Helium (He)
Helium (He, element 2) is a noble gas in group 18, period 1. Atomic mass 4.003, electron configuration 1s², uses and facts.
About Helium
Helium is a noble gas with the symbol He and atomic number 2. It is a gas at room temperature, and it sits in group 18, period 1 of the periodic table. Helium was discovered in 1868 by Pierre Janssen.
Helium key facts
- Atomic number: 2
- Symbol: He
- Atomic mass: 4.003 u
- Category: noble gas
- Group: 18
- Period: 1
- State at room temperature: gas
- Electron configuration: 1s²
- Electronegativity (Pauling): not assigned
- Melting point: 0.95 K (-272.2 °C)
- Boiling point: 4.22 K (-268.93 °C)
- Density: 0.000178 g/cm³
- Common oxidation states: 0
Electron configuration
The electron configuration of helium is 1s². It shows how the electrons fill their subshells. Helium has 2 valence electrons.
Uses of helium
- Balloons
- MRI machines
- Cryogenics
Did you know?
Was discovered in the Sun before Earth. Cannot be made to form compounds under normal conditions.
Other elements in group 18 and neighbours
Frequently asked questions
What is the atomic number of helium?
The atomic number of helium is 2, which means every helium atom has 2 protons.
What is the electron configuration of helium?
The electron configuration of helium is 1s².
What group and period is helium in?
Helium is a noble gas in group 18, period 1.
What state is helium at room temperature?
Helium is a gas at room temperature.
What is helium used for?
Helium is used for balloons, MRI machines, cryogenics.