ଛାଞ୍ଚ:Infobox helium

Helium,  ₂He

Spectral lines of helium
ସାଧାରଣ ଗୁଣ
ନାମ, ପ୍ରତୀକ	helium, He
Appearance	colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
ଉଚ୍ଚାରଣ	/ˈhiːliəm/ HEE-lee-əm
Helium in the periodic table
- ↑ He ↓ Ne hydrogen ← helium → lithium
ପରମାଣୁ କ୍ରମାଙ୍କ (Z)	2
ଶ୍ରେଣୀ, ବ୍ଳକ	group 18 (noble gases), s-block
ପର୍ଯ୍ୟାୟ	period 1
ମୌଳିକ ପ୍ରକାର	noble gas
ମାନକ ପରମାଣବିକ ଓଜନ (±) (Ar)	4.002602(2)
ଇଲେକ୍‌ଟ୍ରୋନ୍ ବିନ୍ୟାସ	1s2
per shell	2
ଭୌତିକ ଗୁଣ
ଅବସ୍ଥା	gas
ଗଳନାଙ୍କ	(at 2.5 MPa) 0.95 K ​(−272.20 °C, ​−457.96 °F)
ସ୍ଫୁଟନାଙ୍କ	4.22 K ​(−268.93 °C, ​−452.07 °F)
ଘନତା at stp (0 °C and 101.325 kPa)	0.1786 g/L
when liquid, at m.p.	0.145 g/cm3
when liquid, at b.p.	0.125 g/cm3
Critical point	5.19 K, 0.227 MPa
Heat of fusion	0.0138 kJ/mol
Heat of	0.0829 kJ/mol
Molar heat capacity	5R/2 = 20.786 J/(mol·K)
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
Atomic properties
Oxidation states	0
Electronegativity	Pauling scale: no data
Covalent radius	28 pm
Van der Waals radius	140 pm
Miscellanea
Crystal structure	​hexagonal close-packed (hcp)
Speed of sound	972 m/s
Thermal conductivity	0.1513 W/(m·K)
Magnetic ordering	diamagnetic
CAS Number	7440-59-7
ଇତିହାସ
ଆବିଷ୍କାର	Pierre Janssen, Norman Lockyer (1868)
First isolation	William Ramsay, Per Teodor Cleve, Abraham Langlet (1895)
Most stable isotopes of helium
iso NA half-life DM DE (MeV) DP 3He 0.000137%* 3He is stable with 1 neutron 4He 99.999863%* 4He is stable with 2 neutrons
Atmospheric value, abundance may differ elsewhere.

References

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