Some Characteristics of Metals

All of the elements on the periodic table break up into three major categories metals, nonmetals, and semimetals. Metals are elements with relatively few valence electrons, which tend to form positive ions by losing one or more electrons. Metals tend to be good conductors of heat and electricity. Nonmetals are elements that have more valence electrons and tend to form negative ions by gaining one or more electrons. Nonmetals tend to be poor conductors of heat and electricity. Semimetals, which are also called metalloids or semiconductors, tend to have some characteristics of metals and some of nonmetals. Figure 3-7b shows a periodic table that shows the locations of the three basic types of elements. 

As you look from left to right on the periodic table, you can see that the metalloids are found between the metals and the nonmetals. A metalloid is an element that has some characteristics of metals and some characteristics of nonmetals. All metalloids are solids at room temperature. They tend to be less malleable than metals but not as brittle as nonmetals. Some metalloids, such as antimony, have a somewhat metallic luster. 

Whereas the quasi-chemical theory has been eminently successful in describing the broad outlines, and even some of the details, of the order-disorder phenomenon in metallic solid solutions, several of its assumptions have been shown to be invalid. The manner of its failure, as well as the failure of the average-potential model to describe metallic solutions, indicates that metal atom interactions change radically in going from the pure state to the solution state. It is clear that little further progress may be expected in the formulation of statistical models for metallic solutions until the electronic interactions between solute and solvent species are better understood. In the area of solvent-solute interactions, the elastic model is unfruitful. Better understanding also is needed of the vibrational characteristics of metallic solutions, with respect to the changes in harmonic force constants and those in the anharmonicity of the vibrations. 

It has also been found that alkali metals dissolve in solvents such as methylamine and ethylenedi-amine. These solutions have some characteristics of the solutions containing ammonia, and they... 

C). However, the characteristics of metals that physically distinguish them are their metallic luster, electrical conductivity, malleability, and ductility. Elements generally classified as metals exhibit wide variation in these properties. Chemically, metals are also reducing agents as a result of their having comparatively low ionization potentials. Another characteristic that differs enormously is their cost. Some of the base metals sell for a few cents per pound, whereas some of the exotic metals sell for a few thousand dollars per gram. 

Metalloids—metals found in the region of the periodic table between groups of metals and nonmetals. Thus, they have some characteristics of both metals and nonmetals. Some are semiconductors. They are boron, silicon, germanium, arsenic, antimony, tellurium, and polonium. 

All of the alkali metals are electropositive and have an oxidation state of 1 and form cations (positively charged ions) by either giving up or sharing their single valence electron. The other elements of group 1 are lithium (jLi), sodium (jjNa), potassium (j K), rubidium (j Rb), cesium (jjCs), and francium (g Fr). Following are some characteristics of the group 1 alkali metals ... 

Fischer-Tropsch Catalysts. - It is well known that all Group VIII transition metals are active for F-T synthesis. However, the only F-T catalysts, which have sufficient CO hydrogenation activity for commercial application, are composed of Ni, Co, Fe or Ru as the active metal phase. These metals are orders-of-magnitude more active than the other Group VIII metals and some characteristics of Ni-, Fe-, Co- and Ru-based F-T catalysts are summarized in Table 2. 

Thus far, we ve discussed the sources, production, and properties of some important metals. Some properties, such as hardness and melting point, vary considerably among metals, but other properties are characteristic of metals in general. For instance, all metals can be drawn into wires (ductility) or beaten into sheets (malleability) without breaking into pieces like glass or an ionic crystal. Furthermore, all metals have a high thermal and electrical conductivity. When you touch a metal, it feels cold because the metal efficiently conducts heat away from your hand, and when you connect a metal wire to the terminals of a battery, it conducts an electric current. 

Mercury, like zinc, appears in some chain-like structures, but apparently only in combination with other metals such as As, Sb, Nb, and Ta. Some of these have the characteristics of metallic conductors.15 Rather high molecular weights have been obtained in the preparation of 6-coordinate cobalt (III) chelate polymers with acetylacetonato and leucinato ligands, 7-coordinate dioxouranium-(VI) dicarboxylate polymers, and 8-coordinate zirconium (IV) polymers with Schiff-base ligands.77... 

Britton, L.G., and Williams, T.J., Some characteristics of liquid-to-metal discharges involving a charged low risk oil, J. Electrostatics, 13, No. 2, 1982. 

Some properties characteristic of metal-doped oxide semiconductors are summarized below as a result of the presented investigations ... 

Some characteristics of drum dryers are given in Table 6.8. In a given application, testing is usually required to establish drum speed, temperature, retention time, product characteristics and feeding equipment. The short time that solid is in contact with hot metal makes these units suitable for heat-sensitive materials. As illustrated in Fig. 6.4, many different feed... 

In redistribution reactions catalyzed by transition metal complexes, di-or polysiloxanes are expected to share some characteristics of both monosilanes and di- or poly silanes. Similarities to the former are expected since the very reactive Si—Si bond is replaced by the less reactive Si—O bond, and to the latter because there are two or more exchangeable sites in the molecule. 

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