2He4.00260
Helium
Noble gasesBlock sPeriod 1Group 18gas at 20 °C
- Configuration :
- 1s²
- Atomic mass :
- 4.002602 u
- French :
- Hélium
3D Bohr-model representation of the Helium atom (symbol He, atomic number Z=2). Electron shell configuration: 2 electrons.
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Bohr model · educational
Bohr model of helium
Helium (He) has 2 electrons, in a single shell. The diagram places them on circles around the nucleus, from the K shell — the closest — outward.
| Shell | Electrons |
|---|---|
| K (n = 1) | 2 |
The Bohr model is a teaching picture: electrons do not travel in circular orbits, but the number of electrons per shell is exact.
Related lesson
First look at the periodic classification
Reading the table, spotting families (alkali metals, halogens, noble gases). Why some elements share properties.
9 minElectron configuration
Full1s²
Short1s²
Valence electrons2
KLMNOPQ shells
K2
Electronegativity
Pauling—
Allen4.16
Mulliken (eV)—
Atomic radii
Empirical120 pm
Calculated31 pm
Covalent28 pm
Van der Waals140 pm
Successive ionisation energies
I₁2372.3 kJ/mol
I₂5250.5 kJ/mol
Electron affinity—
Oxidation states
0
Bold states = most common.
Warm-up
Helium — do you remember?
3 questions on this page. The right answer shows every time, and nothing is asked of you to play.
No account · one minute