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Selenium

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Selenium, 34Se
Selenium
Pípè /sˈlniəm/ (sə-LEE-nee-əm)
ÌhànsójúBlack, gray, and red allotropes
Ìwúwo átọ̀mù Ar, std(Se)78.971(8)[1]
Selenium ní orí tábìlì àyè
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
S

Se

Te
arsenicseleniumbromine
Nọ́mbà átọ̀mù (Z)34
Ẹgbẹ́group 16 (chalcogens)
Àyèàyè 4
Àdìpọ̀Àdìpọ̀-p
Ẹ̀ka ẹ́límẹ́ntì  Reactive nonmetal
Ìtò ẹ̀lẹ́ktrọ́nù[Ar] 3d10 4s2 4p4
Iye ẹ̀lẹ́ktrọ́nù lórí ìpele kọ̀ọ̀kan2, 8, 18, 6
Àwọn ohun ìní ara
Ìfarahàn at STPsolid
Ìgbà ìyọ́494 K ​(221 °C, ​430 °F)
Ígbà ìhó958 K ​(685 °C, ​1265 °F)
Kíki (near r.t.)(gray) 4.81 g/cm3
(alpha) 4.39 g/cm3
(vitreous) 4.28 g/cm3
when liquid (at m.p.)3.99 g/cm3
Critical point1766 K, 27.2 MPa
Heat of fusion(gray) 6.69 kJ/mol
Heat of 95.48 kJ/mol
Molar heat capacity25.363 J/(mol·K)
 pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 500 552 617 704 813 958
Atomic properties
Oxidation states−2, −1, +1,[2] +2, +3, +4, +5, +6 Àdàkọ:Infobox element/symbol-to-oxidation-state/comment
ElectronegativityPauling scale: 2.55
Atomic radiusempirical: 120 pm
Covalent radius120±4 pm
Van der Waals radius190 pm
Color lines in a spectral range
Color lines in a spectral range
Spectral lines of selenium
Other properties
Natural occurrenceprimordial
Crystal structurehexagonal
Hexagonal crystal structure for selenium
Speed of sound thin rod3350 m/s (at 20 °C)
Thermal expansion(amorphous) 37 µm/(m·K) (at 25 °C)
Thermal conductivity(amorphous) 0.519 W/(m·K)
Magnetic orderingdiamagnetic[3]
Young's modulus10 GPa
Shear modulus3.7 GPa
Bulk modulus8.3 GPa
Poisson ratio0.33
Mohs hardness2.0
Brinell hardness736 MPa
CAS Number7782-49-2
Main isotopes of selenium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
72Se syn 8.4 d ε - 72As
γ 0.046 -
74Se 0.87% 74Se is stable with 40 neutrons
75Se syn 119.779 d ε - 75As
γ 0.264, 0.136,
0.279
-
76Se 9.36% 76Se is stable with 42 neutrons
77Se 7.63% 77Se is stable with 43 neutrons
78Se 23.78% 78Se is stable with 44 neutrons
79Se trace 2.95×105 y β 0.151 79Br
80Se 49.61% 80Se is stable with 46 neutrons
82Se 8.73% 1.08×1020 y ββ 2.995 82Kr
Àdàkọ:Category-inline
| references



  1. Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305. 
  2. Àdàkọ:Greenwood&Earnshaw
  3. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  4. "Selenium : Selenium(I) chloride compound data". WebElements.com. Retrieved 2007-12-10.