2
He
Helium
Helium
Helium (He)
Noble Gases · Gas · Period 1 · Group 18
Element Properties
- Atomic Number
- 2
- Symbol
- He
- Atomic Mass
- 4.0026
- Category
- Noble Gases
- Standard State
- Gas
- Period
- 1
- Group
- 18
- Electronegativity
- —
- Atomic Radius
- 140
- Ionization Energy
- 24.59
- Electron Affinity
- —
- Oxidation States
- 0
- Melting Point
- 0.95 K (-272.2 °C)
- Boiling Point
- 4.22 K (-268.93 °C)
- Density
- 0.000179
- Electron Configuration
- 1s2
- Year Discovered
- 1868
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Frequently asked questions
What is the atomic number of Helium?
The atomic number of Helium is 2, which equals the number of protons in its nucleus.
What is the atomic mass of Helium?
The atomic mass of Helium is approximately 4.0026 u (one twelfth of the mass of a carbon-12 atom).
What is the electron configuration of Helium?
The electron configuration of Helium is 1s2.
Where is Helium in the periodic table?
Helium is located in period 1, group 18.
When was Helium discovered?
Helium was discovered in 1868.
Related elements
Same group
10
Ne
Neon
20.18
18
Ar
Argon
39.9
36
Kr
Krypton
83.8
54
Xe
Xenon
131.29
86
Rn
Radon
222.018
118
Og
Oganesson
295.216