Platinum
A dense, unreactive precious metal used in catalysis and jewelry.
Platinum is a chemical element represented by the symbol Pt, with an atomic number of 78. This dense, silverish-white metal is malleable, ductile, and highly unreactive, making it a precious transition metal. The name comes from the Spanish word *platina*, meaning "little silver." It belongs to the platinum group of elements and sits in group 10 of the periodic table. Six naturally occurring isotopes exist for platinum. In Earth's crust, it is quite scarce, averaging about 5 micrograms per kilogram. It can be found in some nickel and copper ores, as well as in native deposits where it appears uncombined.
Because it resists corrosion even at high temperatures, platinum is classified as a noble metal. This property means it often occurs naturally in its pure form, especially in alluvial sands of rivers. Pre-Columbian South American peoples were the first to use it, crafting artifacts from these deposits. European references to platinum appeared as early as the 1500s, but it was not until 1748, when Antonio de Ulloa published a report on a new metal from Colombia, that scientists began to understand it.
Platinum plays a key role in catalytic converters, laboratory gear, electrical contacts and electrodes, platinum resistance thermometers, dentistry tools, and jewelry. It is also used in the glass industry to handle molten glass, which does not stick to platinum. Certain platinum-based compounds—like cisplatin, oxaliplatin, and carboplatin—are used in chemotherapy to treat specific cancers.
**Characteristics**
**Physical** Platinum is a lustrous, ductile, and malleable silver-white metal. It is actually more ductile than gold, silver, or copper, making it the most ductile of all pure metals. Its physical traits and chemical stability make it valuable for industrial uses, while its resistance to wear and tarnish suits it well for fine jewelry.
**Chemical** Platinum does not corrode, and bulk platinum does not oxidize in air at any temperature. However, heated platinum wires lose weight faster in air or oxygen than in a vacuum, suggesting a thin surface film of PtO₂ forms, which breaks down above 500 °C. The most common oxidation states are +2 and +4; +1 and +3 are rarer and often stabilized by metal bonding in bimetallic or polymetallic species. Tetracoordinate platinum(II) compounds typically adopt 16-electron square planar geometries. Though elemental platinum is generally unreactive, it is attacked by chlorine, bromine, iodine, and sulfur. It reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride. Platinum does not dissolve in hydrochloric or nitric acid, but it does dissolve in hot aqua regia (a mix of nitric and hydrochloric acids), producing aqueous chloroplatinic acid (H₂PtCl₆). As a soft acid, the Pt²⁺ ion has a strong affinity for sulfide and sulfur ligands; numerous DMSO complexes have been reported, so care is needed when choosing reaction solvents. In 2007, German scientist Gerhard Ertl won the Nobel Prize in Chemistry for detailing the molecular mechanisms of catalytic carbon monoxide oxidation on platinum, as used in catalytic converters.
**Isotopes** Platinum has six naturally occurring isotopes: ¹⁹⁰Pt, ¹⁹²Pt, ¹⁹⁴Pt, ¹⁹⁵Pt, ¹⁹⁶Pt, and ¹⁹⁸Pt. The most abundant is ¹⁹⁵Pt, making up 33.83% of all platinum; it is the only stable isotope with a non-zero spin (½), making it useful for ¹⁹⁵Pt NMR. Because of its spin and abundance, ¹⁹⁵Pt satellite peaks often appear in ¹H and ³¹P NMR spectroscopy, for example in Pt-phosphine and Pt-alkyl complexes. The radioactive ¹⁹⁰Pt is the least abundant at just 0.012%; it undergoes alpha decay with a half-life of 4.83×10¹¹ years, resulting in a very low activity of 16.8 Bq/kg in natural platinum. This decay has some use in isotope geology, though not for direct dating. The other natural isotopes are theoretically capable of alpha decay, but this has never been observed, so they are considered stable. Platinum also has 38 synthetic isotopes, with atomic masses from 165 to 208, bringing the total known isotopes to 44. The most stable synthetic radioisotope is ¹⁹³Pt, with a half-life of 50 years. Most platinum isotopes decay through a combination of beta decay and, on the proton-rich side, alpha decay. ¹⁸⁸Pt, ¹⁹¹Pt, and ¹⁹³Pt decay only by electron capture (aside from a very small alpha branch in the first). Both ¹⁹⁰Pt and ¹⁹⁸Pt are predicted to have energetically favorable double beta decay paths.
**Occurrence** Platinum is extremely rare on Earth, with a concentration of just 0.005 ppm in the crust. It is often found chemically uncombined as native platinum, usually alloyed with other platinum-group metals. Most native platinum occurs in secondary deposits within alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department of Colombia still yield platinum-group metals today. Another large alluvial deposit is in the Ural Mountains of Russia, which is still mined. In nickel and copper deposits, platinum-group metals appear as sulfides (e.g., (Pt,Pd)S), tellurides (e.g., PtBiTe), antimonides (PdSb), and arsenides (e.g., PtAs₂), as well as end alloys with nickel or copper. Platinum arsenide, known as sperrylite (PtAs₂), is a major source of platinum from nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum, Alaska, about 17,000 kg (550,000 troy ounces) was mined between 1927 and 1975, with the mine closing in 1990. The rare sulfide mineral cooperite, (Pt,Pd,Ni)S, contains platinum along with palladium and nickel.
- symbol
- Pt
- atomic_number
- 78
- group
- 10
- period
- 6
- block
- d
- category
- transition metal
- natural_isotopes
- 6
Lore & Background
Platinum is a dense, malleable, and ductile transition metal with a lustrous, silver-white appearance. It is highly unreactive and does not corrode, even at elevated temperatures, classifying it as a noble metal. This chemical stability means platinum is often found in nature in its uncombined, native form. It is one of the rarest elements in Earth’s crust, with an average abundance of about 5 micrograms per kilogram. Native platinum occurs in secondary deposits within alluvial sands of rivers, a fact that led to its earliest use by pre-Columbian South American peoples for crafting artifacts. The metal is also found in certain nickel and copper ores, often alongside other platinum-group metals, as sulfides, tellurides, antimonides, or arsenides. A key defining characteristic is its resistance to tarnish and wear, making it valuable for fine jewelry and industrial applications. Platinum is more ductile than gold, silver, or copper, and it does not oxidize in air at any temperature in bulk form, though heated wires may form a thin surface film that decomposes above 500°C. It is attacked by halogens and sulfur but is insoluble in hydrochloric and nitric acid, dissolving only in hot aqua regia to form chloroplatinic acid. Its most common oxidation states are +2 and +4, with platinum(II) compounds typically adopting square planar geometries.
Reader's Guide
Platinum is a key component in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. It is also used in the glass industry to manipulate molten glass, which does not 'wet' platinum. Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy as treatment for certain types of cancer. Because of its scarcity in Earth's crust, barely a few hundred metric tonnes are produced annually, and given its critical and important uses, it is highly valuable as well as a major precious metal commodity.
Did You Know?
- Gold is the most ductile of pure metals, not platinum.
- The most abundant isotope of platinum is 195Pt, comprising 33.83% of all platinum.
- Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia to form chloroplatinic acid.
- The radioactive isotope 190Pt undergoes alpha decay with a half-life of approximately 6.5×10^11 years.
Physical & Chemical Properties
Platinum is a lustrous, silver-white transition metal that stands out for its extraordinary ductility, exceeding even gold, silver, and copper among pure metals. It is dense, malleable, and highly resistant to corrosion, earning its classification as a noble metal. Its most common oxidation states are +2 and +4, with tetracoordinate platinum(II) compounds tending to adopt 16-electron square planar geometries. The metal resists hydrochloric and nitric acids individually but dissolves in hot aqua regia to yield chloroplatinic acid. As a soft acid, the Pt²⁺ ion exhibits a strong affinity for sulfide and sulfur ligands, a property that demands careful solvent selection in synthetic chemistry.
Rarity, Occurrence & Mining
Platinum is extraordinarily scarce in Earth's crust, occurring at a concentration of only about 5 micrograms per kilogram. This extreme rarity means barely a few hundred metric tonnes are produced globally each year, yet the metal's critical uses make it a highly valuable precious commodity. It is often found chemically uncombined as native platinum, particularly in alluvial river sands. Pre-Columbian South American natives in Colombia's Chocó Department worked these deposits into artifacts long before European contact. Major geological sources include the Ural Mountains in Russia and the Sudbury Basin in Ontario, Canada, where the arsenide mineral sperrylite (PtAs₂) serves as a key platinum-bearing phase in nickel ores. In nickel and copper deposits, platinum-group metals also occur as sulfides, tellurides, antimonides, and end alloys.
Industrial & Medical Applications
Platinum's chemical inertness and resistance to wear make it indispensable across a remarkable range of industries. Beyond catalysis, platinum appears in laboratory equipment, electrical contacts, electrodes, platinum resistance thermometers, and dentistry. In the glass industry, molten glass does not wet platinum, making the metal ideal for manipulating it. Its resistance to tarnish and wear suits fine jewelry perfectly. Perhaps most remarkably, platinum compounds such as cisplatin, oxaliplatin, and carboplatin serve as chemotherapy agents in the treatment of certain cancers, bridging the gap between inorganic chemistry and life-saving medicine. This versatility, spanning from automotive exhaust systems to oncology wards, underscores why such a scarce element commands such a premium price.
History & Scientific Recognition
Although pre-Columbian South American peoples crafted artifacts from platinum found in alluvial sands, European awareness of the metal remained limited to passing references in 16th-century writings. The element's name derives from the Spanish platina, a diminutive of plata (silver), reflecting its silvery-white appearance. In the modern era, platinum's scientific importance has grown considerably. The element's six naturally occurring isotopes, including the NMR-active ¹⁹⁵Pt with its non-zero nuclear spin, have provided valuable tools in spectroscopy and isotope geology. Together, these contributions cement platinum's dual role as both a practical industrial material and a subject of fundamental scientific inquiry.
Frequently Asked Questions
Who is Platinum?
Platinum is a dense, silvery-white transition metal occupying position 78 on the periodic table. It sits in group 10, period 6, and is a proud member of the platinum-group family.
What are Platinum's standout abilities?
Its most celebrated trait is extreme chemical inertness — it shrugs off nearly every acid and reagent without reacting. On top of that, it is dense, malleable, and ductile, so it can be drawn into fine wire or hammered into sheet without fracturing.
Where does Platinum appear in nature?
It is one of the scarcest elements in Earth's crust, averaging only about 5 micrograms per kilogram of rock. It is most often recovered from nickel and copper ores, though occasional native metal deposits do exist.
What role does Platinum play in the real world?
It serves as a premier catalyst in industrial chemistry and automotive exhaust systems, where it helps decompose toxic pollutants. Its luster and durability also make it a go-to metal for fine jewelry and luxury goods.
Why is Platinum considered so precious?
Its natural scarcity on Earth, six stable isotopes, and near-total resistance to corrosion make it far harder to obtain than common base metals. That combination of rarity and versatility in catalysis and ornamentation keeps its market value consistently high.
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