Lu
Lutetium
Element 71 · Lanthanide
Lutetium (Lu)
Lutetium is the last and hardest lanthanide. It is one of the rarest and most expensive rare-earth metals.
- Lanthanide
- Period 6
- f-block series
- d-block
- solid at room temperature
Key properties
- Atomic mass
- 174.9667
- u
- Electron configuration
- [Xe] 4f14 5d1 6s2
- Melting point
- 1,662.9 °C
- 1,936 K
- Boiling point
- 3,401.9 °C
- 3,675 K
- Density
- 9.84 g/cm³
- Electronegativity
- 1.27
- Pauling
- Atomic radius
- 221 pm
- van der Waals
- 1st ionisation energy
- 5.426 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about lutetium
- 01
Three chemists discovered it independently in the same year.
- 02
Lutetium-177 is used in targeted radiotherapy for prostate and neuroendocrine cancers.
- 03
Lutetium–hafnium dating measures the age of meteorites.
Applications
What is lutetium used for?
- Cancer radiotherapy (Lu-177)
- PET scanner detectors
- Oil-refining catalysts
- Rock and meteorite dating
History
Discovery & name origin
Discovered by
Year
Where
France, Austria and United States
Name origin
Latin Lutetia, the Roman name for Paris.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 71
- Atomic mass
- 174.9667 u
- Group
- Lanthanides (3)
- Period
- 6
- Block
- d-block
- Electron configuration
- [Xe] 4f14 5d1 6s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d1
- Electrons per shell
- 2, 8, 18, 32, 9, 2
- Electronegativity (Pauling)
- 1.27
- Electron affinity
- —
- Atomic radius (van der Waals)
- 221 pm
- Stable isotopes
- 1
Oxidation states
Highlighted: common oxidation states (+3).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st523.5
- 2nd1,340
- 3rd2,022.3
- 4th4,370
- 5th6,445
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,936 K · 1,662.9 °C · 3,025.1 °F
- Boiling point
- 3,675 K · 3,401.9 °C · 6,155.3 °F
- Density
- 9.84 g/cm³
- Molar heat capacity
- 26.86 J/(mol·K)
- Appearance
- Silvery white
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Lutetium questions
What is Lu on the periodic table?
Lu is the symbol for lutetium, element 71 on the periodic table. It sits in period 6, in the f-block, in the lanthanide category, and has an atomic mass of 174.9667.
What is the atomic number of lutetium?
Lutetium has atomic number 71, so every lutetium atom has 71 protons in its nucleus. Its symbol is Lu and its atomic mass is 174.9667.
Who discovered lutetium?
Lutetium was discovered by Georges Urbain, Carl Auer von Welsbach and Charles James in 1907 (France, Austria and United States). The name comes from Latin Lutetia, the Roman name for Paris.
What is lutetium used for?
Lutetium is used for: cancer radiotherapy (Lu-177); PET scanner detectors; oil-refining catalysts; rock and meteorite dating.
Is lutetium a metal?
Yes. Lutetium is a lanthanide, one of the metallic elements.
What is the electron configuration of lutetium?
The electron configuration of lutetium is [Xe] 4f14 5d1 6s2. Its 71 electrons are arranged in shells as 2, 8, 18, 32, 9, 2.