Argon
Argon is a chemical element with symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most common gas in the Earth's atmosphere, at 0.934% (9,340 ppmv), making it over twice as abundant as the next most common atmospheric gas, water vapor (which averages about 4000 ppmv, but varies greatly), and 23 times as abundant as the next most common non-condensing atmospheric gas, carbon dioxide (400 ppmv), and more than 500 times as abundant as the next most common noble gas, neon (18 ppmv).
Physical properties
Values for the element in its standard state.
- Density
- 0.001784g/cm³
- Melting point
- 84K
- Boiling point
- 87K
- Atomic radius
- 97pm
- Bonding type
- Atomic
- Molar heat
- Not available
Inside the atom
Electron arrangement and the energy behind its behavior.
Full electron configuration
[Ne] represents 10 core electrons. The full view shows them explicitly.
- Electronegativity
- Not availablePauling scale
- First ionization energy
- 1,521kJ/mol
- Electron affinity
- 0kJ/mol
- Van der Waals radius
- 188pm
About argon
- Appearance
- Colorless gas exhibiting a lilac/violet glow when placed in a high voltage electric field
- Discovery
- 1894 (Lord Rayleigh)
- Data source
- Read the reference
A missing value means it is unavailable in this reference dataset. Values can vary with measurement method and conditions.