هېليوم

Helium, ₂He
	Spectral lines of helium
عمومي خواص
Pronunciation	/ˈhiːliəm/ ; HEE-lee-əm
Appearance	colorless gas, exhibiting a red-orange glow when placed in an electric field
Helium په دوراني جدول کې
hydrogen ← helium → lithium	‍
اټومي شمیره (Z)	2
گروپ, پیریود	group 18 (noble gases), period 1
بلاک	s-block
Element category	noble gas
معياري اټومي وزن (Ar)	کينډۍ:Val
Electron configuration	1s2
Electrons per shell	2
فزیکي خواص
حالت (at STP)	گاز
دويلې کيدو ټکى	0.95 K (−272.20 °C, −457.96 °F) (at 2.5 MPa)
يشنا ټکی	4.222 K (−268.928 °C, −452.070 °F)
کثافت (at STP)	0.1786 g/L
when liquid, at m.p.	0.145 g/cm3
when liquid, at b.p.	0.125 g/cm3
Triple point	2.177 K, 5.043 kPa
Critical point	5.1953 K, 0.22746 MPa
Heat of fusion	0.0138 kJ/mol
Heat of vaporization	0.0829 kJ/mol
Molar heat capacity	20.78 J/(mol·K)
اټومي خواص
Oxidation states	0
Electronegativity	Pauling scale: no data
Ionization energies	1st: 2372.3 kJ/mol ; 2nd: 5250.5 kJ/mol ; ;
Covalent radius	28 pm
Van der Waals radius	140 pm
Miscellanea
Crystal structure	hexagonal close-packed (hcp) Hexagonal close-packed crystal structure for helium
Speed of sound	972 m/s
د تودوخې تېرېدنه	0.1513 W/(m·K)
Magnetic ordering	diamagnetic
Magnetic susceptibility (χmol)	−1.88·10−6 cm3/mol (298 K)
CAS Number	7440-59-7
History
Naming	after Helios, Greek god of the Sun
Discovery	Pierre Janssen, Norman Lockyer (1868)
First isolation	William Ramsay, Per Teodor Cleve, Abraham Langlet (1895)
Main isotopes of helium
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هېليوم (په انگرېزي: Helium) له کیمیاوي عناصرو څخه یو دی چې په تناوبي جدول کې د He سمبول او ۲ اتمي شمېرې په وسیله ښودل شوی دی.

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