Terbium
Silvery metallic element belonging to the lanthanoids. Tb-159 is the only stable isotope, there are seventeen artificial isotopes. Discovered by G.G. Mosander in 1843.
Gallery
Unknown authorUnknown author, CC BY 1.0 <https://creativecommons.org/licenses/by/1.0>, via Wikimedia Commons, source: https://images-of-elements.com/terbium.php
Physical Propertiesmass · density · phase · crystal
Atomic Mass
158.9254Da
Density
8.2300g/cm³
Phase (STP)
Solid
Melting Point
1632.2K
Boiling Point
3503.2K
Molar Heat
0.1820J/(mol·K)
Crystal Structure
HEX
Lattice Constant
3.600Å
Atomic Radiiatomic · covalent · van der Waals
Atomic (Empirical)
175.00pm
Covalent
168.00pm
Van der Waals
233.00pm
Electronic Propertieselectronegativity · ionization · affinity
Electron Configuration
[Xe] 4f9 6s2
Electron Shells
2, 8, 18, 27, 8, 2
Electronegativity
—
Electron Affinity
1.2kJ/mol
1st Ionization Energy
5.9kJ/mol
Oxidation States
+1, +3, +4
Orbital DiagramAufbau · Hund's rule · Pauli exclusion
Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f9 6s2Short: [Xe] 4f9 6s2
Ionization Energies (65 known)
Emission Spectrumvisible range · characteristic spectral lines
Abundanceby mass
Log scale · ppm = parts per million by mass
Biological Role
No known biological role.
Discovery
Discovered By
Carl Mosander
Named By
—
Year
1843
Nuclear Data
Known Isotopes
40
Stable Isotopes
1
Stable Mass Numbers
159
Natural isotopic abundance (IUPAC recommended values)
Isotopes of Tb40 known
| Nuclide | Z | N | Mass (AMU) | Half-life | Decay | Jπ | Abundance |
|---|---|---|---|---|---|---|---|
| 135Tb | 65 | 70 | 134.964516 | 1.01 ms | p (1%), β⁺ | 7/2- | — |
| 136Tb | 65 | 71 | 135.961460 | Unknown | β⁺, β⁺p | 5- | — |
| 137Tb | 65 | 72 | 136.956020 | Unknown | p, β⁺ | 3/2+ | — |
| 159Tbstable | 65 | 94 | 158.925354 | Stable | stable (1%) | 3/2+ | 10000.0000% |
| 172Tb | 65 | 107 | 171.957391 | 760 ms | β⁻ (1%), β⁻n | 6+ | — |
| 173Tb | 65 | 108 | 172.960805 | Unknown | β⁻, β⁻n | 3/2+ | — |
| 174Tb | 65 | 109 | 173.965679 | Unknown | β⁻, β⁻n | 2- | — |