کينډۍ:Infobox helium

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
– ↑ He ↓ Ne 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)
Vapor pressure (defined by ITS-90) P (Pa) 1 10 100 1 k 10 k 100 k at T (K)     1.23 1.67 2.48 4.21
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
آيسو­ټوپ Abun­dance نیم ژوند (t1/2) Decay mode Pro­duct 3He 0.0002% stable 4He 99.9998% stable

Element navigation

PTheliumPT

H ←

iso 2He ibox    wd:Q560

→ Li

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