Tb Terbium
Element Information, Facts, Properties, Trends, Uses, Comparison with other elements

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.
It belongs to group of the periodic table having trivial name .
Terbium Facts
Read key information and facts about element Terbium
Name | Terbium |
Atomic Number | 65 |
Atomic Symbol | Tb |
Atomic Weight | 158.92534 |
Phase | Solid |
Color | Silver |
Appearance | silvery white |
Classification | Lanthanide |
Group in Periodic Table | - |
Group Name | |
Period in Periodic Table | period 6 |
Block in Periodic Table | f -block |
Electronic Configuration | [Xe] 4f9 6s2 |
Electronic Shell Structure (Electrons per shell) | 2, 8, 18, 27, 8, 2 |
Melting Point | 1629 K |
Boiling Point | 3503 K |
CAS Number | CAS7440-27-9 |
How to Locate Terbium on Periodic Table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 65 to find Terbium on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Terbium on periodic table look for cross section of group - and period 6 in the modern periodic table.
Terbium History
The element Terbium was discovered by G. Mosander in year 1842 in Sweden. Terbium was first isolated by J.C.G. de Marignac in 1886. Terbium derived its name from Ytterby, Sweden.
In 1842 Mosander split yttria into two more earths, erbia and terbia.
Terbium Presence: Abundance in Nature and Around Us
The table below shows the abundance of Terbium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
ppb by weight (1ppb =10^-7 %) | ppb by atoms (1ppb =10^-7 %) | |
---|---|---|
Abundance in Universe | 0.5 | 0.004 |
Abundance in Sun | 0.1 | 0.001 |
Abundance in Meteorites | 40 | 5 |
Abundance in Earth's Crust | 940 | 120 |
Abundance in Oceans | 0.00014 | 0.000005 |
Abundance in Humans | - | - |
Crystal Structure of Terbium
The solid state structure of Terbium is Simple Hexagonal.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.
Unit Cell Parameters
The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)
a | b | c |
---|---|---|
360.1 pm | 360.1 pm | 569.36 pm |
and the angles between them Lattice Angles (alpha, beta and gamma).
alpha | beta | gamma |
---|---|---|
π/2 | π/2 | 2 π/3 |
The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.
Space Group Name | P63/mmc |
Space Group Number | 194 |
Crystal Structure | Simple Hexagonal |
Number of atoms per unit cell |

The number of atoms per unit cell in a simple cubic, face-centered cubic and body-centred cubic are 1,4,2 respectively.
Terbium Atomic and Orbital Properties
Terbium atoms have 65 electrons and the electronic shell structure is [2, 8, 18, 27, 8, 2] with Atomic Term Symbol (Quantum Numbers) 6H15/2.
Atomic Number | 65 |
Number of Electrons (with no charge) | 65 |
Number of Protons | 65 |
Mass Number | 159 |
Number of Neutrons | 94 |
Shell structure (Electrons per energy level) | 2, 8, 18, 27, 8, 2 |
Electron Configuration | [Xe] 4f9 6s2 |
Valence Electrons | 4f9 6s2 |
Valence (Valency) | 3 |
Main Oxidation States | 3 |
Oxidation States | 0, 1, 2, 3, 4 |
Atomic Term Symbol (Quantum Numbers) | 6H15/2 |
Bohr Atomic Model of Terbium - Electrons per energy level

n | s | p | d | f |
---|
Ground State Electronic Configuration of Terbium - neutral Terbium atom
Abbreviated electronic configuration of Terbium
The ground state abbreviated electronic configuration of Neutral Terbium atom is [Xe] 4f9 6s2. The portion of Terbium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Xe]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 4f9 6s2, electrons in the outermost shell that determine the chemical properties of the element.
Unabbreviated electronic configuration of neutral Terbium
Complete ground state electronic configuration for the Terbium atom, Unabbreviated electronic configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f9 6s2
Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.

Atomic Structure of Terbium
Terbium atomic radius is 225 pm, while it's covalent radius is - .
Atomic Radius Calculated | 225 pm (2.25 Å) |
Atomic Radius Empirical | 175 pm (1.75 Å) |
Atomic Volume | 19.336 cm3/mol |
Covalent Radius | - |
Van der Waals Radius | - |
Neutron Cross Section | 23 |
Neutron Mass Absorption | 0.009 |
Atomic Spectrum of Terbium
Terbium Chemical Properties: Terbium Ionization Energies and electron affinity
The electron affinity of Terbium is 50 kJ/mol.
Valence | 3 |
Electronegativity | 1.1 |
ElectronAffinity | 50 kJ/mol |
Ionization Energy of Terbium
Refer to table below for Ionization energies of Terbium
Ionization energy number | Enthalpy - kJ/mol |
---|---|
1st | 565.8 |
2nd | 1110 |
3rd | 2114 |
4th | 3839 |
Terbium Physical Properties
Refer to below table for Terbium Physical Properties
Density | 8.219 g/cm3(when liquid at m.p density is $7.65 g/cm3) |
Molar Volume | 19.336 cm3/mol |
Elastic Properties
Young Modulus | 56 |
Shear Modulus | 22 GPa |
Bulk Modulus | 38.7 GPa |
Poisson Ratio | 0.26 |
Hardness of Terbium - Tests to Measure of Hardness of Element
Mohs Hardness | - |
Vickers Hardness | 863 MPa |
Brinell Hardness | 677 MPa |
Terbium Electrical Properties
Terbium is Conductor of electricity. Refer to table below for the Electrical properties ofTerbium
Electrical Conductivity | 830000 S/m |
Resistivity | 0.0000012 m Ω |
Superconducting Point | - |
Terbium Heat and Conduction Properties
Thermal Conductivity | 11 W/(m K) |
Thermal Expansion | 0.0000103 /K |
Terbium Magnetic Properties
Magnetic Type | Paramagnetic |
Curie Point | 222 K |
Mass Magnetic Susceptibility | 0.0000136 m3/kg |
Molar Magnetic Susceptibility | 0.000002161385 m3/mol |
Volume Magnetic Susceptibility | 0.1117784 |
Optical Properties of Terbium
Refractive Index | - |
Acoustic Properties of Terbium
Speed of Sound | 2620 m/s |
Terbium Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Terbium
Melting Point | 1629 K (1355.85°C, 2472.5299999999997 °F) |
Boiling Point | 3503 K (3229.85°C, 5845.73 °F) |
Critical Temperature | - |
Superconducting Point | - |
Enthalpies of Terbium
Heat of Fusion | 10.8 kJ/mol |
Heat of Vaporization | 295 kJ/mol |
Heat of Combustion | - |
Terbium Isotopes - Nuclear Properties of Terbium
Terbium has 36 isotopes, with between 136 and 171 nucleons. Terbium has 1 stable naturally occuring isotopes.
Isotopes of Terbium - Naturally occurring stable Isotopes: 159Tb.
Isotope | Z | N | Isotope Mass | % Abundance | T half | Decay Mode |
---|---|---|---|---|---|---|
136Tb | 65 | 71 | 136 | Synthetic | ||
137Tb | 65 | 72 | 137 | Synthetic | ||
138Tb | 65 | 73 | 138 | Synthetic | ||
139Tb | 65 | 74 | 139 | Synthetic | ||
140Tb | 65 | 75 | 140 | Synthetic | ||
141Tb | 65 | 76 | 141 | Synthetic | ||
142Tb | 65 | 77 | 142 | Synthetic | ||
143Tb | 65 | 78 | 143 | Synthetic | ||
144Tb | 65 | 79 | 144 | Synthetic | ||
145Tb | 65 | 80 | 145 | Synthetic | ||
146Tb | 65 | 81 | 146 | Synthetic | ||
147Tb | 65 | 82 | 147 | Synthetic | ||
148Tb | 65 | 83 | 148 | Synthetic | ||
149Tb | 65 | 84 | 149 | Synthetic | ||
150Tb | 65 | 85 | 150 | Synthetic | ||
151Tb | 65 | 86 | 151 | Synthetic | ||
152Tb | 65 | 87 | 152 | Synthetic | ||
153Tb | 65 | 88 | 153 | Synthetic | ||
154Tb | 65 | 89 | 154 | Synthetic | ||
155Tb | 65 | 90 | 155 | Synthetic | ||
156Tb | 65 | 91 | 156 | Synthetic | ||
157Tb | 65 | 92 | 157 | Synthetic | ||
158Tb | 65 | 93 | 158 | Synthetic | ||
159Tb | 65 | 94 | 159 | 100% | Stable | |
160Tb | 65 | 95 | 160 | Synthetic | ||
161Tb | 65 | 96 | 161 | Synthetic | ||
162Tb | 65 | 97 | 162 | Synthetic | ||
163Tb | 65 | 98 | 163 | Synthetic | ||
164Tb | 65 | 99 | 164 | Synthetic | ||
165Tb | 65 | 100 | 165 | Synthetic | ||
166Tb | 65 | 101 | 166 | Synthetic | ||
167Tb | 65 | 102 | 167 | Synthetic | ||
168Tb | 65 | 103 | 168 | Synthetic | ||
169Tb | 65 | 104 | 169 | Synthetic | ||
170Tb | 65 | 105 | 170 | Synthetic | ||
171Tb | 65 | 106 | 171 | Synthetic |
Regulatory and Health - Health and Safety Parameters and Guidelines
Database Search
List of unique identifiers to search the element in various chemical registry databases
Database | Identifier number |
---|---|
CAS Number - Chemical Abstracts Service (CAS) | CAS7440-27-9 |
RTECS Number | - |
CID Number | CID23958 |
Gmelin Number | - |
NSC Number | - |
Compare Terbium with other elements
Compare Terbium with all Group elements
Compare Terbium with all Period 6 elements
Compare Terbium with all Lanthanide elements
FAQs
What is the electronic configuration of Terbium?
The electronic configuration of Terbium is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f9 6s2.
What is the abbreviated electronic configuration of Terbium?
The abbreviated electronic configuration of Terbium is [Xe] 4f9 6s2. To form abbreviated notation of electronic configuration, the completely filled subshells are replaced by the noble gas of the preceding period in square brackets.
What is the symbol of Terbium?
Symbol of Terbium is Tb. Terbium is a chemical element with symbol Tb and atomic number 65.
What is the position of Terbium in the Periodic Table?
Terbium is a chemical element with the symbol Tb and atomic number 65. Terbium is the 65 element on the periodic table. It is located in group null and period 6 in the modern periodic table.
What is the atomic number of Terbium?
The atomic number of Terbium is 65.
What is the color of Terbium?
Terbium is of Silver color.
Who discovered Terbium?
The element Terbium was discovered by G. Mosander in year 1842 in Sweden. Terbium was first isolated by J.C.G. de Marignac in 1886.
How many valence electrons does a Terbium atom have?
Terbium has 3 valence electrons. Terbium has 65 electrons out of which 3 valence electrons are present in the 4f9 6s2 outer orbitals of atom.
What is the melting Point of Terbium?
Melting Point of Terbium is 1629 K.
What is the boiling Point of Terbium?
Boiling Point of Terbium is 3503 K.
What is the melting Point of Terbium in Kelvin?
Melting Point of Terbium in Kelvin is 1629 K.
What is the boiling Point of Terbium in Kelvin?
Boiling Point of Terbium in Kelvin is 3503 K.
What is the electronic configuration of Terbium 65?
The electronic configuration of Terbium will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f9 6s2.
How do you write the electron configuration for Terbium?
The electronic configuration of Terbium will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f9 6s2.