Platinum: Difference between revisions
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'''Platinum''' ({{pronEng|ˈplætɨnəm}}, {{respell|PLAT|ə-nəm}}) is a [[chemical element]] with the [[chemical symbol]] '''Pt''' and an [[atomic number]] of 78. Its name is derived from the Spanish term ''platina del Pinto'', which is literally translated into "little silver of the Pinto River."<ref>{{cite book|title = The Elements: Platinum|author = Woods, Ian|publisher = Benchmark Books|date = 2004|isbn = 978-0761415503}}</ref> It is in Group 10 of the [[periodic table of elements]]. A [[density|dense]], [[malleability|malleable]], [[ductility|ductile]], [[precious metal|precious]], gray-white [[transition metal]], platinum is resistant to corrosion and occurs in some [[nickel]] and [[copper]] ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, [[electric]]al contacts and [[electrode]]s, [[platinum resistance thermometer]]s, [[dentistry]] equipment, and [[catalytic converter]]s. Platinum [[bullion]] has the [[ISO 4217|ISO currency code]] of XPT. Platinum is a commodity with a value that fluctuates according to market forces. {{asof|2009|10|30}}, platinum was worth [[US$]]1,324.00 per [[troy ounce]] (approximately US$42.57 per [[gram]]).<ref name="Kitco">{{cite web |title = Live Market Quotes |publisher=Kitco |url=http://www.kitco.com/market/ |accessdate=2009-10-30 }}</ref> |
'''Platinum''' ({{pronEng|ˈplætɨnəm}}, {{respell|PLAT|ə-nəm}}) is a [[chemical element]] with the [[chemical symbol]] '''Pt''' and an [[atomic number]] of 78. Its name is derived from the Spanish term ''platina del Pinto'', which is literally translated into "little silver of the Pinto River."<ref>{{cite book|title = The Elements: Platinum|author = Woods, Ian|publisher = Benchmark Books|date = 2004|isbn = 978-0761415503}}</ref> It is in Group 10 of the [[periodic table of elements]]. A [[density|dense]], [[malleability|malleable]], [[ductility|ductile]], [[precious metal|precious]], gray-white [[transition metal]], platinum is resistant to corrosion and occurs in some [[nickel]] and [[copper]] ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, [[electric]]al contacts and [[electrode]]s, [[platinum resistance thermometer]]s, [[dentistry]] equipment, and [[catalytic converter]]s. Platinum [[bullion]] has the [[ISO 4217|ISO currency code]] of XPT. Platinum is a commodity with a value that fluctuates according to market forces. {{asof|2009|10|30}}, platinum was worth [[US$]]1,324.00 per [[troy ounce]] (approximately US$42.57 per [[gram]]).<ref name="Kitco">{{cite web |title = Live Market Quotes |publisher=Kitco |url=http://www.kitco.com/market/ |accessdate=2009-10-30 }}</ref> |
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treavnte iz da best rappa alive and everybodii knoz it and he doez 2.......so 4get all hataz |
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==Characteristics== |
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As a pure metal, platinum is silvery-white in appearance, lustrous, ductile, and malleable.<ref name="lagowski">{{cite book |title = Chemistry Foundations and Applications|volume = 3 |editor = Lagowski, J. J.|pages=267–268|date = 2004|isbn = 0-02-865724-1|publisher = Thomson Gale}}</ref> It does not oxidize at any temperature, although it is corroded by [[halogen]]s, cyanides, [[sulfur]], and caustic alkalis. Platinum is insoluble in [[hydrochloric acid|hydrochloric]] and [[nitric acid]], but dissolves in [[aqua regia]] to form chloroplatinic acid, H<sub>2</sub>PtCl<sub>6</sub>.<ref name="CRC">{{Cite book| author = CRC contributors| editor = Lide, David R.| chapter = Platinum| year = 2007–2008| title = CRC Handbook of Chemistry and Physics| volume = 4| pages = 26| location = New York| publisher = CRC Press| isbn = 978-0-8493-0488-0}}</ref> |
As a pure metal, platinum is silvery-white in appearance, lustrous, ductile, and malleable.<ref name="lagowski">{{cite book |title = Chemistry Foundations and Applications|volume = 3 |editor = Lagowski, J. J.|pages=267–268|date = 2004|isbn = 0-02-865724-1|publisher = Thomson Gale}}</ref> It does not oxidize at any temperature, although it is corroded by [[halogen]]s, cyanides, [[sulfur]], and caustic alkalis. Platinum is insoluble in [[hydrochloric acid|hydrochloric]] and [[nitric acid]], but dissolves in [[aqua regia]] to form chloroplatinic acid, H<sub>2</sub>PtCl<sub>6</sub>.<ref name="CRC">{{Cite book| author = CRC contributors| editor = Lide, David R.| chapter = Platinum| year = 2007–2008| title = CRC Handbook of Chemistry and Physics| volume = 4| pages = 26| location = New York| publisher = CRC Press| isbn = 978-0-8493-0488-0}}</ref> |
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Revision as of 16:59, 17 November 2009
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Platinum | ||||||||||||||||||||||||||||||||||||||||||||||
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Pronunciation | /ˈplætənəm/ | |||||||||||||||||||||||||||||||||||||||||||||
Appearance | silvery white | |||||||||||||||||||||||||||||||||||||||||||||
Standard atomic weight Ar°(Pt) | ||||||||||||||||||||||||||||||||||||||||||||||
Platinum in the periodic table | ||||||||||||||||||||||||||||||||||||||||||||||
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Atomic number (Z) | 78 | |||||||||||||||||||||||||||||||||||||||||||||
Group | group 10 | |||||||||||||||||||||||||||||||||||||||||||||
Period | period 6 | |||||||||||||||||||||||||||||||||||||||||||||
Block | d-block | |||||||||||||||||||||||||||||||||||||||||||||
Electron configuration | [Xe] 4f14 5d9 6s1 | |||||||||||||||||||||||||||||||||||||||||||||
Electrons per shell | 2, 8, 18, 32, 17, 1 | |||||||||||||||||||||||||||||||||||||||||||||
Physical properties | ||||||||||||||||||||||||||||||||||||||||||||||
Phase at STP | solid | |||||||||||||||||||||||||||||||||||||||||||||
Melting point | 2041.4 K (1768.3 °C, 3214.9 °F) | |||||||||||||||||||||||||||||||||||||||||||||
Boiling point | 4098 K (3825 °C, 6917 °F) | |||||||||||||||||||||||||||||||||||||||||||||
Density (at 20° C) | 21.452 g/cm3 [3] | |||||||||||||||||||||||||||||||||||||||||||||
when liquid (at m.p.) | 19.77 g/cm3 | |||||||||||||||||||||||||||||||||||||||||||||
Heat of fusion | 22.17 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||
Heat of vaporization | 510 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||
Molar heat capacity | 25.86 J/(mol·K) | |||||||||||||||||||||||||||||||||||||||||||||
Vapor pressure
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Atomic properties | ||||||||||||||||||||||||||||||||||||||||||||||
Oxidation states | −3, −2, −1, 0, +1, +2, +3, +4, +5, +6 (a mildly basic oxide) | |||||||||||||||||||||||||||||||||||||||||||||
Electronegativity | Pauling scale: 2.28 | |||||||||||||||||||||||||||||||||||||||||||||
Ionization energies |
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Atomic radius | empirical: 139 pm | |||||||||||||||||||||||||||||||||||||||||||||
Covalent radius | 136±5 pm | |||||||||||||||||||||||||||||||||||||||||||||
Van der Waals radius | 175 pm | |||||||||||||||||||||||||||||||||||||||||||||
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Other properties | ||||||||||||||||||||||||||||||||||||||||||||||
Natural occurrence | primordial | |||||||||||||||||||||||||||||||||||||||||||||
Crystal structure | face-centered cubic (fcc) (cF4) | |||||||||||||||||||||||||||||||||||||||||||||
Lattice constant | a = 392.36 pm (at 20 °C)[3] | |||||||||||||||||||||||||||||||||||||||||||||
Thermal expansion | 8.93×10−6/K (at 20 °C)[3] | |||||||||||||||||||||||||||||||||||||||||||||
Thermal conductivity | 71.6 W/(m⋅K) | |||||||||||||||||||||||||||||||||||||||||||||
Electrical resistivity | 105 nΩ⋅m (at 20 °C) | |||||||||||||||||||||||||||||||||||||||||||||
Magnetic ordering | paramagnetic | |||||||||||||||||||||||||||||||||||||||||||||
Molar magnetic susceptibility | +201.9 × 10−6 cm3/mol (290 K)[4] | |||||||||||||||||||||||||||||||||||||||||||||
Tensile strength | 125–240 MPa | |||||||||||||||||||||||||||||||||||||||||||||
Young's modulus | 168 GPa | |||||||||||||||||||||||||||||||||||||||||||||
Shear modulus | 61 GPa | |||||||||||||||||||||||||||||||||||||||||||||
Bulk modulus | 230 GPa | |||||||||||||||||||||||||||||||||||||||||||||
Speed of sound thin rod | 2800 m/s (at r.t.) | |||||||||||||||||||||||||||||||||||||||||||||
Poisson ratio | 0.38 | |||||||||||||||||||||||||||||||||||||||||||||
Mohs hardness | 3.5 | |||||||||||||||||||||||||||||||||||||||||||||
Vickers hardness | 400–550 MPa | |||||||||||||||||||||||||||||||||||||||||||||
Brinell hardness | 300–500 MPa | |||||||||||||||||||||||||||||||||||||||||||||
CAS Number | 7440-06-4 | |||||||||||||||||||||||||||||||||||||||||||||
History | ||||||||||||||||||||||||||||||||||||||||||||||
Discovery | Antonio de Ulloa (1735) | |||||||||||||||||||||||||||||||||||||||||||||
Isotopes of platinum | ||||||||||||||||||||||||||||||||||||||||||||||
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Platinum (Template:PronEng, PLAT-ə-nəm) is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River."[6] It is in Group 10 of the periodic table of elements. A dense, malleable, ductile, precious, gray-white transition metal, platinum is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and catalytic converters. Platinum bullion has the ISO currency code of XPT. Platinum is a commodity with a value that fluctuates according to market forces. As of 30 October 2009[update], platinum was worth US$1,324.00 per troy ounce (approximately US$42.57 per gram).[7]
treavnte iz da best rappa alive and everybodii knoz it and he doez 2.......so 4get all hataz As a pure metal, platinum is silvery-white in appearance, lustrous, ductile, and malleable.[8] It does not oxidize at any temperature, although it is corroded by halogens, cyanides, sulfur, and caustic alkalis. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in aqua regia to form chloroplatinic acid, H2PtCl6.[9]
Platinum's wear- and tarnish-resistance characteristics are well suited for making fine jewelry. Platinum is more precious than gold or silver. Platinum possesses high resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All of these properties have been exploited for industrial applications.
Isotopes
Platinum has six naturally occurring isotopes: 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt. The most abundant of these is 195Pt, comprising 33.83% of all platinum. 190Pt is the least abundant at only .01%. Of the naturally occurring isotopes, only 190Pt is unstable, though it decays with a half-life of 650×109 years. 198Pt undergoes alpha decay, but because its half-life is estimated as being greater than 320×1012 years, it is considered stable. Platinum also has 31 synthetic isotopes ranging in atomic mass from 166 to 202, making the total number of known isotopes 37. The least stable of these is 166Pt with a half-life of 300 µs, while the most stable is 193Pt with a half-life of 50 years. Most of platinum's isotopes decay by some combination of beta decay and alpha decay. 188Pt, 191Pt, and 193Pt decay primarily by electron capture. 190Pt and 198Pt have double beta decay paths.[10]
Chemistry and compounds
Platinum's most common oxidation states are +2, and +4. The +1 and +3 oxidation states are less common, and are often stabilized by metal bonding in bimetallic (or polymetallic) species. As is expected, tetracoordinate platinum(II) compounds tend to adopt a square planar geometry. While elemental platinum is generally unreactive, it dissolves in aqua regia to give soluble hexachloroplatinic acid ("H2PtCl6", formally (H3O)2PtCl6·nH2O ):[11]
- Pt + 4 HNO3 + 6 HCl → H2PtCl6 + 4 NO2 + 4 H2O
This compound has various applications in photography, zinc etchings, indelible ink, plating, mirrors, porcelain coloring, and as a catalyst.[12]
Treatment of hexachloroplatinic acid with an ammonium salt, such as ammonium chloride, gives ammonium hexachloroplatinate,[11] which is very insoluble in ammonium solutions. Heating the ammonium salt in the presence of hydrogen reduces it to elemental platinum. Platinum is often isolated from ores and recycled thus.[13] Potassium hexachloroplatinate is similarly insoluble, such that the acid has been used in the determination of potassium ions by gravimetry.[14]
When hexachloroplatinic acid is heated, it decomposes through platinum(IV) chloride and platinum(II) chloride to elemental platinum, although the reactions do not occur stepwise, cleanly:[15]
- (H3O)2PtCl6·n H2O ⇌ PtCl4 + 2 HCl + (n + 2) H2O
- PtCl4 ⇌ PtCl2 + Cl2
- PtCl2 ⇌ Pt + Cl2
All three reactions are reversible. Platinum(II) and platinum(IV) bromides are known as well. Platinum hexafluoride is a strong oxidizer capable of oxidising oxygen.
Platinum(IV) oxide, PtO2, also known as Adams' Catalyst, is a black powder which is soluble in KOH solutions and concentrated acids.[16] PtO2 and the less common PtO both decompose upon heating.[8] Platinum(II,IV) oxide, Pt3O4, is formed in the following reaction:
- 2 Pt2+ + Pt4+ + 4 O2− → Pt3O4
Platinum also forms a trioxide, which is actually in the +4 oxidation state.
Unlike palladium acetate, platinum(II) acetate is not commercially available. Where a base is desired, the halides have been used in conjunction with sodium acetate.[17] The use of platinum(II) acetylacetonate has also been reported.[18]
Zeise's salt, containing an ethylene ligand, was one of the first organometallic compounds discovered. Dichloro(cycloocta-1,5-diene)platinum(II) is a commercially available olefin complex, which contains easily displaceable cod ligands ("cod" being an abbreviation of 1,5-cyclooctadiene). The cod complex and the halides are convenient starting points to platinum chemistry. As a soft acid, platinum has a great affinity for sulfur, such as on DMSO; numerous DMSO complexes have been reported and care should be taken in the choice of reaction solvent.[17]
Cisplatin, or cis-diamminedichloroplatinum(II) is the first of a series of square planar platinum(II)-containing chemotherapy drugs, including carboplatin and oxaliplatin. These compounds are capable of crosslinking DNA and kill cells by similar pathways to alkylating chemotherapeutic agents.[19]
-
The hexachloroplatinate ion
-
The anion of Zeise's salt
-
Dichloro(cycloocta-1,5-diene)platinum(II)
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Cisplatin
Several barium platinides have been synthesized, in which platinum exhibits negative oxidation states ranging from −1 to −2. These include BaPt, Ba
3Pt
2, and Ba
2Pt.[20] Caesium platinide, Cs
2Pt, has been shown to contain Pt2−
anions.[21] Platinum is also shown to exhibit negative oxidation states at surfaces reduced electrochemically.[22] The negative oxidation states exhibited by platinum, which are unusual for metallic elements, are believed to be due to the relativistic stabilization of the 6s orbitals.[21]
Occurrence
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/PlatinumOreUSGOV2.jpg/170px-PlatinumOreUSGOV2.jpg)
Platinum is an extremely rare metal,[23] occurring as only 0.003 ppb in the Earth's crust. It is sometimes mistaken for silver (Ag).
Platinum is often found chemically uncombined as native platinum and alloyed with iridium as platiniridium. Most often the native platinum is found in secondary deposits; platinum is combined with the other platinum group metals in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum group metals. Another large alluvial deposit was found in the Ural Mountains, Russia, which is still mined.
In nickel and copper deposits platinum group metals occur as sulfides (i.e. (Pt,Pd)S)), tellurides (i.e. PtBiTe), antimonides (PdSb), and arsenides (i.e. PtAs2), and as end alloys with nickel or copper. Platinum arsenide, sperrylite (PtAs2), is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. The rare sulfide mineral cooperite, (Pt,Pd,Ni)S, contains platinum along with palladium and nickel. Cooperite occurs in the Merensky Reef within the Bushveld complex, Gauteng, South Africa.[24]
The largest known primary reserves are in the Bushveld complex in South Africa.[25] The large copper–nickel deposits near Norilsk in Russia, and the Sudbury Basin, Canada, are the two other large deposits. In the Sudbury Basin the huge quantities of nickel ore processed makes up for the fact that platinum is present as only 0.5 ppm in the ore. Smaller reserves can be found in the United States,[25] for example in the Absaroka Range in Montana.[26] This is also shown in the production of 2005. In 2005, South Africa was the top producer of platinum with an almost 80% share followed by Russia and Canada.[27]
Platinum exists in higher abundances on the Moon and in meteorites. Correspondingly, platinum is found in slightly higher abundances at sites of bolide impact on the Earth that are associated with resulting post-impact volcanism, and can be mined economically; the Sudbury Basin is one such example.
Production
![](http://upload.wikimedia.org/wikipedia/commons/thumb/4/48/One_litre_of_Platinum.jpg/250px-One_litre_of_Platinum.jpg)
Platinum together with the rest of the platinum metals is obtained commercially as a by-product from nickel and copper mining and processing. During electrorefining of copper, noble metals such as silver, gold and the platinum group metals as well as selenium and tellurium settle to the bottom of the cell as anode mud, which forms the starting point for the extraction of the platinum group metals.[28][29]
If pure platinum is found in placer deposits or other ores, it is isolated from them by various methods of subtracting impurities. Because platinum is significantly denser than many of its impurities, the lighter impurities can be removed by simply floating them away in a water bath. Platinum is also non-magnetic, while nickel and iron are both magnetic. These two impurities are thus removed by running an electromagnet over the mixture. Because platinum has a higher melting point than most other substances, many impurities can be burned or melted away without melting the platinum. Finally, platinum is resistant to hydrochloric and sulfuric acids, while other substances are readily attacked by them. Metal impurities can be removed by stirring the mixture in either of the two acids and recovering the remaining platinum.[30]
One suitable method for purification for the raw platinum, which contains platinum, gold, and the other platinum group metals, is to process it with aqua regia, in which palladium, gold and platinum are dissolved, while osmium, iridium, ruthenium and rhodium stay unreacted. The gold is precipitated by the addition of iron(III) chloride and after filtering of the gold, the platinum is precipitated by the addition of ammonium chloride as ammonium chloroplatinate. Ammonium chloroplatinate can be converted to the metal by heating.[31]
Applications
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Aufgeschnittener_Metall_Katalysator_f%C3%BCr_ein_Auto.jpg/220px-Aufgeschnittener_Metall_Katalysator_f%C3%BCr_ein_Auto.jpg)
Of the 239 tonnes of platinum sold in 2006, 130 tonnes were used for automobile emissions control devices, 49 tonnes were used for jewelry, 13.3 tonnes were used in electronics, and 11.2 tonnes were used by the chemical industry as a catalyst. The remaining 35.5 tonnes produced were used in various other minor applications, such as electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.[32]
Catalysis
The most common use of platinum is as a catalyst in chemical reactions. It has been employed in this application since the early 1800s, when platinum powder was used to catalyze the ignition of hydrogen. The most important application of platinum is in automobiles as a catalytic converter, which allows the complete combustion of low concentrations of unburned hydrocarbon from the exhaust into carbon dioxide and water vapor. Platinum is also used in the petroleum industry as a catalyst in a number of separate processes, but especially in catalytic reforming of straight run naphthas into higher-octane gasoline which becomes rich in aromatic compounds. PtO2, also known as Adams' catalyst, is used as a hydrogenation catalyst, specifically for vegetable oils.[12] Platinum metal also strongly catalyzes the decomposition of hydrogen peroxide into water and oxygen gas.[33]
Standard
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Platinum-Iridium_meter_bar.jpg/220px-Platinum-Iridium_meter_bar.jpg)
From 1889 to 1960, the meter was defined as the length of a platinum-iridium (90:10) alloy bar, known as the International Prototype Meter bar. The previous bar was made of platinum in 1799. The International Prototype Kilogram remains defined by a cylinder of the same platinum-iridium alloy made in 1879.
The standard hydrogen electrode also utilizes a platinized platinum electrode due to its corrosion resistance, and other attributes.
Precious metal
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Platinum_eagle101.jpg/100px-Platinum_eagle101.jpg)
Platinum is a precious metal commodity; its bullion has the ISO currency code of XPT. Coins, bars, and ingots are traded or collected. Platinum finds use in jewelry, usually as a 90-95% alloy, due to its inertness and shine. In watchmaking, Vacheron Constantin, Patek Philippe, Rolex, Breitling and other companies use platinum for producing their limited edition watch series. Watchmakers highly appreciate the unique properties of platinum as it neither tarnishes nor wears out.[34]
Price
The price of platinum, like other industrial commodities, is more volatile than that of gold. In 2008 the price of platinum ranged from $774 to $2,252 per oz.[36]
During periods of sustained economic stability and growth, the price of platinum tends to be as much as twice the price of gold, whereas during periods of economic uncertainty[37], the price of platinum tends to decrease due to reduced industrial demand, falling below the price of gold. Gold prices are more stable in slow economic times, as gold is considered a safe haven and gold demand is not driven by industrial uses. In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king.[38]
Other uses
In the laboratory, platinum wire is used for electrodes; platinum pans are used in thermogravimetric analysis. Platinum is used as an alloying agent for various metal products, including fine wires, noncorrosive laboratory containers, medical instruments, dental prostheses, electrical contacts, and thermocouples. Platinum-cobalt, an alloy comprised of roughly 3 parts platinum and 1 part cobalt, is used to make relatively strong permanent magnets.[12] Platinum-based anodes are used in ships, pipelines, and steel piers.[9]
Symbol of prestige
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Platinum_nuggets.jpg/220px-Platinum_nuggets.jpg)
Platinum's rarity as a metal has caused advertisers to associate it with exclusivity and wealth. "Platinum" debit cards have greater privileges than do "gold" ones. "Platinum awards" are the second highest possible, ranking above "gold", "silver" and "bronze", but below diamond. For example, in the United States a musical album that has sold more than 1 million copies, will be credited as "platinum", whereas an album that sold more than 10 million copies will be certified as “diamond”. Some products, such as blenders and vehicles, with a silvery-white color are identified as "platinum". Platinum is considered a precious metal, although its use is not as common as the use of gold or silver. The frame of the Crown of Queen Elizabeth the Queen Mother, manufactured for her Coronation as Consort of King George VI, is made of platinum. It was the first British crown to be made of this particular metal.
History
Platinum occurs naturally in the alluvial sands of various rivers, though there is little evidence of its use by ancient peoples. However, the metal was used by pre-Columbian Americans near modern-day Esmeraldas, Ecuador to produce artifacts of a white gold-platinum alloy. The first European reference to platinum appears in 1557 in the writings of the Italian humanist Julius Caesar Scaliger as a description of an unknown noble metal found between Darién and Mexico, "which no fire nor any Spanish artifice has yet been able to liquefy."[39]
![](http://upload.wikimedia.org/wikipedia/commons/thumb/e/ee/Platinum-symbol.png/75px-Platinum-symbol.png)
In 1741, Charles Wood, a British metallurgist, found various samples of Columbian platinum in Jamaica, which he sent to William Brownrigg for further investigation. Antonio de Ulloa, also credited with the discovery of platinum, returned to Spain from the French Geodesic Mission in 1746 after having been there for eight years. His historical account of the expedition included a description of platinum as being neither separable nor calcinable. Ulloa also anticipated the discovery of platinum mines. After publishing the report in 1748, Ulloa did not continue to investigate the new metal. In 1758, he was sent to superintend mercury mining operations in Huancavelica.[39]
In 1750, after studying the platinum sent to him by Wood, Brownrigg presented a detailed account of the metal to the Royal Society, mentioning that he had seen no mention of it in any previous accounts of known minerals. Brownrigg also made note of platinum's extremely high melting point and refractoriness toward borax. Other chemists across Europe soon began studying platinum, including Torbern Bergman, Jöns Jakob Berzelius, William Lewis, and Pierre Macquer. In 1752, Henrik Scheffer published a detailed scientific description of the metal, which he referred to as "white gold", including an account of how he succeeded in fusing platinum ore with the aid of arsenic. Scheffer described platinum as being less pliable than gold, but with similar resistance to corrosion.[39]
Carl von Sickingen researched platinum extensively in 1772. He succeeded in making malleable platinum by alloying it with gold, dissolving the alloy in aqua regia, precipitating the platinum with ammonium chloride, igniting the ammonium chloroplatinate, and hammering the resulting finely divided platinum to make it cohere. Franz Karl Achard made the first platinum crucible in 1784. He worked with the platinum by fusing it with arsenic, then later volatilizing the arsenic.[39]
In 1786, Charles III of Spain provided a library and laboratory to Pierre-François Chabaneau to aid in his research of platinum. Chabaneau succeeded in removing various impurities from the ore, including gold, mercury, lead, copper, and iron. This led him to believe that he was working with a single metal, but in truth the ore still contained the yet-undiscovered platinum group metals. This led to inconsistent results in his experiments. At times the platinum seemed malleable, but when it was alloyed with iridium, it would be much more brittle. Sometimes the metal was entirely incombustible, but when alloyed with osmium, it would volatilize. After several months, Chabaneau succeeded in producing 23 kilograms of pure, malleable platinum by hammering and compressing the sponge form while white-hot. Chabeneau realized that the infusibility of platinum would lend value to objects made of it, and so started a business with Joaquín Cabezas producing platinum ingots and utensils. This started what is known as the "platinum age" in Spain.[39]
From 1875 to 1960 the SI unit of length (the standard meter) was defined as the distance between two lines on a standard bar of an alloy of ninety percent platinum and ten percent iridium, measured at 0 degrees Celsius.
In 2007 Gerhard Ertl won the Nobel Prize in Chemistry for determining the detailed molecular mechanisms of the catalytic oxidation of carbon monoxide over platinum (catalytic converter).
Precautions
According to the Centers for Disease Control and Prevention, short-term exposure to platinum salts "may cause irritation of the eyes, nose, and throat" and long-term exposure "may cause both respiratory and skin allergies." The current OSHA standard is 0.002 milligram per cubic meter of air averaged over an 8-hour work shift.[40]
Certain platinum complexes are used in chemotherapy and show good anti-tumor activity for some tumors. Cisplatin is particularly effective against testicular cancer; cure rate was improved from 10% to 85%.[41] However, the side effects are severe. Cisplatin causes cumulative, irreversible kidney damage and deafness.[42] As with other ototoxic agents, deafness may be secondary to interactions with melanin in the stria vascularis.
As platinum is a catalyst in the manufacture of the silicone rubber and gel components of several types of medical implants (breast implants, joint replacement prosthetics, artificial lumbar discs, vascular access ports), the possibility that platinum free radicals could enter the body and cause adverse effects has merited study. The FDA and other countries have reviewed the issue and found no evidence to suggest toxicity in vivo.[43]
See also
Notes
- ^ "Standard Atomic Weights: Platinum". CIAAW. 2005.
- ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
- ^ a b c Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
- ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
- ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ Woods, Ian (2004). The Elements: Platinum. Benchmark Books. ISBN 978-0761415503.
- ^ "Live Market Quotes". Kitco. Retrieved 2009-10-30.
- ^ a b Lagowski, J. J., ed. (2004). Chemistry Foundations and Applications. Vol. 3. Thomson Gale. pp. 267–268. ISBN 0-02-865724-1.
- ^ a b CRC contributors (2007–2008). "Platinum". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics. Vol. 4. New York: CRC Press. p. 26. ISBN 978-0-8493-0488-0.
{{cite book}}
:|author=
has generic name (help) - ^ Audi, G. (2003). "The NUBASE Evaluation of Nuclear and Decay Properties". Nuclear Physics A. 729. Atomic Mass Data Center: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.
- ^ a b George B. Kauffman (1967). "Ammonium Hexachloroplatinate(IV)". Inorganic Syntheses. 9: 182–185. doi:10.1002/9780470132401.ch51.
- ^ a b c Krebs, Robert E. (1998). "Platinum". The History and Use of our Earth's Chemical Elements. Greenwood Press. pp. 124–127. ISBN 0-313-30123-9.
- ^ Cotton, S. A. Chemistry of Precious Metals, Chapman and Hall (London): 1997. ISBN 0-7514-0413-6.
- ^ G. F. Smith, J. L. Gring (1933). "The Separation and Determination of the Alkali Metals Using Perchloric Acid. V. Perchloric Acid and Chloroplatinic Acid in the Determination of Small Amounts of Potassium in the Presence of Large Amounts of Sodium". J. Am. Chem. Soc. 55 (10): 3957–3961. doi:10.1021/ja01337a007.
- ^ A. E. Schweizer, G. T. Kerr (1978). "Thermal Decomposition of Hexachloroplatinic Acid". Inorg. Chem. 17 (8): 2326–2327. doi:10.1021/ic50186a067.
- ^ Perry, D. L. (1995). Handbook of Inorganic Compounds. CRC Press. pp. 296–298. ISBN 0-8492-8671-3.
{{cite book}}
: Check|isbn=
value: checksum (help) - ^ a b Y. Han, H. V. Huynh, G. K. Tan (2007). "Mono- vs Bis(carbene) Complexes: A Detailed Study on Platinum(II)−Benzimidazolin-2-ylidenes". Organometallics. 26: 4612. doi:10.1021/om700543p.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ Sebastian Ahrens and Thomas Strassner (2006). "Detour-free synthesis of platinum-bis-NHC chloride complexes, their structure and catalytic activity in the CH activation of methane". Inorganica Chimica Acta. 359: 4789. doi:10.1016/j.ica.2006.05.042.
- ^ Richards, A.D. (2007). "Synthetic metallomolecules as agents for the control of DNA structure". Chem. Soc. Rev. 36: 471–483. doi:10.1039/b609495c.
{{cite journal}}
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suggested) (help) - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1039/b514631c, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1039/b514631c
instead. - ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/j.solidstatesciences.2005.06.015, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1016/j.solidstatesciences.2005.06.015
instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1021/jp068879d, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1021/jp068879d
instead. - ^ Earth's natural wealth: an audit. New Scientist. May 23, 2007.
- ^ Xiao, Z. (2004). "Characterizing and recovering the platinum group minerals—a review". Minerals Engineering. 17: 961–979. doi:10.1016/j.mineng.2004.04.001.
{{cite journal}}
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ignored (|author=
suggested) (help) - ^ a b Seymour, R. J. (2001). "Platinum-group metals". Kirk Othmer Encyclopedia of Chemical Technology. Wiley. doi:10.1002/0471238961.1612012019052513.a01.pub2.
{{cite book}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ "Mining Platinum in Montana". New York Times. 1998-08-13. Retrieved 2008-09-09.
- ^ "Platinum–Group Metals" (PDF). U.S. Geological Survey, Mineral Commodity Summaries. 2007. Retrieved 2008-09-09.
{{cite web}}
: Unknown parameter|month=
ignored (help) - ^ George, M. W. (2008). "Platinum-group metals" (pdf). U.S. Geological Survey Mineral Commodity Summaries. USGS Mineral Resources Program.
- ^ George, M. W. 2006 Minerals Yearbook: Platinum-Group Metals (PDF). United States Geological Survey USGS.
- ^ Heiserman, David L. (1992). Exploring Chemical Elements and their Compounds. TAB Books. pp. 272–274. ISBN 0-8306-3018-X.
- ^ Hunt, L. B. (1969). "Platinum Metals: A Survey of Productive Resources to industrial Uses" (PDF). Platinum Metals Review. 13 (4): 126–138. Retrieved 2009-10-02.
{{cite journal}}
: Unknown parameter|coauthors=
ignored (|author=
suggested) (help) - ^ George, Micheal W. "Mineral Yearbook 2006: Platinum-Group Metals" (PDF). United States Geological Survey. Retrieved 2008-09-25.
- ^ Petrucci, Ralph H. (2007). General Chemistry: Principles & Modern Applications (9th ed.). Prentice Hall. p. 606. ISBN 0131493302.
- ^ "Unknown Facts about Platinum". watches.infoniac.com. Retrieved 2008-09-09.
- ^ "London Platinum and Palladium Market". The London Platinum and Palladium Market. Retrieved 2008-08-08.
- ^ "One Year Platinum". Kitco. Retrieved 2009-01-12.
- ^ "Platinum versus Gold". The Speculative Invertor.
- ^ "Platinum". Minerals Zone. Retrieved 2008-09-09.
- ^ a b c d e Weeks, M. E. (1968). Discovery of the Elements (7 ed.). Journal of Chemical Education. pp. 385–407. ISBN 0848685792. OCLC 23991202.
- ^ "Occupational Health Guideline for Soluble Platinum Salts (as Platinum)" (PDF). Centers for Disease Control and Prevention. Retrieved 2008-09-09.
- ^ Einhorn LH. (1990). "Treatment of testicular cancer: a new and improved model". J. Clin. Oncol. 8 (11): 1777–81. PMID 1700077.
{{cite journal}}
: Unknown parameter|day=
ignored (help); Unknown parameter|month=
ignored (help) - ^ Von Hoff DD; et al. (1979). "Toxic effects of cis-dichlorodiammineplatinum(II) in man". Cancer Treat. Rep. 63 (9–10): 1527–31.
{{cite journal}}
: Explicit use of et al. in:|author=
(help) - ^ "FDA Backgrounder on Platinum in Silicone Breast Implants". U.S. Food and Drug Administration. Retrieved 2008-09-09.
References
- Nuclides and Isotopes Fourteenth Edition: Chart of the Nuclides, General Electric Company, 1989.
- Jefferson Lab — The Element Platinum
External links
![](http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png)
- The Platinum Group Metals Database
- A balanced historical account of the sequence of discoveries of platinum; illustrated.
- WebElements.com — Platinum
- Platinum Metals Review E-Journal
- Platinum Guild International
- United States Geological Survey Platinum-Group Metals Statistics and Information
- picture of a 999.5 fine platinum ingot in the element collection from Heinrich Pniok