Atomic Number: 78
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
References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)
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