Platinum

Platinum is the chemical element with atomic number 78 and the symbol Pt. It is a shiny, silvery-white metal that resists corrosion as well as gold does. Its main use is in catalytic converters for vehicles, and it also serves in jewelry, chemical manufacturing, electronics and cancer drugs.

History of platinum

Probably the oldest worked specimen of platinum comes from an ancient Egyptian casket of the 7th century BC, unearthed at Thebes and dedicated to Queen Shapenapit. Otherwise the metal was unknown in Europe and Asia for the next two thousand years. On the Pacific coast of South America, however, people were able to work platinum, as shown by burial goods dating back 2000 years.

In 1557 an Italian scholar, Julius Scaliger, wrote of a metal from Spanish Central America that could not be made to melt, and this was no doubt platinum. In 1735 Antonio Ulloa encountered the curious metal. As he returned to Europe his ship was captured by the Royal Navy, and he ended up in London, where members of the Royal Society were most interested to hear about it. By the 1750s platinum was being reported and discussed throughout Europe. PubChem lists 1735 as its year of discovery.

The record shows that platinum was worked in ancient Egypt and the Americas long before European chemists studied it, so the date of 1735 marks a European encounter and not the first use of the metal.

Properties of platinum

PubChem, drawing on IUPAC data, gives platinum a standard atomic weight of 195.08. Its electron configuration is [Xe] 6s1 4f14 5d9. The configuration shows one electron in the 6s shell and nine in the 5d shell. Platinum sits in group 10 and period 6 of the periodic table and is a transition metal. Its common oxidation states are +4 and +2, meaning that platinum atoms in compounds usually carry those charges.

Platinum is a dense solid, with a density of 21.46 grams per cubic centimeter, more than 21 times that of water. It melts at 2041.55 kelvin, about 1768 degrees Celsius, and boils at 4098 kelvin, about 3825 degrees Celsius. The Royal Society of Chemistry describes it as a shiny, silvery-white metal that is as resistant to corrosion as gold, a property that makes it a durable metal.

Platinum has an electronegativity of about 2.2 on the Pauling scale, a relative measure of how strongly an atom attracts electrons. Its first ionization energy is 9 electronvolts, or about 864 kilojoules per mole, and its electron affinity is 205.321 kilojoules per mole. The covalent radius is 130 picometers.

Taken together, these properties describe a metal that is dense, hard to melt and chemically stable. They also help explain why platinum appears both in jewelry, where appearance and durability matter, and in industrial equipment that operates at high temperatures or in harsh chemical conditions.

Occurrence and production of platinum

Platinum is found uncombined in alluvial deposits, which are sediments laid down by flowing water. Most commercially produced platinum comes from South Africa, from the mineral cooperite, which is platinum sulfide. Some platinum is also prepared as a by-product of copper and nickel refining.

The by-product route means that platinum supply is linked to the mining of other metals. The Royal Society of Chemistry does not give production tonnages, so none are quoted here.

Uses of platinum

Platinum is used extensively for jewelry. Its main use, however, is in catalytic converters for cars, trucks and buses, which account for about 50 percent of demand each year. A catalyst is a substance that speeds up a chemical reaction without being used up, and platinum is very effective at converting the emissions from a vehicle engine into less harmful waste products.

In the chemicals industry platinum acts as a catalyst for the production of nitric acid, silicone and benzene. It is also used as a catalyst to improve the efficiency of fuel cells.

The electronics industry uses platinum for computer hard disks and thermocouples, which are temperature sensors. Platinum is also used to make optical fibers and liquid crystal displays, turbine blades, spark plugs, pacemakers and dental fillings. Platinum compounds are important chemotherapy drugs used to treat cancers.

Several of these applications rely on devices that are easy to describe. A pacemaker is an implanted device that regulates the heartbeat with electrical pulses. A thermocouple joins two metals to produce a voltage that changes with temperature. A fuel cell produces electricity directly from a chemical reaction between a fuel and oxygen. In each case, platinum is one of the materials the Royal Society of Chemistry lists for the job.

Isotopes of platinum

Platinum has six naturally occurring isotopes. An isotope is a form of an element whose atoms have the same number of protons but different numbers of neutrons. The most abundant are platinum-195 at 33.78 percent, platinum-194 at 32.86 percent and platinum-196 at 25.21 percent. The others are platinum-198 (7.356 percent), platinum-192 (0.782 percent) and platinum-190 (0.012 percent).

Only platinum-190 is listed by the Royal Society of Chemistry as radioactive, decaying by alpha emission with a half-life of 4.5 times 10 to the 11th years. That is far longer than the age of the universe, so natural platinum is effectively stable.

Health and environmental effects of platinum

The Royal Society of Chemistry states that platinum has no known biological role and describes the metal as non-toxic. The platinum compounds used as chemotherapy drugs are a separate matter, because their effects are those of medicines directed by clinicians.

Platinum in catalytic converters is intended to reduce harmful emissions from engines. This entry gives general background drawn from reference sources and is not advice.

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 4, 2026Researched and drafted with AI assistanceReport an issue