CADMIUM

Introduction

Atomic Number: 48
Group: 12 or II B
Atomic Weight: 112.411
Period: 5
CAS Number: 7440-43-9

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 by Stromeyer in 1817 from an impurity in zinc carbonate. Cadmium most often occurs in small quantitiesassociated with zinc ores, such as sphalerite (ZnS). Greenockite (CdS) is the only mineral of any consequence bearing cadmium. Almost all cadmiumis obtained as a by-product in the treatment of zinc, copper, and lead ores. It is a soft, bluish-white metal which is easily cut with a knife. It is similarin many respects to zinc. It is a component of some of the lowest melting alloys; it is used in bearing alloys with low coefficients of friction and greatresistance to fatigue; it is used extensively in electroplating, which accounts for about 60% of its use. It is also used in many types of solder, for standardE.M.F. cells, for Ni-Cd batteries, and as a barrier to control atomic fission. Cadmium compounds are used in black and white television phosphorsand in blue and green phosphors for color TV tubes. It forms a number of salts, of which the sulfate is most common; the sulfide is used as a yellowpigment. Cadmium and solutions of its compounds are toxic. Failure to appreciate the toxic properties of cadmium may cause workers to be unwittinglyexposed to dangerous fumes. Some silver solders, for example, contain cadmium and should be handled with care. Serious toxicity problems have beenfound from long-term exposure and work with cadmium plating baths. In 1927 the International Conference on Weights and Measures redefined themeter in terms of the wavelength of the red cadmium spectral line (i.e. 1 m = 1,553,164.13 wavelengths). This definition has been changed (see underKrypton). The current price of cadmium is about $100/kg (99.5%). It is available in high purity form for about $300/kg. Natural cadmium is madeof eight isotopes. Thirty four other isotopes and isomers are now known and recognized. 1

• "Cadmium is most commonly seen as a whitish metallic protective coat, usually with a soft finish. Most of the metal produced is used in alloys that melt easily. It is also used in the cadmium storage battery." 2

Physical Properties

Melting Point:3*  321.07 °C = 594.22 K = 609.926 °F
Boiling Point:3* 767 °C = 1040.15 K = 1412.6 °F
Sublimation Point:3 
Triple Point:3 
Critical Point:3 
Density:4  8.69 g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration: [Kr] 5s2 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 1.69
Electropositivity (Pauling scale): 2.31
Electron Affinity:6 not stable eV
Oxidation States: +2
Work Function:7 4.12 eV = 6.60024E-19 J

Ionization Potential   eV 8  kJ/mol  
1 8.9938    867.8
Ionization Potential   eV 8  kJ/mol  
2 16.90832    1631.4
Ionization Potential   eV 8  kJ/mol  
3 37.48    3616.3

Thermochemistry

Specific Heat: 0.232 J/g°C 9 = 26.079 J/mol°C = 0.055 cal/g°C = 6.233 cal/mol°C
Thermal Conductivity: 96.8 (W/m)/K, 27°C 10
Heat of Fusion: 6.192 kJ/mol 11 = 55.1 J/g
Heat of Vaporization: 99.57 kJ/mol 12 = 885.8 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 gamma) 0 0 12.37 51.75608 0 0
(s alpha) -0.14 -0.58576 12.37 51.75608 -0.14 -0.58576
(g) 26.77 112.00568 40.066 167.636144 18.51 77.44584

Isotopes

Nuclide Mass 14 Half-Life 14 Nuclear Spin 14 Binding Energy
100Cd 99.92029(10) 49.1(5) s 0+ 844.10 MeV
101Cd 100.91868(16) 1.36(5) min (5/2+) 861.48 MeV
102Cd 101.91446(3) 5.5(5) min 0+ 869.55 MeV
103Cd 102.913419(17) 7.3(1) min 5/2+ 877.63 MeV
104Cd 103.909849(10) 57.7(10) min 0+ 895.01 MeV
105Cd 104.909468(12) 55.5(4) min 5/2+ 903.08 MeV
106Cd 105.906459(6) STABLE 0+ 911.16 MeV
107Cd 106.906618(6) 6.50(2) h 5/2+ 919.23 MeV
108Cd 107.904184(6) STABLE 0+ 927.30 MeV
109Cd 108.904982(4) 461.4(12) d 5/2+ 935.37 MeV
110Cd 109.9030021(29) STABLE 0+ 943.44 MeV
111Cd 110.9041781(29) STABLE 1/2+ 951.51 MeV
112Cd 111.9027578(29) STABLE 0+ 959.58 MeV
113Cd 112.9044017(29) 7.7(3)E+15 a 1/2+ 967.65 MeV
114Cd 113.9033585(29) STABLE 0+ 975.73 MeV
115Cd 114.9054310(29) 53.46(5) h 1/2+ 983.80 MeV
116Cd 115.904756(3) 3.1(4)E+19 a 0+ 991.87 MeV
117Cd 116.907219(4) 2.49(4) h 1/2+ 999.94 MeV
118Cd 117.906915(22) 50.3(2) min 0+ 1,008.01 MeV
119Cd 118.90992(9) 2.69(2) min (3/2+) 1,016.08 MeV
120Cd 119.90985(2) 50.80(21) s 0+ 1,024.15 MeV
121Cd 120.91298(9) 13.5(3) s (3/2+) 1,022.91 MeV
122Cd 121.91333(5) 5.24(3) s 0+ 1,030.98 MeV
123Cd 122.91700(4) 2.10(2) s (3/2)+ 1,039.05 MeV
124Cd 123.91765(7) 1.25(2) s 0+ 1,047.12 MeV
125Cd 124.92125(7) 0.65(2) s (3/2+)# 1,045.88 MeV
126Cd 125.92235(6) 0.515(17) s 0+ 1,053.95 MeV
127Cd 126.92644(8) 0.37(7) s (3/2+) 1,062.02 MeV
128Cd 127.92776(32) 0.28(4) s 0+ 1,070.09 MeV
129Cd 128.93215(32)# 242(8) ms 3/2+# 1,068.85 MeV
130Cd 129.9339(3) 162(7) ms 0+ 1,076.92 MeV
131Cd 130.94067(32)# 68(3) ms 7/2-# 1,075.68 MeV
132Cd 131.94555(54)# 97(10) ms 0+ 1,083.75 MeV
95Cd 94.94987(64)# 5# ms 9/2+# 776.73 MeV
96Cd 95.93977(54)# 1# s 0+ 794.11 MeV
97Cd 96.93494(43)# 2.8(6) s 9/2+# 806.84 MeV
98Cd 97.92740(8) 9.2(3) s 0+ 821.43 MeV
99Cd 98.92501(22)# 16(3) s (5/2+) 831.37 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

Reactions

Abundance

Earth - Source Compounds: sulfides 16
Earth - Seawater: 0.00011 mg/L 17
Earth -  Crust:  0.15 mg/kg = 0.000015% 17
Earth -  Total:  16.4 ppb 18
Mercury -  Total:  0.19 ppb 18
Venus -  Total:  17.2 ppb 18
Chondrites - Total: 0.079 (relative to 106 atoms of Si) 19
Human Body - Total: 0.00007% 20

Compounds

Prices





Safety Information


Material Safety Data Sheet - ACI Alloys, Inc.

For More Information

External Links:

Journals:
(1) Nawrot et al., Environ. Health Perspect. 116, 1620-1628 (2008)
(2) Järup, Alfvén, Persson, Toss and Elinder, Occup. Environ. Med.  55, 435-439 (1998)
(3) Kao, Hsieh, Cheng and Huang, J. Water Pollut. Control Fed. 54, 1118-1126 (1982)
(4) Gunnar F. Nordberg, Ambio 3, 55-66 (1974)
(5) Viaene et al., Occup. Environ. Med.  57, 19-27 (2000)

Sources

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(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) - T > 2567.14215445155
(16) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(17) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(18) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(19) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(20) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.