Terbium
lanthanide · period 6 · group 3 · f-block
Terbium is a chemical element with the 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.
What the numbers say
At standard temperature and pressure Terbium is a solid, sitting in period 6, group 3 of the f-block.
Its melting point of 1629 K (1356 °C) is the 36th highest of the 110 elements with a measured value — mid-range among the elements.
At 8.219 g/cm³ it is the 40th densest of 96 elements with a quoted density.
Pauling electronegativity is 1.1. Paired with oxygen (3.44) that is a difference of 2.34, which puts the bond predominantly ionic — expect a stable oxide ceramic.
In the solid state it takes a simple hexagonal structure — hexagonal packing offers few easy slip systems, so properties are anisotropic and formability is limited.
It is reported in 3 oxidation states (1, 3, 4), which sets how many distinct compounds and phases it can form.
First identified in 1843.
Crystal structure
Solid Terbium adopts a Simple Hexagonal arrangement, in the Hexagonal system — axes a = b ≠ c, angles α = β = 90°, γ = 120°. Symmetry controls the anisotropy of stiffness and thermal expansion, and the available slip systems set how far the metal deforms before it fractures.
Check it against computed structures
The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing Tb — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 27 · O 8 · P 2
Properties
| Atomic number | 65 |
|---|---|
| Atomic mass | 158.925352 u |
| Series | lanthanide |
| Group | 3 |
| Period | 6 |
| Block | f-block |
| Phase at STP | Solid |
| Density | 8.219 g/cm³ |
| Melting point | 1629 K (1356 °C) |
| Boiling point | 3396 K (3123 °C) |
| Electronegativity (Pauling) | 1.1 |
| Electron configuration | [Xe] 4f⁹ 6s² |
| Crystal structure | Simple Hexagonal |
| Oxidation states | 1,3,4 |
| Discovered | 1843 |
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See Tb in context with all 118 elements.
Working with terbium in a real design?
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