Platinum

Platinum,  78Pt
Platinum crystals.jpg
General properties
Pronunciationm/ (PLAT-ə-nǝm)
Appearancesilvery white
Standard atomic weight (Ar, standard)195.084(9)[1]
Platinum in the periodic table
HydrogenHelium
LithiumBerylliumBoronCarbonNitrogenOxygenFluorineNeon
SodiumMagnesiumAluminiumSiliconPhosphorusSulfurChlorineArgon
PotassiumCalciumScandiumTitaniumVanadiumChromiumManganeseIronCobaltNickelCopperZincGalliumGermaniumArsenicSeleniumBromineKrypton
RubidiumStrontiumYttriumZirconiumNiobiumMolybdenumTechnetiumRutheniumRhodiumPalladiumSilverCadmiumIndiumTinAntimonyTelluriumIodineXenon
CaesiumBariumLanthanumCeriumPraseodymiumNeodymiumPromethiumSamariumEuropiumGadoliniumTerbiumDysprosiumHolmiumErbiumThuliumYtterbiumLutetiumHafniumTantalumTungstenRheniumOsmiumIridiumPlatinumGoldMercury (element)ThalliumLeadBismuthPoloniumAstatineRadon
FranciumRadiumActiniumThoriumProtactiniumUraniumNeptuniumPlutoniumAmericiumCuriumBerkeliumCaliforniumEinsteiniumFermiumMendeleviumNobeliumLawrenciumRutherfordiumDubniumSeaborgiumBohriumHassiumMeitneriumDarmstadtiumRoentgeniumCoperniciumNihoniumFleroviumMoscoviumLivermoriumTennessineOganesson
Pd

Pt

Ds
iridiumplatinumgold
Atomic number (Z)78
Groupgroup 10
Periodperiod 6
Element category  transition metal
Blockd-block
Electron configuration[Xe] 4f14 5d9 6s1
Electrons per shell
2, 8, 18, 32, 17, 1
Physical properties
Phase at STPsolid
Melting point2041.4 K ​(1768.3 °C, ​3214.9 °F)
Boiling point4098 K ​(3825 °C, ​6917 °F)
Density (near r.t.)21.45 g/cm3
when liquid (at m.p.)19.77 g/cm3
Heat of fusion22.17 kJ/mol
Heat of vaporization510 kJ/mol
Molar heat capacity25.86 J/(mol·K)
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)2330(2550)2815314335564094
Atomic properties
Oxidation states6, 5, 4, 3, 2, 1, −1, −2, −3 ​(a mildly basic oxide)
ElectronegativityPauling scale: 2.28
Ionization energies
  • 1st: 870 kJ/mol
  • 2nd: 1791 kJ/mol
Atomic radiusempirical: 139 pm
Covalent radius136±5 pm
Van der Waals radius175 pm
Color lines in a spectral range
Miscellanea
Crystal structureface-centered cubic (fcc)
Face-centered cubic crystal structure for platinum
Speed of sound thin rod2800 m/s (at r.t.)
Thermal expansion8.8 µm/(m·K) (at 25 °C)
Thermal conductivity71.6 W/(m·K)
Electrical resistivity105 nΩ·m (at 20 °C)
Magnetic orderingparamagnetic
Magnetic susceptibility+201.9·10−6 cm3/mol (290 K)[2]
Tensile strength125–240 MPa
Young's modulus168 GPa
Shear modulus61 GPa
Bulk modulus230 GPa
Poisson ratio0.38
Mohs hardness3.5
Vickers hardness400–550 MPa
Brinell hardness300–500 MPa
CAS Number7440-06-4
History
DiscoveryAntonio de Ulloa (1735)
Main isotopes of platinum
Iso­topeAbun­danceHalf-life (t1/2)Decay modePro­duct
190Pt0.012%6.5×1011 yα186Os
192Pt0.782%stable
193Ptsyn50 yε193Ir
194Pt32.864%stable
195Pt33.775%stable
196Pt25.211%stable
198Pt7.356%stable
| references | in Wikidata

Platinum is a chemical element with symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name is derived from the Spanish term platina, meaning "little 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.

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 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. Being 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.[5] Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy against certain types of cancer.[6]

Characteristics

Physical

Pure platinum is a lustrous, ductile, and malleable, silver-white metal.[7] Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold.[8][9] The metal has excellent resistance to corrosion, is stable at high temperatures and has stable electrical properties. Platinum does oxidize, forming PtO2, at 500 °C; this oxide can be easily removed thermally.[10] It reacts vigorously with fluorine at 500 °C (932 °F) to form platinum tetrafluoride.[11] It is also attacked by chlorine, bromine, iodine, and sulfur. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia (nitric acid hydrochloride), to form chloroplatinic acid, H2PtCl6.[12]

Its physical characteristics and chemical stability make it useful for industrial applications.[13] Its resistance to wear and tarnish is well suited to use in fine jewellery.

Chemical

Platinum being dissolved in hot aqua regia

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. As is expected, tetracoordinate platinum(II) compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is generally unreactive, it dissolves in hot aqua regia to give aqueous chloroplatinic acid (H2PtCl6):[14]

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

As a soft acid, platinum has a great affinity for sulfur, such as on dimethyl sulfoxide (DMSO); numerous DMSO complexes have been reported and care should be taken in the choice of reaction solvent.[15]

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).[16]

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. It is the only stable isotope with a non-zero spin; with a spin of 1/2, 195Pt satellite peaks are often observed in 1H and 31P NMR spectroscopy (i.e., Pt-phosphine and Pt-alkyl complexes). 190Pt is the least abundant at only 0.01%. Of the naturally occurring isotopes, only 190Pt is unstable, though it decays with a half-life of 6.5×1011 years, causing an activity of 15 Bq/kg of natural platinum. 198Pt 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 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, whereas the most stable is 193Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta decay and alpha decay. 188Pt, 191Pt, and 193Pt decay primarily by electron capture. 190Pt and 198Pt are predicted to have energetically favorable double beta decay paths.[17]

Occurrence

A native platinum nugget, Kondyor mine, Khabarovsk Krai

Platinum is an extremely rare metal,[18] occurring at a concentration of only 0.005 ppm in Earth's crust.[19][20] 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.[12]

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.[21] 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.[22]

In 1865, chromites were identified in the Bushveld region of South Africa, followed by the discovery of platinum in 1906.[23] 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.[24][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 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,[25] for example in the Absaroka Range in Montana.[26] 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).[27]

Large platinum deposits are present in the state of Tamil Nadu, India.[28]

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.[29]

Other Languages
Afrikaans: Platinum
አማርኛ: ፕላቲነም
العربية: بلاتين
aragonés: Platín
armãneashti: Platinâ
asturianu: Platín
azərbaycanca: Platin
تۆرکجه: پلاتین
Bân-lâm-gú: Pe̍h-kim
беларуская: Плаціна
беларуская (тарашкевіца)‎: Плятына
भोजपुरी: प्लैटिनम
български: Платина
bosanski: Platina
brezhoneg: Platin
català: Platí
Чӑвашла: Платина
Cebuano: Platino
čeština: Platina
corsu: Platinu
Cymraeg: Platinwm
dansk: Platin
Deutsch: Platin
eesti: Plaatina
Ελληνικά: Λευκόχρυσος
эрзянь: Ашо сырне
español: Platino
Esperanto: Plateno
euskara: Platino
فارسی: پلاتین
Fiji Hindi: Platinum
français: Platine
furlan: Platin
Gaeilge: Platanam
Gaelg: Platinum
Gàidhlig: Platanum
galego: Platino
Gĩkũyũ: Platinum
ગુજરાતી: પ્લેટિનમ
客家語/Hak-kâ-ngî: Pha̍k-kîm
хальмг: Платинум
한국어: 백금
Հայերեն: Պլատին
हिन्दी: प्लैटिनम
hrvatski: Platina
Ido: Platino
Bahasa Indonesia: Platina
interlingua: Platino
íslenska: Platína
italiano: Platino
עברית: פלטינה
ქართული: პლატინა
kaszëbsczi: Platëna
қазақша: Платина
Kiswahili: Platini
коми: Платина
Kreyòl ayisyen: Platin
kurdî: Platîn
Кыргызча: Платина
кырык мары: Платина
Latina: Platinum
latviešu: Platīns
Lëtzebuergesch: Platin
lietuvių: Platina
Ligure: Plattino
la .lojban.: jinmrplati
magyar: Platina
македонски: Платина
മലയാളം: പ്ലാറ്റിനം
मराठी: प्लॅटिनम
Bahasa Melayu: Platinum
Mìng-dĕ̤ng-ngṳ̄: Băh-gĭng
монгол: Цагаан алт
မြန်မာဘာသာ: ရွှေဖြူ
Nederlands: Platina
नेपाल भाषा: प्वलाख
日本語: 白金
norsk: Platina
norsk nynorsk: Platina
occitan: Platin
ଓଡ଼ିଆ: ପ୍ଲାଟିନମ
oʻzbekcha/ўзбекча: Platina
ਪੰਜਾਬੀ: ਪਲੈਟੀਨਮ
پنجابی: پلاٹینم
Piemontèis: Plàtin
Plattdüütsch: Platin
polski: Platyna
português: Platina
română: Platină
Runa Simi: Qullqiya
русский: Платина
संस्कृतम्: प्लेटिनम्
Scots: Platinum
Seeltersk: Platin
shqip: Platina
sicilianu: Plàtinu
Simple English: Platinum
slovenčina: Platina
slovenščina: Platina
Soomaaliga: Balatiniyaam
کوردی: پلاتین
српски / srpski: Платина
srpskohrvatski / српскохрватски: Platina
Basa Sunda: Platinum
suomi: Platina
svenska: Platina
Tagalog: Platino
татарча/tatarça: Агалтын
тоҷикӣ: Платина
ᏣᎳᎩ: ᏝᏘᏅᎻ
Türkçe: Platin
українська: Платина
اردو: پلاٹینم
ئۇيغۇرچە / Uyghurche: Platina
Vahcuengh: Gimhau
vepsän kel’: Platin
Tiếng Việt: Platin
文言:
Winaray: Platino
吴语:
ייִדיש: פלאטין
Yorùbá: Platinum
粵語: 白金
中文:
Kabɩyɛ: Platɩnɩ