BARIUM

Introduction

Atomic Number: 56
Group: 2 or II A
Atomic Weight: 137.327
Period: 6
CAS Number: 7440-39-3

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

Baryta was distinguishedfrom lime by Scheele in 1774; the element was discovered by Sir Humphrey Davy in 1808. It is found only in combination with other elements, chieflyin barite or heavy spar (sulfate) and witherite (carbonate) and is prepared by electrolysis of the chloride. Barium is a metallic element, soft, and whenpure is silvery white like lead; it belongs to the alkaline earth group, resembling calcium chemically. The metal oxidizes very easily and should bekept under petroleum or other suitable oxygen-free liquids to exclude air. It is decomposed by water or alcohol. The metal is used as a “getter” in vacuumtubes. The most important compounds are the peroxide (BaO2), chloride, sulfate, carbonate, nitrate, and chlorate. Lithopone, a pigment containingbarium sulfate and zinc sulfide, has good covering power, and does not darken in the presence of sulfides. The sulfate, as permanent white or blancfixe, is also used in paint, in X-ray diagnostic work, and in glassmaking. Barite is extensively used as a weighting agent in oilwell drilling fluids, andalso in making rubber. The carbonate has been used as a rat poison, while the nitrate and chlorate give colors in pyrotechny. The impure sulfidephosphoresces after exposure to the light. The compounds and the metal are not expensive. Barium metal (99.7 + % pure) costs about 40¢/gm. Allbarium compounds that are water or acid soluble are poisonous. Naturally occurring barium is a mixture of seven stable isotopes. Thirty nine otherradioactive isotopes and isomers are known to exist. 1

• "is a constituent of alloys that are used for spark plugs because of the ease with which it emits electrons when heated. It is used as a degassing agent for vacuum tubes." 2

Physical Properties

Melting Point:3*  727 °C = 1000.15 K = 1340.6 °F
Boiling Point:3* 1897 °C = 2170.15 K = 3446.6 °F
Sublimation Point:3 
Triple Point:3 
Critical Point:3 
Density:4  3.62 g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration: [Xe] 6s2
Block: s
Highest Occupied Energy Level: 6
Valence Electrons: 2

Quantum Numbers:

n = 6
ℓ = 0
m = 0
ms = -½

Bonding

Electronegativity (Pauling scale):5 0.89
Electropositivity (Pauling scale): 3.11
Electron Affinity:6 0.14462 eV
Oxidation States: +2
Work Function:7 2.35 eV = 3.7647E-19 J

Ionization Potential   eV 8  kJ/mol  
Ionization Potential   eV 8  kJ/mol  
1 5.2117    502.9
Ionization Potential   eV 8  kJ/mol  
2 10.0039    965.2

Thermochemistry

Specific Heat: 0.204 J/g°C 9 = 28.015 J/mol°C = 0.049 cal/g°C = 6.696 cal/mol°C
Thermal Conductivity: 18.4 (W/m)/K, 27°C 10
Heat of Fusion: 7.75 kJ/mol 11 = 56.4 J/g
Heat of Vaporization: 142 kJ/mol 12 = 1034.0 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 14.9 62.3416 0 0
(ℓ) 1.19 4.97896 15.95 66.7348 0.92 3.84928
(g) 42.8 179.0752 40.63 169.99592 35.1 146.8584

Isotopes

Nuclide Mass 14 Half-Life 14 Nuclear Spin 14 Binding Energy
114Ba 113.95068(15) 530(230) ms [0.43(+30-15) s] 0+ 922.89 MeV
115Ba 114.94737(64)# 0.45(5) s (5/2+)# 940.28 MeV
116Ba 115.94138(43)# 1.3(2) s 0+ 948.35 MeV
117Ba 116.93850(32)# 1.75(7) s (3/2)(+#) 965.74 MeV
118Ba 117.93304(21)# 5.2(2) s 0+ 973.81 MeV
119Ba 118.93066(21) 5.4(3) s (5/2+) 981.88 MeV
120Ba 119.92604(32) 24(2) s 0+ 999.26 MeV
121Ba 120.92405(15) 29.7(15) s 5/2(+) 1,007.34 MeV
122Ba 121.91990(3) 1.95(15) min 0+ 1,024.72 MeV
123Ba 122.918781(13) 2.7(4) min 5/2(+) 1,032.79 MeV
124Ba 123.915094(13) 11.0(5) min 0+ 1,040.86 MeV
125Ba 124.914473(12) 3.5(4) min 1/2(+#) 1,048.94 MeV
126Ba 125.911250(13) 100(2) min 0+ 1,057.01 MeV
127Ba 126.911094(12) 12.7(4) min 1/2+ 1,065.08 MeV
128Ba 127.908318(11) 2.43(5) d 0+ 1,082.46 MeV
129Ba 128.908679(12) 2.23(11) h 1/2+ 1,090.54 MeV
130Ba 129.9063208(30) STABLE 0+ 1,098.61 MeV
131Ba 130.906941(3) 11.50(6) d 1/2+ 1,106.68 MeV
132Ba 131.9050613(11) STABLE 0+ 1,114.75 MeV
133Ba 132.9060075(11) 10.51(5) a 1/2+ 1,122.82 MeV
134Ba 133.9045084(4) STABLE 0+ 1,130.89 MeV
135Ba 134.9056886(4) STABLE 3/2+ 1,138.96 MeV
136Ba 135.9045759(4) STABLE 0+ 1,147.04 MeV
137Ba 136.9058274(5) STABLE 3/2+ 1,155.11 MeV
138Ba 137.9052472(5) STABLE 0+ 1,163.18 MeV
139Ba 138.9088413(5) 83.06(28) min 7/2- 1,171.25 MeV
140Ba 139.910605(9) 12.752(3) d 0+ 1,170.01 MeV
141Ba 140.914411(9) 18.27(7) min 3/2- 1,178.08 MeV
142Ba 141.916453(7) 10.6(2) min 0+ 1,186.15 MeV
143Ba 142.920627(14) 14.5(3) s 5/2- 1,184.90 MeV
144Ba 143.922953(14) 11.5(2) s 0+ 1,192.98 MeV
145Ba 144.92763(8) 4.31(16) s 5/2- 1,201.05 MeV
146Ba 145.93022(8) 2.22(7) s 0+ 1,199.80 MeV
147Ba 146.93495(22)# 0.893(1) s (3/2+) 1,207.88 MeV
148Ba 147.93772(9) 0.612(17) s 0+ 1,215.95 MeV
149Ba 148.94258(21)# 344(7) ms 3/2-# 1,214.70 MeV
150Ba 149.94568(43)# 300 ms 0+ 1,222.77 MeV
151Ba 150.95081(43)# 200# ms [>300 ns] 3/2-# 1,221.53 MeV
152Ba 151.95427(54)# 100# ms 0+ 1,229.60 MeV
153Ba 152.95961(86)# 80# ms 5/2-# 1,237.67 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: carbonates/sulfates 16
Earth - Seawater: 0.013 mg/L 17
Earth -  Crust:  425 mg/kg = 0.0425% 17
Earth -  Total:  4.0 ppm 18
Mercury -  Total:  3.1 ppb 18
Venus -  Total:  4.2 ppb 18
Chondrites - Total: 5.0 (relative to 106 atoms of Si) 19
Human Body - Total: 0.00003% 20

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 4:5.
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 931.
(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 > -1014.98320847326
(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.