Introduction
Group: 10 or VIII B
Atomic Weight: 106.42
Period: 5
CAS Number: 7440-05-3
Classification
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
Electron Configuration: *[Kr] 4d10
n = 4
Electronegativity (Pauling scale):5 2.20
Specific Heat: 0.246 J/g°C 9 = 26.179 J/mol°C = 0.059 cal/g°C = 6.257 cal/mol°C
Earth -
Crust:
0.015 mg/kg = 0.0000015% 15
External Links:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:22.
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
Block: d
Highest Occupied Energy Level: 5
Valence Electrons:
Quantum Numbers:
ℓ = 2
mℓ = 2
ms = -½
Bonding
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
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 -
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
palladium(II) bromide
palladium(II) chloride
palladium(II) cyanide
palladium(II) fluoride
palladium(II) iodide
Prices
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
Sources
(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.