Helium (He) — Element 2: Properties & Data | Aladdin Scientific
Helium(He) — Element 2
Helium (He) is a noble gas with atomic number 2 and atomic mass 4.0026. It has melting point 0.95 K (-272 °C), boiling point 4.22 K (-269 °C), density 0.0001785 g/cm³. It sits in group 18 and period 1 of the periodic table and was discovered in 1868.
Key facts
| Atomic mass | 4.0026 u |
|---|---|
| Electron configuration | 1s2 |
| Atomic radius (van der Waals) | 140 pm |
| Ionization energy | 24.587 eV |
| Melting point | 0.95 K |
| Boiling point | 4.22 K |
| Density | 0.0001785 g/cm³ |
| Standard state | Gas |
| Year discovered | 1868 |
Frequently asked questions
What is the electron configuration of helium?
The ground-state electron configuration of helium is 1s2.
What group and period is helium in?
Helium (He) is in group 18 and period 1 of the periodic table, classified as a noble gas.
What is the melting point of helium?
Helium melts at 0.95 K (-272 °C).
What is the standard state of helium?
Helium is a gas at standard temperature and pressure.
Related elements
About this data: property values compiled from IUPAC Standard Atomic Weights (2021), the NIST Atomic Spectra Database, and PubChem. Curated by the Aladdin Scientific technical team. Last reviewed: .