Argon
Argon (氩, symbol Ar) is chemical element number 18, a Noble Gas in period 3, group 18 of the periodic table, with a standard atomic weight of about 39.948. Third most abundant gas in Earth's atmosphere. Inert, used in welding and incandescent bulbs.
Properties
| Atomic number | 18 |
|---|---|
| Symbol | Ar |
| Atomic mass | 39.948 u |
| Category | Noble Gas |
| Period | 3 |
| Group | 18 |
| Electron configuration | [Ne] 3s² 3p⁶ |
| Electronegativity | — |
| Covalent radius | 106 pm |
| Density | 0.0017837 g/cm³ |
| Melting point | 83.8 K |
| Boiling point | 87.3 K |
| Discovery | Rayleigh & Ramsay, 1894 |
Overview
Third most abundant gas in Earth's atmosphere. Inert, used in welding and incandescent bulbs. Argon (Ar) is a Noble Gas with atomic number 18, located in period 3, group 18. As a noble gas it has a full outer shell, is extremely unreactive, and exists as a monatomic gas at room temperature.
It has the configuration [Ne] 3s² 3p⁶; its 8 outer-shell electrons drive its bonding. Under standard conditions it exists as a gas (a very low melting point); it melts near 83.8 K (-189.3 °C), boils near 87.3 K (-185.8 °C), has a density around 0.0017837 g/cm³.
It is widely used in Industrial Gas. It was first described by Rayleigh & Ramsay in 1894. Use the comparison tool to line it up against other elements.
Electron shells
Electrons per shell: 2 · 8 · 8
Main uses
- Industrial Gas
Hazard
Compounds containing Argon
No compounds in this knowledge base contain Argon yet.
Data sources
Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.