Selenio

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Selenium
34Se
S

Se

Te
arsenicseleniumbromine
Appearance
black and red allotropes
General properties
Name, simbolo, kaiphan selenium, Se, 34
Pronunciation Plantilya:IPAc-en Plantilya:Respell
Element category wala puthaw
sometimes considered a metalloid
Group, period, block 164, p
Standard atomic weight 78.96
Electron configuration [Ar] 3d10 4s2 4p4
2, 8, 18, 6
Electron shells of selenium (2, 8, 18, 6)
History
Discovery Jöns Jakob Berzelius and Johann Gottlieb Gahn (1817)
First isolation Jöns Jakob Berzelius and Johann Gottlieb Gahn (1817)
Physical properties
Phase magahi
Density (near r.t.) (gray) 4.81 g·cm−3
Density (near r.t.) (alpha) 4.39 g·cm−3
Density (near r.t.) (vitreous) 4.28 g·cm−3
Liquid density at m.p. 3.99 g·cm−3
Melting point 494 K, 221 °C, 430 °F
Boiling point 958 K, 685 °C, 1265 °F
Critical point 1766 K, 27.2 MPa
Heat of fusion (gray) 6.69 kJ·mol−1
Heat of vaporization 95.48 kJ·mol−1
Molar heat capacity 25.363 J·mol−1·K−1
Vapor 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 6, 4, 2, 1,[1] -2
(strongly acidic oxide)
Electronegativity 2.55 (Pauling scale)
Ionization energies 1st: 941.0 kJ·mol−1
2nd: 2045 kJ·mol−1
3rd: 2973.7 kJ·mol−1
Atomic radius 120 pm
Covalent radius 120±4 pm
Van der Waals radius 190 pm
Miscellanea
Crystal structure hexagonal
Selenium has a hexagonal crystal structure
Magnetic ordering diamagnetic[2]
Thermal conductivity (amorphous) 0.519 W·m−1·K−1
Thermal expansion (25 °C) (amorphous) 37 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 3350 m·s−1
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 registry number 7782-49-2
Most stable isotopes
Main article: Isotopes of selenium
iso NA half-life DM DE (MeV) DP
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 3.27×105 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
t  h  u
· r

Ang selenio (Iningles selenium) mao ang elementong kimiko sa talaang peryodiko nga may simbolo nga Se ug kaiphan nga atomik 34. Ang selenio mao ang wala puthaw.

Ang mga gi basihan niini[usba | edit source]

  1. Plantilya:Greenwood&Earnshaw
  2. Magnetic susceptibility of the elements and inorganic compounds, in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5. 


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