Платина как пишется в таблице менделеева

Platinum
Pronunciation	​(PLAT-ən-əm)
Appearance	silvery white
Standard atomic weight Ar°(Pt)	195.084±0.009 195.08±0.02 (abridged)[1]
Platinum in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Pd ↑ Pt ↓ Ds iridium ← platinum → gold
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 (near r.t.)	21.45 g/cm3
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 P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2330 (2550) 2815 3143 3556 4094
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	1st: 870 kJ/mol 2nd: 1791 kJ/mol
Atomic radius	empirical: 139 pm
Covalent radius	136±5 pm
Van der Waals radius	175 pm
Spectral lines of platinum
Other properties
Natural occurrence	primordial
Crystal structure	​face-centered cubic (fcc)
Speed of sound thin rod	2800 m/s (at r.t.)
Thermal expansion	8.8 µm/(m⋅K) (at 25 °C)
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)[2]
Tensile strength	125–240 MPa
Young’s modulus	168 GPa
Shear modulus	61 GPa
Bulk modulus	230 GPa
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)
Main isotopes of platinum v e
Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct 190Pt 0.012% 6.5×1011 y α 186Os 192Pt 0.782% stable 193Pt syn 50 y ε 193Ir 194Pt 32.864% stable 195Pt 33.775% stable 196Pt 25.211% stable 198Pt 7.356% stable
Category: Platinum view talk edit | references

Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish platina, a diminutive of plata «silver».^[3][4]

Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in Earth’s crust, with an average abundance of approximately 5 μg/kg. It occurs in some nickel and copper ores along with some native deposits, mostly in South Africa, which accounts for ~80% of the world production. Because of its scarcity in Earth’s crust, only a few hundred tonnes are produced annually, and given its important uses, it is highly valuable and is a major precious metal commodity.^[5]

Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts. It was referenced in European writings as early as the 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists.

Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Platinum is used in the glass industry^[6] to manipulate molten glass which does not «wet» platinum. As a heavy metal, it leads to health problems upon exposure to its salts; but due to its corrosion resistance, metallic platinum has not been linked to adverse health effects.^[7] Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy against certain types of cancer.^[8]

Pure platinum is currently less expensive than pure gold, having been so continuously since 2015, but has been twice as expensive or more, mostly prior to 2008.^[9] In early 2021, the value of platinum ranged from US$1,055 to US$1,320 per troy ounce.^[10]

Characteristics[edit]

Physical[edit]

Pure platinum is a lustrous, ductile, and malleable, silver-white metal.^[11] Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold.^[12][13]

Its physical characteristics and chemical stability make it useful for industrial applications.^[14] Its resistance to wear and tarnish is well suited to use in fine jewellery.

Chemical[edit]

Platinum has excellent resistance to corrosion. Bulk platinum does not oxidize in air at any temperature, but it forms a thin surface film of PtO₂ that can be easily removed by heating to about 400 °C.^[15][16]

The most common oxidation states of platinum 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. Tetracoordinate platinum(II) compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is generally unreactive, it is attacked by chlorine, bromine, iodine, and sulfur. It reacts vigorously with fluorine at 500 °C (932 °F) to form platinum tetrafluoride.^[17] Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia (a mixture of nitric and hydrochloric acids), to form aqueous chloroplatinic acid, H₂PtCl₆:^[18][19]

Pt + 4 HNO₃ + 6 HCl → H₂PtCl₆ + 4 NO₂ + 4 H₂O

As a soft acid, the Pt²⁺ ion has a great affinity for sulfide and sulfur ligands. Numerous DMSO complexes have been reported and care is taken in the choosing of reaction solvents.^[20]

In 2007, the German scientist 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).^[21]

Isotopes[edit]

Platinum has six naturally occurring isotopes: ¹⁹⁰
Pt, ¹⁹²
Pt, ¹⁹⁴
Pt, ¹⁹⁵
Pt, ¹⁹⁶
Pt, and ¹⁹⁸
Pt. The most abundant of these is ¹⁹⁵
Pt, comprising 33.83% of all platinum. It is the only stable isotope with a non-zero spin. The spin of ¹/₂ and other favourable magnetic properties of the nucleus are utilised in ¹⁹⁵
Pt NMR. Due to its spin and large abundance, ¹⁹⁵
Pt satellite peaks are also often observed in ¹
H and ³¹
P NMR spectroscopy (e.g., for Pt-phosphine and Pt-alkyl complexes). ¹⁹⁰
Pt is the least abundant at only 0.01%. Of the naturally occurring isotopes, only ¹⁹⁰
Pt is unstable, though it decays with a half-life of 6.5×10¹¹ years, causing an activity of 15 Bq/kg of natural platinum. ¹⁹⁸
Pt can undergo alpha decay, but its decay has never been observed (the half-life is known to be longer than 3.2×10¹⁴ years); therefore, it is considered stable. Platinum also has 34 synthetic isotopes ranging in atomic mass from 165 to 204, making the total number of known isotopes 40. The least stable of these are ¹⁶⁵
Pt and ¹⁶⁶
Pt, with half-lives of 260 µs, whereas the most stable is ¹⁹³
Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta decay and alpha decay. ¹⁸⁸
Pt, ¹⁹¹
Pt, and ¹⁹³
Pt decay primarily by electron capture. ¹⁹⁰
Pt and ¹⁹⁸
Pt are predicted to have energetically favorable double beta decay paths.^[22]

Occurrence[edit]

Platinum is an extremely rare metal,^[23] occurring at a concentration of only 0.005 ppm in Earth’s crust.^[24][25] It is sometimes mistaken for silver. Platinum is often found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly. Most often the native platinum is found in secondary deposits 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 is in the Ural Mountains, Russia, and it is still mined.^[19]

In nickel and copper deposits, platinum-group metals occur as sulfides (e.g., (Pt,Pd)S), tellurides (e.g., PtBiTe), antimonides (PdSb), and arsenides (e.g. 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. At Platinum, Alaska, about 17,000 kg (550,000 ozt) was mined between 1927 and 1975. The mine ceased operations in 1990.^[26] 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.^[27]

In 1865, chromites were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906.^[28] In 1924, the geologist Hans Merensky discovered a large supply of platinum in the Bushveld Igneous Complex in South Africa. The specific layer he found, named the Merensky Reef, contains around 75% of the world’s known platinum.^[29][30] 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 make up for the fact platinum is present as only 0.5 ppm in the ore. Smaller reserves can be found in the United States,^[30] for example in the Absaroka Range in Montana.^[31] In 2010, South Africa was the top producer of platinum, with an almost 77% share, followed by Russia at 13%; world production in 2010 was 192,000 kg (423,000 lb).^[32]

Large platinum deposits are present in the state of Tamil Nadu, India.^[33]

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 Earth that are associated with resulting post-impact volcanism, and can be mined economically; the Sudbury Basin is one such example.^[34]

Compounds[edit]

Halides[edit]

Hexachloroplatinic acid mentioned above is probably the most important platinum compound, as it serves as the precursor for many other platinum compounds. By itself, it has various applications in photography, zinc etchings, indelible ink, plating, mirrors, porcelain coloring, and as a catalyst.^[35]

Treatment of hexachloroplatinic acid with an ammonium salt, such as ammonium chloride, gives ammonium hexachloroplatinate,^[18] which is relatively insoluble in ammonium solutions. Heating this ammonium salt in the presence of hydrogen reduces it to elemental platinum. Potassium hexachloroplatinate is similarly insoluble, and hexachloroplatinic acid has been used in the determination of potassium ions by gravimetry.^[36]

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:^[37]

(H₃O)₂PtCl₆·nH₂O ⇌ 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 oxidizing oxygen.

Oxides[edit]

Platinum(IV) oxide, PtO₂, also known as «Adams’ catalyst», is a black powder that is soluble in potassium hydroxide (KOH) solutions and concentrated acids.^[38] PtO₂ and the less common PtO both decompose upon heating.^[11] Platinum(II,IV) oxide, Pt₃O₄, is formed in the following reaction:

2 Pt²⁺ + Pt⁴⁺ + 4 O²⁻ → Pt₃O₄

Other compounds[edit]

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.^[20] The use of platinum(II) acetylacetonate has also been reported.^[39]

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.^[40] Caesium platinide, Cs
₂Pt, a dark-red transparent crystalline compound^[41] has been shown to contain Pt²⁻
anions.^[42] Platinum also exhibits negative oxidation states at surfaces reduced electrochemically.^[43] The negative oxidation states exhibited by platinum are unusual for metallic elements, and they are attributed to the relativistic stabilization of the 6s orbitals.^[42]

It is predicted that even the cation PtO²⁺
₄ in which platinum exists in +10 oxidation state may be achievable.^[44]

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.^[20]

Cisplatin, or cis-diamminedichloroplatinum(II) is the first of a series of square planar platinum(II)-containing chemotherapy drugs.^[45] Others include carboplatin and oxaliplatin. These compounds are capable of crosslinking DNA, and kill cells by similar pathways to alkylating chemotherapeutic agents.^[46] (Side effects of cisplatin include nausea and vomiting, hair loss, tinnitus, hearing loss, and nephrotoxicity.)^[47][48]

Organoplatinum compounds such as the above antitumour agents, as well as soluble inorganic platinum complexes, are routinely characterised using ¹⁹⁵
Pt nuclear magnetic resonance spectroscopy.

• 

  The hexachloroplatinate ion

• 

  The anion of Zeise’s salt

• 

  Dichloro(cycloocta-1,5-diene)platinum(II)

• 

  Cisplatin

History[edit]

Early uses[edit]

Archaeologists have discovered traces of platinum in the gold used in ancient Egyptian burials as early as 1200 BCE. For example, a small box from burial of Shepenupet II was found to be decorated with gold-platinum hieroglyphics.^[49] However, the extent of early Egyptians’ knowledge of the metal is unclear. It is quite possible they did not recognize there was platinum in their gold.^[50][51]

The metal was used by Native Americans near modern-day Esmeraldas, Ecuador to produce artifacts of a white gold-platinum alloy. Archeologists usually associate the tradition of platinum-working in South America with the La Tolita Culture (c. 600 BCE – 200 CE), but precise dates and location is difficult, as most platinum artifacts from the area were bought secondhand through the antiquities trade rather than obtained by direct archeological excavation.^[52] To work the metal, they would combine gold and platinum powders by sintering. The resulting gold–platinum alloy would then be soft enough to shape with tools.^[53][54] The platinum used in such objects was not the pure element, but rather a naturally occurring mixture of the platinum group metals, with small amounts of palladium, rhodium, and iridium.^[55]

European discovery[edit]

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».^[56] From their first encounters with platinum, the Spanish generally saw the metal as a kind of impurity in gold, and it was treated as such. It was often simply thrown away, and there was an official decree forbidding the adulteration of gold with platinum impurities.^[55]

In 1735, Antonio de Ulloa and Jorge Juan y Santacilia saw Native Americans mining platinum while the Spaniards were travelling through Colombia and Peru for eight years. Ulloa and Juan found mines with the whitish metal nuggets and took them home to Spain. Antonio de Ulloa returned to Spain and established the first mineralogy lab in Spain and was the first to systematically study platinum, which was in 1748. 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.^[56]

In 1741, Charles Wood,^[57] a British metallurgist, found various samples of Colombian platinum in Jamaica, which he sent to William Brownrigg for further investigation.

In 1750, after studying the platinum sent to him by Wood, Brownrigg presented a detailed account of the metal to the Royal Society, stating that he had seen no mention of it in any previous accounts of known minerals.^[58] Brownrigg also made note of platinum’s extremely high melting point and refractoriness toward borax.^{[clarification needed]} Other chemists across Europe soon began studying platinum, including Andreas Sigismund Marggraf,^[59] 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.^[56]

Means of malleability[edit]

Karl von Sickingen researched platinum extensively in 1772. He succeeded in making malleable platinum by alloying it with gold, dissolving the alloy in hot 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.^[56]

Because the other platinum-family members were not discovered yet (platinum was the first in the list), Scheffer and Sickingen made the false assumption that due to its hardness—which is slightly more than for pure iron—platinum would be a relatively non-pliable material, even brittle at times, when in fact its ductility and malleability are close to that of gold. Their assumptions could not be avoided because the platinum they experimented with was highly contaminated with minute amounts of platinum-family elements such as osmium and iridium, amongst others, which embrittled the platinum alloy. Alloying this impure platinum residue called «plyoxen»^{[citation needed]} with gold was the only solution at the time to obtain a pliable compound, but nowadays, very pure platinum is available and extremely long wires can be drawn from pure platinum, very easily, due to its crystalline structure, which is similar to that of many soft metals.^[60]

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 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 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.^[56]

Production[edit]

Platinum, along with the rest of the platinum-group 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.^[62]

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 liquid. Platinum is paramagnetic, whereas nickel and iron are both ferromagnetic. 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, whereas 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.^[63]

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, whereas osmium, iridium, ruthenium and rhodium stay unreacted. The gold is precipitated by the addition of iron(II) chloride and after filtering off the gold, the platinum is precipitated as ammonium chloroplatinate by the addition of ammonium chloride. Ammonium chloroplatinate can be converted to platinum by heating.^[64] Unprecipitated hexachloroplatinate(IV) may be reduced with elemental zinc, and a similar method is suitable for small scale recovery of platinum from laboratory residues.^[65] Mining and refining platinum has environmental impacts.^[66]

Applications[edit]

Of the 218 tonnes of platinum sold in 2014, 98 tonnes were used for vehicle emissions control devices (45%), 74.7 tonnes for jewelry (34%), 20.0 tonnes for chemical production and petroleum refining (9.2%), and 5.85 tonnes for electrical applications such as hard disk drives (2.7%). The remaining 28.9 tonnes went to various other minor applications, such as medicine and biomedicine, glassmaking equipment, investment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.^[67]

Catalyst[edit]

The most common use of platinum is as a catalyst in chemical reactions, often as platinum black. It has been employed as a catalyst since the early 19th century, when platinum powder was used to catalyze the ignition of hydrogen. Its most important application is in automobiles as a catalytic converter, which allows the complete combustion of low concentrations of unburned hydrocarbons 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 that becomes rich in aromatic compounds. PtO₂, also known as Adams’ catalyst, is used as a hydrogenation catalyst, specifically for vegetable oils.^[35] Platinum also strongly catalyzes the decomposition of hydrogen peroxide into water and oxygen^[68] and it is used in fuel cells^[69] as a catalyst for the reduction of oxygen.^[70]

Standard[edit]

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. The previous bar was made of platinum in 1799. Until May 2019, the kilogram was defined as the mass of the international prototype of the kilogram, a cylinder of the same platinum-iridium alloy made in 1879.^[71]

The Standard Platinum Resistance Thermometer (SPRT) is one of the four types of thermometers used to define the International Temperature Scale of 1990 (ITS-90), the international calibration standard for temperature measurements. The resistance wire in the thermometer is made of pure platinum (NIST manufactured the wires from platinum bar stock with a chemical purity of 99.999% by weight).^[72][73] In addition to laboratory uses, Platinum Resistance Thermometry (PRT) also has many industrial applications, industrial standards include ASTM E1137 and IEC 60751.

The standard hydrogen electrode also uses a platinized platinum electrode due to its corrosion resistance, and other attributes.^[74]

As an investment[edit]

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 jewellery, usually as a 90–95% alloy, due to its inertness. It is used for this purpose for its prestige and inherent bullion value. Jewellery trade publications advise jewellers to present minute surface scratches (which they term patina) as a desirable feature in an attempt to enhance value of platinum products.^[75][76]

In watchmaking, Vacheron Constantin, Patek Philippe, Rolex, Breitling, and other companies use platinum for producing their limited edition watch series. Watchmakers appreciate the unique properties of platinum, as it neither tarnishes nor wears out (the latter quality relative to gold).^[77]

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,^[78] 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. Although gold is also used in industrial applications, especially in electronics due to its use as a conductor, its demand is not so 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.^[79]

• 

  1,000 cubic centimeters of 99.9% pure platinum, worth about US$696,000 at 29 Jun 2016 prices^[80]

• 

  Platinum price 1970-2022

Other uses[edit]

In the laboratory, platinum wire is used for electrodes; platinum pans and supports are used in thermogravimetric analysis because of the stringent requirements of chemical inertness upon heating to high temperatures (~1000 °C). 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 of roughly three parts platinum and one part cobalt, is used to make relatively strong permanent magnets.^[35] Platinum-based anodes are used in ships, pipelines, and steel piers.^[19] Platinum drugs are used to treat a wide variety of cancers, including testicular and ovarian carcinomas, melanoma, small-cell and non-small-cell lung cancer, myelomas and lymphomas.^[81]

Symbol of prestige in marketing[edit]

Platinum’s rarity as a metal has caused advertisers to associate it with exclusivity and wealth. «Platinum» debit and credit cards have greater privileges than «gold» cards.^[82] «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 has sold more than 10 million copies will be certified as «diamond».^[83] 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.^[84]

Health problems[edit]

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 2 micrograms per cubic meter of air averaged over an 8-hour work shift.^[85] The National Institute for Occupational Safety and Health has set a recommended exposure limit (REL) for platinum as 1 mg/m³ over an 8-hour workday.^[86]

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, etc.), the possibility that platinum could enter the body and cause adverse effects has merited study. The Food and Drug Administration and other institutions have reviewed the issue and found no evidence to suggest toxicity in vivo.^[87][88] Chemically unbounded platinum has been identified by the FDA as a «fake cancer ‘cure'».^[89] The misunderstanding is created by healthcare workers who are using inappropriately the name of the metal as a slang term for platinum-based chemotherapy medications like cisplatin.^{[citation needed]} They are platinum compounds, not the metal itself.

See also[edit]

References[edit]

Further reading[edit]

• Young, Gordon (November 1983). «The Miracle Metal—Platinum». National Geographic. Vol. 164, no. 5. pp. 686–706. ISSN 0027-9358. OCLC 643483454.

External links[edit]

• Platinum at The Periodic Table of Videos (University of Nottingham)
• Nuclides and Isotopes Fourteenth Edition: Chart of the Nuclides, General Electric Company, 1989.
• NIOSH Pocket Guide to Chemical Hazards – Platinum Centers for Disease Control and Prevention
• «The PGM Database».
• «A balanced historical account of the sequence of discoveries of platinum; illustrated».
• «Johnson Matthey Technology Review: A free, quarterly journal of research exploring science and technology in industrial applications (formerly published as Platinum Metals Review)».
• «Platinum-Group Metals Statistics and Information». United States Geological Survey.
• «International Platinum Group Metals Association».

Platinum
Pronunciation	​(PLAT-ən-əm)
Appearance	silvery white
Standard atomic weight Ar°(Pt)	195.084±0.009 195.08±0.02 (abridged)[1]
Platinum in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Pd ↑ Pt ↓ Ds iridium ← platinum → gold
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 (near r.t.)	21.45 g/cm3
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 P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2330 (2550) 2815 3143 3556 4094
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	1st: 870 kJ/mol 2nd: 1791 kJ/mol
Atomic radius	empirical: 139 pm
Covalent radius	136±5 pm
Van der Waals radius	175 pm
Spectral lines of platinum
Other properties
Natural occurrence	primordial
Crystal structure	​face-centered cubic (fcc)
Speed of sound thin rod	2800 m/s (at r.t.)
Thermal expansion	8.8 µm/(m⋅K) (at 25 °C)
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)[2]
Tensile strength	125–240 MPa
Young’s modulus	168 GPa
Shear modulus	61 GPa
Bulk modulus	230 GPa
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)
Main isotopes of platinum v e
Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct 190Pt 0.012% 6.5×1011 y α 186Os 192Pt 0.782% stable 193Pt syn 50 y ε 193Ir 194Pt 32.864% stable 195Pt 33.775% stable 196Pt 25.211% stable 198Pt 7.356% stable
Category: Platinum view talk edit | references

Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish platina, a diminutive of plata «silver».^[3][4]

Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in Earth’s crust, with an average abundance of approximately 5 μg/kg. It occurs in some nickel and copper ores along with some native deposits, mostly in South Africa, which accounts for ~80% of the world production. Because of its scarcity in Earth’s crust, only a few hundred tonnes are produced annually, and given its important uses, it is highly valuable and is a major precious metal commodity.^[5]

Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts. It was referenced in European writings as early as the 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists.

Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Platinum is used in the glass industry^[6] to manipulate molten glass which does not «wet» platinum. As a heavy metal, it leads to health problems upon exposure to its salts; but due to its corrosion resistance, metallic platinum has not been linked to adverse health effects.^[7] Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy against certain types of cancer.^[8]

Pure platinum is currently less expensive than pure gold, having been so continuously since 2015, but has been twice as expensive or more, mostly prior to 2008.^[9] In early 2021, the value of platinum ranged from US$1,055 to US$1,320 per troy ounce.^[10]

Characteristics[edit]

Physical[edit]

Pure platinum is a lustrous, ductile, and malleable, silver-white metal.^[11] Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold.^[12][13]

Its physical characteristics and chemical stability make it useful for industrial applications.^[14] Its resistance to wear and tarnish is well suited to use in fine jewellery.

Chemical[edit]

Platinum has excellent resistance to corrosion. Bulk platinum does not oxidize in air at any temperature, but it forms a thin surface film of PtO₂ that can be easily removed by heating to about 400 °C.^[15][16]

The most common oxidation states of platinum 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. Tetracoordinate platinum(II) compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is generally unreactive, it is attacked by chlorine, bromine, iodine, and sulfur. It reacts vigorously with fluorine at 500 °C (932 °F) to form platinum tetrafluoride.^[17] Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia (a mixture of nitric and hydrochloric acids), to form aqueous chloroplatinic acid, H₂PtCl₆:^[18][19]

Pt + 4 HNO₃ + 6 HCl → H₂PtCl₆ + 4 NO₂ + 4 H₂O

As a soft acid, the Pt²⁺ ion has a great affinity for sulfide and sulfur ligands. Numerous DMSO complexes have been reported and care is taken in the choosing of reaction solvents.^[20]

In 2007, the German scientist 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).^[21]

Isotopes[edit]

Platinum has six naturally occurring isotopes: ¹⁹⁰
Pt, ¹⁹²
Pt, ¹⁹⁴
Pt, ¹⁹⁵
Pt, ¹⁹⁶
Pt, and ¹⁹⁸
Pt. The most abundant of these is ¹⁹⁵
Pt, comprising 33.83% of all platinum. It is the only stable isotope with a non-zero spin. The spin of ¹/₂ and other favourable magnetic properties of the nucleus are utilised in ¹⁹⁵
Pt NMR. Due to its spin and large abundance, ¹⁹⁵
Pt satellite peaks are also often observed in ¹
H and ³¹
P NMR spectroscopy (e.g., for Pt-phosphine and Pt-alkyl complexes). ¹⁹⁰
Pt is the least abundant at only 0.01%. Of the naturally occurring isotopes, only ¹⁹⁰
Pt is unstable, though it decays with a half-life of 6.5×10¹¹ years, causing an activity of 15 Bq/kg of natural platinum. ¹⁹⁸
Pt can undergo alpha decay, but its decay has never been observed (the half-life is known to be longer than 3.2×10¹⁴ years); therefore, it is considered stable. Platinum also has 34 synthetic isotopes ranging in atomic mass from 165 to 204, making the total number of known isotopes 40. The least stable of these are ¹⁶⁵
Pt and ¹⁶⁶
Pt, with half-lives of 260 µs, whereas the most stable is ¹⁹³
Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta decay and alpha decay. ¹⁸⁸
Pt, ¹⁹¹
Pt, and ¹⁹³
Pt decay primarily by electron capture. ¹⁹⁰
Pt and ¹⁹⁸
Pt are predicted to have energetically favorable double beta decay paths.^[22]

Occurrence[edit]

Platinum is an extremely rare metal,^[23] occurring at a concentration of only 0.005 ppm in Earth’s crust.^[24][25] It is sometimes mistaken for silver. Platinum is often found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly. Most often the native platinum is found in secondary deposits 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 is in the Ural Mountains, Russia, and it is still mined.^[19]

In nickel and copper deposits, platinum-group metals occur as sulfides (e.g., (Pt,Pd)S), tellurides (e.g., PtBiTe), antimonides (PdSb), and arsenides (e.g. 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. At Platinum, Alaska, about 17,000 kg (550,000 ozt) was mined between 1927 and 1975. The mine ceased operations in 1990.^[26] 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.^[27]

In 1865, chromites were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906.^[28] In 1924, the geologist Hans Merensky discovered a large supply of platinum in the Bushveld Igneous Complex in South Africa. The specific layer he found, named the Merensky Reef, contains around 75% of the world’s known platinum.^[29][30] 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 make up for the fact platinum is present as only 0.5 ppm in the ore. Smaller reserves can be found in the United States,^[30] for example in the Absaroka Range in Montana.^[31] In 2010, South Africa was the top producer of platinum, with an almost 77% share, followed by Russia at 13%; world production in 2010 was 192,000 kg (423,000 lb).^[32]

Large platinum deposits are present in the state of Tamil Nadu, India.^[33]

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 Earth that are associated with resulting post-impact volcanism, and can be mined economically; the Sudbury Basin is one such example.^[34]

Compounds[edit]

Halides[edit]

Hexachloroplatinic acid mentioned above is probably the most important platinum compound, as it serves as the precursor for many other platinum compounds. By itself, it has various applications in photography, zinc etchings, indelible ink, plating, mirrors, porcelain coloring, and as a catalyst.^[35]

Treatment of hexachloroplatinic acid with an ammonium salt, such as ammonium chloride, gives ammonium hexachloroplatinate,^[18] which is relatively insoluble in ammonium solutions. Heating this ammonium salt in the presence of hydrogen reduces it to elemental platinum. Potassium hexachloroplatinate is similarly insoluble, and hexachloroplatinic acid has been used in the determination of potassium ions by gravimetry.^[36]

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:^[37]

(H₃O)₂PtCl₆·nH₂O ⇌ 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 oxidizing oxygen.

Oxides[edit]

Platinum(IV) oxide, PtO₂, also known as «Adams’ catalyst», is a black powder that is soluble in potassium hydroxide (KOH) solutions and concentrated acids.^[38] PtO₂ and the less common PtO both decompose upon heating.^[11] Platinum(II,IV) oxide, Pt₃O₄, is formed in the following reaction:

2 Pt²⁺ + Pt⁴⁺ + 4 O²⁻ → Pt₃O₄

Other compounds[edit]

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.^[20] The use of platinum(II) acetylacetonate has also been reported.^[39]

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.^[40] Caesium platinide, Cs
₂Pt, a dark-red transparent crystalline compound^[41] has been shown to contain Pt²⁻
anions.^[42] Platinum also exhibits negative oxidation states at surfaces reduced electrochemically.^[43] The negative oxidation states exhibited by platinum are unusual for metallic elements, and they are attributed to the relativistic stabilization of the 6s orbitals.^[42]

It is predicted that even the cation PtO²⁺
₄ in which platinum exists in +10 oxidation state may be achievable.^[44]

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.^[20]

Cisplatin, or cis-diamminedichloroplatinum(II) is the first of a series of square planar platinum(II)-containing chemotherapy drugs.^[45] Others include carboplatin and oxaliplatin. These compounds are capable of crosslinking DNA, and kill cells by similar pathways to alkylating chemotherapeutic agents.^[46] (Side effects of cisplatin include nausea and vomiting, hair loss, tinnitus, hearing loss, and nephrotoxicity.)^[47][48]

Organoplatinum compounds such as the above antitumour agents, as well as soluble inorganic platinum complexes, are routinely characterised using ¹⁹⁵
Pt nuclear magnetic resonance spectroscopy.

• 

  The hexachloroplatinate ion

• 

  The anion of Zeise’s salt

• 

  Dichloro(cycloocta-1,5-diene)platinum(II)

• 

  Cisplatin

History[edit]

Early uses[edit]

Archaeologists have discovered traces of platinum in the gold used in ancient Egyptian burials as early as 1200 BCE. For example, a small box from burial of Shepenupet II was found to be decorated with gold-platinum hieroglyphics.^[49] However, the extent of early Egyptians’ knowledge of the metal is unclear. It is quite possible they did not recognize there was platinum in their gold.^[50][51]

The metal was used by Native Americans near modern-day Esmeraldas, Ecuador to produce artifacts of a white gold-platinum alloy. Archeologists usually associate the tradition of platinum-working in South America with the La Tolita Culture (c. 600 BCE – 200 CE), but precise dates and location is difficult, as most platinum artifacts from the area were bought secondhand through the antiquities trade rather than obtained by direct archeological excavation.^[52] To work the metal, they would combine gold and platinum powders by sintering. The resulting gold–platinum alloy would then be soft enough to shape with tools.^[53][54] The platinum used in such objects was not the pure element, but rather a naturally occurring mixture of the platinum group metals, with small amounts of palladium, rhodium, and iridium.^[55]

European discovery[edit]

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».^[56] From their first encounters with platinum, the Spanish generally saw the metal as a kind of impurity in gold, and it was treated as such. It was often simply thrown away, and there was an official decree forbidding the adulteration of gold with platinum impurities.^[55]

In 1735, Antonio de Ulloa and Jorge Juan y Santacilia saw Native Americans mining platinum while the Spaniards were travelling through Colombia and Peru for eight years. Ulloa and Juan found mines with the whitish metal nuggets and took them home to Spain. Antonio de Ulloa returned to Spain and established the first mineralogy lab in Spain and was the first to systematically study platinum, which was in 1748. 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.^[56]

In 1741, Charles Wood,^[57] a British metallurgist, found various samples of Colombian platinum in Jamaica, which he sent to William Brownrigg for further investigation.

In 1750, after studying the platinum sent to him by Wood, Brownrigg presented a detailed account of the metal to the Royal Society, stating that he had seen no mention of it in any previous accounts of known minerals.^[58] Brownrigg also made note of platinum’s extremely high melting point and refractoriness toward borax.^{[clarification needed]} Other chemists across Europe soon began studying platinum, including Andreas Sigismund Marggraf,^[59] 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.^[56]

Means of malleability[edit]

Karl von Sickingen researched platinum extensively in 1772. He succeeded in making malleable platinum by alloying it with gold, dissolving the alloy in hot 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.^[56]

Because the other platinum-family members were not discovered yet (platinum was the first in the list), Scheffer and Sickingen made the false assumption that due to its hardness—which is slightly more than for pure iron—platinum would be a relatively non-pliable material, even brittle at times, when in fact its ductility and malleability are close to that of gold. Their assumptions could not be avoided because the platinum they experimented with was highly contaminated with minute amounts of platinum-family elements such as osmium and iridium, amongst others, which embrittled the platinum alloy. Alloying this impure platinum residue called «plyoxen»^{[citation needed]} with gold was the only solution at the time to obtain a pliable compound, but nowadays, very pure platinum is available and extremely long wires can be drawn from pure platinum, very easily, due to its crystalline structure, which is similar to that of many soft metals.^[60]

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 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 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.^[56]

Production[edit]

Platinum, along with the rest of the platinum-group 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.^[62]

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 liquid. Platinum is paramagnetic, whereas nickel and iron are both ferromagnetic. 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, whereas 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.^[63]

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, whereas osmium, iridium, ruthenium and rhodium stay unreacted. The gold is precipitated by the addition of iron(II) chloride and after filtering off the gold, the platinum is precipitated as ammonium chloroplatinate by the addition of ammonium chloride. Ammonium chloroplatinate can be converted to platinum by heating.^[64] Unprecipitated hexachloroplatinate(IV) may be reduced with elemental zinc, and a similar method is suitable for small scale recovery of platinum from laboratory residues.^[65] Mining and refining platinum has environmental impacts.^[66]

Applications[edit]

Of the 218 tonnes of platinum sold in 2014, 98 tonnes were used for vehicle emissions control devices (45%), 74.7 tonnes for jewelry (34%), 20.0 tonnes for chemical production and petroleum refining (9.2%), and 5.85 tonnes for electrical applications such as hard disk drives (2.7%). The remaining 28.9 tonnes went to various other minor applications, such as medicine and biomedicine, glassmaking equipment, investment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines.^[67]

Catalyst[edit]

The most common use of platinum is as a catalyst in chemical reactions, often as platinum black. It has been employed as a catalyst since the early 19th century, when platinum powder was used to catalyze the ignition of hydrogen. Its most important application is in automobiles as a catalytic converter, which allows the complete combustion of low concentrations of unburned hydrocarbons 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 that becomes rich in aromatic compounds. PtO₂, also known as Adams’ catalyst, is used as a hydrogenation catalyst, specifically for vegetable oils.^[35] Platinum also strongly catalyzes the decomposition of hydrogen peroxide into water and oxygen^[68] and it is used in fuel cells^[69] as a catalyst for the reduction of oxygen.^[70]

Standard[edit]

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. The previous bar was made of platinum in 1799. Until May 2019, the kilogram was defined as the mass of the international prototype of the kilogram, a cylinder of the same platinum-iridium alloy made in 1879.^[71]

The Standard Platinum Resistance Thermometer (SPRT) is one of the four types of thermometers used to define the International Temperature Scale of 1990 (ITS-90), the international calibration standard for temperature measurements. The resistance wire in the thermometer is made of pure platinum (NIST manufactured the wires from platinum bar stock with a chemical purity of 99.999% by weight).^[72][73] In addition to laboratory uses, Platinum Resistance Thermometry (PRT) also has many industrial applications, industrial standards include ASTM E1137 and IEC 60751.

The standard hydrogen electrode also uses a platinized platinum electrode due to its corrosion resistance, and other attributes.^[74]

As an investment[edit]

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 jewellery, usually as a 90–95% alloy, due to its inertness. It is used for this purpose for its prestige and inherent bullion value. Jewellery trade publications advise jewellers to present minute surface scratches (which they term patina) as a desirable feature in an attempt to enhance value of platinum products.^[75][76]

In watchmaking, Vacheron Constantin, Patek Philippe, Rolex, Breitling, and other companies use platinum for producing their limited edition watch series. Watchmakers appreciate the unique properties of platinum, as it neither tarnishes nor wears out (the latter quality relative to gold).^[77]

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,^[78] 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. Although gold is also used in industrial applications, especially in electronics due to its use as a conductor, its demand is not so 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.^[79]

• 

  1,000 cubic centimeters of 99.9% pure platinum, worth about US$696,000 at 29 Jun 2016 prices^[80]

• 

  Platinum price 1970-2022

Other uses[edit]

In the laboratory, platinum wire is used for electrodes; platinum pans and supports are used in thermogravimetric analysis because of the stringent requirements of chemical inertness upon heating to high temperatures (~1000 °C). 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 of roughly three parts platinum and one part cobalt, is used to make relatively strong permanent magnets.^[35] Platinum-based anodes are used in ships, pipelines, and steel piers.^[19] Platinum drugs are used to treat a wide variety of cancers, including testicular and ovarian carcinomas, melanoma, small-cell and non-small-cell lung cancer, myelomas and lymphomas.^[81]

Symbol of prestige in marketing[edit]

Platinum’s rarity as a metal has caused advertisers to associate it with exclusivity and wealth. «Platinum» debit and credit cards have greater privileges than «gold» cards.^[82] «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 has sold more than 10 million copies will be certified as «diamond».^[83] 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.^[84]

Health problems[edit]

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 2 micrograms per cubic meter of air averaged over an 8-hour work shift.^[85] The National Institute for Occupational Safety and Health has set a recommended exposure limit (REL) for platinum as 1 mg/m³ over an 8-hour workday.^[86]

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, etc.), the possibility that platinum could enter the body and cause adverse effects has merited study. The Food and Drug Administration and other institutions have reviewed the issue and found no evidence to suggest toxicity in vivo.^[87][88] Chemically unbounded platinum has been identified by the FDA as a «fake cancer ‘cure'».^[89] The misunderstanding is created by healthcare workers who are using inappropriately the name of the metal as a slang term for platinum-based chemotherapy medications like cisplatin.^{[citation needed]} They are platinum compounds, not the metal itself.

See also[edit]

References[edit]

Further reading[edit]

• Young, Gordon (November 1983). «The Miracle Metal—Platinum». National Geographic. Vol. 164, no. 5. pp. 686–706. ISSN 0027-9358. OCLC 643483454.

External links[edit]

• Platinum at The Periodic Table of Videos (University of Nottingham)
• Nuclides and Isotopes Fourteenth Edition: Chart of the Nuclides, General Electric Company, 1989.
• NIOSH Pocket Guide to Chemical Hazards – Platinum Centers for Disease Control and Prevention
• «The PGM Database».
• «A balanced historical account of the sequence of discoveries of platinum; illustrated».
• «Johnson Matthey Technology Review: A free, quarterly journal of research exploring science and technology in industrial applications (formerly published as Platinum Metals Review)».
• «Platinum-Group Metals Statistics and Information». United States Geological Survey.
• «International Platinum Group Metals Association».

Энергия ионизации

Чем ближе электрон к центру атома — тем больше энергии необходимо, что бы его оторвать.
Энергия, затрачиваемая на отрыв электрона от атома называется энергией ионизации и обозначается E_o.
Если не указано иное, то энергия ионизации — это энергия отрыва первого электрона, также существуют энергии
ионизации для каждого последующего электрона.

Энергия ионизации Pt:
E_o = 870 кДж/моль

— Что такое ион читайте в статье.

Перейти к другим элементам таблицы менделеева

Где Pt в таблице менделеева?

Скачать таблицу менделеева в хорошем качестве

Латинские названия химических элементов (Таблица)

По древней традиции, корни которой тянутся к средним векам, все химические элементы получали свои названия на латинском языке; эта традиция не нарушается и в наше время. В начале XIX столетия для химических элементов были предложены сокращенные буквенные обозначения, которыми служили или одна начальная буква латинских названий элементов, или, значительно чаще, две буквы, начальная и одна из последующих. Так образовались современные знаки (символы) химических элементов, получившие впоследствии международное признание.

Русские названия химических элементов в большинстве представляют собой их латинские названия с измененными окончаниями в соответствии с особенностями нашего языка. Но вместе с тем можно назвать много элементов, которые имеют на русском языке особые названия, отличные от латинских. Этими названиями служат или коренные русские слова, например железо (Fe), медь (Сu), ртуть (Hg), или перевод латинского названия элемента на русский язык, например водород (Н), кислород (О). Для того, чтобы в этих случаях можно было понять происхождение символов, следует сопоставить их с латинскими названиями соответствующих элементов, указанными в табл. 2-16.

Попутно в примечаниях к таблице указываются те особые названия и обозначения химических элементов, которые применяются в научной литературе ряда зарубежных стран.

Примечания к таблице:

1) Жансен и независимо от него Локьер в 1868 г. обнаружили в спектре солнца неизвестные до того времени линии; этот новый элемент был назван гелием, так как предполагалось, что он находится только на солнце. Через 27 лет Рамзаи и Клив обнаружили те же линии в спектре нового газа, полученного ими при анализе минерала клевеита; название гелий для этого элемента было сохранено.

2) Еще в конце XVIII в. было известно, что при действии серной кислоты на плавиковый шпат выделяется особая кислота, которая разъедает стекло. В 1810 г. Ампер показал, что эта кислота подобна соляной и является соединением с водородом некоторого неизвестного элемента, который он назвал фтором. В чистом виде фтор удалось получить Муассану только в 1886 г.

3) Окись магния была известна давно, ее исследовал Блэк еще в 1775 г. Деви в 1808 г. пытался получить металлический магний, но в чистом виде металл получить ему не удалось.

4) Двуокись титана была получена лабораторным путем еще в конце XVIII в., Берцелиус получал титан, но не вполне чистый. Более чистый металлический титан был получен Грегор, затем Муассаном.

5) Сернистые соединения мышьяка былп известны в древнее время.

6) В начале XIX в. была получена смесь ниобия и тантала, которая рассматривалась как новый элемент; ему было присвоено название колумбий. В Америке и Англии ниобий до сих пор носит название колумбий.

7) В виде окиси церий был получен в 1803 г.

Долгое время смесь празеодима и неодима считалась отдельным элементом, который назывался дидием (Di).

9) Как особый металл платина была описана в 1750 г.; до 1810 г. единственным местом добычи платины была Колумбия. Затем платина была найдена в других местах, в том числе на Урале, который до настоящего времени является наиболее богатым источником ее получения.

10) Двуокись урана, полученная впервые еще в 1789 г., была принята вначале за новый элемент. Металлический уран был получен впервые в 1842 г., его радиоактивные свойства были открыты только в 1896 г.

_______________

Источник информации: КРАТКИЙ ФИЗИКО-ТЕХНИЧЕСКИЙ СПРАВОЧНИК/ Том 1, — М.: 1960.

Платина
Атомный номер	78
Внешний вид простого вещества	Тяжёлый мягкий серебристо-белый металл
Свойства атома
Атомная масса (молярная масса)	195,08 а. е. м. (г/моль)
Радиус атома	139 пм
Энергия ионизации (первый электрон)	868,1(9,00) кДж/моль (эВ)
Электронная конфигурация	[Xe] 4f14 5d9 6s1
Химические свойства
Ковалентный радиус	130 пм
Радиус иона	(+4e) 65 (+2e) 80 пм
Электроотрицательность (по Полингу)	2,28
Электродный потенциал	Pt←Pt2+ 1,20В
Степени окисления	4, 2, 0
Термодинамические свойства простого вещества
Плотность	21,45 г/см³
Молярная теплоёмкость	25,85[1] Дж/(K·моль)
Теплопроводность	71,6 Вт/(м·K)
Температура плавления	2045 K
Теплота плавления	21,76 кДж/моль
Температура кипения	4100 K
Теплота испарения	~470 кДж/моль
Молярный объём	9,10 см³/моль
Кристаллическая решётка простого вещества
Структура решётки	кубическая гранецентрированая
Параметры решётки	3,920 Å
Отношение c/a	n/a
Температура Дебая	230,00 K

Платина — 78 элемент периодической таблицы, атомная масса 195,08; благородный металл серо-стального цвета. В Старом Свете платина не была известна, однако цивилизации Анд (инки и чибча) добывали и использовали её с незапамятных времён. В Европе платина была неизвестна до XVIII века.

Происхождение названия

Название платине было дано испанскими конкистадорами, которые в середине XVI в. впервые познакомились в Южной Америке (на территории современной Колумбии) с новым металлом, внешне похожим на серебро (plata). Слово исп. Platina буквально означает «маленькое серебро», «серебришко» (платина против серебра стоила вдвое дешевле). Объясняется такое пренебрежительное название исключительной тугоплавкостью платины, которая не поддавалась переплавке, долгое время не находила применения и ценилась вдвое ниже, чем серебро.

Получение

Самородную платину добывают на приисках (см. подробнее в статье Благородные металлы)

Производство платины в виде порошка началось в 1805 английским ученым У. Х. Волластоном из южноамериканской руды. Сегодня платину получают из концентрата платиновых металлов. Концентрат растворяют в царской водке, после чего добавляют этанол и сахарный сироп для удаления избытка HNO₃. При этом иридий и палладий восстанавливаются до Ir³⁺ и Pd²⁺. Последующим добавлением хлорида аммония выделяют (NH₄)₂PtCl₆. Высушенный осадок прокаливают при 800-1000°C: (NH₄)₂PtCl₆ = N₂ + 6HCl + Pt + H₂. Получаемую таким образом губчатую платину подвергают дальнейшей очистке повторным растворением в царской водке, осаждением (NH₄)₂PtCl₆ и прокаливанием остатка. Затем очищенную губчатую платину переплавляют в слитки. При восстановлении платиновых растворов химическим или электрохимическим способом получают мелкодисперсную платину — платиновую чернь.

Физические свойства

Серовато-белый пластичный металл, температуры плавления и кипения — 1769 °C и 3800 °C, удельное электрическое сопротивление — 0,098 мкОм•м. Платина — один из самых тяжелых (плотность 21,5 г/см³; атомная плотность 6.62•10²² ат/см³) и самых редких металлов: среднее содержание в земной коре 5•10⁻⁷% по массе.

Химические свойства

По химическим свойствам платина похожа на палладий, но проявляет большую химическую устойчивость. Реагирует только с горячей царской водкой: 3Pt + 4HNO₃ + 18HCl = 3H₂[PtCl₆] + 4NO + 8H₂O

Платина медленно растворяется в горячей серной кислоте и жидком броме. Она не взаимодействует с другими минеральными и органическими кислотами. При нагревании реагирует со щелочами и пероксидом натрия, галогенами (особенно в присутствии галогенидов щелочных металлов): Pt + 2Cl₂ + 2NaCl = Na₂[PtCl₆]. При нагревании платина реагирует с серой, селеном, теллуром, углеродом и кремнием. Как и палладий, платина может растворять молекулярный водород, но объем поглощаемого водорода меньше и способность его отдавать при нагревании у платины меньше.

При нагревании платина реагирует с кислородом с образованием летучих оксидов. Выделены следующие оксиды платины: черный PtO, коричневый PtO₂, красновато-коричневый PtO₃, а также Pt₂O₃ и Pt₃O₄.

Для платины известны гидроксиды Pt(OH)₂ и Pt(OH)₄. Получают их при щелочном гидролизе соответствующих хлорплатинатов, например: Na₂PtCl₄ + 2NaOH = 4NaCl + Pt(OH)₂I, Na₂PtCl₆ + 4NaOH = 6NaCl + Pt(OH)₄I. Эти гидроксиды проявляют амфотерные свойства: Pt(OH)₂ + 2NaOH = Na₂[Pt(OH)₄], Pt(OH)₂ +4HCl = H₂[PtCl₄] + 2H₂O, Pt(OH)₄ + 6HCl = H₂[PtCl₆] + 4H₂O, Pt(OH)₄ + 2NaOH = Na₂[Pt(OH)₆]. Гексафторид PtF₆ — один из сильнейших окислителей, способный окислить молекулы кислорода, ксенона или NO: O₂ + PtF₆ = O₂+[PtF₆]^—.

C обнаруженного Н. Бартлеттом взаимодействия между Хе и PtF₆, приводящего к образованию XePtF₆, началась химия инертных газов. PtF₆ получают фторированием платины при 1000 °C под давлением. Фторирование платины при нормальным давлении и температуре 350—400 °C даёт фторид Pt(IV): Pt + 2F₂ = PtF₄ Фториды платины гигроскопичны и разлагаются водой. Тетрахлорид платины (IV) с водой образует гидраты PtCl₄·nH₂O, где n = 1, 4, 5 и 7. Растворением PtCl₄ в соляной кислоте получают платинохлористоводородные кислоты H[PtCl₅] и H₂[PtCl₆]. Синтезированы такие галогениды платины как PtBr₄, PtCl₂, PtCl₂·2PtCl₃, PtBr₂ и PtI₂. Для платины характерно образование комплексных соединений состава [PtX₄]₂— и [PtX₆]₂-. Изучая комплексы платины, А. Вернер сформулировал теорию комплексных соединений и объяснил природу возникновения изомеров в комплексных соединениях.

Реакционная способность

Платина является одним из самых инертных металлов. Она нерастворима в кислотах и щелочах, за исключением царской водки. Платина также непосредственно реагирует с бромом, растворяясь в нём.

При нагревании платина становится более реакционноспособной. Она реагирует с пероксидами, а при контакте с кислородом воздуха — с щелочами. Тонкая платиновая проволока горит во фторе с выделением большого количества тепла. Реакции с другими неметаллами (хлором, серой, фосфором) происходят менее охотно. При более сильном нагревании платина реагирует с углеродом и кремнием, образуя твёрдые растворы, аналогично металлам группы железа.

В своих соединениях платина проявляет почти все степени окисления от 0 до +8, из которых наиболее устойчивы +2 и +4. Для платины характерно образование многочисленных комплексных соединений, которых известно много сотен. Многие из них носят имена изучавших их химиков (соли Косса, Магнуса, Пейроне, Цейзе, Чугаева и т. д.). Большой вклад в изучение таких соединений внес русский химик Л. А. Чугаев (1873−1922), первый директор созданного в 1918 году Института по изучению платины.

Гексафторид платины PtF₆ является одним из сильнейших окислителей среди всех известных химических соединений. С помощью него, в частности, канадский химик Нейл Бартлетт в 1962 году получил первое настоящее химическое соединение ксенона XePtF₆.

Катализатор

Платина, особенно в мелкодисперсном состоянии, является очень активным катализатором многих химических реакций, в том числе используемых в промышленных масштабах. Например, платина катализирует реакцию присоединения водорода к ароматическим соединениям даже при комнатной температуре и атмосферном давлении водорода. Еще в 1821 немецкий химик И. В.Дёберейнер обнаружил, что платиновая чернь способствует протеканию ряда химических реакций; при этом сама платина не претерпевала изменений. Так, платиновая чернь окисляла пары винного спирта до уксусной кислоты уже при обычной температуре. Через два года Дёберейнер открыл способность губчатой платины при комнатной температуре воспламенять водород. Если смесь водорода и кислорода (гремучий газ) ввести в соприкосновение с платиновой чернью или с губчатой платиной, то сначала идет сравнительно спокойная реакция горения. Но так как эта реакция сопровождается выделением большого количества теплоты, платиновая губка раскаляется, и гремучий газ взрывается. На основании своего открытия Дёберейнер сконструировал «водородное огниво» — прибор, широко применявшийся для получения огня до изобретения спичек.

Производство

До 1748 г. платина добывалась и производилась только на территории Америки и в Старом Свете не была известна.

Когда платину стали завозить в Европу её цена была вдвое ниже серебра. Ювелиры очень быстро обнаружили, что платина хорошо сплавляется с золотом, а так как плотность платины выше чем у золота, то незначительные добавки серебра позволила изготавливать подделки, которые невозможно было отличить от золотых изделий. Такого рода подделки получили столь широкое распространение, что испанский король приказал прекратить ввоз платины, а оставшиеся запасы утопить в море. Этот закон просуществовал до 1778 года. После отмены закона потребность в платине была небольшой, её использовали в основном для создания химического оборудования, приспособлений и в качестве катализаторов. Добываемой в Америке платины для этих целей было достаточно. Ни о каком значимом промышленном производстве говорить не приходится.

В 1819 году платину впервые обнаружили на Урале близ Екатеринбурга, а в 1824 г. были открыты платиновые россыпи в Нижнетагильском округе. Разведанные запасы платины были столь велики, что Россия почти сразу заняла первое место в мире по добыче этого метала. Только в 1828 году в России было добыто 1,5 т платины — больше, чем за 100 лет в Южной Америке. К концу XIX века в России добывалось платины в 40 раз больше чем во всех остальных странах мира. Причем, представлена она была и весьма увесистыми самородками. Например, один из найденных на Урале самородков весил 9,6 кг.

К середине XIX в. в Англии и Франции были проведены обширные исследования по аффинажу платины. В 1859 году французский химик Анри Этьен Сент-Клер Девиль впервые разработал промышленный способ получения слитков чистой платины. С этого времени, почти вся добываемая на Урале платина скупалась английскими и французскими фирмами, в частности, «Джонсон, Маттей и К°». Позже к закупкам платины у России подключились американские и немецкие компании.

Даже после значительных зарубежных закупок, большая часть добываемой Россией платины не находила достойного применения. Поэтому, начиная с 1828 года, по предложения министра финансов Егора Канкрина, в России начали выпускать платиновые монеты номиналом 3,6 и 12 рублей. При этом, 12-рублевая платиновая монета имела массу 41,41 г, а в рублевой серебряной монете было 18 г чистого серебра. То есть по стоимости металла платиновые монеты были дороже серебряных в 5,2 раза. С 1828 по 1845 гг. было выпушено 1 372 000 трехрублевых монет, 17 582 шестирублевых и 3 303 двенадцатирублевых общей массой 14,7 т. Основную выгоду от добычи получали владельцы рудников — Демидовы. Оцените, — только в 1840 было добыто 3,4 т платины. В 1845 году, по настоянию министра финансов Фёдора Вронченко выпуск платиновых монет был прекращён и все они были срочно изъяты из обращения. Основной версией столь поспешного шага считается повышение европейских цен на платину, в результате которого монеты стали дороже номинала. После прекращения чеканки монет производство платины в России упало в 20 раз и к 1915 году на долю России приходилось лишь 95 % от мирового производства платины. Оставшиеся 5 % производила Колумбия. Причем, почти вся российская платина поступала на экспорт. Например, в 1867 году Англия скупила весь запас российской платины — более 16 т.

К концу XIX в. Россия производила 4,5 т. платины в год.

До Первой мировой войны второй после России страной по объемам добычи платины была Колумбия; с 1930-х гг. стала Канада, а после Второй мировой войны — Южная Африка.

В 1952 году Колумбия добыла 0,75 т платины, США — 0,88 т, в Канада — 3,75 т, а Южно-Африканский Союз — 7,2 т. В СССР данные по добыче платины были засекречены.

В 2007 году в мире было добыто 213 т платины, а в 2008 году — 200 т. Лидерами добычи были: ЮАР (в 2007 году добыто 166,0 т, а в 2008 году — 153,0 т), Россия (27,0/25,0), Канада (6,2/7,2), Зимбабве (5,3/5,6), США (3,9/3,7), Колумбия (1,4/1,7).^[3]

Лидером добычи платины в России является ГМК «Норильский никель».

Разведанные мировые запасы металлов платиновой группы составляют около 80 000 т и распределены, в основном, между Южной Африкой (87,5 %), Россией (8,3 %) и США (2,5 %).

Применение

В технике

• С первой четверти XIX века применялась в России в качестве легирующей добавки для производства высокопрочных сталей^[4]
• Платина применяется как катализатор (чаще всего в сплаве с родием, а также в виде платиновой черни — тонкого порошка платины, получаемой восстановлением ее соединений).
• Платина применяется в ювелирном и зубоврачебном деле, а также в медицине.
• Изготовление стойкой химически и к нагреванию лабораторной посуды.
• Изготовление миниатюрных магнитов огромной силы (сплав платина-кобальт, ПлК-78).
• Специальные зеркала для лазерной техники.
• Чрезвычайно долговечные и стабильные электроконтакты и сплавы для радиотехники (ПлИ-10, ПлИ-20, ПлИ-30 (платина-иридий).
• Гальванические покрытия.
• Перегонные реторты для производства плавиковой кислоты.
• Электроды для получения перхлоратов, перборатов, перкарбонатов, пероксодвусерной кислоты (фактически на платине держится все мировое производство перекиси водорода: электролиз серной кислоты — пероксодвусерная кислота — гидролиз — отгонка перекиси водорода).
• Нерастворимые аноды в гальванотехнике.
• Анодные штанги для защиты от коррозии корпусов подводных лодок.
• Нагревательные элементы печей сопротивления.

В медицине

Соединения платины (преимущественно, тетрахлорплатинаты) применяются, как цитостатики («цис-платина»). Однако в настоящее время имеются более эффективные противораковые лекарственные средства.

В ювелирном деле

Платина и её сплавы широко используются для производства ювелирных изделий.

Ежегодно мировая ювелирная промышленность потребляет около 50 тонн платины. До 2001 года большая часть ювелирных изделий из платины потреблялась в Японии. С 2001 года на долю Китая приходится примерно 50 % мировых продаж. В 1980 г. Китай потреблял около 1 % ювелирных изделий из платины. В настоящее время в Китае ежегодно продаётся около 10 млн изделий из платины общей массой около 25 тонн.

Российский спрос на ювелирную платину составляет 0,1 % от мирового уровня.

Монетарная функция

Платина, золото и серебро — основные металлы, выполняющие монетарную функцию. Однако платину стали использовать для изготовления монет на несколько тысячелетий позже золота и серебра.

Первые в мире платиновые монеты были выпущены и находились в обращении в Российской империи с 1828 по 1845 год. Чеканка началась с трехрублевиков. В 1829 г. «были учреждены платиновые дуплоны» (шестирублевики), а в 1830 г.— «квадрупли» (двенадцати-рублевики). Были отчеканены следующие номиналы монет: достоинством 3, 6 и 12 рублей. Трехрублевиков было отчеканено 1 371 691 шт., шестирубле-виков — 14 847 шт. и двенадцатирублевиков — 3474 шт.^[2]

В 1846 г. чеканка платиновой монеты была прекращена, хотя к этому году добыча уральской платины составила около 2000 пудов или 32 000 кг, из которых в монету было перечеканено 14 669 кг. Громадной количество платины, скопившейся на Петербургском монетном дворе частью в виде монеты, а частью в необработанном виде (по разным данным от 720 до 2000 пудов), было продано английской фирме Джонсон, Маттэ и Ко. В результате Англия, которая не добывала ни одного грамма платины, долго была в этой отрасли монополистом.^[5]

После 1846 года ни одна страна не позволяла себе «роскоши» вводить в обращение платиновые монеты. Выпускаемые разными странами в настоящее время платиновые монеты являются инвестиционными монетами. В период с 1992 по 1995 год инвестиционные платиновые монеты номиналами 25, 50 и 150 рублей выпускал Банк России.

Биологическая роль

Интересные факты

• Самым крупным существующим в настоящий момент платиновым самородком является «Уральский гигант» весом 7 кг 860,5 г. Хранится в Алмазном фонде Московского Кремля.
• В Южной Америке в XVII веке платину считали «поддельным серебром» и однажды её запасы для предотвращения фальшивомонетничества утопили в океане.
• Первые в мире монеты из платины были выпущены в России (см. Платиновые монеты).
• В цикле рассказов Айзека Азимова «Я, робот» и других его произведениях позитронный мозг роботов сделан из губчатой платины (точнее — сплава платины и иридия).

Дополнительная информация

Металлы платиновой группы

Если материал понравился Вам и оказался для Вас полезным, поделитесь им со своими друзьями!