Platinum

General
Name, Symbol, Number	Platinum, Pt, 78
Chemical series	transition metals
Group, Period, Block	10 [?], 6 , d
Density, Hardness	21090 kg/m3, 3.5
Appearance	grayish white
Atomic Properties
Atomic weight	195.078 amu
Atomic radius (calc.)	135 (177) pm
Covalent radius	128 pm
van der Waals radius	175 pm
Electron configuration	[Xe]4f145d96s1
e- 's per energy level	2, 8, 18, 32, 17, 1
Oxidation states (Oxide)	2, 4 (mildly basic)
Crystal structure	Cubic face centered
Physical Properties
State of matter	solid (__)
Melting point	2041.4 K (3214.9 °F)
Boiling point	4098 K (6917 °F)
Molar volume	9.09 ×10-3 m3/mol
Heat of vaporization	510 kJ/mol
Heat of fusion	19.6 kJ/mol
Vapor pressure	0.0312 Pa at 2045 K
Speed of sound	2680 m/s at 293.15 K
Miscellaneous
Electronegativity	2.28 (Pauling scale)
Specific heat capacity	130 J/(kg*K)
Electrical conductivity	09.66 106/m ohm
Thermal conductivity	71.6 W/(m*K)
1st ionization potential	870 kJ/mol
2nd ionization potential	1791 kJ/mol
Most Stable Isotopes
iso NA half-life DM DE MeV DP 190Pt 0.01% 6.5 E11 y α 3.249 186Os 192Pt 0.79% Os is stable with 114 neutrons 193Pt {syn.} 50 y ε[?] 0.057 193Ir 194Pt 32.9% Ir is stable with 116 neutrons 195Pt 33.8% Ir is stable with 117 neutrons 196Pt 25.3% Ir is stable with 118 neutrons 198Pt 7.2% Ir is stable with 120 neutrons
SI units & STP are used except where noted.

Platinum is a chemical element in the periodic table that has the symbol Pt and atomic number 78. A heavy, malleable, ductile, precious, gray-white transition metal, platinum is resistant to corroding and occurs in some nickel and copper ores along with some native deposits. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and anti-pollution devices in automobiles.

Table of contents 1 Notable Characteristics 2 Applications 3 History 4 Occurrence 5 Isotopes 6 Precautions 7 External Links

Notable Characteristics The metal is a beautiful silvery-white when pure, and malleable and ductile. The metal is corrosion-resistant. The catalytic properties of the six platinum family[?] metals are outstanding (hydrogen and oxygen explode in the presence of platinum). Platinum's wear- and tarnish-resistance characteristics are well suited for making fine jewelry.

Other distinctive properties include resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties. All these properties have been exploited for industrial applications. Platinum does not oxidize in air at any temperature but can be corroded by cyanides, halogens, sulfur, and caustic alkalis. This metal is insoluble in hydrochloric and nitric acid but does dissolve when mixed as aqua regia (forming chloroplatinic acid[?]). Common oxidation states of platinum include +2, +3, and +4. Applications Platinum is used extensively in jewelry, wire, in making crucibles for chemical use and for constructing high-temperature electric furnaces. Finely divided platinum is often used as a chemical catalyst. For example, platinum is used in catalytic converters[?] for automobiles and in various industrial processes, such as the manufacture of sulfuric acid. Other uses;

• The metal can absorb large quantities of hydrogen gas and will release it when heated. It is therefore been studied as a possible storage medium for the gas for use in fuel cell vehicles.
• The chemical industry uses a significant amount of either platinum or a platinum-rhodium alloy catalyst in the form of gauze to catalyze the partial oxidation of ammonia to yield nitric oxide, which is the raw material for fertilizers, explosives, and nitric acid.
• Platinum supported catalysts are used in the refining of crude oil, reforming, and other processes used in the production of high-octane gasoline and aromatic compounds for the petrochemical industry.
• This metal has a coefficient of expansion[?] that is almost equal to soda-lime-silica glass and is therefore used to make sealed electrodes in glass systems.
• Alloys of platinum and cobalt have excellent magnetic properties. One alloy that has 76.7% Pt and 23.3% Co, by mass, is forms an extremely powerful magnet.
• 90/10 Platinum/osmium alloy is used to make pacemakers and replacement valves[?] and other surgical implants[?].
• Used for coating missile nose cones, jet engine fuel nozzles, and other devices which must perform reliably at high temperatures for extended periods of time.
• Fine platinum wire glows red hot when exposed to methyl alcohol[?] vapor acting as a catalyst that converts the alcohol to formaldehyde. This phenomenon has been commercially used to make cigarette lighters and hand warmers.
• Cis-platin, [PtCl₂(NH₃)₂], is a drug that is effective in treating certain types of cancer which include leukemia and testicular cancer[?].

History Platinum (Spanish platina meaning "little silver") was discovered in 1735 by astronomer Antonio de Ulloa in South America. British privateers intercepted Ulloa's ship preventing him from presenting his findings until 1748. Before that could happen Charles Wood[?] independently discovered the element in 1741. The metal was used by pre-Columbian Indians.

Naturally occurring platinum and platinum-rich alloys have been known for a long time. The Spaniards named the metal "platina," or little silver, when they first encountered it in Colombia. They regarded platinum as an unwanted impurity in the silver they were mining.

Platinum is now considered more precious than gold, so that a platinum award is better than a golden one.

The standard definition of a metre for a long time was based on the distance between two marks on a bar of platinum-iridium housed in Sevres. This metal is also used in the definition of the Standard Hydrogen Electrode[?]. Occurrence Platinum is often fond in a native state and the ore sperrylite[?] (platinum arsenide, PtAs₂) is a major source of the metal. A naturally occurring platinum/iridium alloy is platiniridium[?] and this metal is also found in the mineral cooperite[?] (platinum sulfide, PtS).

This metal is often accompanied by small amounts of other platinum family[?] metals which are found in alluvial deposits in Columbia, Ontario, the Ural Mountains, and in certain western American states.

Platinum is produced commercially as a by-product of nickel ore processing. The huge quantities of nickel ore processed makes up for the fact that platinum makes up only two parts per million of the ore. Isotopes Naturally occurring platinum is composed of five stable isotopes and one radioisotope, Pt-190, which has a very long half-life (over 6 billion years). There are also many other radioisotopes with the most stable being Pt-193 with a half-life of 50 years. Precautions This metal doesn't normally cause health problems due to its unreactive nature but all compounds of platinum should be considered to be highly toxic.

External Links

• WebElements.com - Platinum (http://www.webelements.com/webelements/elements/text/Pt/index)
• EnvironmentalChemistry.com - Platinum (http://environmentalchemistry.com/yogi/periodic/Pt)

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