Terbium (Tb)
Stable Isotopes of Terbium
| Isotope | Z(p) | N(n) | Atomic Mass | Natural Abundance | Nuclear Spin |
| Tb-159 | 65 | 94 | 158.925343 | 100.00% | 3/2+ |
Terbium was discovered in 1843 by Carl Mosander. It is named for the Swedish town of Ytterby.
A silvery-grey metal, terbium has a metallic luster and a hexagonal crystal structure. It is malleable, ductile, and soft enough to be cut with a knife. Its salts are colorless. It is insoluble in water and soluble in acids. In solution the metal exists only in a trivalent state. Terbium forms binary compounds with a number of elements, including hydrogen, halogens, nitrogen, phosphorus, sulfur, carbon, silicon, selenium, tellurium, boron, arsenic and antimony.
Neither terbium metal nor its salts has any important commercial use.
Properties of Terbium
| Name | Terbium |
| Symbol | Tb |
| Atomic number | 65 |
| Atomic weight | 158.925 |
| Standard state | Solid at 298 ºK |
| CAS Registry ID | 7440-27-9 |
| Group in periodic table | N/A |
| Group name | Lanthanoid |
| Period in periodic table | 6 (Lanthanoid) |
| Block in periodic table | f-block |
| Color | Silvery white |
| Classification | Metallic |
| Melting point | 1359 °C |
| Boiling point | 3123 °C |
| Vaporization point | 3221 ºC |
| Thermal conductivity | 11.1 W/(m·K) at 298.2 ºK |
| Electronegativity | 1.2 |
| Heat of vaporization | 295 kJ·mol-1 |
| Heat of fusion | 10.8 kJ·mol-1 |
| Density of liquid | 7.65 g/cm3 at 1359 °C |
| Density of solid | 8.22 g/cm3 |
| Electron configuration | [Xe]4f96s2 |
| Mean atomic radius | 1.728 Å |
| Ionic radii | Tb3+: 0.923 Å (coordination number 6) and 1.04 Å (coordination number 8) |
| Oxidation states | +3, +4 |
| Most common oxidation state | +3 |
