71
Lu
Lutetium
175
Lutetium (Lu)
LanthanideGroup 3Period 6d-block-blockRadioactive
Lutetium is a chemical element with symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry, but not in moist air. It is considered the first element of the 6th-period transition metals and the last element in the lanthanide series, and is traditionally counted among the rare earths.
Latin name: Lutetium
Atomic Number
71
Atomic Mass
175 g/mol
Phase (STP)
Solid
Electron Config.
[Xe] 4f¹⁴ 5d¹ 6s²
General
SymbolLu
Atomic Number71
Atomic Mass175 g/mol
CategoryLanthanide
Group3
Period6
Blockd-block
Electron Configuration[Xe] 4f¹⁴ 5d¹ 6s²
Valence Electrons17
Coloursilvery-white metallic
Appearancesilvery white
CAS NumberCAS7439-94-3
Physical Properties
Phase (STP)Solid
Density9.84 g/cm³
Melting Point1651.85°C · 3005.33°F · 1925.00 K
Boiling Point3401.85°C · 6155.33°F · 3675.00 K
Atomic Properties
Atomic Radius221 pm
Electronegativity1.27 Pauling
Ionization Energy524 kJ/mol
Oxidation States+3
Ion ChargeLu3+
Thermodynamic
Molar Heat26.86 J/(mol·K)
Crystal Structure
Crystal Structurehexagonal close-packed
Mechanical Properties
Mohs Hardness5.5
Nuclear & Hazards
RadioactiveYes
Half-life3.78×10^10 years (Lu-176)
Abundance
In Universe0.00001%
In Sun0.000008%
In Earth's Crust0.0056%
In Meteorites0.00005%
Discovery & History
Discovery Year1907
Discovered ByGeorges Urbain, Carl Auer von Welsbach
Country of DiscoveryFrance/Austria
Isotopes of Lutetium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Lu-175 | 97.401% | Stable | — |
| Lu-176 | 2.599% | 3.76 × 10¹⁰ years | β⁻ |