Platinum

Atomic Number: 78

Symbol: Pt

Atomic Weight: 195.08

Discovery: It's difficult to assign credit for the discovery. Ulloa 1735 (in South America), Wood in 1741, Julius Scaliger in 1735 (Italy) all can make claims. Platinum was used in relatively pure form by the pre-Columbian Indians.

Electron Configuration: [Xe] 4f¹⁴ 5d⁹ 6s¹

Word Origin: from the Spanish word platina, meaning 'little silver'

Isotopes: Six stable isotopes of platinum occur in nature (190, 192, 194, 195, 196, 198). Information on three additional radioisotopes is available (191, 193, 197).

Properties: Platinum has a melting point of 1772 °C, boiling point of 3827 +/- 100 °C, specific gravity of 21.45 (20 °C), with a valence of 1, 2, 3, or 4. Platinum is a ductile and malleable silvery-white metal. It does not oxidize in air at any temperature, although it is corroded by cyanides, halogens, sulfur, and caustic alkalis. Platinum does not dissolve in hydrochloric or nitric acid, but will dissolve when the two acids are mixed to form aqua regia.

Uses: Platinum is used in jewelry, wire, to make crucibles and vessels for laboratory work, electrical contacts, thermocouples, for coating items that must be exposed to high temperatures for long periods of time or must resist corrosion, and in dentistry. Platinum-cobalt alloys have interesting magnetic properties. Platinum absorbs large amounts of hydrogen at room temperature, yielding it at red heat. The metal is often used as a catalyst. Platinum wire will glow red-hot in the vapor of methanol, where is acts as a catalyst, converting it for formaldyhde. Hydrogen and oxygen will explode in the presence of platinum.

Sources: Platinum occurs in native form, usually with small amounts of other metals belonging to the same group (osmium, iridium, ruthenium, palladium, and rhodium). Another source of the metal is sperrylite (PtAs₂).

Element Classification: Transition Metal

Density (g/cc): 21.45

Melting Point (K): 2045

Boiling Point (K): 4100

Appearance: very heavy, soft, silvery-white metal

Atomic Radius (pm): 139

Atomic Volume (cc/mol): 9.10

Covalent Radius (pm): 130

Ionic Radius: 65 (+4e) 80 (+2e)

Specific Heat (@20°C J/g mol): 0.133

Fusion Heat (kJ/mol): 21.76

Evaporation Heat (kJ/mol): ~470

Debye Temperature (K): 230.00

Pauling Negativity Number: 2.28

First Ionizing Energy (kJ/mol): 868.1

Oxidation States: 4, 2, 0

Lattice Structure: Face-Centered Cubic

Lattice Constant (Å): 3.920

Platinum: uses

•jewellery
•wire and vessels for laboratory use
•thermocouple elements
•electrical contacts
•corrosion-resistant apparatus
•in dentistry
•platinum-cobalt alloys have magnetic properties
•coating missile nose cones, jet engine fuel nozzles
•the metal, like palladium, absorbs large volumes of hydrogen, giving it up at red heat •in the finely divided state platinum is an excellent catalyst (such as the contact process for producing sulphuric acid). Also as a catalyst for cracking oil and as a catalyst in fuel cells and in catalytic converters for cars
•platinum anodes are extensively used in cathodic protection systems for large ships and ocean-going vessels, pipelines, steel piers
•platinum wire glows red hot when placed in the vapor of methanol - acting as a catalyst to convert the alcohol into formaldehyde. This phenomenon has been used commercially to produce cigarette lighters and hand warmers
•sealed electrodes in glass systems
•laboratory vessels, corrosion-resistant equipment
•dentistry •currently fashionable use in antipollution devices in cars •cis-platin, [PtCl2(NH3)2], is an effective drug for certain types of cancer such as leukaemia or testicular cancer
•platinum/osmium 90/10 alloy is used in implants such as pacemakers and replacement valves

Platinum is used extensively for jewellery, but its main use - accounting for about 50% of demand each year - is inside catalytic convertors on cars, trucks and buses. Platinum is very effective at converting emissions from the vehicle's engine into less harmful waste products. It is also used for electrical components, thermocouple elements, corrosion-resisitence apparatus and in dentistry. Platinum is manaufactured into metal gauzes for the production of nitric acid and is also used as a cataylst to improve the efficiency of fuel cells.

Typically, an aircraft engine has up to 23 parts that contain precious metals. Various aircraft engine parts that use precious metals include vanes, stators, blades, fuel nozzles, fuel manifolds, Tobi Ducts, and heat exchangers. Parts of an aircraft's engine turbine system and avionics system use gold and silver. And aircraft blades use platinum.