Helium (He)
Helium
Helium (He) is a noble gas in period 1, group 18. Its relative atomic mass is 4.0026 and the molar mass of the atom is 4.003 g/mol.
Atomic number 2
Atomic mass 4.0026
Molar mass 4.003 g/mol
Category Noble gas Gas
Properties of helium
| Atomic number | 2 |
|---|---|
| Symbol | He |
| Latin name | Helium |
| Relative atomic mass | 4.0026 |
| Molar mass | 4.003 g/mol |
| Group, period, block | 18, 1, s |
| Category | Noble gas |
| State at 20 °C | Gas |
| Electron configuration | 1s² |
Electron configuration of helium
Electrons per shell
K2
Full notation
1s²
Noble-gas notation
2 protons · 2 electrons1s²
Formula and compounds of helium
Simple substanceHeheliumMolar mass of He: 4.003 g/mol
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Frequently asked questions
The relative atomic mass of helium is 4.0026, so the molar mass of the atom is 4.003 g/mol.
Full: 1s². Noble-gas notation: 1s².