Se

Selenium

Identification

CAS Number: 7782-49-2

Discovery Year: 1818

Discoverer: Jöns Berzelius

Discovery Location: Sweden

Properties

Atomic Mass: 78.971 →Density: 4.809 g/cm³ →

Crust Abundance: 0.05 mg/kg

Crystal Structure: HEX

Atomic Dimensions

Atomic Radius: 115 pm →

Atomic Radius (Rahm): 224.00000000000003 pm

Covalent Radius: 120 pm →

Van der Waals Radius: 190 pm

Metallic Radius: 117 pm

Atomic Volume: 16.5 cm³/mol

Lattice Constant: 4.36 Å

Thermodynamics

Melting Point: 490 K →Boiling Point: 958.1 K →Thermal Conductivity: 0.52 W/(m·K) →Heat of Fusion: 5.23 kJ/mol →Heat of Vaporization: 59.7 kJ/mol →

Heat of Formation: 227.2 kJ/mol

Electronic Structure

Electron Config: [Ar] 3d10 4s2 4p4

Block: p

Period: 4 →Group: 16 →Electronegativity: 2.55 →Electron Affinity: 2.02067 eV →

Oxidation States: -2, +4, +6

Abundance & Geochemistry

Crust Abundance: 0.05 mg/kg

Sea Abundance: 0.0002 mg/L

Geochemical Class: semi-volatile

Goldschmidt Class: chalcophile

About

Metalloid element, belongs to group 16 of the periodic table. Multiple allotropic forms exist. Chemically resembles sulphur. Discovered in 1817 by Jons J. Berzelius.

Isotopes

Se-80 80 49.80%

Se-78 78 23.69%

Se-76 76 9.23%

Se-82 82 8.82%

Se-77 77 7.60%

Se-74 74 0.8600%