18 Ar 39.948
Argon
Noble Gas
Argon (Ar) is a chemical element with atomic number 18, classified as a noble gas. At room temperature it is a gas. It was discovered in 1894 by Lord Rayleigh, William Ramsay.
Properties
- Atomic number
- 18
- Atomic mass
- 39.948 u
- Category
- Noble Gas
- Group
- 18
- Period
- 3
- Block
- p-block
- Electron configuration
- [Ne] 3s² 3p⁶
- Phase at STP
- Gas
- Density
- 1.784 g/L
- Melting point
- 83.8 K (-189.3 °C)
- Boiling point
- 87.3 K (-185.8 °C)
- Electronegativity
- —
- Atomic radius
- 71 pm
- Ionization energy
- 15.76 eV
- Discovery
- 1894 · Lord Rayleigh, William Ramsay
Common uses
Light bulbs, welding, wine preservation, medical lasers
Did you know?
Third most abundant gas in Earth's atmosphere but completely unreactive.
Experiment with the elements
Argon doesn't form any compounds in our lab yet, but the periodic table sandbox lets you combine dozens of other real elements into real compounds — water, table salt, ammonia and many more — with their true chemical formulas.