Platinum is a metallic element with symbol Pt and atomic number 78. It is a luxurious and precious metal that resists tarnish and corrosion, and has a high melting point and remarkable catalytic properties.
Discovery and Naming
Platinum was known to indigenous people in Central and South America long before European discovery. In the 16th century, Spanish explorers encountered it while in the New World and named it “platina,” meaning “little silver” in Spanish. However, it wasn’t until the 18th century that European scientists recognized it as a new element. Spanish naval officer and scientists Antonio de Ulloa gets credit for reporting the existence of the new element in 1748. The element name “platinum” derives from the Spanish term.
Appearance and Properties
Platinum is a silvery-white, lustrous metal that is both malleable and ductile. It is more ductile than gold, but less malleable. It does not oxidize in air at any temperature and is resistant to corrosion. Furthermore, it withstands high temperatures, making it an excellent material for various high-temperature applications.
Platinum has six naturally occurring isotopes: 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt. Of these, 195Pt is the most abundant, making up about 33.8% of all natural platinum. Platinum-195 is noteworthy in that it has a non-zero spin. Pt-190 is the only natural isotope that is unstable. There are also 34 synthetic radioisotopes, ranging in mass from 165 to 204.
Abundance, Ores, and Sources
Platinum is a rare element in the Earth’s crust. It occurs in its native form or in the mineral sperrylite. Major sources of platinum include South Africa, Russia, and North America. The mining and refining of platinum are labor-intensive, contributing to its high market value. Platinum separates from lighter elements due to its high density. It separates from iron and nickel based on its magnetic properties, where iron and nickel are ferromagnetic and platinum is paramagnetic. Aqua regia separates platinum from other platinum group metals because the element dissolves in the acid, while other metals in the group do not react.
Uses of Platinum
The uses of platinum relates to its rarity, beauty, electrical properties, and corrosion-resistance.
- Investment: Platinum is a precious metal commodity.
- Jewelry: Due to its luster and resistance to tarnish, platinum is a popular choice for rings, necklaces, and other ornamental items.
- Catalysts: Platinum is important in catalytic converters in vehicles to reduce harmful emissions. It is also a key catalyst in petroleum refining.
- Electrical Contacts: Its conductive properties make platinum ideal for high-quality electrical contacts.
- Medical Instruments: Its non-reactive nature makes it suitable for medical implants and equipment.
- Fuel Cells: Platinum acts as a catalyst in hydrogen fuel cells.
Platinum exhibits several oxidation states, ranging from +1 to +6. The usual oxidation state is +2, but +4 is also common.
Biological Role, Health Effects, and Toxicity
Platinum serves no know biological role in any organism. Platinum compounds, notably cisplatin, find use in chemotherapy treatments for certain types of cancer. While platinum itself is relatively inert and poses minimal health risks, some of its compounds are toxic when ingested in large amounts. Prolonged exposure causes allergic reactions in some individuals.
Key Platinum Element Facts for Chemists
Here is a table of key platinum element facts for chemists, other scientists, and engineers.
|Electron Configuration||[Xe] 4f¹⁴ 5d⁹ 6s¹|
|Electrons per Shell||2, 8, 18, 32, 17, 1|
|State at Room Temperature||Solid|
|Heat of Vaporization||510 kJ/mol|
|Heat of Fusion||22.17 kJ/mol|
|Oxidation States||−3, −2, −1, 0, +1, +2, +3, +4, +5, +6|
|Ionization Energies||870 kJ/mol (1st)|
|Atomic Radius||139 pm|
|Covalent Radius||136 pm|
|van der Waals Radius||175 pm|
|Crystal Structure||Face-centered cubic (fcc)|
|Young’s Modulus||168 GPa|
More Interesting Platinum Element Facts
- Ancient Uses: The ancient Egyptians and pre-Columbian indigenous people of South America used platinum in jewelry and artifacts, long before its official discovery by European explorers.
- Alien Platinum?: Some platinum, along with other precious metals like gold and iridium, originates from bolide meteor impacts.
- Corrosion Resistance: Platinum is so non-reactive that it safely stores certain strong acids and chemicals. It won’t corrode or contaminate the substances inside.
- Platinum in the Ocean: Every year, nearly 30 tons of platinum gets deposited into the oceans through dust and rain. However, extracting it is currently not economically viable due to its extremely low concentration.
- The Moon’s Platinum: Studies suggest that the moon has a higher concentration of platinum than the Earth. Future lunar missions might mine the moon for this precious metal.
- Antitumor Properties: Certain platinum-containing drugs, such as cisplatin, halt the growth of cancer cells. This discovery was accidental when researchers observed that bacteria stopped dividing when exposed to a platinum electrode.
- Anti-Poison: Platinum acts as an antidote for some poisonings. For example, when someone is poisoned by thallium, a platinum-based compound forms an insoluble salt with the thallium, which allows for removal from the body.
- Dissolving Platinum: Although it’s resistant to most acids, platinum dissolves in aqua regia, a mixture of hydrochloric acid and nitric acid.
- A Measure of Quality: The term “platinum” denotes a high level of sales and success. For instance, a “platinum record” signifies that a particular music album has sold over a million copies.
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