• Latin name:
  Selenium
• English name:
  Selenium
• Year discovered:
  1817
• Discovered by:
  Jöns Jakob Berzelius
• Country of Discovery:
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• Cost per 100 grams:
  28 USD
• CAS Number:
  CAS7782-49-2
• Electron shell:
  K2-L8-M18-N6-O0-P0-Q0-R0

Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between those of its periodic table column-adjacent chalcogen elements sulfur and tellurium. It rarely occurs in its elemental state in nature, or as pure ore compounds.

• Atomic number:
  34
• Atomic weight (Relative atomic mass):
  78.9710814817005 (g/mol)
• Density:
  4.81 (g/cm³)
• Melting point:
  221.0°C = 429.80°F = 494.15K
• Boiling point:
  685.0°C = 1265.00°F = 958.15K
• Valence electrons:
  2, 4, 6
• Period:
  4
• Group:
  VIA
• Block:
  p - block
• Emission spectrum:
  

• Phase:
  Solid

  
• Fusion heat:
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• Specific heat:
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• Thermal expansion:
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• Vaporization heat:
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• Electron configuration:
  [Ar] 3d10 4s2 4p4 = 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p4
Oxidation states:

• -
• -1
• -2
• -
• -
• -
• +1
• +2
• -
• +4
• -
• +6
• -
• -
• -
• Ion charge:
  Se^2-
• The ionization potential of an atom:
  9.752 (eV)
• Atomic radius:
  103 (pm)
• Covalent radius:
  118 (pm)
• Van der Waals radius:
  190 (pm)

• Electrical conductivity:
  83333333.3333333 (S/m)
• Electrical type:
  ----
• Magnetic type:
  Diamagnetism
• Volume magnetic susceptibility:
  -1.93 ⋅ 10^-5
• Mass magnetic susceptibility:
  -4 ⋅ 10^-9
• Molar magnetic susceptibility:
  -3.16 ⋅ 10^-10 (m³/mol)
• Resistivity:
  1.2 ⋅ 10¹⁰ (Ω · m)
• Superconducting point:
  ----

• Debye temperature:
  -183.15°C = -297.67°F = 90K

• Colour:
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• CAS Number:
  CAS7782-49-2
• CID Number:
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• RTEC Number:
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• Brinell hardness:
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• Mohs hardness:
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• Vickers hardness:
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• Bulk modulus:
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• Young's modulus:
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• Liquid density:
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• Molar volume:
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• Poisson's ratio:
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• Shear modulus:
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• Speed of sound transmission:
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• Refractive index:
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• Thermal conductivity:
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• Electronegativity:
  2.55
• Valence electrons:
  2, 4, 6
• Electron affinity:
  194.9587 kJ/mole

• Radioactive:
  No
• Half life:
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• Lifetime:
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• Neutron cross section, barn:
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• Universe contains "Selenium" at the rate of
  3 ⋅ 10^-6%
• Sun contains "Selenium" at the rate of
  ----
• Oceans contain "Selenium" at the rate of
  4.5 ⋅ 10^-6%
• Human body contains "Selenium" at the rate of
  2.140230508 ⋅ 10^-5%
• The Earth's crust consists of "Selenium" at the rate of
  5.0⋅ 10^-6%
• Meteorites consist of "Selenium" at the rate of
  0.0013%