Ang helyo (Iningles helium) mao ang elementong kimiko sa talaang peryodiko nga may simbolo nga He ug kaiphan nga atomik 2. Ang helyo mao ang gas nga halangdon.
Quick Facts Helium, Panagway ...
Helium |
2He |
|
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 |
[[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[1] |
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. |
|
· r |
Close
Laser sa Helyo