Platinum is a chemical element with the atomic number 78 in the periodic table. It’s an extremely rare metal with an abundance in Earth’s crust of about a millionth of 1 percent. Known since ancient times, this transition metal has strong anti-corrosive properties and makes for an excellent conductor of electricity.
Being a member of the transition metals (platinum) family of the periodic table, platinum has a divalent electron structure that rarely interacts with other chemical elements or compounds. Its inability to form oxides upon exposure to air classifies platinum as a precious metal, an excellent oxidation catalyst, as well as a symbol of prestige.
Chemical and Physical Properties of Platinum
|The symbol in the periodic table of elements||Pt|
|Group number||10 (Platinum group metals)|
|Color||A silvery-white color|
|Physical state||Solid at room temperature|
|Half-life||From 260(+260-90) milliseconds to 6.50×1011|
|Electronegativity according to Pauling||2.2|
|Density||21.4 g.cm-3 at 20°C|
|Melting point||1768.2°C, 3214.8°F, 2041.4 K|
|Boiling point||3825°C, 6917°F, 4098 K|
|Van der Waals radius||0.138 nm|
|Ionic radius||0.096 nm (+2)|
|Most characteristic isotope||195Pt|
|Electronic shell||[Xe] 4f145d96s1|
|The energy of the first ionization||867 kJ.mol-1|
|The energy of the second ionization||1788 kJ.mol-1|
|Discovery date||In 1557 by Julius Scaliger, and in 1735 by Antonio de Ulloa|
With the periodic table symbol Pt, atomic number 78, atomic mass of X g.mol-1, and electron configuration [Xe] 4f145d96s1, platinum is a soft, dense, ductile, and malleable silvery-white metal. It reaches its boiling point at 3825°C, 6917°F, 4098 K, while the extremely high melting point of this noble metallic element is achieved at 1768.2°C, 3214.8°F, 2041.4 K.
Being a member of the platinum group of elements in the periodic table, element 78 has an electronegativity of 2.2 according to Pauling, whereas platinum’s atomic radius according to van der Waals is 0.138 nm. Platinum’s crystals have a cubic form that creates penetration twins in the form of small waterworn nuggets. At high temperatures, platinum may absorb large quantities of hydrogen gas, just like a sponge.
Furthermore, this member of the transition metals family in the periodic table does not readily form chemical reactions with other chemical elements. This inert, but flexible and highly resistant metal is an excellent conductor of electricity, possesses strong anti-corrosive properties, and is slightly attracted to magnetic fields.
How Was Platinum Discovered?
Before the discovery of the American continent, the ancient people living in the southern parts were using a white gold-platinum alloy to make various ornaments. This chemical element was implemented in the daily life of the native South Americans before Columbus and was taken to Europe around 1750. There are artifacts that point to the fact that the ancient Egyptians were also using platinum alongside gold to make jewelry.
In other words, the Indians in pre-Hispanic times widely exploited the rich sources of minerals and metals in Colombia, Mexico, and Ecuador. Most often, pyroxenes, peridotites, and dunites were the richest sources of this shiny metal. It could also be found in small grains occurring with gold placer deposits.
The Contribution of Julius Caesar Scaliger (Giulio Cesare della Scala)
In 1557, the Italian physician Julius Caesar Scaliger (1484-1558) published his scientific analysis of this shiny substance which confirmed his doubts that it’s not silver, as it was widely believed. However, more than two centuries later, Scaliger was the only scientist who had been interested in the new metal.
The Contribution of the Spanish cruiser Don Antonio de Ulloa
When he traveled around South America, the Spanish general, explorer, naturalist, and scientist Antonio de Ulloa y de la Torre-Girault (1716 – 1795) took home several of those platinum nuggets. By this, he became recognized as the first scientist who has recognized platinum as a chemical element.
To begin with, Antonio de Ulloa became part of the French Geodesic Mission in 1735. The mission aimed to record the degree of meridian arc at the equator in Ecuador. During this expedition, de Ulloa and his fellow colleague Jorge Juan made several astronomical, natural, and social discoveries. The findings of these two scientists and explorers from the aforementioned areas of exploration also included observations of the new shiny white metal, which was later recognized as the element 78, i.e. platinum (Pt).
By bringing several platinum nuggets with him back in Europe, de Ulloa sparked the interest of the alchemists who were trying to convert any base metal they could find into gold.
The Contribution of Henrik Teofilus Scheffer
In 1751, the Swedish chemist Theophil Scheffer conducted a more thorough analysis of platinum. Upon the basis of the scientific data he derived, Scheffer classified the new element as a precious metal. From this moment in history on, the platinum-made objects became ones of prestige.
How Did Platinum Get Its Name?
In the 1500s, the Spanish obtained platinum from the alluvial gold mines of the Río Pinto, Colombia. As it was traced as a shiny silvery-white impurity in some of the mineral ores, they thought it was a form of silver.
For this reason, this chemical element got its name after the Spanish word ‘platina’ (meaning ‘little silver’), since the people of that time were referring to the substance as ‘the platina del Pinto’, meaning “the little silver from the Pinto”.
Where Can You Find Platinum?
Platinum is a transition metal that typically occurs as disseminated grains in iron and magnesium-rich igneous rocks. It can also be traced in quartz veins associated with pyrolusite, hematite, and chlorite. When these rocks weather, the heavy and dense platinum metal forms accumulations in the form of grains or nuggets in the resulting placer deposits. The naturally occurring form of platinum can be traced alongside iron and other metals, such as palladium, iridium, and rhodium. For this reason, it almost always contains some impurities associated with traces of iron, gold, iridium, osmium, copper, nickel, rhodium, or palladium in the ore.
Platinum can be obtained as a byproduct of nickel mining or from the gold-bearing deposits in the USA, Canada, Columbia, and the Ural Mountains in the form of the mineral sperrylite (PtAs2). The world’s largest platinum deposits are found in the Merensky Reef in the Bushveld Complex, South Africa. Lac des Iles Mine, near Thunder Bay, Ontario, is the only active platinum mine in Canada from which palladium ore is primarily obtained. The largest portion of the platinum supplies of the United States come from Stillwater Mine, located in Montana.
Platinum in Everyday Life
Apart from its use as an investment commodity or as jewelry, the chemical inactivity of this noble transition metal has made platinum a component of choice in some highly significant industrial processes, too.
- Strong corrosion-resistant properties often make platinum the metal of choice for making jewelry, wire, electrical contacts, and laboratory vessels;
- The car industry uses platinum black or platinum powder as a catalytic converter that facilitates the complete combustion of the unburned hydrocarbon which passes through the exhaust of the vehicle. Fuel cells also use platinum as a catalyst;
- Platinum is widely used as a catalyst for various purposes in the chemical industry;
- Medicine uses this noble metal for making of dental work (metal tooth filling amalgams), medical implants (breast implants, joint replacements), as well as in the manufacturing a new generation of anticancer drugs;
- A cobalt-platinum alloy is applied in the process of making strong permanent magnets;
- Laboratory equipment is often made of platinum alloys, due to platinum’s lack of chemical interaction with the substances that come into contact with the equipment;
- Element 78 is one of the key components in the process of making silicone, added to the compound for its flexibility and strength;
- The expanding properties of platinum have been utilized in the production of sealed electrodes in glass systems;
- Hexachloroplatinic acid is a platinum compound used in photography, the production of mirrors and porcelain coloring, plating, etc.
- This precious metal is contained in a vast variety of everyday objects, such as luxurious items (jewelry, engagement and wedding rings), medical devices, silicon rubber items (sportswear, kitchen molds, utensils, electronic devices, LED lamps), fountain pens, mechanical pencils, platinum bullion coins, smoking accessories (cigarette and cigar holders, cigarette boxes, lighter cases), golf accessories, money clips, etc.
Platinum Bullion Coins
The coins struck from precious metal with an assigned numismatic value are not used in everyday trade, but are rather kept as objects of value or a precious metal investment. The United States Mint still manufactures platinum bullion coins, including the American Eagle Platinum Bullion which contains one troy ounce of platinum in its composition. The Canadian Platinum Maple Leaf coin is the runner-up to the most treasured models of platinum coins. This is the only platinum bullion coin whose weight, content, and 0.9995 pure platinum content are guaranteed by the United States Government.
How Dangerous Is Platinum?
While the pure, elemental form of platinum is considered to be non-toxic, prolonged occupational exposure to this heavy metal or its compounds can lead to adverse health effects.
In case of prolonged skin contact, chronic exposure, and inhalation of platinum dust or particles, it may accumulate in our body and damage the organs or tissues. In the most severe cases, exposure to high levels of dust particles or fumes containing platinum may result in platinum toxicity.
The toxic effects of platinum overexposure (especially of the platinum salts) include:
- Allergic reactions to the platinum metal;
- Kidney problems;
- Allergies to rubber and silicone;
- Mutation of cells;
- Hearing damage;
- Skin and mucous membranes irritation;
- Fatigue and shortness of breath;
- Digestive problems;
- High blood pressure (hypertension);
- Tumorous growths and various types of cancer.
Platinum may also increase the toxicity of some other dangerous substances accumulated in the body, such as selenium or magnesium. In this regard, the deficiency of these trace elements may often be recognized as a symptom of platinum toxicity.
Environmental Effects of Platinum
Being a rare element, the natural concentrations of this noble metal in the air, soil, or waters is minimal. However, since platinum is mainly used as a catalytic converter in vehicles, the exhausts of cars that use leaded gasoline may severely pollute the air.
On the other hand, the everyday items made with platinum do not pose any environmental hazard.
Isotopes of Platinum
There are six isotopes (190Pt,192Pt, 194Pt, 195Pt, 196Pt, 198Pt) that make up the naturally occurring form of platinum, i.e. the 78Pt isotope. With a half-life of 6.50×1011 years, the platinum-190 isotope is an extremely long-living form of this noble metal. The average half-life of the other isotopes of platinum (165Pt-204Pt) is less than 24 hours.
Platinum-190 is the only naturally occurring radioactive form of platinum. The rest of its radioisotopes are synthetically produced in a strictly controlled laboratory environment.
|Z||N||Isotopic mass (Da)
[n 2][n 3]
[n 6][n 7]
[n 8][n 9]
|Natural abundance (mole fraction)|
|Excitation energy[n 9]||Normal proportion||Range of variation|
|170Pt||78||92||169.982495(20)||14.0(2) ms||α (98%)||166Os||0+|
|171Pt||78||93||170.98124(9)||51(2) ms||α (99%)||167Os||3/2−#|
|172Pt||78||94||171.977347(14)||98.4(24) ms||α (77%)||168Os||0+|
|173Pt||78||95||172.97644(6)||365(7) ms||α (84%)||169Os||5/2−#|
|174Pt||78||96||173.972819(13)||0.889(17) s||α (83%)||170Os||0+|
|175Pt||78||97||174.972421(20)||2.53(6) s||α (64%)||171Os||5/2−#|
|176Pt||78||98||175.968945(15)||6.33(15) s||β+ (62%)||176Ir||0+|
|177Pt||78||99||176.968469(16)||10.6(4) s||β+ (94.4%)||177Ir||5/2−|
|178Pt||78||100||177.965649(12)||21.1(6) s||β+ (92.3%)||178Ir||0+|
|179Pt||78||101||178.965363(10)||21.2(4) s||β+ (99.76%)||179Ir||1/2−|
|180Pt||78||102||179.963031(12)||56(2) s||β+ (99.7%)||180Ir||0+|
|181Pt||78||103||180.963097(16)||52.0(22) s||β+ (99.93%)||181Ir||1/2−|
|182Pt||78||104||181.961171(17)||2.2(1) min||β+ (99.96%)||182Ir||0+|
|183Pt||78||105||182.961597(17)||6.5(10) min||β+ (99.99%)||183Ir||1/2−|
|184Pt||78||106||183.959922(19)||17.3(2) min||β+ (99.99%)||184Ir||0+|
|185Pt||78||107||184.96062(4)||70.9(24) min||β+ (99.99%)||185Ir||(9/2+)|
|186Pt||78||108||185.959351(23)||2.08(5) h||β+ (99.99%)||186Ir||0+|
|188Pt||78||110||187.959395(6)||10.2(3) d||EC (99.99%)||188Ir||0+|
|192Pt||78||114||191.9610380(27)||Observationally Stable[n 10]||0+||0.00782(7)|
|194Pt||78||116||193.9626803(9)||Observationally Stable[n 11]||0+||0.32967(99)|
|195Pt||78||117||194.9647911(9)||Observationally Stable[n 12]||1/2−||0.33832(10)|
|196Pt||78||118||195.9649515(9)||Observationally Stable[n 13]||0+||0.25242(41)|
|198Pt||78||120||197.967893(3)||Observationally Stable[n 14]||0+||0.07163(55)|
List of Platinum Compounds
Platinum adopts the oxidation states of +2 and +4 in a compound. This metal also has extremely strong anti-corrosive properties when exposed to air or water. However, it does corrode when reacting with sulfur, caustic alkalis, cyanides, and halogens. This transition metal does not react with oxygen, but it readily dissolves in aqua regia or a mixture of nitric acid and hydrochloric acid. Otherwise, platinum is unaffected by common acids.
Hexachloroplatinic acid (or chloroplatinic acid) is the most significant compound of platinum because it has the widest industrial application.
The other common compounds of platinum include:
- Adams’ catalyst
- Ammonium hexachloroplatinate
- Bis(triphenylphosphine)platinum chloride
- Chloroplatinic acid
- DioxyOxygengenyl hexafluoroplatinate
- Platinum pentafluoride
- Platinum hexafluoride
- Karstedt’s catalyst
- Krogmann’s salt
- Magnus’s green salt
- Platinum diselenide
- Platinum disulfide
- Platinum tetrafluoride
- Platinum-based antineoplastic
- Platinum(II) acetate
- Platinum(II) bromide
- Platinum(II) chloride
- Platinum(II) sulfide
- Platinum(IV) bromide
- Platinum(IV) chloride
- Potassium hexachloroplatinate
- Potassium tetrachloroplatinate
- Sodium hexachloroplatinate
- Triplatin tetranitrate
- Wolffram’s red salt
- Xenon hexafluoroplatinate
- Zeise’s salt
- Ferronickel platinum
5 Interesting Facts and Explanations
- The platinum family of metals consists of six noble and precious metallic elements of the periodic table: ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). All of the members of this group share a silvery-white color, except the element osmium, which appears as a bluish-white metal. According to the US Geological Survey, platinum group metals frequently occur alongside each other in mineral ore and have some outstanding chemical properties.
- Just like gold and silver, this precious metal is also considered to be a symbol of prestige. In fact, the gold price is often lower than the price of platinum on the precious metals market.
- In the 18th century, platinum was considered to be “white gold” fit only for a king due to its rarity in nature and the fact that this noble metal does not form oxides easily.
- At the end of the 19th century, the world’s renewed jewelers Cartier in France and Tiffany & Co. in New York became the first ones to use platinum for making fine jewelry that is regarded as a status symbol even today.
- After osmium and iridium, platinum is the third most dense member of the platinum group of elements.