Barium

Barium (Ba)

Silvery-white reactive element, belonging to group 2 of the periodic table. Soluble barium compounds are extremely poisonous. Identified in 1774 by Karl Scheele and extracted in 1808 by Humphry Davy.
Atomic Number56
Atomic Weight137.327
Mass Number138
Group2
Period6
Blocks
Protons56 p+
Neutrons82 n0
Electrons56 e-
Barium 1.jpg Animated Bohr Model of Ba (Barium) Enhanced Bohr Model of Ba (Barium) Bohr Model: Ba (Barium) Orbital Diagram of Ba (Barium)

Properties

Atomic Radius
215 pm
Molar Volume
Covalent Radius
196 pm
Metallic Radius
198 pm
Ionic Radius
135 pm
Crystal Radius
149 pm
Van der Waals Radius
268 pm
Density
3.62 g/cm³
Energy
Proton Affinity
Electron Affinity
0.14462 eV/particle
Ionization Energy
5.211664 eV/particle
Heat of Vaporization
142 kJ/mol
Heat of Fusion
7.66 kJ/mol
Heat of Formation
179.1 kJ/mol
Electrons
Electron Shells2, 8, 18, 18, 8, 2
Valence Electrons2
Electron Configuration[Xe] 6s2
Oxidation States1, 2
Electronegativity
0.89
Electrophilicity
0.7077543210759566 eV/particle
Phases
PhaseSolid
Gas Phase
Boiling Point
2,118.15 K
Melting Point
1,000.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Silver
Appearance
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
0.0000206 1/K
Molar Heat Capacity
28.07 J/(mol K)
Specific Heat Capacity
0.204 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeConductor
Electrical Conductivity
2.9 MS/m
Electrical Resistivity
0.00000035 m Ω
Superconducting Point
Magnetism
Typeparamagnetic
Magnetic Susceptibility (Mass)
0.0000000113 m³/Kg
Magnetic Susceptibility (Molar)
0.000000001552 m³/mol
Magnetic Susceptibility (Volume)
0.00003966
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal StructureBody Centered Cubic (BCC)
Lattice Constant
5.02 Å
Lattice Anglesπ/2, π/2, π/2
Mechanical Properties
Hardness
1.25 MPa
Bulk Modulus
9.6 GPa
Shear Modulus
4.9 GPa
Young Modulus
13 GPa
Poisson Ratio
Speed of Sound
1,620 m/s
Classification
CategoryAlkaline earth metals, Alkaline earth metals
CAS GroupIIA
IUPAC GroupIIA
Glawe Number14
Mendeleev Number9
Pettifor Number14
Geochemical Classalkaline earth metal
Goldschmidt Classlitophile
Other
Gas Basicity
Dipole Polarizability
272 ± 10 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
1.3
Neutron Mass Absorption
0.00027
Quantum Numbers1S0
Space Group229 (Im_3m)

Isotopes of Barium

Stable Isotopes7
Unstable Isotopes35
Radioactive Isotopes35

113Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
112.95737 ± 0.000322 Da
Mass Number113
G-Factor
Half Life
Spin5/2
Quadrupole Moment
Discovery Year
Parity+

113Ba Decay Modes
Decay ModeIntensity
p (proton emission)%
α (α emission)%

114Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
113.950718489 ± 0.000110227 Da
Mass Number114
G-Factor
0
Half Life
460 ± 125 ms
Spin0
Quadrupole Moment
0
Discovery Year1995
Parity+

114Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)20%
α (α emission)0.9%
12C0.0034%

115Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
114.947482 ± 0.000215 Da
Mass Number115
G-Factor
Half Life
450 ± 50 ms
Spin5/2
Quadrupole Moment
Discovery Year1997
Parity+

115Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)15%

116Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
115.941621 ± 0.000215 Da
Mass Number116
G-Factor
0
Half Life
1.3 ± 0.2 s
Spin0
Quadrupole Moment
0
Discovery Year1997
Parity+

116Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)3%

117Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
116.938316403 ± 0.000268749 Da
Mass Number117
G-Factor
Half Life
1.75 ± 0.07 s
Spin3/2
Quadrupole Moment
Discovery Year1977
Parity+

117Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)13%
β+α (β+-delayed α emission)0.024%

118Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
117.933226 ± 0.000215 Da
Mass Number118
G-Factor
0
Half Life
5.2 ± 0.2 s
Spin0
Quadrupole Moment
0
Discovery Year1997
Parity+

118Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

119Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
118.930659683 ± 0.000214997 Da
Mass Number119
G-Factor
Half Life
5.4 ± 0.3 s
Spin5/2
Quadrupole Moment
Discovery Year1974
Parity+

119Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)25%

120Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
119.926044997 ± 0.000322241 Da
Mass Number120
G-Factor
0
Half Life
24 ± 2 s
Spin0
Quadrupole Moment
0
Discovery Year1974
Parity+

120Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

121Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
120.924052286 ± 0.000152333 Da
Mass Number121
G-Factor
0.264 ± 0.0004
Half Life
29.7 ± 1.5 s
Spin5/2
Quadrupole Moment
1.89 ± 0.13
Discovery Year1975
Parity+

121Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.02%

122Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
121.919904 ± 0.00003 Da
Mass Number122
G-Factor
0
Half Life
1.95 ± 0.15 m
Spin0
Quadrupole Moment
0
Discovery Year1974
Parity+

122Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

123Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
122.91878106 ± 0.000013 Da
Mass Number123
G-Factor
-0.272 ± 0.0004
Half Life
2.7 ± 0.4 m
Spin5/2
Quadrupole Moment
1.57 ± 0.13
Discovery Year1962
Parity+

123Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

124Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
123.915093627 ± 0.000013416 Da
Mass Number124
G-Factor
0
Half Life
11 ± 0.5 m
Spin0
Quadrupole Moment
0
Discovery Year1967
Parity+

124Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

125Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
124.91447184 ± 0.0000118 Da
Mass Number125
G-Factor
0.354 ± 0.024
Half Life
3.3 ± 0.3 m
Spin1/2
Quadrupole Moment
0
Discovery Year1968
Parity+

125Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

126Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
125.911250202 ± 0.000013416 Da
Mass Number126
G-Factor
0
Half Life
100 ± 2 m
Spin0
Quadrupole Moment
0
Discovery Year1954
Parity+

126Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

127Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
126.911091272 ± 0.000012192 Da
Mass Number127
G-Factor
0.1668 ± 0.002
Half Life
12.7 ± 0.4 m
Spin1/2
Quadrupole Moment
0
Discovery Year1952
Parity+

127Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

128Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
127.908352446 ± 0.000001728 Da
Mass Number128
G-Factor
0
Half Life
2.43 ± 0.05 d
Spin0
Quadrupole Moment
0
Discovery Year1950
Parity+

128Ba Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

129Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
128.908683409 ± 0.000011276 Da
Mass Number129
G-Factor
Half Life
2.23 ± 0.11 h
Spin1/2
Quadrupole Moment
0
Discovery Year1950
Parity+

129Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

130Ba

Abundance
0.11 ± 0.01
Relative Atomic Mass
129.906326002 ± 0.000000308 Da
Mass Number130
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1936
Parity+

130Ba Decay Modes
Decay ModeIntensity
+ (double β+ decay)%

131Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
130.906946315 ± 0.000000445 Da
Mass Number131
G-Factor
1.4166 ± 0.0004
Half Life
11.52 ± 0.01 d
Spin1/2
Quadrupole Moment
0
Discovery Year1947
Parity+

131Ba Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

132Ba

Abundance
0.1 ± 0.01
Relative Atomic Mass
131.905061231 ± 0.00000113 Da
Mass Number132
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1936
Parity+

132Ba Decay Modes
Decay ModeIntensity
+ (double β+ decay)%

133Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
132.906007443 ± 0.000001065 Da
Mass Number133
G-Factor
1.5438 ± 0.0004
Half Life
10.5379 ± 0.0016 y
Spin1/2
Quadrupole Moment
0
Discovery Year1941
Parity+

133Ba Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

134Ba

Abundance
2.42 ± 0.15
Relative Atomic Mass
133.904508249 ± 0.000000269 Da
Mass Number134
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1936
Parity+

135Ba

Abundance
6.59 ± 0.1
Relative Atomic Mass
134.905688447 ± 0.000000263 Da
Mass Number135
G-Factor
0.55873333333333 ± 0.00013333333333333
Half Life
Spin3/2
Quadrupole Moment
0.153 ± 0.002
Discovery Year1932
Parity+

136Ba

Abundance
7.85 ± 0.24
Relative Atomic Mass
135.9045758 ± 0.000000262 Da
Mass Number136
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1932
Parity+

137Ba

Abundance
11.23 ± 0.23
Relative Atomic Mass
136.905827207 ± 0.000000266 Da
Mass Number137
G-Factor
0.625 ± 0.00013333333333333
Half Life
Spin3/2
Quadrupole Moment
0.236 ± 0.003
Discovery Year1932
Parity+

138Ba

Abundance
71.7 ± 0.29
Relative Atomic Mass
137.905247059 ± 0.000000267 Da
Mass Number138
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1925
Parity+

139Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
138.908841164 ± 0.000000271 Da
Mass Number139
G-Factor
-0.278 ± 0.0014285714285714
Half Life
82.93 ± 0.09 m
Spin7/2
Quadrupole Moment
-0.552 ± 0.013
Discovery Year1937
Parity-

139Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

140Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
139.910608231 ± 0.00000848 Da
Mass Number140
G-Factor
0
Half Life
12.7534 ± 0.0021 d
Spin0
Quadrupole Moment
0
Discovery Year1939
Parity+

140Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

141Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
140.914403653 ± 0.000005709 Da
Mass Number141
G-Factor
-0.22466666666667 ± 0.0033333333333333
Half Life
18.27 ± 0.07 m
Spin3/2
Quadrupole Moment
0.437 ± 0.01
Discovery Year1945
Parity-

141Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

142Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
141.916432904 ± 0.000006355 Da
Mass Number142
G-Factor
0
Half Life
10.6 ± 0.2 m
Spin0
Quadrupole Moment
0
Discovery Year1959
Parity+

142Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

143Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
142.920625149 ± 0.000007253 Da
Mass Number143
G-Factor
0.1772 ± 0.0044
Half Life
14.5 ± 0.3 s
Spin5/2
Quadrupole Moment
-0.85 ± 0.02
Discovery Year1962
Parity-

143Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

144Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
143.922954821 ± 0.000007661 Da
Mass Number144
G-Factor
0
Half Life
11.73 ± 0.08 s
Spin0
Quadrupole Moment
0
Discovery Year1967
Parity+

144Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

145Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
144.9275184 ± 0.0000091 Da
Mass Number145
G-Factor
-0.114 ± 0.0028
Half Life
4.31 ± 0.16 s
Spin5/2
Quadrupole Moment
1.18 ± 0.02
Discovery Year1974
Parity-

145Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

146Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
145.9303632 ± 0.0000019 Da
Mass Number146
G-Factor
0
Half Life
2.15 ± 0.04 s
Spin0
Quadrupole Moment
0
Discovery Year1970
Parity+

146Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

147Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
146.9353039 ± 0.0000212 Da
Mass Number147
G-Factor
Half Life
893 ± 1 ms
Spin5/2
Quadrupole Moment
Discovery Year1978
Parity-

147Ba Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.07%

148Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
147.938223 ± 0.0000016 Da
Mass Number148
G-Factor
0
Half Life
620 ± 5 ms
Spin0
Quadrupole Moment
0
Discovery Year1979
Parity+

148Ba Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.4%

149Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
148.943284 ± 0.0000027 Da
Mass Number149
G-Factor
Half Life
349 ± 4 ms
Spin3/2
Quadrupole Moment
Discovery Year1993
Parity-

149Ba Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)3.9%

150Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
149.9464411 ± 0.0000061 Da
Mass Number150
G-Factor
0
Half Life
258 ± 5 ms
Spin0
Quadrupole Moment
0
Discovery Year1994
Parity+

150Ba Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)1%

151Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
150.951755 ± 0.000429 Da
Mass Number151
G-Factor
Half Life
167 ± 5 ms
Spin3/2
Quadrupole Moment
Discovery Year1994
Parity-

151Ba Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

152Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
151.95533 ± 0.000429 Da
Mass Number152
G-Factor
0
Half Life
139 ± 8 ms
Spin0
Quadrupole Moment
0
Discovery Year2010
Parity+

152Ba Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

153Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
152.960848 ± 0.000429 Da
Mass Number153
G-Factor
Half Life
113 ± 39 ms
Spin5/2
Quadrupole Moment
Discovery Year2016
Parity-

153Ba Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

154Ba

AbundanceRadioactive ☢️
Relative Atomic Mass
153.964659 ± 0.000537 Da
Mass Number154
G-Factor
0
Half Life
53 ± 48 ms
Spin0
Quadrupole Moment
0
Discovery Year2017
Parity+

154Ba Decay Modes
Decay ModeIntensity
β (β decay)100%

History

Barium was identified as a new element in 1774 by Carl Wilhelm Scheele. Barium was first isolated by electrolysis of molten barium salts in 1808, by Sir Humphry Davy in England. Robert Bunsen and Augustus Matthiessen obtained pure barium by electrolysis of a molten mixture of barium chloride and ammonium chloride. From the Greek word barys, heavy

DiscoverersSir Humphrey Davy
Discovery LocationEngland
Discovery Year1808
Etymology (Name Origin)Greek: barys (heavy or dense).
PronunciationBAR-i-em (English)
Water-soluble barium compounds are poisonous
At low doses, barium acts as a muscle stimulant

Uses

Barium is used as a flashed getter in vacuum tubes to remove the last traces of gases. It is often used in barium-nickel alloys for spark plug wire. Barium sulfate is important to the petroleum industry as a drilling fluid in oil and gas wells. Barium is also used in medicine to detect abnormalities in the digestive system. Barite, or barium sulfate (BaSO4), when ground is used as a filter for rubber, plastics, and resins. It is insoluable in water and so is used in X-rays of the digestive system. Barium nitrate, Ba(NO3)2, burns brilliant green and is used in fireworks.

Sources

Found in barytine (BaSO4) and witherite (BaCO3), never found in pure form due to its reactivity. Must be stored under kerosene to remain pure.

Abundance
Abundance in Earth's crust
425 mg/kg
Abundance in Oceans
0.013 mg/L
Abundance in Human Body
0.00003 %
Abundance in Meteor
0.00027 %
Abundance in Sun
0.000001 %
Abundance in Universe
0.000001 %

Nuclear Screening Constants

1s1.1139
2p4.1904
2s14.7532
3d13.9757
3p18.6836
3s18.8444
4d32.216
4p29.1968
4s28.08
5p41.1995
5s39.3805
6s48.425