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Terbium (Tb)

Terbium is a chemical element of the periodic table with chemical symbol Tb and atomic number 65 with an atomic weight of 158.925 u and is classed as lanthanide. Terbium is solid at room temperature.

Terbium in the periodic table

Atomic number65
AppearanceSilvery white
Color Silver
Number of protons65 p+
Number of neutrons94 n0
Number of electrons65 e-
From Wikipedia, the free encyclopediaTerbium 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.

Physical properties

Phase at STPSolid
Density8.23 g/cm3
Atomic weight158.925 u

Thermal properties

Melting point1629 K
1355.85 °C
2472.53 °F
Boiling point3396 K
3122.85 °C
5653.13 °F
Heat of vaporization330.9 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)1.1
Electron affinity112.4 kJ/mol
Oxidation states0, +1, +2, +3, +4
(a weakly basic oxide)
Ionization energies
  1. 565.8 kJ/mol
  2. 1110 kJ/mol
  3. 2114 kJ/mol
  4. 3839 kJ/mol

Electron configuration for terbium

Electron configuration
Shorthand configuration
[Xe] 4f9 6s2
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f9 5s2 5p6 6s2
Electron configuration chart
Electrons per shell2, 8, 18, 27, 8, 2
Valence electrons 2
Valency electrons 3
Bohr model
TerbiumElectron shell for Terbium, created by Injosoft ABTb
Figure: Shell diagram of Terbium (Tb) atom.
Orbital Diagram

The history of Terbium

Discovery and first isolationCarl Gustaf Mosander (1843)
Discovery of terbium
Swedish chemist Carl Gustaf Mosander discovered terbium as a chemical element in 1843. He detected it as an impurity in yttrium oxide, Y2O3. Yttrium and terbium, as well as erbium and ytterbium, are named after the village of Ytterby in Sweden. Terbium was not isolated in pure form until the advent of ion exchange techniques.


List of unique identifiers for Terbium in various chemical registry databases
CAS Number7440-27-9
ChemSpider ID22397
EC number231-137-6
PubChem CID Number23958