Element: Ruthenium
General data
| Element name | Ruthenium |
|---|---|
| Chemical symbol | Ru |
| Atomic number Z | 44 |
| Year discovered | 1827 |
| Standard state (25°C) | Solid |
| Category | Transition metal |
| Block | d |
| Atomic mass | 101.07 |
| CPK color | #248F8F |
Physical properties
| Melting point | 2607 K (2334 °C) |
|---|---|
| Boiling point | 4423 K (4150 °C) |
| Density | 12.1 g/cm³ |
Energy properties
| First ionization energy | 7.361 eV |
|---|---|
| Electron affinity | 1.05 eV |
Atomic structure
| Protons | 44 (Atomic number) |
|---|---|
| Neutrons (Ru-102, most abundant isotope) | 58 |
| Electrons | 44 |
| Electron configuration | [Kr] 5s¹ 4d⁷ |
| Oxidation states | +3 |
| Electronegativity (Pauling) | 2.2 |
| Atomic radius (van der Waals) | 207 pm |
Ionization energies - NIST ASD (44 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| Ru I | 0+ | 7.3605 ± 0.00005 | measured |
| Ru II | 1+ | 16.76 ± 0.06 | semi-empirical |
| Ru III | 2+ | 28.47 | semi-empirical |
| Ru IV | 3+ | 45 ± 1.7 | calculated |
| Ru V | 4+ | 59 ± 1.9 | calculated |
| Ru VI | 5+ | 76 ± 2 | calculated |
| Ru VII | 6+ | 93 ± 2 | calculated |
| Ru VIII | 7+ | 110 ± 2.1 | calculated |
| Ru IX | 8+ | 178.41 ± 0.05 | semi-empirical |
| Ru X | 9+ | 198 ± 2.2 | calculated |
| Ru XI | 10+ | 219.9 ± 2.4 | calculated |
| Ru XII | 11+ | 245 ± 2.5 | calculated |
| Ru XIII | 12+ | 271 ± 3 | calculated |
| Ru XIV | 13+ | 295.9 ± 0.09 | semi-empirical |
| Ru XV | 14+ | 348 ± 3 | calculated |
| Ru XVI | 15+ | 376.25 ± 0.1 | measured |
| Ru XVII | 16+ | 670 ± 3 | calculated |
| Ru XVIII | 17+ | 723 ± 3 | calculated |
| Ru XIX | 18+ | 784 ± 3 | calculated |
| Ru XX | 19+ | 845 ± 4 | calculated |
| Ru XXI | 20+ | 905 ± 4 | calculated |
| Ru XXII | 21+ | 981 ± 4 | calculated |
| Ru XXIII | 22+ | 1048 ± 4 | calculated |
| Ru XXIV | 23+ | 1115 ± 4 | calculated |
| Ru XXV | 24+ | 1187 ± 4 | calculated |
| Ru XXVI | 25+ | 1253 ± 4 | calculated |
| Ru XXVII | 26+ | 1447 ± 4 | semi-empirical |
| Ru XXVIII | 27+ | 1506.7 ± 1.6 | semi-empirical |
| Ru XXIX | 28+ | 1577 ± 2.1 | semi-empirical |
| Ru XXX | 29+ | 1659 ± 6 | semi-empirical |
| Ru XXXI | 30+ | 1743 ± 4 | semi-empirical |
| Ru XXXII | 31+ | 1794 ± 8 | semi-empirical |
| Ru XXXIII | 32+ | 1949 ± 3 | semi-empirical |
| Ru XXXIV | 33+ | 2013.04 ± 0.06 | semi-empirical |
| Ru XXXV | 34+ | 4758 ± 3 | semi-empirical |
| Ru XXXVI | 35+ | 4939 ± 8 | semi-empirical |
| Ru XXXVII | 36+ | 5136 ± 11 | semi-empirical |
| Ru XXXVIII | 37+ | 5330 ± 40 | semi-empirical |
| Ru XXXIX | 38+ | 5647 ± 6 | semi-empirical |
| Ru XL | 39+ | 5861 ± 4 | semi-empirical |
| Ru XLI | 40+ | 6137 ± 6 | semi-empirical |
| Ru XLII | 41+ | 6311.721 ± 0.019 | calculated |
| Ru XLIII | 42+ | 26229.888 ± 0.011 | calculated |
| Ru XLIV | 43+ | 27033.564 ± 0.005 | 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 (41)
| A | N | Half-life | Decay |
|---|---|---|---|
| Ru-85 | 41 | unknown | p |
| Ru-86 | 42 | unknown | EC/β⁺ |
| Ru-87 | 43 | unknown | EC/β⁺ |
| Ru-88 | 44 | 1.4 s | EC/β⁺ |
| Ru-89 | 45 | 1.33 s | EC/β⁺ |
| Ru-90 | 46 | 11.7 s | EC/β⁺ |
| Ru-91 | 47 | 8.0 s | EC/β⁺ |
| Ru-92 | 48 | 3.65 min | EC/β⁺ |
| Ru-93 | 49 | 59.7 s | EC/β⁺ |
| Ru-94 | 50 | 52.1 min | EC/β⁺ |
| Ru-95 | 51 | 1.607 h | EC/β⁺ |
| Ru-96 | 52 | stable | - |
| Ru-97 | 53 | 2.8376 d | EC/β⁺ |
| Ru-98 | 54 | stable | - |
| Ru-99 | 55 | stable | - |
| Ru-100 | 56 | stable | - |
| Ru-101 | 57 | stable | - |
| Ru-102 | 58 | stable | - |
| Ru-103 | 59 | 39.247 d | β⁻ |
| Ru-104 | 60 | stable | - |
| Ru-105 | 61 | 4.44 h | β⁻ |
| Ru-106 | 62 | 371.8 d | β⁻ |
| Ru-107 | 63 | 3.73 min | β⁻ |
| Ru-108 | 64 | 4.55 min | β⁻ |
| Ru-109 | 65 | 34.4 s | β⁻ |
| Ru-110 | 66 | 12.04 s | β⁻ |
| Ru-111 | 67 | 2.12 s | β⁻ |
| Ru-112 | 68 | 1.75 s | β⁻ |
| Ru-113 | 69 | 0.80 s | β⁻ |
| Ru-114 | 70 | 540 ms | β⁻ |
| Ru-115 | 71 | 318 ms | β⁻ |
| Ru-116 | 72 | 203 ms | β⁻ |
| Ru-117 | 73 | 152 ms | β⁻ |
| Ru-118 | 74 | 99 ms | β⁻ |
| Ru-119 | 75 | 69.2 ms | β⁻ |
| Ru-120 | 76 | 45 ms | β⁻ |
| Ru-121 | 77 | 30 ms | β⁻ |
| Ru-122 | 78 | 25 ms | β⁻ |
| Ru-123 | 79 | 19 ms | β⁻ |
| Ru-124 | 80 | 15 ms | β⁻ |
| Ru-125 | 81 | 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