Th

Thorium

Identification

CAS Number: 7440-29-1

Discovery Year: 1828

Discoverer: Jöns Berzelius

Discovery Location: Sweden

Properties

Atomic Mass: 232.0377 →Density: 11.7 g/cm³ →

Crust Abundance: 9.6 mg/kg

Crystal Structure: FCC

Atomic Dimensions

Atomic Radius: 180 pm →

Atomic Radius (Rahm): 288 pm

Covalent Radius: 206 pm →

Van der Waals Radius: 245.00000000000003 pm

Atomic Volume: 19.8 cm³/mol

Lattice Constant: 5.08 Å

Thermodynamics

Melting Point: 2028 K →Boiling Point: 5060 K →Specific Heat: 0.113 J/(g·K) →Heat of Fusion: 16.11 kJ/mol →Heat of Vaporization: 513.7 kJ/mol →

Heat of Formation: 602 kJ/mol

Electronic Structure

Electron Config: [Rn] 6d2 7s2

Block: f

Period: 7 →Electronegativity: 1.3 →

Oxidation States: +4

Abundance & Geochemistry

Crust Abundance: 9.6 mg/kg

Sea Abundance: 0.000001 mg/L

Geochemical Class: rare earth & related

Goldschmidt Class: litophile

About

Grey radioactive metallic element. Belongs to actinoids. Found in monazite sand in Brazil, India and the US. Thorium-232 has a half-life of 1.39x10^10 years. Can be used as a nuclear fuel for breeder reactors. Thorium-232 captures slow Neutrons and breeds uranium-233. Discovered by Jons J. Berzelius in 1829.

Isotopes

Th-232 232 99.98%

Th-230 230 0.0200%