2
He
Helium
4.0026022
2
#2
Helium
noble gas· Gas·4.0026022 u
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.
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Identity
- Symbol
- He
- Atomic Number
- 2
- Atomic Mass
- 4.0026022 u
- Category
- noble gas
- Block
- s-block
- Period
- 1
- Group
- 18
- Appearance
- colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
- Year Discovered
- 1868 CE
- Discovered By
- Pierre Janssen
- Named By
- Helios
Electrons
- Configuration
- 1s2
- Full Configuration
- 1s2
- Shells
- 2
- Electronegativity
- n/a
- Electron Affinity
- -48
- Oxidation States
- 0
- Ionization Energies
- 2372.3, 5250.5
Physical Properties
- State at
- Gas
- Melting Point
- n/a
- Boiling Point
- 4.222
- Density
- 0.1786
- Crystal Structure
- HEX
- Magnetic Ordering
- Diamagnetic
Mechanical
- Atomic Radius
- 31 pm
- Covalent Radius
- 46 pm
- Van der Waals
- 140 pm
Thermal & Electrical
- Thermal Conductivity
- 0.1513 W/(m K) W/(m·K)
- Specific Heat
- 5193 J/(kg K) J/(g·K)
- Heat of Vaporization
- 0.083 kJ/mol kJ/mol
- Heat of Fusion
- 0.02 kJ/mol kJ/mol
Abundance
- Universe
- 24.0%
- Sun
- 23.0%
- Meteorite
- 0
- Earth's Crust
- 178.5 ppb
- Ocean
- 7.20 ppt
- Human Body
- 0