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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 studies. Using the "Periodic Table of Elements Quick Navigation" graphic at the bottom of the sidebar menu, one can quickly jump from chemical element to chemical element.

Selenium Menu

• Selenium Page One
  • Overview of Selenium
  • Selenium's Name in Other Languages
  • Atomic Structure of Selenium
  • Chemical Properties of Selenium
  • Physical Properties of Selenium
  • Regulatory / Health
  • Who/When/Where/How
• Selenium Page Two
  • Nuclides / Isotopes
  • Potential Parent Nuclides
• Selenium Page Three
  • Common Chemical Compounds of Selenium

Overview of Selenium

• Atomic Number:34
• Group: 16
• Period: 4
• Series: Nonmetals

Selenium's Name in Other Languages

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

Atomic Structure of Selenium

• Atomic Radius: 1.22Å
• Atomic Volume: 16.45cm³/mol
• Covalent Radius: 1.16Å
• Cross Section (Thermal Neutron Capture) _a/barns: 11.7
• Crystal Structure: Hexagonal

  

• Electron Configuration:

  1s² 2s²p⁶ 3s²p⁶d¹⁰ 4s²p⁴

• Electrons per Energy Level: 2,8,18,6

  Shell Model
  

• Ionic Radius: 0.5Å
• Filling Orbital: 4p⁴
• Number of Electrons (with no charge): 34
• Number of Neutrons (most common/stable nuclide): 45
• Number of Protons: 34
• Oxidation States: ±2,4,6
• Valence Electrons: 4s²p⁴

  Electron Dot Model
  

Chemical Properties of Selenium

• Electrochemical Equivalent: 0.7365g/amp-hr
• Electron Work Function: 5.9eV
• Electronegativity: 2.55 (Pauling); 2.48 (Allrod Rochow)
• Heat of Fusion: 6.694kJ/mol
• Incompatibilities:

  Acids, strong oxidizers, chromium trioxide, potassium bromate, cadmium

• Ionization Potential
  • First: 9.752
  • Second: 21.19
  • Third: 30.82
• Valence Electron Potential (-eV): 120

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
  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)
  • TWA: 0.2 mg/m³
• OSHA PEL Vacated 1989
  • TWA: 0.2 mg/m³
• NIOSH Recommended Exposure Limit (REL)
  • TWA: 0.2 mg/m³
  • IDLH: 1 mg/m³
• 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.

[Last update: 2/22/2007]

Selenium Menu

• Selenium Page One
  • Overview of Selenium
  • Selenium's Name in Other Languages
  • Atomic Structure of Selenium
  • Chemical Properties of Selenium
  • Physical Properties of Selenium
  • Regulatory / Health
  • Who/When/Where/How
• Selenium Page Two
  • Nuclides / Isotopes
  • Potential Parent Nuclides
• Selenium Page Three
  • Common Chemical Compounds of Selenium

Related Resources

• Anatomy of the Atom
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• Molarity, Molality and Normality
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• Molar Mass Calculations and Javascript Calculator
  Molar mass calculations are explained and there is a JavaScript calculator to aid calculations.
• Chemical Database
  This database focuses on the most common chemical compounds used in the home and industry.

Citing this page

If you need to cite this page, you can copy this text:

Kenneth Barbalace. Periodic Table of Elements - Selenium – Se. EnvironmentalChemistry.com. 1995 - 2009. Accessed on-line: 7/4/2009
http://EnvironmentalChemistry.com/yogi/periodic/Se.html
.