Astronomy · Chemical element
Argon
Argon (Ar) is a chemical element belonging to the category Noble gas, with atomic number 18 and standard atomic mass 39.9480 u. This sheet describes its fundamental properties, periodic position and physical characteristics.
Identity
- Name: Argon
- Symbol: Ar
- Atomic number: 18
- Atomic mass: 39.9480 u
Position in the periodic table
- Group: 18
- Period: 3
- Category: Noble gas
Physico-chemical properties
- Standard state: Gas
- Melting point: −189.3 °C
- Boiling point: −185.8 °C
- Density (gas, 0 °C, 1 atm): 0.001784 g/cm³
- Electron configuration: [Ne] 3s² 3p⁶
Scientific description
Argon is a colorless, odourless noble gas with symbol Ar and atomic number 18. It occupies group 18 and period 3 of the periodic table and is chemically very inert under standard conditions. Its standard atomic mass is 39.9480 u, and it is the third most abundant gas in the Earth's atmosphere.