2 He
Noble gas
Helium
Used in balloons and MRI cooling.
Properties of Helium
- Atomic number (Z)
- 2
- Symbol
- He
- Atomic mass
- 4.0026 g/mol
- Category
- Noble gas
- Group
- 18
- Period
- 1
- Electron configuration
- 1s²
- Electronegativity (Pauling)
- —
- Atomic radius
- 31 pm
- First ionization energy
- 2372 kJ/mol
- Melting point
- 0.95 K (-272.2 °C)
- Boiling point
- 4.22 K (-268.9 °C)
- Density
- 0.0001785 g/cm³
- Phase at 25 °C
- Gas
- Discovered
- Discovered in 1868
Frequently asked questions
What is Helium?
Helium (He) is a noble gas, element number 2 on the periodic table. Used in balloons and MRI cooling.
What is the atomic number and atomic mass of Helium?
Helium has atomic number 2 and an atomic mass of about 4.0026 g/mol.
What is the electron configuration of Helium?
The electron configuration of Helium is 1s².
Where is Helium on the periodic table?
Helium sits in group 18, period 1, and is classified as a noble gas.