noble metals

The term noble metal describes any of several metallic chemical elements that have outstanding resistance to oxidation, even at high temperatures. Although the grouping is not strictly defined, it usually is considered to include ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold; i.e., the metals of groups 8, 9, 10, and 11 of the second and third transition series of the periodic system, as well as group 7ís rhenium.