- Platinum (Pt) is a noble metal with atomic number 78, belonging to Group 10 of the periodic table, alongside nickel and palladium.
- Its electron configuration is [Xe] 4f¹⁴ 5d⁹ 6s¹, reflecting its partially filled d-orbitals that contribute to its stability and versatile bonding. Each atom of platinum contains seventy-eight protons, seventy-eight electrons, and typically 117 to 120 neutrons, depending on the isotope.
- Naturally occurring platinum consists of six stable isotopes, with platinum-195 (¹⁹⁵Pt) being the most abundant.
- Platinum was known to pre-Columbian civilizations in South America, where it was used in jewelry and ceremonial artifacts. It was first introduced to Europe in the 16th century by Spanish explorers, who encountered the metal in Colombia and referred to it as platina, meaning “little silver.” In 1735, Spanish scientist Antonio de Ulloa provided the first detailed European description of platinum, bringing it to the attention of the scientific community.
- Physically, platinum is a dense, malleable, ductile, and highly lustrous silver-white metal. It has a density of 21.45 g/cm³, a melting point of 1,768 °C (3,214 °F), and a boiling point of 3,825 °C (6,917 °F). Platinum is one of the least reactive metals, demonstrating remarkable resistance to tarnishing, oxidation, and corrosion even at high temperatures. These qualities make it an ideal material for long-lasting industrial and decorative purposes.
- Chemically, platinum is classified as a noble metal due to its stability and reluctance to react with most chemicals. It resists attack from acids but can be dissolved in aqua regia, a mixture of nitric and hydrochloric acid. Platinum exhibits oxidation states ranging from 0 to +6, with +2 and +4 being the most common. Important compounds include platinum(II) chloride (PtCl₂), platinum(IV) chloride (PtCl₄), and cisplatin (PtCl₂(NH₃)₂), a groundbreaking chemotherapy drug.
- Platinum’s applications are widespread and highly valuable. It is essential in catalytic converters in automobiles, where it helps reduce harmful emissions by facilitating the conversion of toxic gases such as carbon monoxide and nitrogen oxides into less harmful substances. In the chemical industry, platinum catalysts are used for petroleum refining, hydrogenation reactions, and the production of nitric acid. Platinum is also used in jewelry, where its rarity, luster, and resistance to tarnishing make it a symbol of prestige. In electronics, it is applied in thermocouples, electrodes, and hard disks. In medicine, platinum-based drugs such as cisplatin, carboplatin, and oxaliplatin are critical in cancer treatment.
- Biologically, platinum has no natural role in living organisms. However, its compounds, particularly in the medical field, are biologically significant. Cisplatin, for example, works by binding to DNA in cancer cells, disrupting cell division and inducing apoptosis. While highly effective, platinum-based drugs can also have toxic side effects, requiring careful dosing and monitoring.
- Environmentally, platinum is one of the rarest elements in Earth’s crust, with an abundance of about 0.005 parts per million. It is typically mined from placer deposits or extracted as a by-product of nickel and copper refining. Major producers include South Africa, Russia, and Canada, with South Africa holding the largest reserves. Because of its scarcity and importance in industrial and medical applications, platinum is considered a strategic and critical metal. Recycling from catalytic converters and electronic waste is an important source to meet global demand.
