GERMANIUM

Introduction

Atomic Number: 32
Group: 14 or IV A
Atomic Weight: 72.64
Period: 4
CAS Number: 7440-56-2

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

Predicted by Mendeleev in 1871 as ekasilicon, and discovered by Winkler in 1886. The metal is found in argyrodite, a sulfide of germanium and silver;in germanite, which contains 8% of the element; in zinc ores; in coal; and in other minerals. The element is frequently obtained commercially fromflue dusts of smelters processing zinc ores, and has been recovered from the by-products of combustion of certain coals. Its presence in coal insuresa large reserve of the element in the years to come. Germanium can be separated from other metals by fractional distillation of its volatile tetrachloride.The tetrachloride may then be hydrolyzed to give GeO2; the dioxide can be reduced with hydrogen to give the metal. Recently developed zone-refiningtechniques permit the production of germanium of ultra-high purity. The element is a gray-white metalloid, and in its pure state is crystalline and brittle,retaining its luster in air at room temperature. It is a very important semiconductor material. Zone-refining techniques have led to production ofcrystalline germanium for semiconductor use with an impurity of only one part in 10^10. Doped with arsenic, gallium, or other elements, it is used asa transistor element in thousands of electronic applications. Its application as a semiconductor element now provides the largest use for germanium.Germanium is also finding many other applications including use as an alloying agent, as a phosphor in fluorescent lamps, and as a catalyst. Germaniumand germanium oxide are transparent to the infrared and are used in infrared spectroscopes and other optical equipment, including extremely sensitiveinfrared detectors. Germanium oxide’s high index of refraction and dispersion has made it useful as a component of glasses used in wide-angle cameralenses and microscope objectives. The field of organogermanium chemistry is becoming increasingly important. Certain germanium compounds havea low mammalian toxicity, but a marked activity against certain bacteria, which makes them of interest as chemotherapeutic agents. The cost ofgermanium is about $3/g (99.999% purity). Twenty nine isotopes and isomers are known, five of which occur naturally. 1

• "is a semimetal used mainly in the manufacture of semiconductors for transistors and similar electronic devices" 2

Physical Properties

Melting Point:3*  938.25 °C = 1211.4 K = 1720.85 °F
Boiling Point:3* 2833 °C = 3106.15 K = 5131.4 °F
Sublimation Point:3 
Triple Point:3 
Critical Point:3 
Density:4  5.3234 g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration: [Ar] 4s2 3d10 4p2
Block: p
Highest Occupied Energy Level: 4
Valence Electrons: 4

Quantum Numbers:

n = 4
ℓ = 1
m = 0
ms = +½

Bonding

Electronegativity (Pauling scale):5 2.01
Electropositivity (Pauling scale): 1.99
Electron Affinity:6 1.232712 eV
Oxidation States: +4,2
Work Function:7 5.0 eV = 8.01E-19 J

Ionization Potential   eV 8  kJ/mol  
1 7.8994    762.2
Ionization Potential   eV 8  kJ/mol  
2 15.93462    1537.5
3 34.2241    3302.1
Ionization Potential   eV 8  kJ/mol  
4 45.7131    4410.6
5 93.5    9021.4

Thermochemistry

Specific Heat: 0.320 J/g°C 9 = 23.245 J/mol°C = 0.076 cal/g°C = 5.556 cal/mol°C
Thermal Conductivity: 59.9 (W/m)/K, 27°C 10
Heat of Fusion: 36.94 kJ/mol 11 = 508.5 J/g
Heat of Vaporization: 330.9 kJ/mol 12 = 4555.3 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 7.43 31.08712 0 0
(g) 90.0 376.56 40.103 167.790952 80.3 335.9752

Isotopes

Nuclide Mass 14 Half-Life 14 Nuclear Spin 14 Binding Energy
58Ge 57.99101(34)# 0+ 451.48 MeV
59Ge 58.98175(30)# 7/2-# 468.87 MeV
60Ge 59.97019(25)# 30# ms 0+ 487.19 MeV
61Ge 60.96379(32)# 39(12) ms (3/2-)# 501.78 MeV
62Ge 61.95465(15)# 129(35) ms 0+ 518.23 MeV
63Ge 62.94964(21)# 142(8) ms (3/2-)# 530.96 MeV
64Ge 63.94165(3) 63.7(25) s 0+ 546.49 MeV
65Ge 64.93944(11) 30.9(5) s (3/2)- 556.42 MeV
66Ge 65.93384(3) 2.26(5) h 0+ 570.08 MeV
67Ge 66.932734(5) 18.9(3) min 1/2- 579.08 MeV
68Ge 67.928094(7) 270.95(16) d 0+ 590.88 MeV
69Ge 68.9279645(14) 39.05(10) h 5/2- 599.88 MeV
70Ge 69.9242474(11) STABLE 0+ 610.75 MeV
71Ge 70.9249510(11) 11.43(3) d 1/2- 618.82 MeV
72Ge 71.9220758(18) STABLE 0+ 628.76 MeV
73Ge 72.9234589(18) STABLE 9/2+ 635.90 MeV
74Ge 73.9211778(18) STABLE 0+ 645.83 MeV
75Ge 74.9228589(18) 82.78(4) min 1/2- 652.97 MeV
76Ge 75.9214026(18) 1.78(8)E+21 a 0+ 661.97 MeV
77Ge 76.9235486(18) 11.30(1) h 7/2+ 668.18 MeV
78Ge 77.922853(4) 88(1) min 0+ 677.18 MeV
79Ge 78.9254(1) 18.98(3) s (1/2)- 682.46 MeV
80Ge 79.92537(3) 29.5(4) s 0+ 690.53 MeV
81Ge 80.92882(13) 7.6(6) s 9/2+# 695.81 MeV
82Ge 81.92955(26) 4.55(5) s 0+ 702.95 MeV
83Ge 82.93462(21)# 1.85(6) s (5/2+)# 706.36 MeV
84Ge 83.93747(32)# 0.947(11) s 0+ 711.64 MeV
85Ge 84.94303(43)# 535(47) ms 5/2+# 714.12 MeV
86Ge 85.94649(54)# >150 ns 0+ 719.40 MeV
87Ge 86.95251(54)# 0.14# s 5/2+# 721.88 MeV
88Ge 87.95691(75)# >=300 ns 0+ 726.23 MeV
89Ge 88.96383(97)# >150 ns 3/2+# 727.78 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 - Source Compounds: sulfides 15
Earth - Seawater: 0.00005 mg/L 16
Earth -  Crust:  1.5 mg/kg = 0.00015% 16
Earth -  Total:  7.6 ppm 17
Mercury -  Total:  1.24 ppm 17
Venus -  Total:  8.4 ppm 17
Chondrites - Total: 20 (relative to 106 atoms of Si) 18

Compounds

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 4:13.
(2) - Zumdahl, Steven S. Chemistry, 4th ed.; Houghton Mifflin: Boston, 1997; p 889.
(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.