2Gas
He 4.003 Atomic mass · uNoble gases
Helium
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.
Discovery 1868 (Pierre Janssen)
K2
Physical properties
Values for the element in its standard state.
- Density
- 0.0001785g/cm³
- Melting point
- Not available
- Boiling point
- 4K
- Atomic radius
- 32pm
- Bonding type
- Atomic
- Molar heat
- Not available
Inside the atom
Electron arrangement and the energy behind its behavior.
Full electron configuration
1s, 2 electrons;
All electrons are already written explicitly.
2 electrons Orbital order preserved from source
- Electronegativity
- Not availablePauling scale
- First ionization energy
- 2,372kJ/mol
- Electron affinity
- 0kJ/mol
- Van der Waals radius
- 140pm
He HeliumAtomic number 2
2,372kJ/mol
Atomic numberGaps indicate unavailable data
About helium
- Appearance
- Colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
- Discovery
- 1868 (Pierre Janssen)
- Data source
- Read the reference
A missing value means it is unavailable in this reference dataset. Values can vary with measurement method and conditions.