Arsenic physical properties

Impurities in cmde metal can occur as other metals or nonmetals, either dissolved or in some occluded form. Normally, impurities are detrimental, making the metal less useful and less valuable. Sometimes, as in the case of copper, extremely small impurity concentrations, eg, arsenic, can impart a harmful effect on a given physical property, eg, electrical conductivity. On the other hand, impurities may have commercial value. For example, gold, silver, platinum, and palladium, associated with copper, each has value. In the latter situation, the purity of the metal is usually improved by some refining technique, thereby achieving some value-added and by-product credit. 

Physical properties of a-crystaUine metallic arsenic are given in Table 1. The properties of P-arsenic are not completely defined. The density of P-arsenic is 4700 kg/m it transforms from the amorphous to the crystalline form at 280 °C and the electrical resistivity is reported to be 107 H-cm. 

Arsenic Halides. Arsenic forms a complete series of trihaUdes, but arsenic pentafluoride is the only well-known simple pentahaUde. AH of the arsenic haUdes, the physical properties of which are given in Table 2, are covalent compounds that hydrolyze in the presence of water. The trihaUdes form pyramidal molecules similar to the trivalent phosphoms analogues and may be prepared by direct combination of the elements. 

Arsenic Sulfides. The physical properties of the common arsenic sulfides are given in Table 3. Numerous arsenic sulfides have been reported as well as compounds containing the As2S" 4 cation [77825-63-9] (24). 

Copper. The physical properties of pure copper are given in Table 11. The mechanical properties of pure copper are essentially the same as those for ClOl and CllO. The coppers represent a series of alloys ranging from the commercially pure copper, ClOl, to the dispersion hardened alloy C157. The difference within this series is the specification of small additions of phosphoms, arsenic, cadmium, tellurium, sulfur, zirconium, as well as oxygen. To be classified as one of the coppers, the alloy must contain at least 99.3% copper. 

Arsenic exists as grey, yellow and black forms of differing physical properties and susceptibilities towards atmospheric oxygen. The general chemistry is similar to that of phosphorus but whereas phosphorus is non-metallic, the common form of arsenic is metallic. Traces of arsenides may be present in metallic residues and drosses these may yield highly toxic arsine, ASH3, with water. 

Arsenic, Antimony and Bismuth Table 13.4 Some physical properties of Group 15 elements... 

T ble 13.6 Some physical properties of the trihalides of arsenic, antimony and bismuth... 

The coating chamber was equipped with a set of independently controlled stainless steel boats and a shutter system to enable the fabrication of multilayer structures. Pure selenium pellets were loaded into one boat and As Sei alloys into another. The two sources were evaporated sequentially (without breaking the vacuum) at boat temperatures of about 450 K. Typical coating rates were l j,m/min. After evaporation, they were allowed to anneal over several weeks in the dark at room temperature. During this period, due to structural bulk relaxation, most physical properties of the photoconductor film become stabilized. The compositions of the deposited films were determined by electron probe microanalysis, and the compositions quoted (0 < X < 0.20) are accurate to within 0.5 at.%. By shuttering the beginning and the end of the evaporation, a uniform arsenic composition across the film thickness can be obtained. In all experiments, a transparent gold electrode ( 300 jm thick) was used as the top contact. 

Berzelius in 1817 investigated the stoichiometrical relations of arsenic with other elements and examined the various compounds with sulphur. The physical properties of the element caused it to be classed with the metals, but its non-metallic chemical properties and its similarity in chemical behaviour to nitrogen and phosphorus were gradually recognised. 

Physical Properties.—Arsenic trichloride is a colourless, transparent oily liquid at ordinary temperatures. The following values for the density,13 specific cohesion, surface tension14 and molecular surface energy were determined by Jager 15... 

Physical Properties.—Arsenic tribromide is a solid at ordinary temperatures, crystallising in beautiful colourless rhombic prisms6 which possess a feebly aromatic odour 7 and are stable in dry air. In the presence of moisture slight fuming occurs. The crystals melt sharply at 31° C.8 The density 9 at 15° C. is 3-66 after fusion and resolidification, the product has density 3-54 at 25° C.10 The density of the liquid at various temperatures may be obtained from the expression 11... 

Physical Properties.—Arsenic trisulphide crystallises in short octahedral prisms which were at first described as rhombic 8 but which Groth described as monoclinic.9 The crystals are greasy and possess a lustre which is nacreous at the plane of cleavage. The cleavage on the (OlO)-face is perfect, while that on the (100)-faee shows in traces. The (OOl)-face is a gliding plane.10 The optical character is negative.11 The... 

History—Preparation—Allotropy—Colloidal Arsenio—General Physical Properties of Arsenic—Spectrum—Chemical Properties—Atomic Weight—... 

Arsenic Suboxide—Arsenious Oxide Polymorphism and Physical Properties of Arsenious Oxide, Chemical Properties, Uses—The Arsenites—Arsenic Tetroxide. 

Arsenic is a metalloid. Solid samples of elemental arsenic (As(0)) tend to be brittle, nonductile, and insoluble in water. These properties largely result from arsenic atoms forming strong covalent bonds with each other. Table 2.3 lists the common chemical and physical properties of arsenic, including its density, electronegativity, and first ionization potential. 

Table 2.3 Selected chemical and physical properties of arsenic. See Table 2.4 for additional information on the elemental polymorphs of arsenic. See Appendix B and the text for explanations of some of the terms and units of measure.

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