Periodic Table of Elements

Element Selenium - Se

Comprehensive data on the chemical element Selenium is provided on this page; including scores of properties, element names in many languages, most known nuclides of Selenium. Common chemical compounds are also provided for many elements. In addition technical terms are linked to their definitions and the menu contains links to related articles that are a great aid in one's studies.

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Overview of Selenium

Selenium's Name in Other Languages

  • Latin: Selenium
  • Czech: Selen
  • Croatian: Selenij
  • French: Sélénium
  • German: Selen - r
  • Italian: Selenio
  • Norwegian: Selen
  • Portuguese: Selênio
  • Russian: Селен
  • Spanish: Selenio
  • Swedish: Selen

Atomic Structure of Selenium

Chemical Properties of Selenium

Physical Properties of Selenium

  • Atomic Mass Average: 78.96
  • Boiling Point: 958K 685°C 1265°F
  • Coefficient of lineal thermal expansion/K-1: 36.9E-6
  • Conductivity
    Electrical: 1.0E-12 106/cm Ω
    Thermal: 0.0204 W/cmk
  • Density: 4.79g/cc @ 300K
  • Description:
    Dark gray lustrous rods or dark red crystals of non-metal. Burns in contact with air but is unaffected by water. Disolves in alkalis and concentrated HNO3.
  • Elastic Modulus:
    • Bulk: 8.3/GPa
    • Rigidity: 3.7/GPa
    • Youngs: 58/GPa
  • Enthalpy of Atomization: 205.9 kJ/mole @ 25°C
  • Enthalpy of Fusion: 6.69 kJ/mole
  • Enthalpy of Vaporization: 26.3 kJ/mole
  • Flammablity Class: Combustible Solid
  • Freezing Point: see melting point
  • Hardness Scale
    • Brinell: 736 MN m-2
    • Mohs: 2
  • Heat of Vaporization: 37.7kJ/mol
  • Melting Point: 494K 221°C 430°F
  • Molar Volume: 16.42 cm3/mole
  • Optical Refractive Index: 1.000895
  • Physical State (at 20°C & 1atm): Solid
  • Specific Heat: 0.32J/gK
  • Vapor Pressure = 0.695Pa@221°C

Regulatory / Health

  • CAS Number
    • 7782-49-2 powder
  • UN/NA ID and ERG Guide Number
    • 2658  / 152 powder
  • RTECS: VS7700000
  • OSHA Permissible Exposure Limit (PEL)
  • OSHA PEL Vacated 1989
  • NIOSH Recommended Exposure Limit (REL)
  • Routes of Exposure: Inhalation; Ingestion; Skin and/or eye contact
  • Target Organs: Eyes, skin, respiratory system, liver, kidneys, blood, spleen
  • Levels In Humans:
    Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
    • Blood/mg dm-3: 0.171
    • Bone/p.p.m: 1-9
    • Liver/p.p.m: 0.35-2.4
    • Muscle/p.p.m: 0.42-1.9
    • Daily Dietary Intake: 0.006-0.2 mg
    • Total Mass In Avg. 70kg human: 10-65 mg

Who / Where / When / How

  • Discoverer: Jöns J. Berzelius
  • Discovery Location: Stockholm Sweden
  • Discovery Year: 1817
  • Name Origin:
    Greek: Selênê (Moon)
  • Abundance of Selenium:
    • Earth's Crust/p.p.m.: 0.05
    • Seawater/p.p.m.:
      • Atlantic Suface: 4.6E-08
      • Atlantic Deep: 1.8E-07
      • Pacific Surface: 1.5E-08
      • Pacific Deep: 1.65E-07
    • Atmosphere/p.p.m.: N/A
    • Sun (Relative to H=1E12): N/A
  • Sources of Selenium:
    Obtained as a by-product of lead, copper and nickel refining. World wide annual production is around 600 tons. Primary mining areas are Canada, USA, Bolivia and Russia.
  • Uses of Selenium:
    Used in photoelectric cells, TV cameras, as a semiconductor in solar batteries, light meters, copy machines, anti-dandruff shampoo and rectifiers. Also colors glass red.
  • Additional Notes:
    A dose of selenium as small as 5 mg per day can be lethal for many humans.

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A list of reference sources used to compile the data provided on our periodic table of elements can be found on the main periodic table page.

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