There are two reasons for this: first is that silver has a greater tendency to tarnish; and second is that silver is much more expensive. As a precious metal, silver has been much valued for ages with its so many applications, as in the following: 1. Jewelry (sterling silver is used in making fine jewelry and watches). Because it was first chanced upon in silver mine in South America, platinum was named as such, after the Spanish word "platina", which translates to "little silver". 2. Palladium - William Hyde Wollaston, an English chemist and physicist, discovered palladium in 1803 in samples of platinum ore obtained from South America. One of the advantages of the gold standard is that it sort of restricts the government's power in inflating prices, which is possible through excessive issuance of paper currency. Also by providing a fixed pattern of exchange rates, the gold standard may effectively lessen uncertainty in international trade. mol-1 (third) The principal use of rhodium is as a catalytic converter in automotive vehicles, which reduces the toxicity of engine emissions by converting these into less harmful gases. Rhodium is likewise used in jewelry, such as when it is electroplated on platinum, sterling silver, or white gold (called rhodium flashing) to strengthen the metal or give it a reflective surface. cm-3 Melting Point: 1064.18 C, 1947.52 F, 1337.33 K Boiling Point: 2856 C, 5173 F, 3129 K Heat of Fusion: 12.55 kJ.mol-1 Heat of Vaporization: 324 kJ.mol-1 Atomic: Oxidation States: -1, 1, 2, 3, 4, 5 Electronegativity: 2.54 (Pauling scale) Atomic Radius: 144 picometre Covalent Radius: 136 6 picometre Van der Waals Radius: 166 picometre Ionization Energies: 890.1 kJ. This yields a powder which, in turn, is consolidated by means of a technique called argon-arc welding. In terms of abundance in the Earth's crust, ruthenium ranks 74th among all the different known elements or metals and is, therefore, one of the rarest. Estimates place world reserves at 5,000 tonnes, and annual mining output about 12 tonnes.
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