Metallic elements that are nearly chemically inert
Periodic table extract showing approximately how often each element tends to be recognized as a noble metal: 7 most often (Ru, Rh, Pd, Os, Ir, Pt, Au, Ag) [1]1 often (Ag)[2]2 sometimes (Cu, Hg)[3]6 in a limited sense (Tc, Re, As, Sb, Bi, Po) The thick black line encloses the seven to eight metals most often to often so recognized. * may be tarnished in moist air or corrode in an acidic solution containing oxygen and an oxidant † attacked by sulfur or hydrogen sulfide § self-attacked by radiation-generated ozone
In more specialized fields of study and applications the number of elements counted as noble metals can be smaller or larger. In physics, there are only three noble metals: copper, silver, and gold. In dentistry, silver widely used because of antimicrobial properties.[4]
^Balcerzak, M (2021). "Noble Metals, Analytical Chemistry of". Encyclopedia of Analytical Chemistry: Applications, Theory and Instrumentation. Wiley Online Library. pp. 1–36. doi:10.1002/9780470027318.a2411.pub3. ISBN9780471976707.
^Schlamp, G (2018). "Noble metals and noble metal alloys". In Warlimont, H; Martienssen, W (eds.). Springer Handbook of Materials Data. Springer Handbooks. Cham: Springer. pp. 339–412. doi:10.1007/978-3-319-69743-7_14. ISBN978-3-319-69741-3.