Noble metal

A noble metal is a metal that is resistant to both corrosion and oxidation when exposed to air. Metals such as gold, silver, platinum, iridium, rhodium, palladium and rhenium are examples. Sometimes, mercury and copper can be regarded as noble metals. Some metals like titanium are not, even though they are resistant to corrosion. Noble metals are valuable, because they are not commonly found in the Earth's crust. They have many uses in everyday things including chemical engineering, electronics, and jewelry.

Noble Metal Media

• 

  • 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) *  1  often (Ag)*  2  sometimes (Cu, Hg)*  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. Silver is sometimes not recognized as a noble metal on account of its greater reactivity.* 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
• 

  Abundance of the chemical elements in the Earth's crust as a function of atomic number. The rarest elements (shown in yellow, including the noble metals) are not the heaviest, but are rather the siderophile (iron-loving) elements in the Goldschmidt classification of elements.

• 

  Chalcopyrite, which is copper iron sulfide (CuFeS2), is the most abundant copper ore mineral

• 

  One half of a ruthenium bar.Size ~ 40 × 15 × 10 mmWeight ~44 g

• 

  Rhodium: 1 g powder, 1g pressed cylinder, 1 g pellet.

• 

  The noble metal palladium is very similar to platinum, and, like platinum, is often used for catalysts and for jewellery. Palladium is more reactive than platinum. Palladium has excellent capability to absorb, store, and then release hydrogen.

• 

  Acanthite, or silver sulfide (Ag2S)

• 

  Osmium Os, crystals, purity ≥ 99.99%, 2.2 g. Produced by chemical transport reaction in chlorine gas

• 

  Pieces of pure iridium, 1 g, size: 1–3 mm each

• 

  Crystals of pure platinum grown by gas phase transport.

Related pages

• Precious metal