Sm

Samarium

Identification

CAS Number: 7440-19-9

Discovery Year: 1879

Discoverer: Paul Émile Lecoq de Boisbaudran

Discovery Location: France

Properties

Atomic Mass: 150.36 →Density: 7.52 g/cm³ →

Crust Abundance: 7.05 mg/kg

Crystal Structure: RHL

Atomic Dimensions

Atomic Radius: 185 pm →

Atomic Radius (Rahm): 280 pm

Covalent Radius: 198 pm →

Van der Waals Radius: 236 pm

Atomic Volume: 19.9 cm³/mol

Lattice Constant: 9 Å

Thermodynamics

Melting Point: 1350 K →Boiling Point: 2064 K →Specific Heat: 0.18 J/(g·K) →Heat of Fusion: 8.9 kJ/mol →Heat of Vaporization: 165 kJ/mol →

Heat of Formation: 206.7 kJ/mol

Electronic Structure

Electron Config: [Xe] 4f6 6s2

Block: f

Period: 6 →Electronegativity: 1.17 →

Oxidation States: +2, +3

Abundance & Geochemistry

Crust Abundance: 7.05 mg/kg

Sea Abundance: 4.5e-7 mg/L

Geochemical Class: rare earth & related

Goldschmidt Class: litophile

About

Soft silvery metallic element, belongs to the lanthanoids. Seven natural isotopes, Sm-147 is the only radioisotope, and has a half-life of 2.5*10^11 years. Used for making special alloys needed in the production of nuclear reactors. Also used as a neutron absorber. Small quantities of samarium oxide is used in special optical glasses. The largest use of the element is its ferromagnetic alloy which produces permanent magnets that are five times stronger than magnets produced by any other material. Discovered by Francois Lecoq de Boisbaudran in 1879.

Isotopes

Sm-152 152 26.74%

Sm-154 154 22.74%

Sm-147 147 15.00%

Sm-149 149 13.82%

Sm-148 148 11.25%

Sm-150 150 7.37%

Sm-144 144 3.08%