Plantilya:Infobox helium

Helium
2He
- ↑ He ↓ Ne Periodic table hydrogen ← helium → lithium
Panagway
colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field Spectral lines of helium
Kinatibuk-ang mga kinaiya
Ngalan, simbolo, kaiphan	helium, He, 2
Paglitok	/ˈhiːliəm/ [[Help:Pronunciation respelling key|Plantilya:Smallcaps all-lee-əm]]
Kategoriyang elemento	gas nga halangdon
Group, period, block	18, 1, s
Gibug-aton sa atomo	4.002602(2)
Kontorno sa elektron	1s2 2 Electron shells of helium (2)
History
Pagkadiskobre	Pierre Janssen, Norman Lockyer (1868)
First isolation	William Ramsay, Per Teodor Cleve, Abraham Langlet (1895)
Physical properties
Phase	gas
Density	(0 °C, 101.325 kPa) 0.1786 g/L
Liquid density at m.p.	0.145 g·cm−3
Liquid density at b.p.	0.125 g·cm−3
Melting point	(at 2.5 MPa) 0.95 K, −272.20 °C, −457.96 °F
Boiling point	4.22 K, −268.93 °C, −452.07 °F
Critical point	5.19 K, 0.227 MPa
Heat of fusion	0.0138 kJ·mol−1
Heat of vaporization	0.0829 kJ·mol−1
Molar heat capacity	5R/2 = 20.786 J·mol−1·K−1
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
Atomic properties
Oxidation states	0
Electronegativity	no data (Pauling scale)
Ionization energies	1st: 2372.3 kJ·mol−1
	2nd: 5250.5 kJ·mol−1
Covalent radius	28 pm
Van der Waals radius	140 pm
Miscellanea
Crystal structure	hexagonal close-packed
Magnetic ordering	diamagnetic
Thermal conductivity	0.1513 W·m−1·K−1
Speed of sound	972 m·s−1
CAS registry number	7440-59-7
Most stable isotopes
Main article: 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.