General: |
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Name: Selenium
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Symbol: Se
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Group: Non-Metal, Chalcogen
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Atomic weight: 78.96
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Density @ 293 K: 4.79 g/cm3
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Atomic volume: 16.45 cm3/mol
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Group: Non-Metal, Chalcogen
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discovered: 1818
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States: |
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state (s, l, g): s
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melting point: 490.2 K
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boiling point: 958 K
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Heat of fusion: 6.694 kJ/mol
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Heat of vaporization: 37.70 kJ/mol
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Energies: |
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1st ionization energy: 940.9 kJ/mole
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electronegativity: 2.55
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2nd ionization energy: 2044.5 kJ/mole
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electron affinity: 194.97 kJ/mole
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3rd ionization energy: 2973.7 kJ/mole
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Specific heat: 0.32 J/gK
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heat atomization: 227 kJ/mole atoms
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Oxidation & Electrons: |
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Shells: 2,8,18,6
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electron configuration: [Ar] 3d10 4s2 4p4
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minimum oxidation number: -2
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maximum oxidation number: 6
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min. common oxidation no.: -2
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max. common oxidation no.: 6
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Appearance & Characteristics: |
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structure: parallel chains
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color: black
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uses: Xerography, medicines
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toxicity: yes
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hardness: 2 mohs
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characteristics: 6 forms
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Reactions: |
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reaction with air: vigorous, w/ht =>SeO2
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reaction with 6M HCl: none
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reaction with 6M HCl: none
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reaction with 15M HNO3: mild, =>H2SeO3, NOx
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reaction with 6M NaOH:
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Other Forms: |
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number of isotopes: 6
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hydride(s): SeH2
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oxide(s): SeO2 SeO3
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chloride(s): Se2Cl2 Se4Cl16
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Radius: |
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ionic radius (2- ion): 184 pm
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ionic radius (1- ion): pm
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atomic radius: 119 pm
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ionic radius (1+ ion): pm
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ionic radius (2+ ion): pm
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ionic radius (3+ ion): pm
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Conductivity: |
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thermal conductivity: 0.52 J/m-sec-deg
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electrical conductivity: 0 1/mohm-cm
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polarizability: 3.8 A^3
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Abundance: |
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source: Cu smelting by-product
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rel. abund. solar system: 1.793 log
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abundance earth's crust: -1.3 log
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cost, pure: 14 $/100g
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cost, bulk: $/100g
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