Promethium

Promethium (Pm)

Soft silvery metallic element, belongs to the lanthanoids. Pm-147, the only natural isotope, is radioactive and has a half-life of 252 years. Eighteen radioisotopes have been produced, but all have very short half-lives. Found only in nuclear decay waste. Pm-147 is of interest as a beta-decay source, however Pm-146 and Pm-148 have to be removed from it first, as they generate gamma radiation. Discovered by J.A. Marinsky, L.E. Glendenin and C.D. Coryell in 1947.
Atomic Number61
Atomic Weight144.91276
Mass Number126
Group
Period6
Blockf
Protons61 p+
Neutrons65 n0
Electrons61 e-
Promethium.jpg Promethium spectrum visible.png Animated Bohr Model of Pm (Promethium) Enhanced Bohr Model of Pm (Promethium) Bohr Model: Pm (Promethium) Orbital Diagram of Pm (Promethium)

Properties

Atomic Radius
185 pm
Molar Volume
Covalent Radius
173 pm
Metallic Radius
Ionic Radius
97 pm
Crystal Radius
111 pm
Van der Waals Radius
238 pm
Density
7.26 g/cm³
Energy
Proton Affinity
Electron Affinity
Ionization Energy
Heat of Vaporization
Heat of Fusion
Heat of Formation
Electrons
Electron Shells2, 8, 18, 23, 8, 2
Valence Electrons3
Electron Configuration[Xe] 4f5 6s2
Oxidation States2, 3
Electronegativity
Electrophilicity
Phases
PhaseSolid
Gas Phase
Boiling Point
Melting Point
1,315.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Silver
Appearancemetallic
Refractive Index
Thermodynamic Properties
Thermal Conductivity
17.9 W/(m K)
Thermal Expansion
0.000011 1/K
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeConductor
Electrical Conductivity
1.3 MS/m
Electrical Resistivity
0.00000075 m Ω
Superconducting Point
Magnetism
Type
Magnetic Susceptibility (Mass)
Magnetic Susceptibility (Molar)
Magnetic Susceptibility (Volume)
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal Structure ()
Lattice Constant
Lattice Angles
Mechanical Properties
Hardness
Bulk Modulus
33 GPa
Shear Modulus
18 GPa
Young Modulus
46 GPa
Poisson Ratio
0.28
Speed of Sound
Classification
CategoryLanthanides, Lanthanides
CAS Group
IUPAC Group
Glawe Number28
Mendeleev Number21
Pettifor Number29
Geochemical Classrare earth & related
Goldschmidt Classlitophile
Other
Gas Basicity
Dipole Polarizability
200 ± 20 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
8,400
Neutron Mass Absorption
Quantum Numbers6H5/2
Space Group ()

Isotopes of Promethium

Stable Isotopes0
Unstable Isotopes40
Radioactive Isotopes40

126Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
125.957327 ± 0.000537 Da
Mass Number126
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year
Parity

126Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)%
β+ p (β+-delayed proton emission)%

127Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
126.951358 ± 0.000429 Da
Mass Number127
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year
Parity+

127Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)%
p (proton emission)%

128Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
127.948234 ± 0.000322 Da
Mass Number128
G-Factor
Half Life
1 ± 0.3 s
Spin4
Quadrupole Moment
Discovery Year1999
Parity+

128Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%
p (proton emission)0%

129Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
128.942909 ± 0.000322 Da
Mass Number129
G-Factor
Half Life
2.4 ± 0.9 s
Spin5/2
Quadrupole Moment
Discovery Year2004
Parity+

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

130Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
129.940451 ± 0.000215 Da
Mass Number130
G-Factor
Half Life
2.6 ± 0.2 s
Spin5
Quadrupole Moment
Discovery Year1985
Parity+

130Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

131Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
130.935834 ± 0.000215 Da
Mass Number131
G-Factor
Half Life
6.3 ± 0.8 s
Spin11/2
Quadrupole Moment
Discovery Year1998
Parity-

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

132Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
131.93384 ± 0.00016 Da
Mass Number132
G-Factor
Half Life
6.2 ± 0.6 s
Spin3
Quadrupole Moment
Discovery Year1977
Parity+

132Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)5%

133Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
132.929782 ± 0.000054 Da
Mass Number133
G-Factor
Half Life
13.5 ± 2.1 s
Spin3/2
Quadrupole Moment
Discovery Year1977
Parity+

133Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

134Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
133.928326 ± 0.000045 Da
Mass Number134
G-Factor
Half Life
22 ± 1 s
Spin5
Quadrupole Moment
Discovery Year1977
Parity+

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

135Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
134.924785 ± 0.000089 Da
Mass Number135
G-Factor
Half Life
49 ± 3 s
Spin3/2
Quadrupole Moment
Discovery Year1975
Parity+

135Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

136Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
135.923595949 ± 0.000074152 Da
Mass Number136
G-Factor
Half Life
107 ± 6 s
Spin7
Quadrupole Moment
Discovery Year1988
Parity+

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

137Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
136.920479519 ± 0.000014 Da
Mass Number137
G-Factor
Half Life
Spin5/2
Quadrupole Moment
Discovery Year1975
Parity-

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

138Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
137.919576119 ± 0.000012456 Da
Mass Number138
G-Factor
1.0666666666667 ± 0.3
Half Life
3.24 ± 0.05 m
Spin3
Quadrupole Moment
Discovery Year1973
Parity-

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

139Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
138.916799228 ± 0.000014587 Da
Mass Number139
G-Factor
Half Life
4.15 ± 0.05 m
Spin5/2
Quadrupole Moment
Discovery Year1967
Parity

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

140Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
139.916035918 ± 0.000026001 Da
Mass Number140
G-Factor
Half Life
9.2 ± 0.2 s
Spin1
Quadrupole Moment
Discovery Year1966
Parity+

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

141Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
140.913555081 ± 0.000015 Da
Mass Number141
G-Factor
Half Life
20.9 ± 0.05 m
Spin5/2
Quadrupole Moment
Discovery Year1952
Parity+

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

142Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
141.912890982 ± 0.00002533 Da
Mass Number142
G-Factor
Half Life
40.5 ± 0.5 s
Spin1
Quadrupole Moment
Discovery Year1959
Parity+

142Pm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
e+ (positron emission)77.1%
ϵ (electron capture)22.9%

143Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
142.910938068 ± 0.00000316 Da
Mass Number143
G-Factor
1.52 ± 0.2
Half Life
265 ± 7 d
Spin5/2
Quadrupole Moment
Discovery Year1952
Parity+

143Pm Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%
e+ (positron emission)5.7%

144Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
143.912596208 ± 0.000003126 Da
Mass Number144
G-Factor
0.338 ± 0.028
Half Life
363 ± 14 d
Spin5
Quadrupole Moment
Discovery Year1952
Parity-

144Pm Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%
e+ (positron emission)8%

145Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
144.912755748 ± 0.000003011 Da
Mass Number145
G-Factor
1.52 ± 0.064
Half Life
17.7 ± 0.4 y
Spin5/2
Quadrupole Moment
0.23 ± 0.08
Discovery Year1951
Parity+

145Pm Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%
α (α emission)2.8%

146Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
145.91470224 ± 0.000004589 Da
Mass Number146
G-Factor
Half Life
5.53 ± 0.05 y
Spin3
Quadrupole Moment
Discovery Year1960
Parity-

146Pm Decay Modes
Decay ModeIntensity
ϵ (electron capture)66%
β (β decay)34%

147Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
146.915144944 ± 0.000001382 Da
Mass Number147
G-Factor
0.73714285714286 ± 0.02
Half Life
2.6234 ± 0.0002 y
Spin7/2
Quadrupole Moment
0.74 ± 0.2
Discovery Year1947
Parity+

147Pm Decay Modes
Decay ModeIntensity
β (β decay)100%

148Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
147.917481091 ± 0.000006108 Da
Mass Number148
G-Factor
2.1 ± 0.2
Half Life
5.368 ± 0.007 d
Spin1
Quadrupole Moment
0.2 ± 0.2
Discovery Year1947
Parity-

148Pm Decay Modes
Decay ModeIntensity
β (β decay)100%

149Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
148.918341507 ± 0.000002344 Da
Mass Number149
G-Factor
0.94285714285714 ± 0.14285714285714
Half Life
53.08 ± 0.05 h
Spin7/2
Quadrupole Moment
Discovery Year1947
Parity+

149Pm Decay Modes
Decay ModeIntensity
β (β decay)100%

150Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
149.920990014 ± 0.000021504 Da
Mass Number150
G-Factor
Half Life
2.698 ± 0.015 h
Spin1
Quadrupole Moment
Discovery Year1952
Parity-

150Pm Decay Modes
Decay ModeIntensity
β (β decay)100%

151Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
150.921216613 ± 0.000004949 Da
Mass Number151
G-Factor
0.72 ± 0.08
Half Life
28.4 ± 0.04 h
Spin5/2
Quadrupole Moment
2.2 ± 0.9
Discovery Year1952
Parity+

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

152Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
151.923505185 ± 0.000027809 Da
Mass Number152
G-Factor
Half Life
4.12 ± 0.08 m
Spin1
Quadrupole Moment
Discovery Year1958
Parity+

152Pm Decay Modes
Decay ModeIntensity
β (β decay)100%

153Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
152.924156252 ± 0.000009729 Da
Mass Number153
G-Factor
Half Life
5.25 ± 0.02 m
Spin5/2
Quadrupole Moment
Discovery Year1962
Parity-

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

154Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
153.926712791 ± 0.000026861 Da
Mass Number154
G-Factor
Half Life
2.68 ± 0.07 m
Spin4
Quadrupole Moment
Discovery Year1958
Parity+

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

155Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
154.928136951 ± 0.000005065 Da
Mass Number155
G-Factor
Half Life
41.5 ± 0.2 s
Spin5/2
Quadrupole Moment
Discovery Year1982
Parity-

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

156Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
155.931114059 ± 0.000001275 Da
Mass Number156
G-Factor
Half Life
27.4 ± 0.5 s
Spin4
Quadrupole Moment
Discovery Year1986
Parity+

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

157Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
156.933121298 ± 0.000007521 Da
Mass Number157
G-Factor
Half Life
10.56 ± 0.1 s
Spin5/2
Quadrupole Moment
Discovery Year1987
Parity-

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

158Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
157.936546948 ± 0.000000953 Da
Mass Number158
G-Factor
0
Half Life
4.8 ± 0.5 s
Spin0
Quadrupole Moment
0
Discovery Year1987
Parity+

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

159Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
158.939286409 ± 0.000010777 Da
Mass Number159
G-Factor
Half Life
1.49 ± 0.13 s
Spin5/2
Quadrupole Moment
Discovery Year1998
Parity-

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

160Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
159.943215272 ± 0.0000022 Da
Mass Number160
G-Factor
Half Life
725 ± 57 ms
Spin6
Quadrupole Moment
Discovery Year2012
Parity-

160Pm Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

161Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
160.946229837 ± 0.0000097 Da
Mass Number161
G-Factor
Half Life
1.05 ± 0.15 s
Spin5/2
Quadrupole Moment
Discovery Year2012
Parity-

161Pm Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

162Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
161.950574 ± 0.000322 Da
Mass Number162
G-Factor
Half Life
630 ± 180 ms
Spin2
Quadrupole Moment
Discovery Year2012
Parity+

162Pm Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

163Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
162.953881 ± 0.000429 Da
Mass Number163
G-Factor
Half Life
255 ± 25 ms
Spin5/2
Quadrupole Moment
Discovery Year2012
Parity-

163Pm Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

164Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
163.958819 ± 0.000429 Da
Mass Number164
G-Factor
Half Life
Spin5
Quadrupole Moment
Discovery Year2018
Parity-

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

165Pm

AbundanceRadioactive ☢️
Relative Atomic Mass
164.96278 ± 0.000537 Da
Mass Number165
G-Factor
Half Life
Spin5/2
Quadrupole Moment
Discovery Year2018
Parity-

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

History

The existence of an element between neodymium and samarium was first predicted by Czech chemist Bohuslav Brauner in 1902. Promethium was first produced and characterized at Oak Ridge National Laboratory in 1945 by Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell. It was produced by the separation and analysis of the fission products of uranium fuel irradiated in a graphite reactor. Named after the Greek Prometheus, who, according to mythology, stole fire from heaven

DiscoverersJ.A. Marinsky, L.E. Glendenin, C.D. Coryell
Discovery LocationUnited States
Discovery Year1945
Etymology (Name Origin)Named for the Greek god, Prometheus.
Pronunciationpro-MEE-thi-em (English)
Promethium is harmful due to its radioactivity
Promethium is the only lanthanide that has no stable isotopes

Uses

Promethium is also used in atomic batteries for spacecraft and guided missiles. Promethium is also used to measure the thickness of materials by evaluating the amount of radiation from a promethium source that passes through the sample. It has possible future uses in portable X-ray sources, and as auxiliary heat or power sources for space probes and satellites. It has been used as a source of radioactivity for thickness-measuring gages.

Sources

Does not occur naturally. Found among fission products of uranium, thorium, and plutonium.

Abundance
Abundance in Earth's crust
Abundance in Oceans
Abundance in Human Body
0 %
Abundance in Meteor
0 %
Abundance in Sun
0 %
Abundance in Universe
0 %

Nuclear Screening Constants

1s1.2042
2p4.2562
2s16.0296
3d13.9018
3p19.4461
3s19.8154
4d33.26
4f37.866
4p30.3768
4s29.3604
5p44.586
5s42.1645
6s51.6046