Lutetium (Lu): Electron Configuration, Properties and Uses
Lutetium (Lu): Electron Configuration, Properties and Uses
Electron configuration [Xe] 6s2 4f14 5d1 · f-block, lanthanide series · period 6 · Ar 174.97
Lutetium data
- Atomic number
- 71
- Relative atomic mass
- 174.97
- Group
- – (lanthanide series)
- Period
- 6
- Block
- f
- Category
- Lanthanide
- Electron configuration
- [Xe] 6s2 4f14 5d1
- 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 (K L M N O P)
- Valence electrons
- 2 (in the outer shell)
- Electronegativity (Pauling)
- 1.27
- First ionisation energy
- 5.426 eV
- Atomic radius (van der Waals)
- 221 pm
- State at room temperature
- Solid
- Melting point
- 1663 °C
- Boiling point
- 3402 °C
- Density
- 9.84 g/cm³
- Common oxidation states
- +3
- Discovered
- 1907
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 32 · O 9 · P 2
Orbital diagram (outer electrons)
About lutetium
Lutetium, symbol Lu, is element number 71 in the periodic table. It belongs to the lanthanide series in period 6 (f-block), usually shown below the main table. The element was discovered in 1907. Lutetium is a solid at room temperature, melting at 1663 °C and boiling at 3402 °C.
Lutetium electron configuration
The electron configuration of lutetium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d1, or in short [Xe] 6s2 4f14 5d1. Its electrons occupy 6 shells: K = 2, L = 8, M = 18, N = 32, O = 9, P = 2. As a lanthanide, lutetium fills the 4f subshell. Its outer 6s subshell holds 2 electrons; valence electrons for this series are not assigned by the usual group rule. When it forms cations, electrons leave the outermost subshell first: Lu3+ = [Xe] 4f14.
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p6(36) → 5s2(38) → 4d10(48) → 5p6(54) → 6s2(56) → 4f14(70) → 5d1(71)
Uses of lutetium
Well-known applications of lutetium include PET detector crystals (LSO), cracking catalysts and Lu-177 radiopharmaceuticals for prostate cancer therapy.
Safety
Lutetium metal is generally safe to handle, but avoid breathing its dust and read the SDS before using Lutetium compounds. Always read the safety data sheet (SDS) before working with a chemical.
Other lanthanides
Frequently asked questions
What is the electron configuration of lutetium?
The electron configuration of lutetium (Lu, atomic number 71) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d1, or [Xe] 6s2 4f14 5d1 in short. By shell: 2, 8, 18, 32, 9, 2.
How many valence electrons does lutetium have?
Lutetium has 2 electrons in its outer shell. For lanthanides and actinides, valence electrons are not assigned by the usual group rule.
Which group and period is lutetium in?
Lutetium is in the lanthanide series, period 6, f-block.
What is the atomic mass of lutetium?
The relative atomic mass of lutetium is 174.97. Use it to calculate molar mass with the molar mass calculator.
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