65
Tb
Terbium
159
Terbium (Tb)
LanthanidePeriod 6f-block-block
Terbium is a chemical element with symbol Tb and atomic number 65. It is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime and euxenite.
Latin name: Terbium
Atomic Number
65
Atomic Mass
159 g/mol
Phase (STP)
Solid
Electron Config.
[Xe] 4f⁹ 6s²
General
SymbolTb
Atomic Number65
Atomic Mass159 g/mol
CategoryLanthanide
Period6
Blockf-block
Electron Configuration[Xe] 4f⁹ 6s²
Valence Electrons11
Coloursilvery-gray metallic
Appearancesilvery white
CAS NumberCAS7440-27-9
Physical Properties
Phase (STP)Solid
Density8.23 g/cm³
Melting Point1355.85°C · 2472.53°F · 1629.00 K
Boiling Point3229.85°C · 5845.73°F · 3503.00 K
Atomic Properties
Atomic Radius221 pm
Electronegativity1.2 Pauling
Ionization Energy566 kJ/mol
Oxidation States+3, +4
Ion ChargeTb3+/Tb4+
Thermodynamic
Molar Heat28.91 J/(mol·K)
Crystal Structure
Crystal Structurehexagonal close-packed
Mechanical Properties
Mohs Hardness2.5
Nuclear & Hazards
Half-lifestable (Tb-159)
Abundance
In Universe0.000025%
In Sun0.00002%
In Earth's Crust0.0093%
In Meteorites0.00005%
Discovery & History
Discovery Year1843
Discovered ByCarl Gustaf Mosander
Country of DiscoverySweden
Isotopes of Terbium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Tb-159 | 100% | Stable | — |