بلاتين (Pt)

الاكتشاف والتاريخ

تاريخ الاكتشاف: 1557 · Julius Caesar Scaliger

Archaeologists have discovered traces of platinum in the gold used in ancient Egyptian burials. For example, a small box from burial of Shepenupet II was found to be decorated with gold-platinum hieroglyphs. However, the extent of early Egyptians' knowledge of the metal is unclear. It is possible they did not recognize there was platinum in their gold. The metal was used by Native Americans near modern-day Esmeraldas, Ecuador to produce artifacts of a white gold-platinum alloy. Archeologists usually associate the tradition of platinum-working in South America with the La Tolita Culture (c. 600 BCE – 200 CE), but precise dates and location are difficult, as most platinum artifacts from the area were bought secondhand through the antiquities trade rather than obtained by direct archeological excavation. To work the metal, they would combine gold and platinum powders by sintering. The resul

الاستخدامات والتطبيقات

Platinum is an extremely rare metal on Earth, occurring at a concentration of only 0.005 ppm in Earth's crust. Platinum is often found chemically uncombined as native platinum and as alloy with the other platinum-group metals mostly. Most often native platinum is found in secondary deposits among alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum-group metals. Another large alluvial deposit is in the Ural Mountains, Russia, and it is still mined. In nickel and copper deposits, platinum-group metals occur as sulfides (e.g., (Pt,Pd)S), tellurides (e.g., PtBiTe), antimonides (PdSb), and arsenides (e.g. PtAs2), and as end alloys with nickel or copper. Platinum arsenide, sperrylite (PtAs2), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum,

النظائر

Platinum has six naturally occurring isotopes: 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt. The most abundant of these is 195Pt, comprising 33.83 % of all platinum; it is the only stable isotope with a non-zero spin, of ½, and it is favorable for use in 195Pt NMR. Due to its spin and large abundance, 195Pt satellite peaks are also often observed in 1H and 31P NMR spectroscopy (e.g., for Pt-phosphine and Pt-alkyl complexes). The radioactive 190Pt is the least abundant of these at only 0.012 %; it undergoes alpha decay with a half-life of 4.83×1011 years, causing the very low activity of 16.8 Bq/kg of natural platinum. The decay of this isotope has some use in isotope geology, though not directly for dating. The other natural isotopes are theoretically capable of alpha decay also, but this has never been observed, and therefore they are considered stable. Platinum also has 38 synthetic is