Noble metal

A noble metal is ordinarily regarded as a metallic <a href="/facts/Chemical_element/0jducgWD">element</a> that is generally resistant to <a href="/facts/Corrosion/lIC7H4we">corrosion</a> and is usually found in nature in its <a href="/facts/Native_element/kWjWAus5">raw form</a>. <a href="/facts/Gold/1znknojp">Gold</a>, <a href="/facts/Platinum/qJC6lQf7">platinum</a>, and the other <a href="/facts/Platinum_group_metal/pbDgst54">platinum group metals</a> (<a href="/facts/Ruthenium/uzCm4ufn">ruthenium</a>, <a href="/facts/Rhodium/xmBd9aFG">rhodium</a>, <a href="/facts/Palladium/P7y0ESWf">palladium</a>, <a href="/facts/Osmium/1TjXD69n">osmium</a>, <a href="/facts/Iridium/cB4n6MbQ">iridium</a>) are most often so classified. <a href="/facts/Silver/xXe41BGg">Silver</a>, <a href="/facts/Copper/I8PEE8oX">copper</a>, and <a href="/facts/Mercury_(element)/WlxfoHva">mercury</a> are sometimes included as noble metals, but each of these usually occurs in nature combined with <a href="/facts/Sulfur/IK0amTfM">sulfur</a>.
In more specialized fields of study and applications the number of elements counted as noble metals can be smaller or larger. It is sometimes used for the three metals <a href="/facts/Copper/I8PEE8oX">copper</a>, silver, and gold which have filled <a href="/facts/D_electron_count/DdXMds5z">d-bands</a>, while it is often used mainly for silver and gold when discussing <a href="/facts/Surface-enhanced_Raman_spectroscopy/cgHonFXa">surface-enhanced Raman spectroscopy</a> involving metal <a href="/facts/Nanoparticle/k8kNxX4E">nanoparticles</a>. It is sometimes applied more broadly to any metallic or <a href="/facts/Semimetal/ELtXVlI5">semimetallic</a> element that does not react with a weak acid and give off hydrogen gas in the process. This broader set includes copper, <a href="/facts/Mercury_(element)/WlxfoHva">mercury</a>, <a href="/facts/Technetium/MGYWNI5d">technetium</a>, <a href="/facts/Rhenium/TzyqJYEn">rhenium</a>, <a href="/facts/Arsenic/k1c4f44D">arsenic</a>, <a href="/facts/Antimony/YsA7lVgT">antimony</a>, <a href="/facts/Bismuth/75FLjkoX">bismuth</a>, <a href="/facts/Polonium/G4rzsyjP">polonium</a>, gold, the six <a href="/facts/Platinum_group_metal/pbDgst54">platinum group metals</a>, and silver.
Many of the noble metals are used in alloys for jewelry or coinage. In <a href="/facts/Dentistry/p8b1zmts">dentistry</a>, silver is not always considered a noble metal because it is subject to corrosion when present in the mouth. All the metals are important <a href="/facts/Heterogeneous_catalysis/ju7E0bab">heterogeneous catalysts</a>.

Noble metal open-in-new

Noble metal