Element: Terbium
General data
| Element name | Terbium |
|---|---|
| Chemical symbol | Tb |
| Atomic number Z | 65 |
| Year discovered | 1843 |
| Standard state (25°C) | Solid |
| Category | Lanthanide |
| Block | f |
| Atomic mass | 158.93 |
| CPK color | #30FFC7 |
Physical properties
| Melting point | 1629 K (1356 °C) |
|---|---|
| Boiling point | 3503 K (3230 °C) |
| Density | 8.23 g/cm³ |
Energy properties
| First ionization energy | 5.864 eV |
|---|---|
| Electron affinity | no data |
Atomic structure
| Protons | 65 (Atomic number) |
|---|---|
| Neutrons (Tb-159, most abundant isotope) | 94 |
| Electrons | 65 |
| Electron configuration | [Xe] 6s² 4f⁹ |
| Oxidation states | +3 |
| Electronegativity (Pauling) | no data |
| Atomic radius (van der Waals) | 221 pm |
Ionization energies - NIST ASD (65 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| Tb I | 0+ | 5.8638 ± 0.0006 | measured |
| Tb II | 1+ | 11.513 ± 0.02 | semi-empirical |
| Tb III | 2+ | 21.82 ± 0.03 | semi-empirical |
| Tb IV | 3+ | 39.33 ± 0.04 | semi-empirical |
| Tb V | 4+ | 66.5 ± 0.3 | semi-empirical |
| Tb VI | 5+ | 90 ± 4 | calculated |
| Tb VII | 6+ | 108 ± 5 | calculated |
| Tb VIII | 7+ | 125 ± 6 | calculated |
| Tb IX | 8+ | 143 ± 7 | calculated |
| Tb X | 9+ | 168 ± 8 | calculated |
| Tb XI | 10+ | 186 ± 9 | calculated |
| Tb XII | 11+ | 216 ± 11 | calculated |
| Tb XIII | 12+ | 250 ± 12 | calculated |
| Tb XIV | 13+ | 273 ± 14 | calculated |
| Tb XV | 14+ | 294 ± 15 | calculated |
| Tb XVI | 15+ | 325 ± 16 | calculated |
| Tb XVII | 16+ | 358 ± 17 | calculated |
| Tb XVIII | 17+ | 393 ± 20 | calculated |
| Tb XIX | 18+ | 426.6 ± 2.5 | calculated |
| Tb XX | 19+ | 613 ± 4 | calculated |
| Tb XXI | 20+ | 651 ± 4 | calculated |
| Tb XXII | 21+ | 690 ± 4 | calculated |
| Tb XXIII | 22+ | 732 ± 4 | calculated |
| Tb XXIV | 23+ | 772 ± 4 | calculated |
| Tb XXV | 24+ | 816 ± 4 | calculated |
| Tb XXVI | 25+ | 866 ± 4 | calculated |
| Tb XXVII | 26+ | 909 ± 4 | calculated |
| Tb XXVIII | 27+ | 954 ± 4 | calculated |
| Tb XXIX | 28+ | 997 ± 4 | calculated |
| Tb XXX | 29+ | 1165 ± 4 | calculated |
| Tb XXXI | 30+ | 1208 ± 4 | calculated |
| Tb XXXII | 31+ | 1256 ± 4 | calculated |
| Tb XXXIII | 32+ | 1301 ± 4 | calculated |
| Tb XXXIV | 33+ | 1393 ± 5 | calculated |
| Tb XXXV | 34+ | 1443 ± 5 | calculated |
| Tb XXXVI | 35+ | 1559 ± 5 | calculated |
| Tb XXXVII | 36+ | 1610.4 ± 0.7 | semi-empirical |
| Tb XXXVIII | 37+ | 2750 ± 4 | calculated |
| Tb XXXIX | 38+ | 2852 ± 4 | calculated |
| Tb XL | 39+ | 2961 ± 4 | calculated |
| Tb XLI | 40+ | 3078 ± 4 | calculated |
| Tb XLII | 41+ | 3189 ± 4 | calculated |
| Tb XLIII | 42+ | 3300 ± 4 | calculated |
| Tb XLIV | 43+ | 3458 ± 4 | calculated |
| Tb XLV | 44+ | 3573 ± 4 | calculated |
| Tb XLVI | 45+ | 3698 ± 4 | calculated |
| Tb XLVII | 46+ | 3814 ± 4 | calculated |
| Tb XLVIII | 47+ | 4139 ± 4 | calculated |
| Tb XLIX | 48+ | 4242 ± 4 | calculated |
| Tb L | 49+ | 4355 ± 4 | calculated |
| Tb LI | 50+ | 4460 ± 4 | calculated |
| Tb LII | 51+ | 4760 ± 4 | calculated |
| Tb LIII | 52+ | 4877 ± 4 | calculated |
| Tb LIV | 53+ | 5103 ± 5 | calculated |
| Tb LV | 54+ | 5217 ± 5 | calculated |
| Tb LVI | 55+ | 11673 ± 5 | calculated |
| Tb LVII | 56+ | 11957 ± 5 | calculated |
| Tb LVIII | 57+ | 12272 ± 6 | calculated |
| Tb LIX | 58+ | 12563 ± 6 | calculated |
| Tb LX | 59+ | 13658 ± 7 | calculated |
| Tb LXI | 60+ | 14003 ± 10 | calculated |
| Tb LXII | 61+ | 14434 ± 12 | calculated |
| Tb LXIII | 62+ | 14721.02 ± 0.1 | calculated |
| Tb LXIV | 63+ | 59741.12 ± 0.09 | calculated |
| Tb LXV | 64+ | 61050.1 ± 0.6 | 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 |
|---|---|---|---|
| Tb-135 | 70 | 0.9 ms | p |
| Tb-138 | 73 | unknown | EC/β⁺ |
| Tb-139 | 74 | 1.6 s | EC/β⁺ |
| Tb-140 | 75 | 2.3 s | EC/β⁺ |
| Tb-141 | 76 | 3.5 s | EC/β⁺ |
| Tb-142 | 77 | 597 ms | EC/β⁺ |
| Tb-143 | 78 | 12 s | EC/β⁺ |
| Tb-144 | 79 | ≈ 1 s | EC/β⁺ |
| Tb-145 | 80 | 30.9 s | EC/β⁺ |
| Tb-146 | 81 | 8 s | EC/β⁺ |
| Tb-147 | 82 | 1.64 h | EC/β⁺ |
| Tb-148 | 83 | 60 min | EC/β⁺ |
| Tb-149 | 84 | 4.12 h | EC/β⁺ |
| Tb-150 | 85 | 3.48 h | EC/β⁺ |
| Tb-151 | 86 | 17.609 h | EC/β⁺ |
| Tb-152 | 87 | 17.48 h | EC/β⁺ |
| Tb-153 | 88 | 2.34 d | EC/β⁺ |
| Tb-154 | 89 | 21.5 h | EC/β⁺ |
| Tb-155 | 90 | 5.32 d | EC |
| Tb-156 | 91 | 5.35 d | EC/β⁺ |
| Tb-157 | 92 | 71 a | EC |
| Tb-158 | 93 | 180 a | EC/β⁺ |
| Tb-159 | 94 | stable | - |
| Tb-160 | 95 | 72.3 d | β⁻ |
| Tb-161 | 96 | 6.958 d | β⁻ |
| Tb-162 | 97 | 7.60 min | β⁻ |
| Tb-163 | 98 | 19.5 min | β⁻ |
| Tb-164 | 99 | 3.0 min | β⁻ |
| Tb-165 | 100 | 2.11 min | β⁻ |
| Tb-166 | 101 | 27.1 s | β⁻ |
| Tb-167 | 102 | 18.9 s | β⁻ |
| Tb-168 | 103 | 9.4 s | β⁻ |
| Tb-169 | 104 | 5.1 s | β⁻ |
| Tb-170 | 105 | 0.96 s | β⁻ |
| Tb-171 | 106 | 1.24 s | β⁻ |
| Tb-172 | 107 | 0.76 s | β⁻ |
| Tb-173 | 108 | unknown | β⁻ |
| Tb-174 | 109 | 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