Lutetium (Lu)

Silvery white

Lutetium is the densest and hardest lanthanide, used in PET scan detectors and oil refining catalysts, and with a completely filled 4f¹⁴ shell and one 5d electron, lutetium has the smallest ionic radius (86 pm) of any lanthanide. Lutetium oxyorthosilicate (LSO) scintillators detect gamma rays in PET scanners.

Key metrics

Density9.84g/cm³

Melting point1,925K

Boiling point3,675K

Electronegativity1.27Pauling

Discovery

1907discovered

Discovered by: Georges Urbain
Reactivity profile: Least reactive lanthanide
Reactivity: Medium
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Xe]}\; \textcolor{#a855f7}{4_{f}^{14}}\; \textcolor{#22c55e}{5_{d}^{1}}\; \textcolor{#ef4444}{6_{s}^{2}}

[Xe] 4f14 5d1 6s2

Wave function

\Psi_{\text{Lu}} \approx \frac{1}{\sqrt{71!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{71}(\mathbf{r}_{71}) \right|

Probability density $|\Psi|^2$ across the Lu valence shell.

Crystal structure

Hexagonal Close-Packed

Lattice constantsa 1.00 · b 1.00 · c 1.63

Cell anglesα 90° · β 90° · γ 120°

Coordination number12

Atoms per cell2

Atomic packing factor0.74

Physical properties

Atomic radius: 173 pm
Ionization energy: 523 kJ/mol
Electron affinity: 50 kJ/mol
Crystal structure: Hexagonal close-packed (hcp)

Oxidation states

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1925 K3675 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

452.3nmLu I (blue)Blue100%

468.5nmLu IBlue70%

537.4nmLu I (green)Green40%

Dominant line 452.3 nmRange 452–537 nmTransitions 3