Selenio

Selenium
34Se
S ↑ Se ↓ Te Periodic table arsenic ← selenium → bromine
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	16, 4, p
Standard atomic weight	78.96
Electron configuration	[Ar] 3d10 4s2 4p4 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, -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
Magnetic ordering	diamagnetic
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 β−β− 2.995 82Kr

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.

Galeriya sa hulagway

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