2 He 4.003
Helium
noble gas
Properties
- Atomic number
- 2
- Atomic mass
- 4.003 u
- Category
- noble gas
- Group
- 18
- Period
- 1
- Block
- s-block
- State (room temp)
- Gas
- Outer-shell electrons
- 2
- Electronegativity
- —
- Density
- —
- Melting point
- -272.2 °C
- Boiling point
- -268.93 °C
Electron configuration
1s²
Noble-gas shorthand: 1s²
Electrons per shell: 2 — that's 2 in the outermost shell.
About Helium
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.
- Discovered by Pierre Janssen
- Appearance: colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field
Position in the periodic table
Data compiled from Wikipedia, PubChem, and IUPAC. Source.