Rhodium atomic weight

The trans- [Rh(PR3)2Cl(CO)] complexes were prepared by treating [RhCl(CO)2]2 under nitrogen in chloroform solution with 2 equiv of tertiary phosphine per rhodium atom. The only side product was carbon monoxide so that purification by recrystallization from ethanol or ethanol-chloroform was relatively simple. The lower-molecular-weight trialkylphosphine and higher-molecular-weight triarylphos-phine complexes were orange, viscous oils the others were cream-colored, low-melting crystalline solids. 

The most appropriate position for ruthenium in the Periodic Table is as the first member of the second series of horizontal triads. Hence its atomic weight should lie between that of molybdenum (96) and rhodium (102-9), but nearer in point of magnitude to the last named since an element should be in Group VII between it and molybdenum, but has yet to be discovered. 

Atomic Weight.—Approximate Atomic Weight—-That the atomic weight of rhodium is approximately 103 and not a multiple or fraction... 

According to Dulong and Petit s Law the atomic weight of rhodium is of the order of 110, its specific heat being 0-058, and a mean atomic heat of 6-4 being assumed. 

According to the Periodic Classification, rhodium, which in its properties forms a mean between cobalt and iridium, and betw een ruthenium and palladium, should have an atomic weight intermediate between the values for these extreme elements, namely, from 102 to 105. 

Exact Atomic Weight—The earliest determinations of the atomic weight of rhodium, published by Berzelius1 in 1828, are now only of historical interest, his results, obtained from analyses of the sodium and potassium ehlor-rhodites, Na3RhCl6 and K2RhCl5, varying from Rh = 103-1 to Rh =--106-1. 

The Grouping of Elements into Triads—Atomic Weights of the Elements— General Properties of tho Elements—Comparative Study of Iron, Cobalt, and Nickel—Their Position in tho Periodic Table—Comparative Study of Iron, Ruthenium, and Osmium—Comparative Study of Cobalt, Rhodium, and Iridium—Comparative Study of Nickel, Palladium, and Platinum. 

However, its bine chloride solntion had been previously observed by Vauquehn in Paris in 1804. Rnthenium is the least abundant platinum metal (10 to 10 ppm) after rhodium. In 2002, the demand for ruthenium was 11.6 tons, an increase of 1.8 tons compared to 2001, mainly becanse of increased sales of rnthenium paste to the electronics industry, for the manufacture of chip resistors and hybrid integrated circuits (HIC). Its atomic number is 44, its atomic weight 101.07, and its electronic configuration [Kr]4d 5s. Seven stable isotopes are known. Some physical data are reported in Table 1 (see Coordination Chemistry History mA Coordination Numbers Geometries). 

Table 2 shows average rhodium dispersions for each of the five weight loaded catalysts. These were calculated from the hydrogen uptakes in Table 1 by assuming each hydrogen atom represented one rhodium surface site and from the definition of dispersion which is the fraction of total rhodium atoms that... 

RHODIUM (metal fume and insoluble compounds, as Rh)(The atomic formula for rhodium metal is Rh. The atomic weight for rhodium metal is 102.91. Insoluble rhodium compounds have variable molecular formulas and variable formula weights, depending upon the specific compound.)... 

As a result investments are reduced by 30%. Also, iridium is several times cheaper than rhodium (on average by a factor of 10 per kilogram over the last 5 years, which should be corrected for the atomic weight ) the prices of both show an enormous fluctuation [124]. The catalyst system exhibits high stability allowing a wide range of process conditions and compositions to be accessed without catalyst precipitation. 

The structure of the rhodium complex has no features attributable to a high hydride ligand. For the salt K2[ReH9], there are three formula weights per unit cell 192), and the rhenium atoms are separated by large distances (minimum of 5.5 A) so that discrete enneahydridorhenate anions must exist in the crystal. The anion has Da, symmetry with six hydrogens at the comers of a trigonal prism and three beyond the centers of each equatorial face. The Re—H distance varies between 1.6 and 1.72 A... 

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