کينډۍ:Infobox selenium

Selenium,  ₃₄Se

عمومي خواص
Pronunciation	/sɪˈliːniəm/ SI-LEE-NEE-əm
Appearance	black, red, and gray (not pictured) allotropes
Selenium په دوراني جدول کې
S ↑ Se ↓ Te arsenic ← selenium → bromine ‍
اټومي شمیره (Z)	34
گروپ, پیریود	group 16 (chalcogens), period 4
بلاک	p-block
Element category	polyatomic nonmetal, sometimes considered a metalloid
معياري اټومي وزن (Ar)	کينډۍ:Val
Electron configuration	[Ar] 3d10 4s2 4p4
Electrons per shell	2, 8, 18, 6
فزیکي خواص
حالت (at STP)	جامد
دويلې کيدو ټکى	494 K ​(221 °C, ​430 °F)
يشنا ټکی	958 K ​(685 °C, ​1265 °F)
Density 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 vaporization	95.48 kJ/mol
Molar heat capacity	25.363 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 500 552 617 704 813 958
اټومي خواص
Oxidation states	6, 5, 4, 3, 2, 1, −1, −2 ​(a strongly acidic oxide)
Electronegativity	Pauling scale: 2.55
Ionization energies	1st: 941.0 kJ/mol 2nd: 2045 kJ/mol 3rd: 2973.7 kJ/mol
Atomic radius	empirical: 120 pm
Covalent radius	120±4 pm
Van der Waals radius	190 pm
Miscellanea
Crystal structure	​hexagonal Hexagonal crystal structure for selenium
Speed of sound thin rod	3350 m/s (at 20 °C)
Thermal expansion	amorphous: 37 µm/(m·K) (at 25 °C)
د تودوخې تېرېدنه	amorphous: 0.519 W/(m·K)
Magnetic ordering	diamagnetic
Magnetic susceptibility (χmol)	−25.0·10−6 cm3/mol (298 K)
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
History
Naming	after Selene, Greek goddess of the moon
Discovery and first isolation	Jöns Jakob Berzelius and Johann Gottlieb Gahn (1817)
Main isotopes of selenium
آيسو­ټوپ Abun­dance نیم ژوند (t1/2) Decay mode Pro­duct 74Se 0.86% stable 76Se 9.23% stable 77Se 7.60% stable 78Se 23.69% stable 79Se trace 3.27×105 y β− 79Br 80Se 49.80% stable 82Se 8.82% 1.08×1020 y β−β− 82Kr

Element navigation

PTseleniumPT

As ←

iso 34Se ibox    wd:Q876

→ Br

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