PLATINE

introduction

Numéro atomique: 78
Groupe: 10 or VIII B
Poids atomique: 195.078
Période: 6
Numero CAS: 7440-06-4

Classification

chalcogènes
Halogène
Gaz rare
lanthanides
actinides
Rare Earth Element
Groupe Platine Métal
Transuranium
Pas d'isotopes stables
Solide
Liquide
Gaz
Solide (prédit)

La description • Usages / Fonction

Discovered in South America by Ulloa in 1735 and by Wood in 1741. The metal was used by pre-Columbian Indians. Platinum occurs native,accompanied by small quantities of iridium, osmium, palladium, ruthenium, and rhodium, all belonging to the same group of metals. These are foundin the alluvial deposits of the Ural mountains, of Columbia, and of certain western American states. Sperrylite (PtAs2), occurring with the nickel-bearingdeposits of Sudbury, Ontario, is the source of a considerable amount of metal. The large production of nickel offsets there being only one part of theplatinum metals in two million parts of ore. Platinum is a beautiful silvery-white metal, when pure, and is malleable and ductile. It has a coefficientof expansion almost equal to that of soda-lime-silica glass, and is therefore used to make sealed electrodes in glass systems. The metal does not oxidizein air at any temperature, but is corroded by halogens, cyanides, sulfur, and caustic alkalis. It is insoluble in hydrochloric and nitric acid, but dissolveswhen they are mixed as aqua regia, forming chloroplatinic acid (H2PtCl6), an important compound. Natural platinum contains six isotopes, one ofwhich, platinum-190, is radioactive with a long half-life. Thirty five other radioactive isotopes and isomers are recognized. The metal is extensively used injewelry, wire, and vessels for laboratory use, and in many valuable instruments including thermocouple elements. It is also used for electrical contacts,corrosion-resistant apparatus, and in dentistry. Platinum-cobalt alloys have magnetic properties. One such alloy made of 76.7% Pt and 23.3% Co, byweight, is an extremely powerful magnet that offers a B-H (max) almost twice that of Alnico V. Platinum resistance wires are used for constructinghigh-temperature electric furnaces. The metal is used for coating missile nose cones, jet engine fuel nozzles, etc., which must perform reliably for long periods of time at high temperatures. The metal, like palladium, absorbs large volumes, of hydrogen, retaining it at ordinary temperatures but givingit up at red heat. In the finely divided state platinum is an excellent catalyst, having long been used in the contact process for producing sulfuric acid.It is also used as a catalyst in cracking petroleum products. There is also much current interest in the use of platinum as a catalyst in fuel cells and inits use as antipollution devices for automobiles. Platinum anodes are extensively used in cathodic protection systems for large ships and ocean-goingvessels, pipelines, steel piers, etc. Pure platinum wire will glow red hot when placed in the vapor of methyl alcohol. It acts here as a catalyst, convertingthe alcohol to formaldehyde. This phenomenon has been used commercially to produce cigarette lighters and hand warmers. Hydrogen and oxygenexplode in the presence of platinum. The price of platinum has varied widely; more than a century ago it was used to adulterate gold. It was nearlyeight times as valuable as gold in 1920. The price in January 1996 was about $400/troy oz. ($13/g), about the same price as gold. 1

• "The difficulty of melting platinum and its failure to react with ordinary chemicals render it very important in chemical operations. In the laboratory it is used in the form of dishes, crucibles, wire, and foil. Its cost has been a drawback to its more extensive use. Large amounts of platinum are used as catalyst in the manufacture of sulfuric and nitric acid. It is a fair conductor of electricity, and was the first filament to be used in electric lamps. Pure platinum is rather soft. It is hardened by adding iridium. This hard platinum is used in most platinum ware. A large amount of platinum is used in jewelry." 2

Propriétés physiques

Point de fusion:3*  1768.4 °C = 2041.55 K = 3215.12 °F
Point d'ébullition:3* 3825 °C = 4098.15 K = 6917 °F
sublimation point:3 
Triple point:3 
Point critique:3 
Densité:4  21.5 g/cm3

* - at 1 atm

Configuration de l'électron

Configuration de l'électron: [Xe] 6s2 4f14 5d8
Bloque: d
Plus haut niveau d'énergie occupés: 6
Électrons de valence: 

Nombres quantiques:

n = 5
ℓ = 2
m = 0
ms = -½

Bonding

Électronégativité (échelle de Pauling):5 2.2
Electropositivity (échelle de Pauling): 1.8
Electron Affinity:6 2.128 eV
oxydation États: +4,2
Fonction de travail:7 5.40 eV = 8.6508E-19 J

ionisation potentiel   eV 8  kJ/mol  
ionisation potentiel   eV 8  kJ/mol  
1 8.9587    864.4
ionisation potentiel   eV 8  kJ/mol  
2 18.563    1791.1

Thermochimie

Chaleur spécifique: 0.133 J/g°C 9 = 25.945 J/mol°C = 0.032 cal/g°C = 6.201 cal/mol°C
Conductivité thermique: 71.6 (W/m)/K, 27°C 10
Température de fusion: 19.6 kJ/mol 11 = 100.5 J/g
Chaleur de vaporisation: 510 kJ/mol 12 = 2614.3 J/g
État de la matière Enthalpie de formation (ΔHf°)13 Entropy (S°)13 Gibbs Free Energy (ΔGf°)13
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 9.95 41.6308 0 0
(g) 135.1 565.2584 45.960 192.29664 124.4 520.4896

isotopes

Nuclide Masse 14 Demi vie 14 Spin nucléaire 14 Énergie de liaison
166Pt 165.99486(54)# 300(100) μs 0+ 1,288.13 MeV
167Pt 166.99298(44)# 700(200) μs 7/2-# 1,296.20 MeV
168Pt 167.98815(22) 2.00(18) ms 0+ 1,313.59 MeV
169Pt 168.98672(22)# 3.7(15) ms 3/2-# 1,321.66 MeV
170Pt 169.982495(20) 14.0(2) ms 0+ 1,329.73 MeV
171Pt 170.98124(9) 51(2) ms 3/2-# 1,337.80 MeV
172Pt 171.977347(14) 98.4(24) ms 0+ 1,355.19 MeV
173Pt 172.97644(6) 365(7) ms 5/2-# 1,363.26 MeV
174Pt 173.972819(13) 0.889(17) s 0+ 1,371.33 MeV
175Pt 174.972421(20) 2.53(6) s 5/2-# 1,379.40 MeV
176Pt 175.968945(15) 6.33(15) s 0+ 1,396.79 MeV
177Pt 176.968469(16) 10.6(4) s 5/2- 1,404.86 MeV
178Pt 177.965649(12) 21.1(6) s 0+ 1,412.93 MeV
179Pt 178.965363(10) 21.2(4) s 1/2- 1,421.00 MeV
180Pt 179.963031(12) 56(2) s 0+ 1,429.07 MeV
181Pt 180.963097(16) 52.0(22) s 1/2- 1,437.14 MeV
182Pt 181.961171(17) 2.2(1) min 0+ 1,445.21 MeV
183Pt 182.961597(17) 6.5(10) min 1/2- 1,453.29 MeV
184Pt 183.959922(19) 17.3(2) min 0+ 1,470.67 MeV
185Pt 184.96062(4) 70.9(24) min (9/2+) 1,469.43 MeV
186Pt 185.959351(23) 2.08(5) h 0+ 1,486.81 MeV
187Pt 186.96059(3) 2.35(3) h 3/2- 1,485.57 MeV
188Pt 187.959395(6) 10.2(3) d 0+ 1,502.96 MeV
189Pt 188.960834(12) 10.87(12) h 3/2- 1,501.71 MeV
190Pt 189.959932(6) 6.5(3)E+11 a 0+ 1,519.10 MeV
191Pt 190.961677(5) 2.862(7) d 3/2- 1,517.86 MeV
192Pt 191.9610380(27) STABLE 0+ 1,525.93 MeV
193Pt 192.9629874(18) 50(6) a 1/2- 1,534.00 MeV
194Pt 193.9626803(9) STABLE 0+ 1,542.07 MeV
195Pt 194.9647911(9) STABLE 1/2- 1,550.14 MeV
196Pt 195.9649515(9) STABLE 0+ 1,558.21 MeV
197Pt 196.9673402(9) 19.8915(19) h 1/2- 1,566.28 MeV
198Pt 197.967893(3) STABLE 0+ 1,574.36 MeV
199Pt 198.970593(3) 30.80(21) min 5/2- 1,573.11 MeV
200Pt 199.971441(22) 12.5(3) h 0+ 1,581.18 MeV
201Pt 200.97451(5) 2.5(1) min (5/2-) 1,589.25 MeV
202Pt 201.97574(32)# 44(15) h 0+ 1,597.33 MeV
Les valeurs marquées # ne sont pas purement dérivées des données expérimentales, mais au moins en partie des tendances systématiques. Spins avec de faibles arguments d'affectation sont entre parenthèses. 14

Abondance

Terre - composés Source: uncombined 15
Terre -  Croûte:  0.005 mg/kg = 0.0000005% 15
Terre -  Total:  1.67 ppm 16
Planète Mercure) -  Total:  1.29 ppm 16
Vénus -  Total:  1.76 ppm 16
chondrites - Total: 1.30 (relative to 106 atoms of Si) 17

composés

prix





Information de sécurité


Fiche signalétique - ACI Alloys, Inc.

Pour plus d'informations

Liens externes:

Sources

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:23.
(2) - Brownlee, Raymond B., Fuller, Robert W., and Whitsit, Jesse E. Elements of Chemistry; Allyn and Bacon: Boston, Massachusetts, 1959; pp 544-5.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(5) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(7) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(13) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(14) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(15) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(16) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(17) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(18) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.