Introduction
Group: 2 or II A
Atomic Weight: 137.327
Period: 6
CAS Number: 7440-39-3
Classification
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
Electron Configuration: [Xe] 6s2
n = 6
Electronegativity (Pauling scale):5 0.89
Specific Heat: 0.204 J/g°C 9 = 28.015 J/mol°C = 0.049 cal/g°C = 6.696 cal/mol°C
Earth - Source Compounds: carbonates/sulfates 15
External Links:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:5.
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
Block: s
Highest Occupied Energy Level: 6
Valence Electrons: 2
Quantum Numbers:
ℓ = 0
mℓ = 0
ms = -½
Bonding
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
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 - Seawater: 0.013 mg/L 16
Earth -
Crust:
425 mg/kg = 0.0425% 16
Earth -
Total:
4.0 ppm 17
Mercury -
Total:
3.1 ppb 17
Venus -
Total:
4.2 ppb 17
Chondrites - Total: 5.0 (relative to 106 atoms of Si) 18
Human Body - Total: 0.00003% 19
Compounds
barium aluminate
barium arsenate
barium arsenite
barium azide
barium boride
barium bromate
barium bromide
barium bromide dihydrate
barium carbide
barium carbonate
barium chlorate
barium chlorate monohydrate
barium chloride
barium chloride dihydrate
barium chromate
barium cyanide
barium dichromate
barium dinonylnaphthalenesulfonate
barium disilicate
barium fluoride
barium formate
barium hexafluorosilicate
barium hydroxide
barium hydroxide monohydrate
barium hydroxide octahydrate
barium hyrdosulfide
barium iodate
barium iodate monohydrate
barium iodide
barium iodide dihydrate
barium iodide hexahydrate
barium manganate
barium metaphosphate
barium metasilicate
barium molybdate
barium niobate
barium nitrate
barium nitride
barium nitrite
barium nitrite monohydrate
barium orthovanadate
barium oxalate
barium oxide
barium permanganate
barium peroxide; barium dioxide
barium perrhenate
barium pyrophosphate
barium selenate
barium selenide
barium selenite
barium silicide
barium stannate
barium stearate
barium sulfate
barium sulfide
barium sulfite
barium tartrate
barium tetraiodomercurate
barium thiocyanate
barium thiosulfate
barium titanate
barium tungstate
barium vanadate
barium zirconate
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) - 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) - 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.
(19) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.