Elemental Silver and Gold

Of interest also is the high-temperature liquid-liquid extraction of molten silver dissolved in molten lead, the extraction solvent being molten zinc (Parkes process) this process is analogous to the familiar extraction of bromine from water using carbon tetrachloride, and is used to recover silver from lead ores. 

Most salts of silver are relatively insoluble in water, the important exceptions being the low-melting nitrate and perchlorate, AgN03 and AgCiCL, and silver fluoride, AgF. These, as well as many other silver salts, are colorless but certain of the silver salts with relatively polarizable anions (Chap. 3), besides being insoluble in water, are brightly colored. Thus the colorless sulfate, chloride, and fluohorate of silver may be compared to the yellow iodide, the red arsenate and chromate, and the black sulfide. 

In addition to the nitrate, sulfate, acetate, and halides of silver, all of which are familiar, the subfluoride, Ag2F, should be mentioned. This unusual compound, prepared by the reaction of the ordinary fluoride with silver metal, may be considered to contain alternate Ag and F ions, for the Ag—Ag distance has been found to be almost exactly twice the covalent radius of silver and the Ag—F distance about the same as that in silver fluoride. As might be expected (considering the odd number of electrons in the AgJ ion), the compound is colored (it has a bronzelike lustre). Pauling described this substance picturesquely as being intermediate in character between a salt and a metal.  

Silver oxide, Ag20, easily prepared by basic precipitation from solutions containing the silver ion, is a convenient reagent, both in organic and inorganic chemistry, for preparing soluble hydroxides from the corresponding halides since the silver halide formed at the same time may be con- 

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Copper, a reddish colored metal, is a relatively rare element, accounting for only 0.0068% of the earth s crust by mass. Like the other group IB elements silver and gold, copper is found in nature in the elemental state. Its most important ores are sulfides, such as chalcopyrite, CuFeSo. In a multistep process, copper sulfides are concentrated, separated from iron, and converted to molten copper sulfide, which is then reduced to elemental copper by blowing air through the hot liquid ... 

Copper and the other Group IB elements, silver and gold, can be found in nature as the free metals. This is a reflection of the stability of their 0 oxidation states. For example, copper is not attacked by most acids. 

Nonessential metals are found in the same columns of the periodic table as are the essential metals. For example, the essential micronutrient copper is found in the same column as the elements silver and gold, both of which are toxic. Likewise, the essential metal zinc is found in the same column of the periodic table as the toxic... 

Refining. The alloy of bismuth and lead from the separation procedures is treated with molten caustic soda to remove traces of such acidic elements as arsenic and teUutium (4). It is then subjected to the Parkes desilverization process to remove the silver and gold present. This process is also used to remove these elements from lead. 

Copper, the first element of Group 11 (IB) of the Periodic Table, is immediately above silver and gold. It is classed with silver and gold as a noble metal and can be found in nature in the elemental form. Copper occurs as two natural isotopes, Cu and Cu (1). 

Table 28.1 Some properties of the elements copper, silver and gold...

Just like chemists today, ancient Egyptians also used symbols as well as words to represent common elements and compounds. Electrum is an alloy of silver and gold. 

E. Miscellaneous methods. Exchange reactions between the tetracyano-nickelate(II) ion [Ni(CN)4]2 (the potassium salt is readily prepared) and the element to be determined, whereby nickel ions are set free, have a limited application. Thus silver and gold, which themselves cannot be titrated complexometrically, can be determined in this way. 

Identify the element with the larger atomic radius in each of the following pairs (a) vanadium and titanium (b) silver and gold (c) vanadium and tantalum (d) rhodium and iridium. 

Equations (11a) and (12a) are based upon the values 1-399 and 1-430 for R sp3) for tin and lead, respectively, with slopes as indicated by the tetrahedral radii for the heavier elements. The value 1-430 for quadrivalent lead was obtained by adding to the radius for quadrivalent tin the difference 0-031A between the Mg-Pb distance in Mg2Pb and the Mg-Sn distance in Mg2Sn. The simple form of equations (116) and (126) was assumed in analogy with (106), and the equal values of the constant were obtained from the observed distances for silver and gold, both assumed to have valence 5 . 

The name copper and the symbol Cu are derived from the Latin cuprum, after the island of Cyprus, where the Romans first obtained copper metal. The symbols Ag and Au for silver and gold come from the Latin names for these elements argentum... 

Two metals that are chemically related and that have atoms of nearly the same size form disordered alloys with each other. Silver and gold, both crystallizing with cubic closest-packing, have atoms of nearly equal size (radii 144.4 and 144.2 pm). They form solid solutions (mixed crystals) of arbitrary composition in which the silver and the gold atoms randomly occupy the positions of the sphere packing. Related metals, especially from the same group of the periodic table, generally form solid solutions which have any composition if their atomic radii do not differ by more than approximately 15% for example Mo +W, K + Rb, K + Cs, but not Na + Cs. If the elements are less similar, there may be a limited miscibility as in the case of, for example, Zn in Cu (amount-of-substance fraction of Zn maximally 38.4%) and Cu in Zn (maximally 2.3% Cu) copper and zinc additionally form intermetallic compounds (cf. Section 15.4). 

This volume is concerned with fundamental developments in the coordination chemistry of the elements of Groups 9-12 since 1982. The individual chapters cover the coordination chemistry of cobalt, iridium, nickel, palladium, platinum, copper, silver and gold, zinc and cadmium, and mercury. Unfortunately, because of factors beyond the Editors control, the manuscript for the proposed chapter on rhodium was not available in time for publication. 

Elements have varying abilities to combine. Among the most reactive metals are the alkali metals and the alkaline earth metals. On the opposite end of the scale of reactivities, among the least active metals or the most stable metals are silver and gold, prized for their lack of reactivity. Reactive means the opposite of stable, but means the same as active. 

The more massive a star is, the higher the central temperatures and pressures are in the later stages. When the helium is consumed, the star fuses the carbon and oxygen into heavier atoms of neon, magnesium, silicon and even silver and gold. In this way, all the elements of the earth... 

In the periodic table of the elements, copper is listed in group 11, together with silver and gold. Copper, as a late transition element, occurs in a range of oxidation states (Cu(0), Cu(I), Cu(II), Cu(III), and Cu(IV)), and the ions readily form complexes yielding a variety of coordination compounds. Oxidation states I, II, and III... 

Several scientists in the early 1800s were aware that there were other elements mixed with platinum and other ores (i.e., nickel, copper, silver, and gold). They had difficulty separating the metals because these elements (metals) were so similar in their physical and chemical characteristics. 

Platinum is the 75th most abundant element and, unlike many elements, is found in its pure elemental form in nature, as are deposits of silver and gold. Platinum is widely distributed over the Earth and is mined mainly in the Ural Mountains in Russia and in South Africa, Alaska, the western United States, Columbia in South America, and Ontario in Canada. When found in the mineral sperryhte (PtAs ), it is dissolved with aqua regia to form a precipitate called sponge that is then converted into platinum metal. It is also recovered as a by-product of nickel mining, mainly in Ontario, Canada. 

This is done by dividing the number of mole of one element by the sum of the number of moles of both gold and silver in the mixture. The mole fraction of silver is found to be 0.959. This means that 959 out of every 1,000 atoms in the mixture are silver atoms. The mole fraction of gold is 0.04l, which means that 41 of every 1,000 atoms in the mixture are gold. The sum of the mole fractions of silver and gold will equal 1.00. 

Early human civilizations used stone, bone, and wood for objects. Approximately ten thousand years ago, metals first appeared. The first metals used were those found in their native form, or in a pure, uncombined state. Most metals today are acquired from an ore containing the metal in combination with other elements such as oxygen. The existence of native metals is rare, and only a few metals exist in native form. Iron and nickel were available in limited supply from meteorites. The first metals utilized widely by humans were copper, silver, and gold. Pure nuggets of these metals were pounded, in a process known as cold hammering, with stones into various shapes used for weapons, jewelry, art, and various domestic implements. Eventually, smiths discovered if a metal was heated it could be shaped more easily. The heating process is known as annealing. Because the supply of native metals was limited, metal items symbolized wealth and status for those who possessed them. 

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