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, which is 2 in the outermost shell.
Related: electron configuration, the Bohr model, valence electrons.
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
Helium: frequently asked questions
- What is Helium?
- Helium (He) is the chemical element with atomic number 2. It is a nonmetal: specifically a noble gas, the group with full outer electron shells.
- What is the atomic number of Helium?
- Helium's atomic number is 2, which means every Helium atom has 2 protons in its nucleus.
- What is the electron configuration of Helium?
- The electron configuration of Helium is 1s2 (noble-gas shorthand: 1s2). Its electrons are arranged in shells of 2, with 2 in the outermost shell.
- Is Helium a metal or a nonmetal?
- Helium is a nonmetal: specifically a noble gas, the group with full outer electron shells.
- What group and period is Helium in?
- Helium is in group 18 and period 1 of the periodic table.
- Is Helium a solid, liquid, or gas?
- At room temperature, Helium is a gas.
Position in the periodic table
Data compiled from Wikipedia, PubChem, and IUPAC. Source.