page_title: Platinum group
section_title: Properties and uses
hierarchical_section_title: Platinum group / Properties and uses
caption_attribution_description: English: Replica of the national prototype kilogram standard no. K20 kept by the US government National Institute of Standards and Technology (NIST), Bethesda, Maryland, shown as it is normally stored, inside two glass bell jars. This is the primary standard defining all units of mass and weight in the US. It is a polished cylinder made of 90% platinum - 10% iridium alloy, 39 mm (1.5 inches) in diameter and 39 mm high. It is an exact copy of the International Prototype Kilogram (IPK) kept at the International Bureau of Weights and Measures (Bureau International des Poids et Measures) in Sevres, France. It was one of 43 copies which were presented by France in 1889 to different nations as national standards, and became the primary standard of mass for the US in 1893 when the US switched to metric standards. Its exact mass, carefully compared to the IPK every 40 years, is 39 micrograms less than the IPK. The handling of actual prototype kilograms like K20 is kept to an absolute minimum to avoid wear that results in changes in mass; even a single atomic layer of atoms removed from the bottom surface by a slight abrasion during lifting would result in a measureable decrease in mass of 10 μg. So the actual prototype is left in a locked basement vault safe from damage. This is an exact replica fabricated for public display.
context_page_description: The platinum-group metals are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block.
  The six platinum-group metals are ruthenium, rhodium, palladium, osmium, iridium, and platinum. They have similar physical and chemical properties, and tend to occur together in the same mineral deposits. However they can be further subdivided into the iridium-group platinum-group elements and the palladium-group platinum-group elements based on their behaviour in geological systems.
  The three elements above the platinum group in the periodic table are all ferromagnetic, these being the only known transition metals with this property.
  With the platinum group metals having many desirable properties, they have a wide application of uses. This leads to an increased demand for these metals as well as an increase in their production for use.
  The increase in platinum group use as well as production activity could cause environmental and human health risks not previously considered where more research is needed to determine the risks associated with platinum group metal use and production.
context_section_description: As of 1996, the largest applications of platinum metals were, in thousands of troy ounces/year: Pd for autocatalysts (4470), Pt for jewelry (2370), Pd for electronics (2070), Pt for autocatalysts (1830), Pd for dental (1230), Rh for autocatalysts (490), and Pd for chemical reagents (230).
  The platinum metals have many useful catalytic properties. They are highly resistant to wear and tarnish, making platinum, in particular, well suited for fine jewellery. Other distinctive properties include resistance to chemical attack, excellent high-temperature characteristics, high mechanical strength, good ductility, and stable electrical properties. Apart from their application in jewellery, platinum metals are also used in anticancer drugs, industries, dentistry, electronics, and vehicle exhaust catalysts (VECs). VECs contain solid platinum (Pt), palladium (Pd), and rhodium (Rh) and are installed in the exhaust system of vehicles to reduce harmful emissions, such as carbon monoxide (CO), by converting them into less harmful emissions.
caption: Replica of the NIST national prototype kilogram standard, made in 90% platinum - 10% iridium alloy
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