Element: Thulium
General data
| Element name | Thulium |
|---|---|
| Chemical symbol | Tm |
| Atomic number Z | 69 |
| Year discovered | 1879 |
| Standard state (25°C) | Solid |
| Category | Lanthanide |
| Block | f |
| Atomic mass | 168.93 |
| CPK color | #00D452 |
Physical properties
| Melting point | 1818 K (1545 °C) |
|---|---|
| Boiling point | 2223 K (1950 °C) |
| Density | 9.32 g/cm³ |
Energy properties
| First ionization energy | 6.184 eV |
|---|---|
| Electron affinity | no data |
Atomic structure
| Protons | 69 (Atomic number) |
|---|---|
| Neutrons (Tm-169, most abundant isotope) | 100 |
| Electrons | 69 |
| Electron configuration | [Xe] 6s² 4f¹³ |
| Oxidation states | +3 |
| Electronegativity (Pauling) | 1.25 |
| Atomic radius (van der Waals) | 227 pm |
Ionization energies - NIST ASD (69 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| Tm I | 0+ | 6.184402 ± 0.000009 | measured |
| Tm II | 1+ | 12.065 ± 0.02 | semi-empirical |
| Tm III | 2+ | 23.66 ± 0.03 | semi-empirical |
| Tm IV | 3+ | 42.41 ± 0.04 | semi-empirical |
| Tm V | 4+ | 65.4 ± 0.3 | semi-empirical |
| Tm VI | 5+ | 98 ± 5 | calculated |
| Tm VII | 6+ | 116 ± 6 | calculated |
| Tm VIII | 7+ | 133 ± 7 | calculated |
| Tm IX | 8+ | 160 ± 8 | calculated |
| Tm X | 9+ | 180 ± 9 | calculated |
| Tm XI | 10+ | 205 ± 10 | calculated |
| Tm XII | 11+ | 239 ± 12 | calculated |
| Tm XIII | 12+ | 274 ± 14 | calculated |
| Tm XIV | 13+ | 295 ± 15 | calculated |
| Tm XV | 14+ | 317 ± 16 | calculated |
| Tm XVI | 15+ | 352 ± 17 | calculated |
| Tm XVII | 16+ | 387 ± 20 | calculated |
| Tm XVIII | 17+ | 424 ± 21 | calculated |
| Tm XIX | 18+ | 460 ± 24 | calculated |
| Tm XX | 19+ | 496 ± 25 | calculated |
| Tm XXI | 20+ | 530 ± 30 | calculated |
| Tm XXII | 21+ | 570 ± 30 | calculated |
| Tm XXIII | 22+ | 603 ± 6 | calculated |
| Tm XXIV | 23+ | 825 ± 4 | calculated |
| Tm XXV | 24+ | 866 ± 4 | calculated |
| Tm XXVI | 25+ | 911 ± 4 | calculated |
| Tm XXVII | 26+ | 958 ± 4 | calculated |
| Tm XXVIII | 27+ | 1004 ± 4 | calculated |
| Tm XXIX | 28+ | 1050 ± 4 | calculated |
| Tm XXX | 29+ | 1110 ± 4 | calculated |
| Tm XXXI | 30+ | 1157 ± 4 | calculated |
| Tm XXXII | 31+ | 1207 ± 4 | calculated |
| Tm XXXIII | 32+ | 1255 ± 4 | calculated |
| Tm XXXIV | 33+ | 1442 ± 5 | calculated |
| Tm XXXV | 34+ | 1490 ± 5 | calculated |
| Tm XXXVI | 35+ | 1542 ± 5 | calculated |
| Tm XXXVII | 36+ | 1591 ± 5 | calculated |
| Tm XXXVIII | 37+ | 1706 ± 4 | calculated |
| Tm XXXIX | 38+ | 1761 ± 4 | calculated |
| Tm XL | 39+ | 1889 ± 4 | calculated |
| Tm XLI | 40+ | 1945.2 ± 1 | semi-empirical |
| Tm XLII | 41+ | 3298 ± 4 | calculated |
| Tm XLIII | 42+ | 3409 ± 4 | calculated |
| Tm XLIV | 43+ | 3528 ± 4 | calculated |
| Tm XLV | 44+ | 3653 ± 4 | calculated |
| Tm XLVI | 45+ | 3775 ± 4 | calculated |
| Tm XLVII | 46+ | 3895 ± 4 | calculated |
| Tm XLVIII | 47+ | 4075 ± 4 | calculated |
| Tm XLIX | 48+ | 4199 ± 4 | calculated |
| Tm L | 49+ | 4335 ± 4 | calculated |
| Tm LI | 50+ | 4461 ± 4 | calculated |
| Tm LII | 51+ | 4812 ± 4 | calculated |
| Tm LIII | 52+ | 4922 ± 4 | calculated |
| Tm LIV | 53+ | 5044 ± 5 | calculated |
| Tm LV | 54+ | 5157 ± 5 | calculated |
| Tm LVI | 55+ | 5527 ± 5 | calculated |
| Tm LVII | 56+ | 5656 ± 5 | calculated |
| Tm LVIII | 57+ | 5901 ± 6 | calculated |
| Tm LIX | 58+ | 6023 ± 6 | calculated |
| Tm LX | 59+ | 13347 ± 7 | calculated |
| Tm LXI | 60+ | 13651 ± 10 | calculated |
| Tm LXII | 61+ | 13988 ± 12 | calculated |
| Tm LXIII | 62+ | 14300 ± 15 | calculated |
| Tm LXIV | 63+ | 15663 ± 19 | calculated |
| Tm LXV | 64+ | 16036 ± 24 | calculated |
| Tm LXVI | 65+ | 16510 ± 30 | calculated |
| Tm LXVII | 66+ | 16814.34 ± 0.14 | calculated |
| Tm LXVIII | 67+ | 67965.25 ± 0.12 | calculated |
| Tm LXIX | 68+ | 69387.45 ± 0.09 | calculated |
Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.
Photos
Isotopes (38)
| A | N | Half-life | Decay |
|---|---|---|---|
| Tm-144 | 75 | 1.9 μs | p |
| Tm-145 | 76 | 3.16 μs | p |
| Tm-146 | 77 | 155 ms | p |
| Tm-147 | 78 | 0.58 s | EC/β⁺ |
| Tm-148 | 79 | 0.7 s | EC/β⁺ |
| Tm-149 | 80 | 0.9 s | EC/β⁺ |
| Tm-150 | 81 | 2.20 s | EC/β⁺ |
| Tm-151 | 82 | 4.17 s | EC/β⁺ |
| Tm-152 | 83 | 5.2 s | EC/β⁺ |
| Tm-153 | 84 | 1.48 s | α |
| Tm-154 | 85 | 8.1 s | α |
| Tm-155 | 86 | 21.6 s | EC/β⁺ |
| Tm-156 | 87 | 83 s | EC/β⁺ |
| Tm-157 | 88 | 3.63 min | EC/β⁺ |
| Tm-158 | 89 | 3.98 min | EC/β⁺ |
| Tm-159 | 90 | 9.13 min | EC/β⁺ |
| Tm-160 | 91 | 9.4 min | EC/β⁺ |
| Tm-161 | 92 | 30.2 min | EC/β⁺ |
| Tm-162 | 93 | 21.80 min | EC/β⁺ |
| Tm-163 | 94 | 1.810 h | EC/β⁺ |
| Tm-164 | 95 | 1.95 min | EC/β⁺ |
| Tm-165 | 96 | 30.06 h | EC/β⁺ |
| Tm-166 | 97 | 7.70 h | EC/β⁺ |
| Tm-167 | 98 | 9.28 d | EC |
| Tm-168 | 99 | 93.1 d | EC/β⁺ |
| Tm-169 | 100 | stable | - |
| Tm-170 | 101 | 128.4 d | β⁻ |
| Tm-171 | 102 | 702 d | β⁻ |
| Tm-172 | 103 | 63.6 h | β⁻ |
| Tm-173 | 104 | 8.24 h | β⁻ |
| Tm-174 | 105 | 5.4 min | β⁻ |
| Tm-175 | 106 | 15.2 min | β⁻ |
| Tm-176 | 107 | 1.85 min | β⁻ |
| Tm-177 | 108 | 95 s | β⁻ |
| Tm-178 | 109 | unknown | β⁻ |
| Tm-179 | 110 | unknown | β⁻ |
| Tm-180 | 111 | unknown | β⁻ |
| Tm-181 | 112 | unknown | β⁻ |
Data sources
- PubChem Periodic Table API - Retrieved on 29 June 2026 - licence: CC0
- IUPAC CIAAW - Abridged Standard Atomic Weights 2024 - Table version: 2024 - licence: Public domain
- NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain
- NIST Atomic Spectra Database (ASD) - Retrieved on 29 June 2026 - licence: © U.S. Secretary of Commerce
- Images of Elements - Retrieved on 29 June 2026 - licence: CC BY 3.0