Platinum Group Elements

Platinum group elements are ruthenium, rhodium and palladium (of similar weight as, but lighter than silver, the next element in the periodic table by atomic number) and osmium, iridium and platinum (of similar weight as, but lighter than gold, the next element in the periodic table by atomic number). As opposed to gold and silver, known probably since the stone age, the first certain discovery of platinum, in the alluvial deposits of the Rio Pinto – Columbia, is as recent as 1741. Platinum was introduced to Europe by Sir Charles Wood who brought it to England during that same year. Osmium and iridium were isolated together from the residues of platinum ores in aqua regia in 1803 or 1804 by English chemist Smithson Tennant. The existence of rhodium and palladium was established in 1803 by English doctor W. Hyde Wollaston. Ruthenium was recognized as an element in 1844 or 1845 by Russian chemist C.E. Claus.