Thulium

Thulium (Tm)

Soft grey metallic element that belongs to the lanthanoids. One natural isotope exists, Tm-169, and seventeen artificial isotopes have been produced. No known uses for the element. Discovered in 1879 by Per Theodor Cleve.
Atomic Number69
Atomic Weight168.93422
Mass Number169
Group
Period6
Blockf
Protons69 p+
Neutrons100 n0
Electrons69 e-
Thulium sublimed dendritic and 1cm3 cube.jpg Animated Bohr Model of Tm (Thulium) Enhanced Bohr Model of Tm (Thulium) Bohr Model: Tm (Thulium) Orbital Diagram of Tm (Thulium)

Properties

Atomic Radius
175 pm
Molar Volume
Covalent Radius
164 pm
Metallic Radius
Ionic Radius
103 pm
Crystal Radius
117 pm
Van der Waals Radius
227 pm
Density
9.321 g/cm³
Energy
Proton Affinity
Electron Affinity
Ionization Energy
6.18431 eV/particle
Heat of Vaporization
232 kJ/mol
Heat of Fusion
Heat of Formation
232.2 kJ/mol
Electrons
Electron Shells2, 8, 18, 31, 8, 2
Valence Electrons3
Electron Configuration[Xe] 4f13 6s2
Oxidation States0, 1, 2, 3
Electronegativity
1.25
Electrophilicity
1.2616079623752015 eV/particle
Phases
PhaseSolid
Gas Phase
Boiling Point
2,223.15 K
Melting Point
1,818.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Silver
Appearancesilvery gray
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
0.0000133 1/K
Molar Heat Capacity
27.03 J/(mol K)
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeConductor
Electrical Conductivity
1.4 MS/m
Electrical Resistivity
0.0000007 m Ω
Superconducting Point
Magnetism
Typeparamagnetic
Magnetic Susceptibility (Mass)
0.00000199 m³/Kg
Magnetic Susceptibility (Molar)
0.000000336179 m³/mol
Magnetic Susceptibility (Volume)
0.0185488
Magnetic Ordering
Curie Point
25 K
Neel Point
56 K
Structure
Crystal StructureSimple Hexagonal (HEX)
Lattice Constant
3.54 Å
Lattice Anglesπ/2, π/2, 2 π/3
Mechanical Properties
Hardness
Bulk Modulus
45 GPa
Shear Modulus
31 GPa
Young Modulus
74 GPa
Poisson Ratio
0.21
Speed of Sound
Classification
CategoryLanthanides, Lanthanides
CAS Group
IUPAC Group
Glawe Number20
Mendeleev Number37
Pettifor Number22
Geochemical Classrare earth & related
Goldschmidt Classlitophile
Other
Gas Basicity
Dipole Polarizability
144 ± 15 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
105
Neutron Mass Absorption
0.025
Quantum Numbers2F7/2
Space Group194 (P63/mmc)

Isotopes of Thulium

Stable Isotopes1
Unstable Isotopes38
Radioactive Isotopes37

144Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
143.976211 ± 0.000429 Da
Mass Number144
G-Factor
Half Life
2.3 ± 0.9 us
Spin10
Quadrupole Moment
Discovery Year2005
Parity+

144Tm Decay Modes
Decay ModeIntensity
p (proton emission)%
β+ (β+ decay; β+ = ϵ + e+)%

145Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
144.970389 ± 0.00021 Da
Mass Number145
G-Factor
Half Life
3.17 ± 0.2 us
Spin11/2
Quadrupole Moment
Discovery Year1998
Parity-

145Tm Decay Modes
Decay ModeIntensity
p (proton emission)100%

146Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
145.966661 ± 0.000215 Da
Mass Number146
G-Factor
Half Life
155 ± 20 ms
Spin1
Quadrupole Moment
Discovery Year1993
Parity+

146Tm Decay Modes
Decay ModeIntensity
p (proton emission)100%
β+ (β+ decay; β+ = ϵ + e+)%
β+ p (β+-delayed proton emission)%

147Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
146.961379887 ± 0.000007341 Da
Mass Number147
G-Factor
Half Life
580 ± 30 ms
Spin11/2
Quadrupole Moment
Discovery Year1982
Parity-

147Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)85%
p (proton emission)15%

148Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
147.958384026 ± 0.000011 Da
Mass Number148
G-Factor
Half Life
700 ± 200 ms
Spin10
Quadrupole Moment
Discovery Year1982
Parity+

148Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

149Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
148.952828 ± 0.000215 Da
Mass Number149
G-Factor
Half Life
900 ± 200 ms
Spin11/2
Quadrupole Moment
Discovery Year1987
Parity-

149Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.26%

150Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
149.95009 ± 0.00021 Da
Mass Number150
G-Factor
Half Life
Spin1
Quadrupole Moment
Discovery Year1982
Parity+

150Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

151Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
150.945494433 ± 0.000020799 Da
Mass Number151
G-Factor
Half Life
4.17 ± 0.11 s
Spin11/2
Quadrupole Moment
Discovery Year1982
Parity-

151Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

152Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
151.944476 ± 0.000058 Da
Mass Number152
G-Factor
Half Life
8 ± 1 s
Spin2
Quadrupole Moment
Discovery Year1980
Parity

152Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

153Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
152.942058023 ± 0.00001286 Da
Mass Number153
G-Factor
1.26 ± 0.02
Half Life
1.48 ± 0.01 s
Spin11/2
Quadrupole Moment
0.5 ± 1
Discovery Year1964
Parity-

153Tm Decay Modes
Decay ModeIntensity
α (α emission)91%
β+ (β+ decay; β+ = ϵ + e+)9%

154Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
153.941570062 ± 0.000015471 Da
Mass Number154
G-Factor
-0.57 ± 0.01
Half Life
8.1 ± 0.3 s
Spin2
Quadrupole Moment
0.4 ± 0.9
Discovery Year1964
Parity

154Tm Decay Modes
Decay ModeIntensity
α (α emission)54%
β+ (β+ decay; β+ = ϵ + e+)46%

155Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
154.939209576 ± 0.000010651 Da
Mass Number155
G-Factor
Half Life
21.6 ± 0.2 s
Spin11/2
Quadrupole Moment
Discovery Year1971
Parity-

155Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)99.17%
α (α emission)0.83%

156Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
155.938985746 ± 0.000015328 Da
Mass Number156
G-Factor
0.2 ± 0.015
Half Life
83.8 ± 1.8 s
Spin2
Quadrupole Moment
-0.48 ± 0.11
Discovery Year1971
Parity-

156Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
α (α emission)0.064%

157Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
156.936973 ± 0.00003 Da
Mass Number157
G-Factor
0.952 ± 0.03
Half Life
3.63 ± 0.09 m
Spin1/2
Quadrupole Moment
0
Discovery Year1974
Parity+

157Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
α (α emission)7.5%

158Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
157.936979525 ± 0.000027074 Da
Mass Number158
G-Factor
0.02 ± 0.01
Half Life
3.98 ± 0.06 m
Spin2
Quadrupole Moment
0.74 ± 0.11
Discovery Year1970
Parity-

158Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

159Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
158.934975 ± 0.00003 Da
Mass Number159
G-Factor
1.368 ± 0.012
Half Life
9.13 ± 0.16 m
Spin5/2
Quadrupole Moment
1.93 ± 0.07
Discovery Year1971
Parity+

159Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

160Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
159.935264177 ± 0.000035089 Da
Mass Number160
G-Factor
0.16 ± 0.02
Half Life
9.4 ± 0.3 m
Spin1
Quadrupole Moment
0.58 ± 0.04
Discovery Year1970
Parity-

160Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

161Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
160.933549 ± 0.00003 Da
Mass Number161
G-Factor
0.68571428571429 ± 0.0057142857142857
Half Life
30.2 ± 0.8 m
Spin7/2
Quadrupole Moment
2.9 ± 0.07
Discovery Year1959
Parity+

161Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

162Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
161.934001211 ± 0.000027974 Da
Mass Number162
G-Factor
0.068 ± 0.008
Half Life
21.7 ± 0.19 m
Spin1
Quadrupole Moment
0.69 ± 0.03
Discovery Year1963
Parity-

162Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

163Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
162.932658282 ± 0.00000592 Da
Mass Number163
G-Factor
Half Life
1.81 ± 0.005 h
Spin1/2
Quadrupole Moment
0
Discovery Year1959
Parity+

163Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

164Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
163.933538019 ± 0.000026845 Da
Mass Number164
G-Factor
2.37 ± 0.03
Half Life
2 ± 0.1 m
Spin1
Quadrupole Moment
0.71 ± 0.05
Discovery Year1960
Parity+

164Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
ϵ (electron capture)61%
e+ (positron emission)39%

165Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
164.932441843 ± 0.000001779 Da
Mass Number165
G-Factor
-0.278 ± 0.004
Half Life
30.06 ± 0.03 h
Spin1/2
Quadrupole Moment
0
Discovery Year1953
Parity+

165Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

166Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
165.933562136 ± 0.000012401 Da
Mass Number166
G-Factor
0.0463 ± 0.00035
Half Life
7.7 ± 0.03 h
Spin2
Quadrupole Moment
2.14 ± 0.03
Discovery Year1948
Parity+

166Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

167Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
166.932857206 ± 0.00000135 Da
Mass Number167
G-Factor
-0.394 ± 0.004
Half Life
9.25 ± 0.02 d
Spin1/2
Quadrupole Moment
0
Discovery Year1948
Parity+

167Tm Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

168Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
167.934178457 ± 0.0000018 Da
Mass Number168
G-Factor
0.075666666666667 ± 0.0036666666666667
Half Life
93.1 ± 0.2 d
Spin3
Quadrupole Moment
3.23 ± 0.07
Discovery Year1949
Parity+

168Tm Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β (β decay)0.01%

169Tm

Abundance
100
Relative Atomic Mass
168.934218956 ± 0.000000792 Da
Mass Number169
G-Factor
-0.462 ± 0.003
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year1934
Parity+

170Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
169.935807093 ± 0.000000785 Da
Mass Number170
G-Factor
0.247 ± 0.004
Half Life
128.6 ± 0.3 d
Spin1
Quadrupole Moment
0.74 ± 0.02
Discovery Year1936
Parity-

170Tm Decay Modes
Decay ModeIntensity
β (β decay)99.869%
ϵ (electron capture)0.131%

171Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
170.936435162 ± 0.000001043 Da
Mass Number171
G-Factor
-0.46 ± 0.008
Half Life
1.92 ± 0.01 y
Spin1/2
Quadrupole Moment
0
Discovery Year1948
Parity+

171Tm Decay Modes
Decay ModeIntensity
β (β decay)100%

172Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
171.938406959 ± 0.000005884 Da
Mass Number172
G-Factor
Half Life
63.6 ± 0.3 h
Spin2
Quadrupole Moment
Discovery Year1956
Parity-

172Tm Decay Modes
Decay ModeIntensity
β (β decay)100%

173Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
172.93960663 ± 0.000004723 Da
Mass Number173
G-Factor
Half Life
8.24 ± 0.08 h
Spin1/2
Quadrupole Moment
0
Discovery Year1961
Parity+

173Tm Decay Modes
Decay ModeIntensity
β (β decay)100%

174Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
173.942174061 ± 0.00004801 Da
Mass Number174
G-Factor
Half Life
5.4 ± 0.1 m
Spin4
Quadrupole Moment
Discovery Year1960
Parity-

174Tm Decay Modes
Decay ModeIntensity
β (β decay)100%

175Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
174.94384231 ± 0.000053677 Da
Mass Number175
G-Factor
Half Life
15.2 ± 0.5 m
Spin1/2
Quadrupole Moment
0
Discovery Year1961
Parity

175Tm Decay Modes
Decay ModeIntensity
β (β decay)100%

176Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
175.946997707 ± 0.000107354 Da
Mass Number176
G-Factor
Half Life
1.85 ± 0.03 m
Spin4
Quadrupole Moment
Discovery Year1961
Parity+

176Tm Decay Modes
Decay ModeIntensity
β (β decay)100%

177Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
176.948932 ± 0.000215 Da
Mass Number177
G-Factor
Half Life
95 ± 7 s
Spin1/2
Quadrupole Moment
0
Discovery Year1989
Parity+

177Tm Decay Modes
Decay ModeIntensity
β (β decay)100%

178Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
177.952506 ± 0.000322 Da
Mass Number178
G-Factor
Half Life
Spin1
Quadrupole Moment
Discovery Year2008
Parity-

178Tm Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%

179Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
178.955018 ± 0.000429 Da
Mass Number179
G-Factor
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year2012
Parity+

179Tm Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%

180Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
179.959023 ± 0.000429 Da
Mass Number180
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year2012
Parity

180Tm Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%

181Tm

AbundanceRadioactive ☢️
Relative Atomic Mass
180.961954 ± 0.000537 Da
Mass Number181
G-Factor
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year2012
Parity+

181Tm Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%

182Tm

Abundance
Relative Atomic Mass
181.966194 ± 0.000537 Da
Mass Number182
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year
Parity

182Tm Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%

History

Thulium was discovered by Swedish chemist Per Teodor Cleve in 1879 by looking for impurities in the oxides of other rare earth elements. The first researcher to obtain nearly pure thulium was Charles James, a British expatriate working on a large scale at New Hampshire College in Durham. High-purity thulium oxide was first offered commercially in the late 1950s. Named after Thule, the earliest name for Scandinavia

DiscoverersPer Theodor Cleve
Discovery LocationSweden
Discovery Year1879
Etymology (Name Origin)From Thule ancient name of Scandinavia.
PronunciationTHOO-li-em (English)
Thulium is considered to be non-toxic
Thulium ore occurs most commonly in China

Uses

Thulium is used to dope yttrium aluminum garnets used in lasers. It has also been used in high-temperature superconductors similarly to yttrium. Thulium has use in ferrites, ceramic magnetic materials that are used in microwave equipment. Thulium is used in euro banknotes for its blue fluorescence under UV light to defeat counterfeiters. Radioactive thulium is used to power portable x-ray machines, eliminating the need for electrical equipment.

Sources

Found with other rare earths in the minerals gadolinite, euxenite, xenotime, and monazite. Monazite is often 50% rare earth by weight and 0.007% thulium.

Abundance
Abundance in Earth's crust
0.52 mg/kg
Abundance in Oceans
0.00000017 mg/L
Abundance in Human Body
Abundance in Meteor
0.0000029 %
Abundance in Sun
0.00000002 %
Abundance in Universe
0.00000001 %

Nuclear Screening Constants

1s1.3437
2p4.3588
2s18.0522
3d13.6257
3p20.5239
3s21.0816
4d36.056
4f40.366
4p33.012
4s31.8624
5p51.272
5s48.963
6s60.4158