Metal general characteristics

The general characteristics of all these elements generally preclude their extraction by any method involving aqueous solution. For the lighter, less volatile metals (Li, Na, Be, Mg, Ca) electrolysis of a fused salt (usually the chloride), or of a mixture of salts, is used. The heavier, more volatile metals in each group can all be similarly obtained by electrolysis, but it is usually more convenient to take advantage of their volatility and obtain them from their oxides or chlorides by displacement, i.e. by general reactions such as... 

Space does not permit a survey of all the various weldable metals and their associated problems, although some suggestions are made in Table 9.9. It is sufficient to state that with a knowledge of the general characteristics of the welding process and its effects on a metal (e.g. type of thermal cycle imposed, residual stress production of crevices, likely weldability problems) and of the corrosion behaviour of a material in the environment under consideration, a reliable joint for a particular problem will normally be the rule and not the exception. 

The high values of E generally characteristic of the decomposition reactions of metal oxyhalides are widely interpreted as evidence that the initial step in anion breakdown is the rupture of the X—O bond and that the energy barrier to this reaction is not very sensitive to the properties of the cation present. Information of use in the formulation of reaction mechanisms has been obtained from radiolytic studies of oxyhalogen salts [887-889],... 

The simplest transition metal carbonyls are mononuclear of the type M(CO)x, in other words those with only one metal atom. They are hydrophobic but soluble to some extent in nonpolar liquids, such as n-butane or propane. The dinuclear carbonyls are more complex but have the same general characteristics as the mononuclear carbonyls. The carbonyls, which are or could be used in CVD, are listed in Table 3.4 with some of their properties. 

At this time, no all-inclusive rule can be given that will predict whether a given compound will intercalate or not. Most of the information available seems to have been obtained empirically. Such analogies as similar chemical properties have been helpful. The many factors that infiuence the intercalation process have been surveyed by Herold (H14). In Tables II-VI are listed metal halides considered to intercalate into graphite, together with some structural information (S2J, i 9). Several general characteristics have been ascribed to intercalat-... 

Describe the general characteristics of metals, nonmetals, and metalloids. 

III. Solvent Exchange and Ligand Substitution on Transition Metal Ions A. General Characteristics... 

Although the subject of stability of complexes will be discussed in greater detail in Chapter 19 it is appropriate to note here some of the general characteristics of the metal-ligand bond. One of the most relevant principles in this consideration is the hard-soft interaction principle. Metal-ligand bonds are acid-base interactions in the Lewis sense, so the principles discussed in Sections 9.6 and 9.8 apply to these interactions. Soft electron donors in which the donor atom is sulfur or phosphorus form more stable complexes with soft metal ions such as Pt2+ or Ag+, or with metal atoms. Hard electron donors such as H20, NH3( or F generally form stable complexes with hard metal ions like Cr3+ or Co3+. 

In this section the salts based on metallocenium cations and metal bisdichalcogenate anions will be reviewed according to the previously referred structural classification. After referring to the general characteristics of the crystal structures the supramolec-ular features will be correlated with the magnetic properties. 

Classification of biologically important metal ions and ligands according to the hard-soft acid-base concept and their general characteristics... 

General characteristics of alloys such as those presented in Fig. 3.3 have been discussed by Fassler and Hoffmann (1999) in a paper dedicated to valence compounds at the border of intermetallics (alkali and alkaline earth metal stannides and plumbides) . Examples showing gradual transition from valence compounds to intermetallic phases and new possibilities for structural mechanisms and bonding for Sn and Pb have been discussed. Structural relationships with Zintl phases (see Chapter 4) containing discrete and linked polyhedra have been considered. See 3.12 for a few remarks on the relationships between liquid and amorphous glassy alloys. 

Within the lanthanides the first ones from La to Eu are the so-called light lanthanides, the other are the heavy ones. Together with the heavy lanthanides it may be useful to consider also yttrium the atomic dimensions of this element and some general characteristics of its alloying behaviour are indeed very similar to those of typical heavy lanthanides, such as Dy or Ho. An important subdivision within the lanthanides, or more generally within the rare earth metals, is that between the divalent ones (europium and ytterbium which have been described together with other divalent metals in 5.4) and the trivalent ones (all the others, scandium and yttrium included). 

Interpreting Data Metals are usually malleable and good conductors of electricity. They are generally lustrous and silver or white in color. Many react with acids. Write the word metal beneath the Classification heading in the data table for those element samples that display the general characteristics of metals. 

---