Lutetium
lanthanide · period 6 · group 3 · d-block
Lutetium is a chemical element with the symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry air, but not in moist air.
What the numbers say
At standard temperature and pressure Lutetium is a solid, sitting in period 6, group 3 of the d-block.
Its melting point of 1925 K (1652 °C) is the 21st highest of the 110 elements with a measured value — mid-range among the elements.
At 9.841 g/cm³ it is the 28th densest of 96 elements with a quoted density.
Pauling electronegativity is 1.27. Paired with oxygen (3.44) that is a difference of 2.17, 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.
First identified in 1907.
Crystal structure
Solid Lutetium 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 Lu — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 32 · O 9 · P 2
Properties
| Atomic number | 71 |
|---|---|
| Atomic mass | 174.96681 u |
| Series | lanthanide |
| Group | 3 |
| Period | 6 |
| Block | d-block |
| Phase at STP | Solid |
| Density | 9.841 g/cm³ |
| Melting point | 1925 K (1652 °C) |
| Boiling point | 3675 K (3402 °C) |
| Electronegativity (Pauling) | 1.27 |
| Electron configuration | [Xe] 4f¹⁴ 5d¹ 6s² |
| Crystal structure | Simple Hexagonal |
| Oxidation states | 3 |
| Discovered | 1907 |
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See Lu in context with all 118 elements.
Working with lutetium in a real design?
Ask the materials chat how Lu behaves in your alloy system, what it does to weldability, and which grades to look at — with the source of every number named.