beyond the closed [Xe] shell (65 remains essentially in place while electrons are added to the inner 4f orbital. Such disposition of electrons about the nucleus of the rare earth atoms is responsible for the small effect an atomic number increase from 57 to 71 has on the physical and chemical properties of the rare earths. Their assignment to the 4f orbital leads to slow contraction of rare earth size with increasing atomic number. The 4f orbitals of both europium and gadolinium are half occupied [Xe] (4F6s and [Xe] (4F5d 6s, so that there... 

The syntheses, physical properties, and molecular structures of alkoxides and aryloxides have been discussed in CCC (1987).161 The alkoxides of scandium and yttrium were reviewed in CCC (1987).1 There have been more recent developments in this area and the impetus for this chemistry has been the developments in materials research. Metal alkoxides and /3-diketonates can be used as precursors for oxide and nonoxide thin films.162 The stable M—O bond and the volatility of the metal alkoxides are important features of this area of chemistry. This has lead to more research in this area particularly in synthesis, NMR, and X-ray crystallography. 

The most famous of Mendeleev s predictions involved eka-boron (scandium), eka-aluminium (gallium), and eka-silicon (germanium). For example, for eka-silicon he predicted its atomic weight, its density, the compounds it would form, and details about their physical properties. When thirteen years later germanium was discovered and it was determined that Mendeleev s predictions had been correct, scientists began to recognize the importance of the Periodic Table, and its discovery was quite naturally associated with Mendeleev, who encouraged this association. 

The radioactive isotopes used in the tracer particles are made of scandium-46 (Sc46) and sodium-24 (Na24), their physical properties are listed in Table 9.1. 

Analyze and Plan We are asked about one physical property of scandium oxide—its state at room temperature and one chemical property—how it reacts with nitric add. 

Electronic Structures. Almost all the physical properties and chemical behavior of the rare earth elements find a logical explanation in terms of their electronic structures. Scandium, yttrium, lanthanum, and actinium are the first members, respectively, of the first, second, third, and fourth transition sequences of elements. In other words, each such element marks the beginning of an inner building where a stable group of 8 electrons is expanding to a completed (or more nearly complete) group of IS. This situation is illustrated for the first transition sequence. 

In early 1871, Mendeleev published a list of detailed predictions on each element for the first time. It was ako in this paper that he now referred to them provisionally as eka-boron (scandium), eka-aluminum aUium),and eka-sihcon (germanium). These were his most celebrated cases, and he was able to predict then-chemical and physical properties to an astonishing degree. It would take 15 years from the time of these detailed predictions for all three of these new elements to be isolated and characterized, but in the end Mendeleev would be almost completely vindicated. 

It is mentioned in the preceding section that for the elements potassium, calcium, scandium, titanium, vanadium, and chromium the physical properties indicate that all of the electrons outside of the argon shell are used in forming bonds, and that the metallic valences for these elements are 1, 2, 3, 4, 5, and 6, respectively. 

THE RARE EARTH elements are those from atomic numbers 57 (lanthanum) to 71 (lutetium) inclusive and elements 21 (scandium) and 39 (yttrium). They represent the largest group of chemically similar elements, but their physical properties differ markedly due to subtle features of electronic structure. Because of the similarity between... 

Andrusyak, R.I., 1988, Interaction of scandium with transition metals of IVth period and germanium (equilibrium phase diagrams, crystal structures and physical properties of compounds) Ph.D. Chemistry Thesis (Lvov State University, Lvov) pp. 1-235. 

Since scandium is one of the nomnagnetic elements among the rare-earth series one might expect that the physical properties of compounds with scandium and the other nonmagnetic rare-earth elements (Y, La or Lu) are the same or at least very similar. This supposition is true in principle, however because of the much smaller atomic size of scandium compared with yttrium and also lutetium a deviating physical behaviour of the corresponding scandium compounds is frequently observable. 

Occurrence and extraction Applications Physical properties Inorganic and coordination chemistry of the metals scandium to zinc... 

Within a matter of a few years, other chemists used Mendeleev s predictions to discover several elements that had been unknown in 1869—galUum, germanium, and scandium. These elements fit neatly into the spaces that Mendeleev had left blank, and they had chemical and physical properties that were very close to the ones that Mendeleev had predicted. At the time Mendeleev developed his periodic table, the noble gases had not yet been discovered. Mendeleev lived to witness their discovery and their placement into their own family of elements. 

Weaver, J., C. Krafka, D. Lynch, and E. Koch, 1981b. Physics Data Optical Properties of Metals, Pt. II Noble Metals, Aluminum, Scandium, Yttrium, the Lanthanides and the Actinides, Fach-Informations-Zentrum, Karlsruhe. 

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