ElementsWhat is lutetium?
Lutetium is a hard, silvery metal and the last of the lanthanides. It is rare and costly to separate.
What is lutetium used for?
Detectors in PET medical scanners, catalysts in oil refining, and some cancer treatments that use a radioactive form.
Where the name comes from
From Lutetia, the Latin name for Paris.
Key facts
- Symbol
- Lu
- Atomic number
- 71
- Atomic mass
- 174.9667 u
- Family
- Lanthanide
- Period
- 6
- Group
- none (f-block)
- Block
- f
- State at room temperature
- Solid
- Melting point
- 1,663 °C (1,936 K, 3,025 °F)
- Boiling point
- 3,402 °C (3,675 K, 6,155 °F)
- Density
- 9.84 g/cm³
- Electrons per shell
- 2, 8, 18, 32, 9, 2
- Electron configuration
- [Xe]6s2 4f14 5d1
- Common oxidation states
- +3
- Electronegativity (Pauling)
- 1.27
- First ionisation energy
- 5.426 eV
- Electron affinity
- no value
- Atomic radius (van der Waals)
- 221 pm
- Discovered
- 1907
Place in the periodic table
Lutetium is element number 71. It sits in period 6 (row 6) of the periodic table, in the separate row of lanthanides drawn below the main table, and belongs to the f-block. Just before it comes ytterbium (70), and just after it comes hafnium (72).
Family: Lanthanides.
Physical properties
At room temperature lutetium is a solid. It melts at 1,663 °C and boils at 3,402 °C, so it stays liquid over a range of 1,739 degrees. Its density is 9.84 grams per cubic centimetre, so a one-litre block would weigh about 9.84 kilograms. By density it ranks 27th among the 96 elements with a measured value.
Inside the atom
An atom of lutetium has 71 protons in its nucleus and, when neutral, 71 electrons around it. The electrons are arranged in 6 shells: 2, 8, 18, 32, 9, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [Xe]6s2 4f14 5d1.
Its electronegativity on the Pauling scale is 1.27. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 5.426 electronvolts (about 524 kilojoules per mole). One mole of lutetium weighs 174.9667 grams, so a single gram contains about 3.44 × 1021 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains lutetium with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.