Platinum
Introduction
Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name is derived from the Spanish term platino, meaning "little silver".
Properties and Characteristics
Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts.
Occurrence and Production
Platinum is an extremely rare metal, occurring at a concentration of only 0.005 ppm in the Earth's crust. It is sometimes mistaken for silver (Ag). Platinum is often found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly. Most often the native platinum is found in secondary deposits in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum-group metals.
Applications
Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Being a heavy metal, it leads to health problems upon exposure to its salts; but due to its corrosion resistance, metallic platinum has not been linked to adverse health effects.
Health and Environmental Effects
While platinum is not considered a health hazard, certain platinum compounds have been identified as carcinogenic and can cause allergic reactions. However, the widespread use of platinum in automobile catalytic converters poses a potential environmental risk. Platinum, palladium, and rhodium in catalytic converters are recycled, and as of 2003, recycled platinum made up a significant portion of overall platinum consumption.