Tb
Terbium
Element 65 · Lanthanide
Terbium (Tb)
Terbium is a soft, silvery rare-earth metal. It produces bright green light in screens and low-energy lamps.
- Lanthanide
- Period 6
- f-block series
- f-block
- solid at room temperature
Key properties
- Atomic mass
- 158.9254
- u
- Electron configuration
- [Xe] 4f9 6s2
- Melting point
- 1,355.9 °C
- 1,629 K
- Boiling point
- 3,229.9 °C
- 3,503 K
- Density
- 8.23 g/cm³
- Electronegativity
- 1.1
- Pauling
- Atomic radius
- 221 pm
- van der Waals
- 1st ionisation energy
- 5.864 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about terbium
- 01
Terbium-doped phosphors produce the green in many fluorescent lamps and displays.
- 02
Terfenol-D, a terbium alloy, changes shape more than any other material in a magnetic field.
- 03
Terbium and erbium names were confused and swapped for a while in the 1860s.
Applications
What is terbium used for?
- Green phosphors
- Sonar and actuators (Terfenol-D)
- Solid-state devices
- Fuel cells
History
Discovery & name origin
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 65
- Atomic mass
- 158.9254 u
- Group
- Lanthanides (3)
- Period
- 6
- Block
- f-block
- Electron configuration
- [Xe] 4f9 6s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f9
- Electrons per shell
- 2, 8, 18, 27, 8, 2
- Electronegativity (Pauling)
- 1.1
- Electron affinity
- —
- Atomic radius (van der Waals)
- 221 pm
- Stable isotopes
- 1
Oxidation states
Highlighted: common oxidation states (+3).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st565.8
- 2nd1,110
- 3rd2,114
- 4th3,839
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,629 K · 1,355.9 °C · 2,472.5 °F
- Boiling point
- 3,503 K · 3,229.9 °C · 5,845.7 °F
- Density
- 8.23 g/cm³
- Molar heat capacity
- 28.91 J/(mol·K)
- Appearance
- Silvery white
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Terbium questions
What is Tb on the periodic table?
Tb is the symbol for terbium, element 65 on the periodic table. It sits in period 6, in the f-block, in the lanthanide category, and has an atomic mass of 158.9254.
What is the atomic number of terbium?
Terbium has atomic number 65, so every terbium atom has 65 protons in its nucleus. Its symbol is Tb and its atomic mass is 158.9254.
Who discovered terbium?
Terbium was discovered by Carl Gustaf Mosander in 1843 (Sweden). The name comes from from Ytterby, Sweden.
What is terbium used for?
Terbium is used for: green phosphors; sonar and actuators (Terfenol-D); solid-state devices; fuel cells.
Is terbium a metal?
Yes. Terbium is a lanthanide, one of the metallic elements.
What is the electron configuration of terbium?
The electron configuration of terbium is [Xe] 4f9 6s2. Its 65 electrons are arranged in shells as 2, 8, 18, 27, 8, 2.