PLATINUM

Name: Platinum

Symbol: Pt

Group: 10

Period: 6

Block: d

Category: Transition Metals

Atomic Number: 78

Atomic Mass: 195.084 u

Electrons per Shell: 2, 8, 18, 32, 17, 1

Electronegativity: 2.28

Density: 21.45 g/cc

Melting Point: 1768°C

Boiling Point: 3825°C

Thermal Conductivity: 71 W (m·K)

Electrical Conductivity: 9.4 × 10^6 S/m

Magnetic Order: Paramagnetic

Ordinary State: Solid

Oxidation States: +2, +4

Mohs Hardness: 3.5

Vickers hardness: 549 MPa

Brinell hardness: 392 MPa

Most stable isotopes: Pt-190 (0.012%), Pt-192 (0.782%), Pt-194 (32.864%), Pt-195 (33.775%), Pt-196 (25.211%), and Pt-198 (7.356%)

Discoverer: Antonio de Ulloa, Spanish (1735)

Platinum (Pt), a chemical element with atomic number 78, is a noble transition metal known for its exceptional corrosion resistance, high density (21.45 g/cm³), and versatility in industrial and ornamental applications. Its history, although less ancient than that of gold (Au) or silver (Ag), is rich in nuances, marked by its discovery in South America, its scientific recognition in Europe, and its rise as an essential material in modern technology. The narrative of platinum reflects both scientific advancements and cultural exchanges between the Old and New Worlds, challenging historical myths and highlighting the role of key figures such as Antonio de Ulloa.

Platinum was known to the pre-Columbian cultures of South America, particularly in what is now Colombia and Ecuador, long before its formal identification by Europeans. Indigenous peoples, such as those of the La Tolita culture (circa 600 BC–200 AD), worked platinum in natural alloys with gold, creating ceremonial and decorative objects using hammering and sintering techniques, as platinum's high melting point (1,768°C) prevented its smelting using the technologies of the time. These alloys, known as "white gold" or "platina" (a term derived from the Spanish "small silver" due to their silvery appearance), were found in alluvial deposits along rivers such as the San Juan in the Chocó region of Colombia. The abundance of platinum in these areas (approximately 0.005 ppm in the Earth's crust, comparable to gold) contrasted with its rarity in Europe, where it was unknown before the 16th century. The recognition of platinum in European science began with the Spanish navigator and scientist Antonio de Ulloa, who, during the French-Spanish Geodesic Mission (1735–1744) in the Viceroyalty of New Granada (present-day Colombia), documented this metal in 1748. Ulloa, along with mathematician Jorge Juan, described platinum as a "non-malleable" material that resisted smelting with available techniques, observing it in the gold mines of Chocó. His report, published in the Historical Account of the Voyage to South America, was the first to introduce platinum to European scientific knowledge, although the metal was not isolated in pure form until decades later. 

It is important to note that Ulloa did not extract or exploit platinum for colonial purposes, as the "black legend" that caricatures Spanish colonization sometimes suggests. His work was primarily scientific, focused on describing the properties of a material unknown to Europe, and his contribution was key to sparking interest in platinum. Despite Ulloa's report, platinum remained poorly understood in Europe during the 18th century, in part because its high density and heat resistance made it difficult to work with the technologies of the time. Some considered it a "waste" in gold mines, as it complicated gold extraction. It wasn't until 1750 that English scientist William Brownrigg presented platinum samples to the Royal Society, and in 1786, French chemist Pierre-François Chabaneau developed a method to purify and work platinum, rendering it malleable by heating and hammering in controlled atmospheres. This advance allowed its use in jewelry, coins, and scientific equipment, such as crucibles for chemical experiments due to its resistance to acids, even aqua regia (HNO₃ + HCl), which dissolves gold but not platinum.

Platinum gained prominence in the 19th century, when its rarity and properties made it a symbol of prestige. In 1820, Russia began minting platinum coins, taking advantage of deposits in the Ural Mountains, which represented one of the world's main sources until the 20th century. Today, South Africa dominates global production (70–80% of the ~200 tonnes per year), followed by Russia and Zimbabwe. Platinum is mainly extracted from minerals such as sperrylite (PtAs₂) and cooperite (PtS), often as a byproduct of nickel (Ni) and copper (Cu) mines. Its importance grew exponentially in the 20th century with industrial applications: in catalytic converters to reduce vehicle emissions (50% of demand), in electrodes for fuel cells, and in jewelry, where its silvery luster and durability make it comparable to gold. Furthermore, platinum compounds, such as cisplatin (PtCl₂(NH₃)₂), are essential in chemotherapy to treat certain types of cancer.

The history of platinum also reflects cultural and economic tensions. During the colonial period, the Spanish government prohibited its export from the Americas to prevent counterfeiting of silver coins, which limited its initial diffusion. This measure, often misinterpreted as an act of greed, sought to protect the colonial economy, not to exploit platinum, which did not yet have significant practical applications. The "black legend" narrative has exaggerated Spain's role in this context, ignoring the fact that platinum was a secondary material compared to gold and silver in the colonial economy. Ulloa's work, far from being extractive, was a scientific endeavor that laid the foundations for the modern study of platinum, consolidating its place as an indispensable noble metal in contemporary technology and culture.

Platinum (Pt), a chemical element with atomic number 78, is a noble and precious metal that, although ranked just behind gold (Au) in terms of cultural prestige and economic value, stands out for its unique physical and chemical properties. Its silvery appearance with a metallic "steel" hue distinguishes it, combining a soft luster with remarkable corrosion resistance, even surpassing gold in certain chemical environments, such as aqua regia (HNO₃ + HCl). With a density of 21.45 g/cm³, platinum is denser than gold (19.32 g/cm³), making it one of the heaviest metals, surpassed only by osmium (Os) and iridium (Ir). Its melting point of 1,768°C and boiling point of nearly 3,827°C are significantly higher than those of gold (1,064°C and 2,856°C, respectively), making it ideal for high-temperature applications such as catalytic converters and laboratory crucibles.

Platinum is remarkably ductile and malleable, allowing it to be formed into fine wires or thin sheets, although it is harder than gold, with a hardness of 3.5 on the Mohs scale, comparable to that of copper (Cu). This combination of softness and mechanical strength facilitates its use in jewelry, where it competes with gold for durability and aesthetics, and in industrial applications requiring precision. As the leader of the platinum group of metals (which includes rhodium (Rh), ruthenium (Ru), palladium (Pd), osmium, and iridium), platinum is frequently found in natural deposits alongside these elements, often in minerals such as sperryllite (PtAs₂) or cooperite (PtS). It belongs to group 10 of the periodic table, headed by nickel (Ni), which explains its presence as a byproduct in nickel and copper mining, with a global abundance of approximately 0.005 ppm in the Earth's crust, similar to that of gold.

Chemically, platinum is extremely inert, resisting oxidation and reaction with most acids, bases, and halogens at moderate temperatures, making it a key material for chemical equipment and electrodes. It can form alloys with metals such as nickel, copper, cobalt (Co), and other platinum group metals, improving its mechanical properties for applications in aerospace superalloys and electrical contacts. In industry, platinum dominates in catalytic converters (50% of global demand, ~200 tons per year), where it catalyzes reactions to reduce vehicle emissions, and in chemotherapy, with compounds such as cisplatin (PtCl₂(NH₃)₂) that treat certain types of cancer. Its electrical conductivity, although lower than that of copper or silver (Ag), along with its chemical stability, makes it essential in high-reliability electronics, such as connectors and circuits. The combination of these properties, along with its scarcity and prestige, consolidates platinum as an indispensable material in technology, medicine, and jewelry.

Platinum (Pt), a chemical element with atomic number 78, is a noble metal whose exceptional corrosion resistance places it among the most stable materials on the periodic table, surpassed only marginally by gold (Au) in certain contexts. Its chemical inertness is due to its low reactivity, which allows it to resist most acids and bases, including corrosive environments such as hydrochloric acid (HCl) or nitric acid (HNO₃). However, platinum can slowly dissolve in aqua regia, a 1:3 mixture of nitric acid (HNO₃) and hydrochloric acid (HCl), especially at moderately high temperatures (above 100°C), forming platinum chloride (PtCl₂ or PtCl₄). This reaction is slower than that of gold, reflecting its greater chemical stability under extreme conditions. Platinum exhibits remarkable resistance to oxidation, both to oxygen (O₂) and halogens. Unlike many metals, it does not oxidize in the presence of oxygen at ambient or moderate temperatures, and only forms oxides, such as platinum oxide (PtO₂), above 500°C. This process is reversible by controlled heating, allowing the pure metal to be recovered. Halogens, such as gaseous fluorine (F₂), attack platinum at temperatures above 400°C, forming salts such as platinum tetrafluoride (PtF₄), which are more difficult to reverse due to their chemical stability. This corrosion resistance, combined with a density of 21.45 g/cm³ and a melting point of 1,768°C, makes it ideal for applications in aggressive environments, such as laboratory crucibles, electrodes in fuel cells, and catalytic converters, where it represents approximately 50% of global demand (~200 tons per year).

Unlike less noble metals such as copper (Cu), silver (Ag), or iron (Fe), platinum can be worked in the presence of oxygen without oxidizing, similar to gold, silver, tin (Sn), lead (Pb), and bismuth (Bi). However, its high melting point, higher than that of pure iron (1,538°C), makes it difficult to process manually, especially in jewelry. Most platinum pieces, such as wedding bands or industrial components, are manufactured by vacuum casting or in inert atmospheres (such as argon) using specialized equipment to reach temperatures above 1,700°C. This complexity explains the prevalence of simple designs, such as cylindrical rings, in platinum jewelry, as its hardness (3.5 on the Mohs scale) and heat resistance limit the creation of intricate shapes without advanced technology. In industrial applications, its chemical inertness and stability at high temperatures make it indispensable in sectors such as automotive (catalytic converters), medicine (cisplatin chemotherapy, PtCl₂(NH₃)₂), and electronics (high-reliability contacts), consolidating its value despite its scarcity (0.005 ppm in the Earth's crust).

Platinum (Pt), chemical element with atomic number 78, is the mainstay of the platinum group of metals, which includes rhodium (Rh), ruthenium (Ru), palladium (Pd), osmium (Os), and iridium (Ir). As the most versatile, valuable, and relatively easy-to-work member of this group, thanks to its malleability and ductility (hardness of 3.5 on the Mohs scale), platinum excels in industrial, technological, and luxury applications. Its high density (21.45 g/cm³), corrosion resistance, and high melting point (1,768 °C) make it ideal for extreme environments, surpassing the lighter but less durable palladium in some respects. Global platinum production of approximately 200 tonnes per year comes primarily from South Africa (70–80%), with an abundance in the Earth's crust of 0.005 ppm, contributing to its high cost, often comparable to or higher than 18-carat gold (Au).

The main use of platinum, which accounts for about 50% of its demand, is as a catalyst in catalytic converters in the automotive industry. These devices transform harmful exhaust gases into less harmful compounds, reducing the environmental impact of vehicles. Specifically, platinum catalyzes the oxidation of carbon monoxide (CO) to carbon dioxide (CO₂), the combustion of hydrocarbons (CₓHᵧ) to water vapor (H₂O) and carbon dioxide, and the reduction of nitrogen dioxide (NO₂) to molecular nitrogen (N₂), an inert and non-toxic gas. This catalytic capacity, derived from its electronic structure and active surface, makes it irreplaceable in reducing emissions, especially in internal combustion engines and industrial gas control systems. In the petrochemical industry, platinum is used in refining processes, such as catalytic cracking, to improve efficiency in the production of fuels and chemicals. 

The second most significant use of platinum is in luxury jewelry, where its silvery luster, corrosion resistance, and prestige position it as an alternative to white gold and 18k gold (75% Au). Its price, which ranges between $900 and $1,200 per ounce (compared to $2,400 for gold in 2025), reflects its rarity and the difficulty of its extraction, often as a byproduct of nickel (Ni) and copper (Cu) mines. In jewelry, platinum is valued for its durability and ability to maintain its shine without tarnishing, ideal for pieces such as wedding bands and high-end designs. Its malleability allows it to be worked into precise shapes, although its high melting point requires vacuum casting or in inert atmospheres (such as argon) to prevent oxidation, which raises production costs. 

Other significant uses include applications in the chemical industry, where platinum is used in electrodes and laboratory crucibles due to its resistance to acids, even aqua regia (HNO₃ + HCl), which dissolves it only at high temperatures. 

In electronics, platinum coats electrical contacts and connectors, taking advantage of its conductivity (albeit lower than that of copper or silver) and its chemical inertness to ensure reliability in high-precision devices, such as in the aerospace and medical industries. In medicine, compounds such as cisplatin (PtCl₂(NH₃)₂) are essential in chemotherapy to treat cancers such as testicular and ovarian cancer. Historically, platinum has been used in commemorative coins, such as those issued by Russia in the 19th century, although its high cost limits this use to special editions. Platinum's versatility, combined with its scarcity and unique properties, cements it as an essential material in modern technology, medicine, and luxury, rivaling gold in prestige and functionality.