Selenium, 34 Se Selenium Pípè / s ᵻ ˈ l iː n i ə m / (sə-LEE -nee-əm ) Ìhànsójú Black, gray, and red allotropes Ìwúwo átọ̀mù A r, std (Se) 78.971(8) [ 1] Selenium ní orí tábìlì àyè
Nọ́mbà átọ̀mù (Z ) 34 Ẹgbẹ́ group 16 (chalcogens) Àyè àyè 4 Àdìpọ̀ Àdìpọ̀-p Ẹ̀ka ẹ́límẹ́ntì Reactive nonmetal Ìtò ẹ̀lẹ́ktrọ́nù [Ar ] 3d10 4s2 4p4 Iye ẹ̀lẹ́ktrọ́nù lórí ìpele kọ̀ọ̀kan 2, 8, 18, 6 Àwọn ohun ìní ara Ìfarahàn at STP solid Ìgbà ìyọ́ 494 K (221 °C, 430 °F) Ígbà ìhó 958 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 point 1766 K, 27.2 MPa Heat of fusion (gray) 6.69 kJ/mol Heat of 95.48 kJ/mol Molar heat capacity 25.363 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 Electronegativity Pauling scale: 2.55 Atomic radius empirical: 120 pm Covalent radius 120±4 pm Van der Waals radius 190 pm Color lines in a spectral range Spectral lines of seleniumOther properties Natural occurrence primordial Crystal structure hexagonal Speed of sound thin rod 3350 m/s (at 20 °C) Thermal expansion (amorphous) 37 µm/(m·K) (at 25 °C) Thermal conductivity (amorphous) 0.519 W/(m·K) Magnetic ordering diamagnetic [ 3] Young's modulus 10 GPa Shear modulus 3.7 GPa Bulk modulus 8.3 GPa Poisson ratio 0.33 Mohs hardness 2.0 Brinell hardness 736 MPa CAS Number 7782-49-2 Main isotopes of selenium
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References
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↑ 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 .
↑ Àdàkọ:Greenwood&Earnshaw
↑ Magnetic susceptibility of the elements and inorganic compounds , in Handbook of Chemistry and Physics 81st edition, CRC press.
↑ "Selenium : Selenium(I) chloride compound data" . WebElements.com. Retrieved 2007-12-10 .