మూస:హీలియం మూలకము

హీలియం, ₀₀He
హీలియం
Pronunciation	/ˈhiːliəm/ (HEE-lee-əm)
Appearance	colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
Standard atomic weight Ar°(He)
	4.002602±0.000002; 4.0026±0.0001 (abridged);
హీలియం in the periodic table
	హైడ్రోజన్ ← హీలియం → లిథియం
Group	మూస:Infobox element/symbol-to-group/format
Period	period 1
Block	s-block
Electron configuration	1s2
Electrons per shell	2
Physical properties
Phase at STP	gas
Melting point	(at 2.5 MPa) 0.95 K (−272.20 °C, −457.96 °F)
Boiling point	4.222 K (−268.928 °C, −452.070 °F)
Density (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	5R/2 = 20.786 J/(mol·K)
Atomic properties
Oxidation states	0
Electronegativity	Pauling scale: no data
Covalent radius	28 pm
Van der Waals radius	140 pm
	Spectral lines of హీలియం
Other properties
Natural occurrence	primordial
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
History
Discovery	Pierre Janssen, Norman Lockyer (1868)
First isolation	William Ramsay, Per Teodor Cleve, Abraham Langlet (1895)
Isotopes of హీలియం v; e;
	Template:infobox హీలియం isotopes does not exist
	Category: హీలియం; view; talk; edit; \| references

References

↑ "Standard Atomic Weights: Helium". CIAAW. 1983.
↑ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; et al. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry (in ఇంగ్లీష్). doi:10.1515/pac-2019-0603. ISSN 1365-3075.
↑ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.

[1] "Standard Atomic Weights: Helium". CIAAW. 1983.

[CIAAW2021-2] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; et al. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry (in ఇంగ్లీష్). doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[3] Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.

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