Terbium (Tb) is chemical element 65, a lanthanide in the f-block, period 6 (PubChem).
- Atomic number: 65
- Symbol: Tb
- Group: none (f-block)
- Period: 6
- Atomic mass: 158.92535 u
- Electron configuration: [Xe]6s2 4f9
- Atomic radius (van der Waals): 221 pm
- Ionization energy: 5.864 eV
- Oxidation states: +3
- Standard state: Solid
- Melting point: 1629 K
- Boiling point: 3503 K
- Density: 8.23 g/cm³
- Chemical group: Lanthanide
- Year discovered: 1843