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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Selenium Menu

Selenium Page OneOverview of SeleniumSelenium"s Name in Other LanguagesAtomic Structure of SeleniumChemical Properties of SeleniumPhysical Properties of SeleniumRegulatory / HealthWho/When/Where/HowSelenium Page TwoNuclides / IsotopesPotential Parent NuclidesSelenium Page ThreeCommon Chemical Compounds of Selenium

Overview of Selenium

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

Selenium"s Name in Other Languages

Latin: SeleniumCzech: SelenCroatian: SelenijFrench: SéléniumGerman: Selen - rItalian: SelenioNorwegian: SelenPortuguese: SelênioRussian: СеленSpanish: SelenioSwedish: SelenAtomic Structure of SeleniumAtomic Radius: 1.22ÅAtomic Volume: 16.45cm3/molCovalent Radius: 1.16ÅCross Section (Thermal Neutron Capture) σa/barns: 11.7Crystal Structure: Hexagonal
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Electron Configuration:1s2 2s2p6 3s2p6d10 4s2p4Electrons per Energy Level: 2,8,18,6Shell Model
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Ionic Radius:
0.5ÅFilling Orbital: 4p4Number of Electrons (with no charge): 34Number of Neutrons (most common/stable nuclide): 45Number of Protons: 34Oxidation States: ±2,4,6Valence Electrons: 4s2p4Electron Dot Model
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Chemical Properties of Selenium

Electrochemical Equivalent:
0.7365g/amp-hrElectron Work Function: 5.9eVElectronegativity: 2.55 (Pauling); 2.48 (Allrod Rochow)Heat of Fusion: 6.694kJ/molIncompatibilities:Acids, strong oxidizers, chromium trioxide, potassium bromate, cadmiumIonization PotentialFirst: 9.752Second: 21.19Third: 30.82Valence Electron Potential (-eV): 120

Physical Properties of Selenium

Atomic Mass Average: 78.96Boiling Point: 958K 685°C 1265°FCoefficient of lineal thermal expansion/K-1: 36.9E-6ConductivityElectrical: 1.0E-12 106/cm ΩThermal: 0.0204 W/cmkDensity: 4.79g/cc
300KDescription: 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/GPaRigidity: 3.7/GPaYoungs: 58/GPaEnthalpy of Atomization: 205.9 kJ/mole
25°CEnthalpy of Fusion: 6.69 kJ/moleEnthalpy of Vaporization: 26.3 kJ/moleFlammablity Class: Combustible SolidFreezing Point: see melting pointHardness ScaleBrinell: 736 MN m-2Mohs: 2Heat of Vaporization: 37.7kJ/molMelting Point: 494K 221°C 430°FMolar Volume: 16.42 cm3/moleOptical Refractive Index: 1.000895Physical State (at 20°C & 1atm): SolidSpecific Heat: 0.32J/gKVapor Pressure = 0.695Pa
221°C

Regulatory / Health

CAS Number7782-49-2powderUN/NA ID and ERG Guide Number2658 / 152powderRTECS: VS7700000OSHA Permissible Exposure Limit (PEL)TWA: 0.2 mg/m3OSHA PEL Vacated 1989TWA: 0.2 mg/m3NIOSH Recommended Exposure Limit (REL)TWA: 0.2 mg/m3IDLH: 1 mg/m3 Routes of Exposure: Inhalation; Ingestion; Skin and/or eye contactTarget Organs: Eyes, skin, respiratory system, liver, kidneys, blood, spleenLevels 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: 0.171Bone/p.p.m: 1-9Liver/p.p.m: 0.35-2.4Muscle/p.p.m: 0.42-1.9Daily Dietary Intake: 0.006-0.2 mgTotal Mass In Avg. 70kg human: 10-65 mg

Who / Where / When / How

Discoverer: Jöns J. BerzeliusDiscovery Location: Stockholm SwedenDiscovery Year: 1817Name Origin:Greek: Selênê (Moon)Abundance of Selenium:Earth"s Crust/p.p.m.: 0.05Seawater/p.p.m.: Atlantic Suface: 4.6E-08Atlantic Deep: 1.8E-07Pacific Surface: 1.5E-08Pacific Deep: 1.65E-07Atmosphere/p.p.m.: N/ASun (Relative to H=1E12): N/ASources 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.

Selenium Menu

Selenium Page OneOverview of SeleniumSelenium"s Name in Other LanguagesAtomic Structure of SeleniumChemical Properties of SeleniumPhysical Properties of SeleniumRegulatory / HealthWho/When/Where/HowSelenium Page TwoNuclides / IsotopesPotential Parent NuclidesSelenium Page ThreeCommon Chemical Compounds of Selenium

References

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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