Metals to Nonmetals

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... 

The transition elements form three series of metals that progress from elements that give up or lose electrons (metals) to elements that gain or accept electrons (nonmetals). The elements that are in transition from metals to nonmetals are located in the center of the periodic table in periods 4, 5, and 6 and are found in groups 3 through 12. 

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.)... 

The major characteristic of technetium is that it is the only element within the 29 transition metal-to-nonmetal elements that is artificially produced as a uranium-fission product in nuclear power plants. It is also the tightest (in atomic weight) of all elements with no stable isotopes. Since all of technetiums isotopes emit harmful radiation, they are stored for some time before being processed by solvent extraction and ion-exchange techniques. The two long-lived radioactive isotopes, Tc-98 and Tc-99, are relatively safe to handle in a well-equipped laboratory. 

Why do carbides and nitrides exhibit the properties that make them so useful in industrial applications It is well accepted that these properties are related to the strength of interatomic bonding.2 In transition metal carbides and nitrides, bonding is believed to have both covalent and ionic contributions.3 The carbon or nitrogen atoms occupy interstitial sites in the metal lattice and are believed to promote strong metal-to-nonmetal and metal-to-metal bonds.1 More detailed bonding explanations require... 

The metal to nonmetal transition, a basic electronic change, has proven surprisingly difficult to understand in detail. The underlying reason is the diametrically opposite modes of description natural for the metal (extended electronic states) and for the insulator (localized states, often with local constraints on electron number). The observed diversity of systems and phenomena indicates that a number of causes may be at work, e.g., disorder, short-range electron correlation, long-range Coulomb interaction, and election lattice coupling. The effects... 

Fig. 11. The Si3N4-Si02-Al203-AlN-Be0-Be3N2 system. A wide solid solution range was observed in this system. The single-phase /8—Si 3N4 solid solution region is restricted to the metal-to-nonmetal ratio of 3 4 plane. This indicates that the solid-solution is substitutional and no lattice defects exist in the structure [23].

However, it turns out that native copper is extraordinaiily variable in composition even within single sources. Native copper nonnally contains a vaiiable amount of other, nonmetallic minerals including copper sulfides, oxides, and silicates. These other minerals are not ductile but break upon cold-working the copper, which decreases the amounts of these minerals in varying amounts and thus alters the composition. Other elements that are soluble in an alloy solution with copper increase in abundance simply because the ratio of metal to nonmetal changes. 

Describe the changes in properties (from metals to nonmetals or from nonmetals to metals) as we move (a) down a periodic group and (b) across the periodic table. 

Ions arise through e transfer from metal to nonmetal... 

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