PALLADIUM

Introduction

Atomic Number: 46
Group: 10 or VIII B
Atomic Weight: 106.42
Period: 5
CAS Number: 7440-05-3

Classification

Chalcogen
Halogen
Noble Gas
Lanthanoid
Actinoid
Rare Earth Element
Platinum Group Metal
Transuranium
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)

Description • Uses/Function

Discovered in 1803 by Wollaston. Palladium is found along with platinum andother metals of the platinum group in placer deposits of Russia, South and North America, Ethiopia, and Australia. Natural palladium contains six stableisotopes. Twenty five other isotopes are recognized, all of which are radioactive. It is also found associated with the nickel-copper deposits of SouthAfrica and Ontario. Its separation from the platinum metals depends upon the type of ore in which it is found. It is a steel-white metal, does not tarnishin air, and is the least dense and lowest melting of the platinum group of metals. When annealed, it is soft and ductile; cold working greatly increasesits strength and hardness. Palladium is attacked by nitric and sulfuric acid. At room temperatures the metal has the unusual property of absorbing upto 900 times its own volume of hydrogen, possibly forming Pd2H. It is not yet clear if this a true compound. Hydrogen readily diffuses through heatedpalladium and this provides a means of purifying the gas. Finely divided palladium is a good catalyst and is used for hydrogenation and dehydrogenationreactions. It is alloyed and used in jewelry trades. White gold is an alloy of gold decolorized by the addition of palladium. Like gold, palladium canbe beaten into leaf as thin as 1/250,000 in. The metal is used in dentistry, watchmaking, and in making surgical instruments and electrical contacts.The metal sells for about $140/troy oz. ($4.50/g). 1

• "Palladium is next to platinum [among platinum group metals] in the amount sold, and is the least expensive. It exceeds platinum in its power of adsorbing gases, and has considerable use as a catalyst. It is frequently used instead of platinum for some electrical and dental purposes, in jewelry, and in pen points." 2

Physical Properties

Melting Point:3*  1554.9 °C = 1828.05 K = 2830.82 °F
Boiling Point:3* 2963 °C = 3236.15 K = 5365.4 °F
Sublimation Point:3 
Triple Point:3 
Critical Point:3 
Density:4  12.0 g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration:  *[Kr] 4d10
Block: d
Highest Occupied Energy Level: 5
Valence Electrons: 

Quantum Numbers:

n = 4
ℓ = 2
m = 2
ms = -½

Bonding

Electronegativity (Pauling scale):5 2.20
Electropositivity (Pauling scale): 1.8
Electron Affinity:6 0.562 eV
Oxidation States: +2,4
Work Function:7 5.00 eV = 8.01E-19 J

Ionization Potential   eV 8  kJ/mol  
1 8.3369    804.4
Ionization Potential   eV 8  kJ/mol  
2 19.43    1874.7
Ionization Potential   eV 8  kJ/mol  
3 32.93    3177.3

Thermochemistry

Specific Heat: 0.246 J/g°C 9 = 26.179 J/mol°C = 0.059 cal/g°C = 6.257 cal/mol°C
Thermal Conductivity: 71.8 (W/m)/K, 27°C 10
Heat of Fusion: 17.6 kJ/mol 11 = 165.4 J/g
Heat of Vaporization: 357 kJ/mol 12 = 3354.6 J/g
State of Matter Enthalpy of 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 9.04 37.82336 0 0
(g) 90.4 378.2336 39.90 166.9416 81.2 339.7408

Isotopes

Nuclide Mass 14 Half-Life 14 Nuclear Spin 14 Binding Energy
100Pd 99.908506(12) 3.63(9) d 0+ 856.84 MeV
101Pd 100.908289(19) 8.47(6) h 5/2+ 872.36 MeV
102Pd 101.905609(3) STABLE 0+ 880.43 MeV
103Pd 102.906087(3) 16.991(19) d 5/2+ 888.51 MeV
104Pd 103.904036(4) STABLE 0+ 896.58 MeV
105Pd 104.905085(4) STABLE 5/2+ 904.65 MeV
106Pd 105.903486(4) STABLE 0+ 912.72 MeV
107Pd 106.905133(4) 6.5(3)E+6 a 5/2+ 920.79 MeV
108Pd 107.903892(4) STABLE 0+ 928.86 MeV
109Pd 108.905950(4) 13.7012(24) h 5/2+ 936.93 MeV
110Pd 109.905153(12) STABLE 0+ 945.01 MeV
111Pd 110.907671(12) 23.4(2) min 5/2+ 953.08 MeV
112Pd 111.907314(19) 21.03(5) h 0+ 961.15 MeV
113Pd 112.91015(4) 93(5) s (5/2+) 959.90 MeV
114Pd 113.910363(25) 2.42(6) min 0+ 967.98 MeV
115Pd 114.91368(7) 25(2) s (5/2+)# 976.05 MeV
116Pd 115.91416(6) 11.8(4) s 0+ 984.12 MeV
117Pd 116.91784(6) 4.3(3) s (5/2+) 992.19 MeV
118Pd 117.91898(23) 1.9(1) s 0+ 1,000.26 MeV
119Pd 118.92311(32)# 0.92(13) s 999.02 MeV
120Pd 119.92469(13) 0.5(1) s 0+ 1,007.09 MeV
121Pd 120.92887(54)# 400# ms [>300 ns] 1,015.16 MeV
122Pd 121.93055(43)# 300# ms [>300 ns] 0+ 1,013.92 MeV
123Pd 122.93493(64)# 200# ms [>300 ns] 1,021.99 MeV
124Pd 123.93688(54)# 100# ms [>300 ns] 0+ 1,030.06 MeV
91Pd 90.94911(61)# 10# ms [>1.5 μs] 7/2+# 746.01 MeV
92Pd 91.94042(54)# 1.1(3) s [0.7(+4-2) s] 0+ 762.46 MeV
93Pd 92.93591(43)# 1.07(12) s (9/2+) 775.19 MeV
94Pd 93.92877(43)# 9.0(5) s 0+ 789.78 MeV
95Pd 94.92469(43)# 10# s 9/2+# 801.58 MeV
96Pd 95.91816(16) 122(2) s 0+ 815.24 MeV
97Pd 96.91648(32) 3.10(9) min 5/2+# 825.17 MeV
98Pd 97.912721(23) 17.7(3) min 0+ 836.97 MeV
99Pd 98.911768(16) 21.4(2) min (5/2)+ 845.97 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 14

Abundance

Earth -  Crust:  0.015 mg/kg = 0.0000015% 15
Earth -  Total:  0.89 ppm 16
Mercury -  Total:  1.79 ppm 16
Venus -  Total:  0.87 ppm 16
Chondrites - Total: ~0.9 (relative to 106 atoms of Si) 17

Compounds

Prices





Safety Information


Material Safety Data Sheet - ACI Alloys, Inc.

For More Information

External Links:

Sources

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:22.
(2) - Brownlee, Raymond B., Fuller, Robert W., and Whitsit, Jesse E. Elements of Chemistry; Allyn and Bacon: Boston, Massachusetts, 1959; p 545.
(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) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(16) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(17) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.