Samarium

Samarium (Sm)

Soft silvery metallic element, belongs to the lanthanoids. Seven natural isotopes, Sm-147 is the only radioisotope, and has a half-life of 2.5*10^11 years. Used for making special alloys needed in the production of nuclear reactors. Also used as a neutron absorber. Small quantities of samarium oxide is used in special optical glasses. The largest use of the element is its ferromagnetic alloy which produces permanent magnets that are five times stronger than magnets produced by any other material. Discovered by Francois Lecoq de Boisbaudran in 1879.
Atomic Number62
Atomic Weight150.36
Mass Number152
Group
Period6
Blockf
Protons62 p+
Neutrons90 n0
Electrons62 e-
Samarium 1.jpg Animated Bohr Model of Sm (Samarium) Enhanced Bohr Model of Sm (Samarium) Bohr Model: Sm (Samarium) Orbital Diagram of Sm (Samarium)

Properties

Atomic Radius
185 pm
Molar Volume
Covalent Radius
172 pm
Metallic Radius
Ionic Radius
122 pm
Crystal Radius
136 pm
Van der Waals Radius
236 pm
Density
7.52 g/cm³
Energy
Proton Affinity
Electron Affinity
Ionization Energy
5.64371 eV/particle
Heat of Vaporization
165 kJ/mol
Heat of Fusion
8.9 kJ/mol
Heat of Formation
206.7 kJ/mol
Electrons
Electron Shells2, 8, 18, 24, 8, 2
Valence Electrons3
Electron Configuration[Xe] 4f6 6s2
Oxidation States0, 1, 2, 3
Electronegativity
1.17
Electrophilicity
Phases
PhaseSolid
Gas Phase
Boiling Point
2,067.15 K
Melting Point
1,345.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Silver
Appearancesilvery white
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
0.0000127 1/K
Molar Heat Capacity
29.54 J/(mol K)
Specific Heat Capacity
0.197 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeConductor
Electrical Conductivity
1.1 MS/m
Electrical Resistivity
0.00000094 m Ω
Superconducting Point
Magnetism
Typeparamagnetic
Magnetic Susceptibility (Mass)
0.000000111 m³/Kg
Magnetic Susceptibility (Molar)
0.00000001669 m³/mol
Magnetic Susceptibility (Volume)
0.00081618
Magnetic Ordering
Curie Point
Neel Point
106 K
Structure
Crystal StructureSimple Trigonal (RHL)
Lattice Constant
9 Å
Lattice Anglesπ/2, π/2, 2 π/3
Mechanical Properties
Hardness
Bulk Modulus
38 GPa
Shear Modulus
20 GPa
Young Modulus
50 GPa
Poisson Ratio
0.27
Speed of Sound
2,130 m/s
Classification
CategoryLanthanides, Lanthanides
CAS Group
IUPAC Group
Glawe Number27
Mendeleev Number23
Pettifor Number28
Geochemical Classrare earth & related
Goldschmidt Classlitophile
Other
Gas Basicity
Dipole Polarizability
192 ± 20 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
5,900
Neutron Mass Absorption
4.7
Quantum Numbers7F0
Space Group166 (R_3m)

Isotopes of Samarium

Stable Isotopes7
Unstable Isotopes34
Radioactive Isotopes36

128Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
127.957971 ± 0.000537 Da
Mass Number128
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year
Parity+

128Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)%
β+ p (β+-delayed proton emission)%

129Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
128.954557 ± 0.000537 Da
Mass Number129
G-Factor
Half Life
550 ± 100 ms
Spin1/2
Quadrupole Moment
0
Discovery Year1999
Parity+

129Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

130Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
129.948792 ± 0.000429 Da
Mass Number130
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1999
Parity+

130Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)%

131Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
130.946022 ± 0.000429 Da
Mass Number131
G-Factor
Half Life
1.2 ± 0.2 s
Spin5/2
Quadrupole Moment
Discovery Year1986
Parity+

131Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

132Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
131.940805 ± 0.000322 Da
Mass Number132
G-Factor
0
Half Life
4 ± 0.3 s
Spin0
Quadrupole Moment
0
Discovery Year1989
Parity+

132Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

133Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
132.93856 ± 0.00032 Da
Mass Number133
G-Factor
Half Life
2.89 ± 0.16 s
Spin5/2
Quadrupole Moment
Discovery Year1977
Parity+

133Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

134Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
133.93411 ± 0.00021 Da
Mass Number134
G-Factor
0
Half Life
9.5 ± 0.8 s
Spin0
Quadrupole Moment
0
Discovery Year1977
Parity+

134Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

135Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
134.93252 ± 0.000166 Da
Mass Number135
G-Factor
Half Life
10.3 ± 0.5 s
Spin7/2
Quadrupole Moment
Discovery Year1977
Parity+

135Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.02%

136Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
135.928275553 ± 0.000013416 Da
Mass Number136
G-Factor
0
Half Life
47 ± 2 s
Spin0
Quadrupole Moment
0
Discovery Year1982
Parity+

136Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

137Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
136.927007959 ± 0.000030718 Da
Mass Number137
G-Factor
Half Life
45 ± 1 s
Spin9/2
Quadrupole Moment
Discovery Year1986
Parity-

137Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

138Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
137.923243988 ± 0.000012686 Da
Mass Number138
G-Factor
0
Half Life
3.1 ± 0.2 m
Spin0
Quadrupole Moment
0
Discovery Year1982
Parity+

138Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

139Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
138.922296631 ± 0.000011684 Da
Mass Number139
G-Factor
-1.06 ± 0.04
Half Life
2.57 ± 0.1 m
Spin1/2
Quadrupole Moment
0
Discovery Year1971
Parity+

139Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

140Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
139.918994714 ± 0.000013416 Da
Mass Number140
G-Factor
0
Half Life
14.82 ± 0.12 m
Spin0
Quadrupole Moment
0
Discovery Year1967
Parity+

140Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

141Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
140.918481545 ± 0.000009162 Da
Mass Number141
G-Factor
-1.48 ± 0.04
Half Life
10.2 ± 0.2 m
Spin1/2
Quadrupole Moment
0
Discovery Year1967
Parity+

141Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

142Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
141.915209415 ± 0.000002002 Da
Mass Number142
G-Factor
0
Half Life
72.49 ± 0.05 m
Spin0
Quadrupole Moment
0
Discovery Year1959
Parity+

142Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
e+ (positron emission)5%

143Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
142.914634848 ± 0.000002951 Da
Mass Number143
G-Factor
0.67333333333333 ± 0.013333333333333
Half Life
8.75 ± 0.06 m
Spin3/2
Quadrupole Moment
0.4 ± 0.2
Discovery Year1956
Parity+

143Sm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
e+ (positron emission)40%
ϵ (electron capture)60%

144Sm

Abundance
3.08 ± 0.04
Relative Atomic Mass
143.912006285 ± 0.000001566 Da
Mass Number144
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1933
Parity+

144Sm Decay Modes
Decay ModeIntensity
+ (double β+ decay)%

145Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
144.913417157 ± 0.000001594 Da
Mass Number145
G-Factor
-0.32 ± 0.0031428571428571
Half Life
340 ± 3 d
Spin7/2
Quadrupole Moment
-0.6 ± 0.07
Discovery Year1947
Parity-

145Sm Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

146Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
145.913046835 ± 0.000003269 Da
Mass Number146
G-Factor
0
Half Life
68 ± 7 My
Spin0
Quadrupole Moment
0
Discovery Year1953
Parity+

146Sm Decay Modes
Decay ModeIntensity
α (α emission)100%

147Sm

AbundanceRadioactive ☢️
15 ± 0.14
Relative Atomic Mass
146.914904401 ± 0.000001354 Da
Mass Number147
G-Factor
-0.23114285714286 ± 0.0004
Half Life
106.6 ± 0.5 Gy
Spin7/2
Quadrupole Moment
-0.26 ± 0.03
Discovery Year1933
Parity-

147Sm Decay Modes
Decay ModeIntensity
α (α emission)100%

148Sm

AbundanceRadioactive ☢️
11.25 ± 0.09
Relative Atomic Mass
147.914829233 ± 0.000001337 Da
Mass Number148
G-Factor
0
Half Life
6.3 ± 1.3 Py
Spin0
Quadrupole Moment
0
Discovery Year1933
Parity+

148Sm Decay Modes
Decay ModeIntensity
α (α emission)100%

149Sm

Abundance
13.82 ± 0.1
Relative Atomic Mass
148.917191211 ± 0.000001241 Da
Mass Number149
G-Factor
-0.19077142857143 ± 0.00031428571428571
Half Life
Spin7/2
Quadrupole Moment
0.075 ± 0.008
Discovery Year1933
Parity-

149Sm Decay Modes
Decay ModeIntensity
α (α emission)%

150Sm

Abundance
7.37 ± 0.09
Relative Atomic Mass
149.917281993 ± 0.000001193 Da
Mass Number150
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1934
Parity+

151Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
150.919938859 ± 0.000001191 Da
Mass Number151
G-Factor
-0.1442 ± 0.00024
Half Life
94.6 ± 0.6 y
Spin5/2
Quadrupole Moment
0.71 ± 0.07
Discovery Year1947
Parity-

151Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

152Sm

Abundance
26.74 ± 0.09
Relative Atomic Mass
151.919738646 ± 0.00000109 Da
Mass Number152
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1933
Parity+

153Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
152.922103576 ± 0.0000011 Da
Mass Number153
G-Factor
-0.014 ± 0.002
Half Life
46.2846 ± 0.0023 h
Spin3/2
Quadrupole Moment
1.3 ± 0.12
Discovery Year1938
Parity+

153Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

154Sm

Abundance
22.74 ± 0.14
Relative Atomic Mass
153.922215756 ± 0.0000014 Da
Mass Number154
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1933
Parity+

154Sm Decay Modes
Decay ModeIntensity
(double β decay)%

155Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
154.924646645 ± 0.000001429 Da
Mass Number155
G-Factor
Half Life
22.18 ± 0.06 m
Spin3/2
Quadrupole Moment
1.13 ± 0.13
Discovery Year1951
Parity-

155Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

156Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
155.925538191 ± 0.000009148 Da
Mass Number156
G-Factor
0
Half Life
9.4 ± 0.2 h
Spin0
Quadrupole Moment
0
Discovery Year1951
Parity+

156Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

157Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
156.928418598 ± 0.000004759 Da
Mass Number157
G-Factor
Half Life
8.03 ± 0.07 m
Spin3/2
Quadrupole Moment
Discovery Year1973
Parity-

157Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

158Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
157.929949262 ± 0.000005133 Da
Mass Number158
G-Factor
0
Half Life
5.3 ± 0.03 m
Spin0
Quadrupole Moment
0
Discovery Year1970
Parity+

158Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

159Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
158.93321713 ± 0.00000637 Da
Mass Number159
G-Factor
Half Life
11.37 ± 0.15 s
Spin5/2
Quadrupole Moment
Discovery Year1986
Parity-

159Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

160Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
159.935337032 ± 0.0000021 Da
Mass Number160
G-Factor
0
Half Life
9.6 ± 0.3 s
Spin0
Quadrupole Moment
0
Discovery Year1986
Parity+

160Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

161Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
160.939160062 ± 0.000007318 Da
Mass Number161
G-Factor
Half Life
4.8 ± 0.4 s
Spin7/2
Quadrupole Moment
Discovery Year1998
Parity+

161Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

162Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
161.941621687 ± 0.000003782 Da
Mass Number162
G-Factor
0
Half Life
2.7 ± 0.3 s
Spin0
Quadrupole Moment
0
Discovery Year2005
Parity+

162Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

163Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
162.945679085 ± 0.0000079 Da
Mass Number163
G-Factor
Half Life
1.3 ± 0.5 s
Spin1/2
Quadrupole Moment
0
Discovery Year2012
Parity-

163Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

164Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
163.948550061 ± 0.0000044 Da
Mass Number164
G-Factor
0
Half Life
1.43 ± 0.24 s
Spin0
Quadrupole Moment
0
Discovery Year2012
Parity+

164Sm Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

165Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
164.95329 ± 0.000429 Da
Mass Number165
G-Factor
Half Life
980 ± 210 ms
Spin5/2
Quadrupole Moment
Discovery Year2012
Parity-

165Sm Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

166Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
165.956575 ± 0.000429 Da
Mass Number166
G-Factor
0
Half Life
800 ± 630 ms
Spin0
Quadrupole Moment
0
Discovery Year2017
Parity+

166Sm Decay Modes
Decay ModeIntensity
β (β decay)100%

167Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
166.962072 ± 0.000537 Da
Mass Number167
G-Factor
Half Life
Spin7/2
Quadrupole Moment
Discovery Year2018
Parity-

167Sm Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%

168Sm

AbundanceRadioactive ☢️
Relative Atomic Mass
167.966033 ± 0.000322 Da
Mass Number168
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year2018
Parity+

168Sm Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%

History

In 1853, Jean Charles Galissard de Marignac discovered samarium when he found lines in mineral spectra. Paul Émile Lecoq de Boisbaudran isolated a samarium salt in Paris in 1879 from the mineral samarskite and identified a new element in it via sharp optical absorption lines. The pure element was produced only in 1901 by Eugène-Anatole Demarçay. From samarskite, a mineral named after Russian mine official, Col. Samarski

DiscoverersPaul Émile Lecoq de Boisbaudran
Discovery LocationFrance
Discovery Year1879
Etymology (Name Origin)Named after the mineral samarskite.
Pronunciationseh-MER-i-em (English)
Samarium is considered to be moderately toxic
Samarium metal can be produced by reducing the oxide with lanthanum

Uses

Samarium's main use is in samarium-cobalt alloy magnets for headphones, small motors and pickups for some electric guitars. Radioactive samarium-153 is used to kill cancer cells in the treatment of lung cancer, prostate cancer, breast cancer and osteosarcoma. Samarium and its compounds are also used as catalyst and chemical reagent. It is used in the electronics and ceramics industries. It is easily magnetized and very difficult to demagnetize. This suggests important future applications in solid-state and superconductor technologies.

Sources

Found with other rare earths in monazite sand. The sand is often 50% rare earths by weight and 2.8% samarium.

Abundance
Abundance in Earth's crust
7.05 mg/kg
Abundance in Oceans
0.00000045 mg/L
Abundance in Human Body
Abundance in Meteor
0.000017 %
Abundance in Sun
0.0000001 %
Abundance in Universe
0.0000005 %

Nuclear Screening Constants

1s1.2217
2p4.269
2s16.2652
3d13.7711
3p19.5815
3s19.9736
4d33.7604
4f38.4684
4p30.912
4s29.7076
5p45.719
5s43.751
6s53.9882