Gold Exchange Standard: In this gold standard, only the circulation of coins minted from lesser valuable metals (such as silver) may be involved. The authorities, however, will have undertaken a fixed exchange rate with a country that's on the gold standard. Before the turn of the 20th century, countries that were still on silver standard started pegging their monetary units to the gold standard of either the United States or the United Kingdom. Its occurrence is similar to that of ruthenium, and its primary use is as a catalytic converter. Rhodium is considered perhaps the rarest element. It is also known to be the most expensive precious metal, with a price estimated to be about USD2,750 per troy ounce (USD88,415 per kilogram) as of January 2010. Such items, particularly those made of silver, gold, or platinum, are struck with an official mark (or series of marks), which guarantees fineness or purity of the metal used. To determine the precious metal content in an item, certain non-destructive assay techniques are used. Two examples are the touchstone method (a very old assay method) and the X-ray fluorescence method (the modern, non-destructive assay method). mol-1 (third) Palladium is used in the following: 1. Catalytic converters; 2. Jewelry and watch making; 3. Dentistry and surgical instruments; 4. Aircraft spark plugs; 5. Electrical contacts; 6. Connector platings; 7. Manuscript illumination. Since the late 1930s, palladium has been utilized as a precious metal in jewelry. While bullion coins are issued as legal tender, with nominal values assigned to them on minting, such face values are far below the commodity value of the metals themselves. Here's an example: Most of the gold coins issued by national governments, particularly those with currency values of between 10 and 100 U. mol-1 Electron Configuration: [Xe] 4f14 5d10 6s1 Physical: Density (near room temperature): 19.30 g.cm-3 Liquid Density (at melting point): 17.31 g.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.