Element: Samarium
General data
| Element name | Samarium |
|---|---|
| Chemical symbol | Sm |
| Atomic number Z | 62 |
| Year discovered | 1879 |
| Standard state (25°C) | Solid |
| Category | Lanthanide |
| Block | f |
| Atomic mass | 150.36 |
| CPK color | #8FFFC7 |
Physical properties
| Melting point | 1347 K (1074 °C) |
|---|---|
| Boiling point | 2067 K (1794 °C) |
| Density | 7.52 g/cm³ |
Energy properties
| First ionization energy | 5.644 eV |
|---|---|
| Electron affinity | no data |
Atomic structure
| Protons | 62 (Atomic number) |
|---|---|
| Neutrons (Sm-152, most abundant isotope) | 90 |
| Electrons | 62 |
| Electron configuration | [Xe] 6s² 4f⁶ |
| Oxidation states | +3, +2 |
| Electronegativity (Pauling) | 1.17 |
| Atomic radius (van der Waals) | 229 pm |
Ionization energies - NIST ASD (62 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| Sm I | 0+ | 5.643722 ± 0.000021 | measured |
| Sm II | 1+ | 11.078 ± 0.02 | semi-empirical |
| Sm III | 2+ | 23.55 ± 0.08 | semi-empirical |
| Sm IV | 3+ | 41.64 ± 0.11 | semi-empirical |
| Sm V | 4+ | 62.7 ± 0.4 | semi-empirical |
| Sm VI | 5+ | 87 ± 4 | calculated |
| Sm VII | 6+ | 103 ± 5 | calculated |
| Sm VIII | 7+ | 118 ± 6 | calculated |
| Sm IX | 8+ | 141 ± 7 | calculated |
| Sm X | 9+ | 158 ± 8 | calculated |
| Sm XI | 10+ | 179 ± 9 | calculated |
| Sm XII | 11+ | 208 ± 10 | calculated |
| Sm XIII | 12+ | 237 ± 12 | calculated |
| Sm XIV | 13+ | 257 ± 12 | calculated |
| Sm XV | 14+ | 276 ± 14 | calculated |
| Sm XVI | 15+ | 306.5 ± 0.5 | semi-empirical |
| Sm XVII | 16+ | 474 ± 3 | calculated |
| Sm XVIII | 17+ | 506 ± 3 | calculated |
| Sm XIX | 18+ | 543 ± 3 | calculated |
| Sm XX | 19+ | 581 ± 4 | calculated |
| Sm XXI | 20+ | 617 ± 4 | calculated |
| Sm XXII | 21+ | 658 ± 4 | calculated |
| Sm XXIII | 22+ | 702 ± 4 | calculated |
| Sm XXIV | 23+ | 742 ± 4 | calculated |
| Sm XXV | 24+ | 782 ± 4 | calculated |
| Sm XXVI | 25+ | 822 ± 4 | calculated |
| Sm XXVII | 26+ | 976 ± 4 | calculated |
| Sm XXVIII | 27+ | 1016 ± 4 | calculated |
| Sm XXIX | 28+ | 1060 ± 4 | calculated |
| Sm XXX | 29+ | 1103 ± 4 | calculated |
| Sm XXXI | 30+ | 1180 ± 4 | calculated |
| Sm XXXII | 31+ | 1226 ± 4 | calculated |
| Sm XXXIII | 32+ | 1332 ± 4 | calculated |
| Sm XXXIV | 33+ | 1381.56 ± 0.21 | semi-empirical |
| Sm XXXV | 34+ | 2371 ± 5 | calculated |
| Sm XXXVI | 35+ | 2466 ± 5 | calculated |
| Sm XXXVII | 36+ | 2569 ± 5 | calculated |
| Sm XXXVIII | 37+ | 2676 ± 4 | calculated |
| Sm XXXIX | 38+ | 2782 ± 4 | calculated |
| Sm XL | 39+ | 2887 ± 4 | calculated |
| Sm XLI | 40+ | 3028 ± 4 | calculated |
| Sm XLII | 41+ | 3137 ± 4 | calculated |
| Sm XLIII | 42+ | 3253 ± 4 | calculated |
| Sm XLIV | 43+ | 3363 ± 4 | calculated |
| Sm XLV | 44+ | 3669 ± 4 | calculated |
| Sm XLVI | 45+ | 3766 ± 4 | calculated |
| Sm XLVII | 46+ | 3873 ± 4 | calculated |
| Sm XLVIII | 47+ | 3971 ± 4 | calculated |
| Sm XLIX | 48+ | 4227 ± 4 | calculated |
| Sm L | 49+ | 4337 ± 4 | calculated |
| Sm LI | 50+ | 4548 ± 4 | calculated |
| Sm LII | 51+ | 4655 ± 4 | calculated |
| Sm LIII | 52+ | 10494 ± 4 | calculated |
| Sm LIV | 53+ | 10762 ± 5 | calculated |
| Sm LV | 54+ | 11060 ± 5 | calculated |
| Sm LVI | 55+ | 11337 ± 5 | calculated |
| Sm LVII | 56+ | 12264 ± 5 | calculated |
| Sm LVIII | 57+ | 12588 ± 6 | calculated |
| Sm LIX | 58+ | 12992 ± 6 | calculated |
| Sm LX | 59+ | 13262.85 ± 0.09 | calculated |
| Sm LXI | 60+ | 53986.12 ± 0.07 | calculated |
| Sm LXII | 61+ | 55214.3 ± 0.05 | 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 (40)
| A | N | Half-life | Decay |
|---|---|---|---|
| Sm-129 | 67 | 0.55 s | EC/β⁺ |
| Sm-130 | 68 | unknown | EC/β⁺ |
| Sm-131 | 69 | 1.2 s | EC/β⁺ |
| Sm-132 | 70 | 4.0 s | EC/β⁺ |
| Sm-133 | 71 | 2.9 s | EC/β⁺ |
| Sm-134 | 72 | 9.5 s | EC/β⁺ |
| Sm-135 | 73 | 10.3 s | EC/β⁺ |
| Sm-136 | 74 | 45 s | EC/β⁺ |
| Sm-137 | 75 | 45 s | EC/β⁺ |
| Sm-138 | 76 | 3.1 min | EC/β⁺ |
| Sm-139 | 77 | 2.57 min | EC/β⁺ |
| Sm-140 | 78 | 14.78 min | EC/β⁺ |
| Sm-141 | 79 | 10.4 min | EC/β⁺ |
| Sm-142 | 80 | 72.48 min | EC/β⁺ |
| Sm-143 | 81 | 8.83 min | EC/β⁺ |
| Sm-144 | 82 | stable | - |
| Sm-145 | 83 | 340 d | EC |
| Sm-146 | 84 | 6.8×10⁷ a | α |
| Sm-147 | 85 | 1.068×10¹¹ a | α |
| Sm-148 | 86 | 6.8×10¹⁵ a | α |
| Sm-149 | 87 | stable | - |
| Sm-150 | 88 | stable | - |
| Sm-151 | 89 | 94.6 a | β⁻ |
| Sm-152 | 90 | stable | - |
| Sm-153 | 91 | 46.283 h | β⁻ |
| Sm-154 | 92 | stable | - |
| Sm-155 | 93 | 22.18 min | β⁻ |
| Sm-156 | 94 | 9.4 h | β⁻ |
| Sm-157 | 95 | 8.04 min | β⁻ |
| Sm-158 | 96 | 5.32 min | β⁻ |
| Sm-159 | 97 | 11.37 s | β⁻ |
| Sm-160 | 98 | 9.6 s | β⁻ |
| Sm-161 | 99 | 4.6 s | β⁻ |
| Sm-162 | 100 | 3.1 s | β⁻ |
| Sm-163 | 101 | 1.67 s | β⁻ |
| Sm-164 | 102 | 1.42 s | β⁻ |
| Sm-165 | 103 | 610 ms | β⁻ |
| Sm-166 | 104 | 400 ms | β⁻ |
| Sm-167 | 105 | 330 ms | β⁻ |
| Sm-168 | 106 | 0.35 s | 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