Platinum
Atomic Data
| Atomic Number | 78 |
| Symbol | Pt |
| Atomic Weight | 195.08 u |
| Density (STP) | 21.45 g/cm³ |
| Melting Point | 1768.25 °C (2041.4 K) |
| Boiling Point | 3824.85 °C (4098 K) |
| Electronegativity | 2.28 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d9 6s1 |
| Oxidation States | +2, +4 |
| Phase at STP | Solid |
| Category | Transition Metal |
| Period / Group | 6 / 10 |
| CAS Number | 7440-06-4 |
Electron Configuration
[Xe] 4f14 5d9 6s1
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 14 | 60 |
| O | 5 | 5s | 2 | 62 |
| O | 5 | 5p | 6 | 68 |
| O | 5 | 5d | 9 | 77 |
| P | 6 | 6s | 1 | 78 |
| Total | 78 | 78 | ||
Isotopes of Platinum
Platinum has six naturally occurring stable isotopes. The most abundant is ¹⁹⁵Pt, comprising 33.832% of all naturally occurring Platinum.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Platinum-190 | ¹⁹⁰Pt | 78 | 112 | 0.012 | Stable |
| Platinum-192 | ¹⁹²Pt | 78 | 114 | 0.782 | Stable |
| Platinum-194 | ¹⁹⁴Pt | 78 | 116 | 32.967 | Stable |
| Platinum-195 | ¹⁹⁵Pt | 78 | 117 | 33.832 | Stable |
| Platinum-196 | ¹⁹⁶Pt | 78 | 118 | 25.242 | Stable |
| Platinum-198 | ¹⁹⁸Pt | 78 | 120 | 7.163 | Stable |
Abundance & Occurrence
Platinum is present in Earth's crust at approximately 0.005 ppm by mass and at approximately 0.5 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Platinum salts: sensitisation: Soluble platinum salts (chloroplatinates, platinum chloride) are potent respiratory and skin sensitisers; once sensitised, workers develop occupational asthma and contact urticaria to even trace platinum compound exposures: a significant hazard in platinum refining and catalysis industries.
- Platinum compound toxicity: Cisplatin and other platinum chemotherapy drugs are acutely toxic (nephrotoxic, neurotoxic, myelosuppressive); oncology pharmacy and nursing staff handling these drugs require closed-system drug-transfer devices and appropriate PPE under NIOSH guidance.
- Bulk metal: Bulk platinum metal is inert and has very low acute toxicity; primary hazards arise from soluble platinum compounds generated in chemical processing or pharmaceutical manufacturing.
- Catalytic converters: spent material: Spent platinum group metal catalysts contain finely divided metals in a support matrix; grinding or processing generates respirable dust requiring respiratory controls.
Platinum in the Real World
Real-World Uses
- Catalytic converters: Platinum oxidises carbon monoxide and unburned hydrocarbons in both gasoline and diesel catalytic converters; in diesel oxidation catalysts (DOC), platinum is particularly important for converting CO and volatile organic compounds under lean-burn conditions.
- Cancer chemotherapy: Platinum-based drugs: cisplatin, carboplatin, and oxaliplatin: form cross-links in tumour cell DNA that trigger apoptosis and are among the most widely used chemotherapy agents for lung, ovarian, testicular, and colorectal cancers.
- Fuel cells: Platinum nanoparticles dispersed on carbon black are the electrocatalyst at both the hydrogen oxidation anode and oxygen reduction cathode in proton-exchange membrane (PEM) fuel cells used in hydrogen-powered vehicles and backup power systems.
- Petroleum reforming catalysts: Platinum on alumina, modified with rhenium or tin, catalyses the dehydrogenation and isomerisation reactions in catalytic naphtha reformers that produce high-octane aromatic compounds for unleaded petrol.
- Jewellery: Platinum's white colour, corrosion resistance, hypoallergenic properties, and high density make it the premier metal for diamond engagement rings and fine jewellery; platinum prongs hold gemstones more securely than gold due to their greater hardness.
- Laboratory apparatus and standards: Platinum-rhodium and platinum-iridium alloys form the thermocouples, resistance thermometers (RTDs), and crucibles that define and maintain temperature and mass standards in metrology laboratories worldwide.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is platinum used for?
Platinum's largest use is in catalytic converters for vehicle exhaust, where it catalyses the oxidation of carbon monoxide and unburned hydrocarbons. Platinum is widely used in jewellery for its lustrous appearance and resistance to tarnish. It is used in laboratory equipment (crucibles, electrodes), in petroleum refining catalysts, in the platinum-based chemotherapy drugs cisplatin and carboplatin, and in fuel cells.
Why is platinum used in catalytic converters?
Platinum is an exceptionally effective catalyst for oxidation reactions at the temperatures found in vehicle exhaust streams (400–900 °C). Its d-orbital electrons bind strongly enough to CO and hydrocarbon molecules to activate them but weakly enough to release the products. Platinum is also chemically stable under the corrosive conditions inside an exhaust system. Together with palladium and rhodium, it forms the three-way catalytic system that removes three major pollutants simultaneously.
How was platinum discovered?
Platinum was unknown to ancient Europeans but was used by pre-Columbian South Americans in the Pacific coast region of modern Ecuador and Colombia. Spanish conquistadors encountered it in the 16th century and initially considered it an impurity in gold: the name platina means 'little silver' in Spanish. The metal was brought to Europe and studied in detail by Antonio de Ulloa in 1748 and independently by Charles Wood, who sent samples to scientists in Britain.
What are platinum-based chemotherapy drugs?
Cisplatin (cis-diamminedichloroplatinum(II)) was the first platinum-based anticancer drug, discovered accidentally in 1965 by Barnett Rosenberg when he noticed that platinum electrodes inhibited bacterial cell division. Cisplatin forms crosslinks within DNA strands, preventing cancer cells from replicating. It is highly effective against testicular, ovarian, bladder, and other cancers. Carboplatin and oxaliplatin are later-generation platinum drugs with improved safety profiles. These drugs have cured many cases of otherwise fatal cancers.