विकिपिडिया, एक स्वतन्त्र विश्वकोशबाट
हेलियम, 00 He Pronunciation (HEE -lee-əm ) Appearance colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
Group group 18 (noble gases) Period period 1 Block s-block Electron configuration 1s2 Electrons per shell 2 Phase at STP gas Melting point 0.95 K (−272.20 °C, −457.96 °F) (at 2.5 MPa) 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 20.78[१] 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
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 Spectral lines of हेलियमNatural occurrence primordial Crystal structure hexagonal close-packed (hcp) Thermal conductivity 0.1513 W/(m⋅K) Magnetic ordering diamagnetic [२] Speed of sound 972 m/s CAS Number 7440-59-7 Naming after Helios , Greek god of the Sun Discovery Pierre Janssen , Norman Lockyer (1868) First isolation William Ramsay , Per Teodor Cleve , Abraham Langlet (1895) Template:infobox हेलियम isotopes does not exist ढाँचा:Category-inline | references
हीलियम लेजर
हेलियम सबैभन्दा हलुको ग्यस हो र यो सबैभन्दा कम आणविक संख्या भएको निस्क्रिय ग्यास पनि हो। येसलाई सङ्केत He ले जनाइन्छ।
↑ Shuen-Chen Hwang, Robert D. Lein, Daniel A. Morgan (2005). "Noble Gases". Kirk Othmer Encyclopedia of Chemical Technology. Wiley. pp. 343–383. doi:10.1002/0471238961.0701190508230114.a01.
↑ Magnetic susceptibility of the elements and inorganic compounds , in Handbook of Chemistry and Physics 81st edition, CRC press.