Noble metals are metals that are resistant to corrosion or oxidation, unlike most base metals. They tend to be precious metals, often due to perceived rarity. Examples include gold, silver, tantalum, platinum, palladium and rhodium. Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily loses electrons to form positive ions (cations) and has metallic bonds between metal atoms. ... See corrosive for the hazard. ... The most fundamental reactions in chemistry are the redox processes. ... In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with diluted hydrochloric acid (HCl) to form hydrogen. ... A gold nugget A precious metal is a rare metallic chemical element of high economic value. ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... General Name, Symbol, Number silver, Ag, 47 Chemical series transition metals Group, Period, Block 11, 5, d Appearance lustrous white metal Standard atomic weight 107. ... General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Atomic mass 180. ... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... General Name, Symbol, Number palladium, Pd, 46 Chemical series transition metals Group, Period, Block 10, 5, d Appearance silvery white metallic Standard atomic weight 106. ... General Name, Symbol, Number rhodium, Rh, 45 Chemical series transition metals Group, Period, Block 9, 5, d Appearance silvery white metallic Atomic mass 102. ...

Some of the noble metals can be dissolved in aqua regia, a highly concentrated mixture of acids. Freshly prepared aqua regia is colorless, but it turns orange within seconds. ... Acidity redirects here. ...

The term can also be used in a relative sense. A "Galvanic series" is a hierarchy of metals (or other electrically conductive materials, including composites and semimetals) that runs from noble to active, and allows designers to see at a glance how materials will interact in the environment used to generate the series. In this sense of the word, graphite is more noble than silver (even though it is alchemically more base) and the relative nobility of many materials is highly dependent upon context, as for aluminium and stainless steel in conditions of varying pH. The galvanic series determines the nobility of metals and semi-metals. ... Together with the metals and nonmetals, the metalloids (in Greek metallon = metal and eidos = sort - also called semimetals) form one of the three categories of chemical elements as classified by ionization and bonding properties. ... Graphite (named by Abraham Gottlob Werner in 1789 from the Greek γραφειν (graphein): to draw/write, for its use in pencils) is one of the allotropes of carbon. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Standard atomic weight 26. ... The 630 foot high, stainless-clad (type 304L) Gateway Arch defines St. ... The correct title of this article is . ...

Noble metals

In physics the definition of a noble metal is even more strict. It is required that the d-bands of the electronic structure are filled. Taking this into account, only copper, silver and gold are noble metals, as all d-like band are filled and don't cross the Fermi level. For platinum two d-bands cross the Fermi level, changing its chemical behaviour; it is used (in contrast to e.g. gold) as a catalyst. The different reactivity can easily be seen while preparing clean metal surfaces in ultra high vacuum; surfaces of noble metals (e.g. gold) are easy to clean and stay clean for a long time, while those of e.g. platinum or palladium are covered by carbon monoxide very quickly. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... In chemistry, an atomic orbital is the region in which an electron may be found around a single atom. ... In solid state physics, the electronic band structure, or simply band structure, refers to the dispersion relation (the relation between energy versus momentum) of electrons in a crystal. ... In quantum mechanics, particles with a half-integer spin, usually spin 1/2 (for example electrons) follow the Pauli exclusion principle, which states that no two particles may occupy the same quantum state. ... It has been suggested that this article or section be merged into Catalysis. ... Look up Vacuum in Wiktionary, the free dictionary. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ...

External links

• To see which bands cross the Fermi level, the Fermi surfaces of almost all the metals can be found at the Fermi Surface Database
• The following article might also clarify the correlation between band structure and the term noble metal E. Hüger and K. Osuch, Making a noble Metal of Pd, Europhys. Lett., 71 (2005) 276

In condensed matter physics, the Fermi surface is an abstract boundary useful for predicting the thermal, electrical, magnetic, and optical properties of metals, semimetals, and doped semiconductors. ...

See also

• Base metal
• Synthesis of noble metals