We continue to review some of the most important materials in heat treatment and metallurgy.
Platinum (chemical symbol: Pt)
Platinum is a very soft and malleable silvery-white metal that is extremely resistant to tarnishing and corrosion. It is one of the noble metals, which include ruthenium, rhodium, palladium, silver, osmium, iridium and gold. Noble metals tend to have a high economic value due to their scarcity. They are used in metallurgy, sophisticated devices and decorative ornaments (e.g., jewelry, art). Platinum is also one of the densest elements known with a density that is six times that of a diamond, yet it is also the most ductile of the pure metals. Pure platinum has a bright, lustrous shine (Fig. 1) that is often mistaken for silver.
Platinum has been used since ancient times in combination with gold to make jewelry and ceremonial statues. The first recorded occurrence of platinum was when Italian physician Julius Scaliger noted in 1557 that the silvery metal found in Central American mines was unbreakable by fire and that none of their current Spanish techniques could melt it.
Francois Chabaneaus patented a method of producing workable platinum in 1783, but the method used led to inconsistent results from each batch due to the presence of undiscovered metals within the results. It wasn’t until the 19th century when William Wollaston had developed a process to extract pure platinum – a process that is still repeated today. In his process of studying platinum ore, Wollaston also discovered osmium, iridium, rhodium and palladium.
While platinum sees plenty of use in the creation of jewelry (Fig. 2) and other decorative products, its most widespread use today is as a catalyst for chemical reactions, particularly in vehicle catalytic converters. The presence of platinum as a catalyst allows the unburned hydrocarbons in the vehicle’s exhaust to convert to carbon dioxide and water vapor.
Furthermore, platinum sees use in a number of applications as a minor role, including: medicine and biomedicine, glassmaking equipment, electrodes, anticancer drugs, oxygen sensors, spark plugs and turbine engines. Due to its lustrous shine and economic desirability, platinum as a commodity investment is more subject to market value fluctuations than gold, but it is still lucrative.
Here are a few important facts about platinum.[2,5]
- Atomic number: 78
- Atomic weight: 195.084
- Melting point: 2041.55 K (1768.4°C or 3215.1°F)
- Boiling point: 4098 K (3825°C or 6917°F)
- Density: 21.46 grams per cubic centimeter
- Phase at room temperature: Solid
- Element classification: Metal
- Period number: 6
- Group number: 10
- Group name: none
- Electron configuration: [Xe] 4f145d96s1