Element 18
Argon
Noble gases
Argon (Ar) is in the p-block of the periodic table — group 18, period 3.
Argon is a chemical element with symbol Ar and atomic number 18.
Key data
- Atomic number
- 18
- Atomic mass
- 39.948 u
- Group / Period
- 18 / 3
- Block
- p-block
- Phase at STP
- Gas
- Density
- 1.784 g/cm³
- Melting point
- -189.3 °C
- Boiling point
- -185.8 °C
- Electron configuration
- [Ne] 3s2 3p6
Periodic table block
Argon is in the p-block (group 18, period 3). Elements land in the p-block when their highest-energy electrons fill a p subshell — this region holds most nonmetals, the metalloids, and the metals on the right of the table.
New to this? Periodic table blocks explained: s, p, d, and f
Common uses
- •Welding shield
- •Insulating windows
- •Light bulb fill
Discovery
Year: 1894
Discovered by: Lord Rayleigh
Frequently asked questions
What is the atomic number of Argon?
Argon has atomic number 18. Its symbol is Ar and its atomic mass is 39.948 u.
What category of element is Argon?
Argon is classified as noble gases. It sits in group 18, period 3 of the periodic table.
What block of the periodic table is Argon in?
Argon is in the p-block (group 18, period 3). Its highest-energy electrons occupy the p subshell — you can see this in its electron configuration, [Ne] 3s2 3p6.
What is Argon used for?
Common uses of Argon include: Welding shield, Insulating windows, Light bulb fill.
When was Argon discovered?
Argon was discovered in 1894 by Lord Rayleigh.
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