About

Lutetium is the last element in the lanthanide series, and is sometimes considered the first of the 6th-period transition metals. It is a very rare and expensive silvery-white metal. Its uses are limited, but its radioactive isotopes can be used in targeted cancer therapy, and it serves as a catalyst in cracking hydrocarbons in oil refineries. It is the densest lanthanide.

Atomic Properties

Atomic Number71

Atomic Weight174.967 u

Neutrons (common)104

Electron Configuration[Xe] 4f¹⁴ 5d¹ 6s²

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹ 6s²

Electrons per Shell2, 8, 18, 32, 9, 2

Electronegativity1.27

Electron Affinity33.4 kJ/mol

Oxidation States+3

Covalent Radius160 pm

Ionic Radius86 pm

Periodic Table Position

Group3

Period6

BlockD

Chemical SeriesLanthanoids

Physical Properties

State at STPsolid

AppearanceSilvery-white metallic

Crystal Structurehcp

Magnetic Orderingparamagnetic

Poisson Ratio0.261

Thermal Properties

Melting Point1,925 K

Boiling Point3,675 K

Thermal Expansion0 1/K

Thermal Conductivity16.4 W/(m·K)

Specific Heat0.154 J/(g·K)

Molar Heat26.9 J/(mol·K)

Heat of Fusion22 kJ/mol

Heat of Vaporization414 kJ/mol

Abundance

In Earth's Crust0.8 ppm

In Ocean0 ppm

In Solar System0 ppm

In Universe0 ppm

Discovery

Discovered byGeorges Urbain, Carl Auer von Welsbach

Discovery Year1,907

Occurrenceprimordial

CAS Number7439-94-3

Electron Configuration

Energy

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Isotopes of Lutetium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
¹⁷⁵Lu	174.940770	97.401%	Stable	Stable
¹⁷⁶Lu	175.942680	2.599%	37.01 Gy	Beta Minus Decay

Interactive Visualization

Explore the 3D Bohr model of Lutetium in our interactive viewer.

View 3D Model of Lutetium