Lutetium
[Xe] 4f¹⁴ 5d¹ 6s² · 2 · 8 · 18 · 32 · 9 · 2
The last and densest lanthanide, with a completely filled 4f shell. Chemically lutetium sits closer to scandium and yttrium than to its neighbours, and many tables place it in group 3.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 71
- Atomic mass
- 174.967 а.е.м.
- Electron configuration
- [Xe] 4f¹⁴ 5d¹ 6s²
- Electrons per shell
- 2 · 8 · 18 · 32 · 9 · 2
- Block
- d-block
- Group
- no data
- Period
- 6
- Electronegativity (Pauling)
- 1.27
- Electronegativity (Allen)
- 1.14
- Atomic radius
- 221 pm
- Covalent radius
- 187 pm
- Van der Waals radius
- 221 pm
- Ionisation energy 1
- 523.5 kJ/mol
- Ionisation energy 2
- 1 340 kJ/mol
- Ionisation energy 3
- 2 022.3 kJ/mol
- Ionisation energy 4
- 4 370 kJ/mol
- Electron affinity
- 50 kJ/mol
- Common oxidation states
- +3
- Oxidation states
- +2, +3
Physical properties
- State at 25 °C
- solid
- Density
- 9.841 g/cm³
- Melting point
- 1 925 K · 1 651.9 °C
- Boiling point
- 3 675 K · 3 401.9 °C
- Speed of sound
- no data
Thermal properties
- Heat of fusion
- 22 kJ/mol
- Heat of vaporisation
- 414 kJ/mol
- Specific heat capacity
- 0.154 J/(g·K)
- Thermal conductivity
- 16.4 W/(m·K)
Mechanical properties
- Young's modulus
- 68.6 GPa
- Shear modulus
- 27.2 GPa
- Bulk modulus
- 47.6 GPa
- Poisson ratio
- 0.26
- Mohs hardness
- no data
- Brinell hardness
- 893 MPa
Electrical and magnetic properties
- Electrical resistivity
- 582 nΩ·m
- Magnetic ordering
- paramagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- 0.022 K
Crystal structure
- Crystal structure
- hexagonal close-packed (hcp)
- Lattice constants
- a = 350.52 pm · c = 554.94 pm
Abundance
- In the crust
- 0.8 mg/kg
- In the ocean
- 1.5·10⁻⁷ mg/L
- In the universe
- 0.01 mg/kg
- In the human body
- 0 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 175Lu | 97.401 % | stable | — |
| 176Lu | 2.599 % | 37.71 Gyr | β− |
Lutetium-176 is 2.6 % of natural lutetium and radioactive with a 37-billion-year half-life; the lutetium-hafnium pair is an important geochronometer.
Discovery
- Year of discovery
- 1907
- Discovered by
- Georges Urbain, Carl Auer von Welsbach and Charles James
- Where
- France, Austria, USA
- Origin of the name
- from Lutetia, the Latin name for Paris
History
In 1907 Urbain in France, Auer von Welsbach in Austria and James in the United States independently split Marignac's ytterbium into two elements. Priority went to Urbain, who named the new one after Lutetia, the Latin for Paris.
Where it occurs
0.8 mg/kg of the crust. The rarest and dearest of the non-radioactive lanthanides.
How it is produced
It separates last in the rare-earth chain, which is exactly why it is expensive.
Role in living things
No biological role.
Safety
Of low toxicity. Natural lutetium is faintly radioactive because of ¹⁷⁶Lu, but the dose is negligible against natural background.
Uses
- Lutetium oxyorthosilicate — the best scintillator for PET scanners
- Lutetium-177 in targeted therapy of neuroendocrine tumours and prostate cancer
- Cracking and polymerisation catalysts
- Lutetium-hafnium geochronology
Curiosities
- Lutetium is named after Paris, and its discovery came with a priority dispute across three countries that ran for years.
- LSO crystals in PET scanners are faintly radioactive in themselves because of lutetium-176, which calibration has to account for.
- Lutetium-177 became the basis of one of the first genuinely successful targeted radiopharmaceuticals.
- Lutetium is formally a lanthanide, but by outer-shell structure it is a full d-block element.