Ar
39.950Argon
Argon
Argon is a colorless, odorless noble gas with atomic number 18. It makes up nearly 1% of Earth’s atmosphere and is used where an inert atmosphere is needed, including welding, light bulbs, windows and semiconductor production.
18
39.95 g/mol
[Ne] 3s² 3p⁶
2 | 8 | 8
—
1.78e-3 g/cm³
-189.3 °C
-185.8 °C
Lord Rayleigh & William Ramsay
Argon was discovered in 1894 by Lord Rayleigh and William Ramsay while studying nitrogen from air. Its name comes from the Greek argos, meaning inactive, because argon is very unreactive.
Argon-36
Natural abundance: About 0.34%. Stable isotope of argon.Argon-38
Natural abundance: About 0.06%. Rare stable isotope of argon.Argon-40
Natural abundance: About 99.60%. The dominant isotope in Earth’s atmosphere, largely produced by potassium-40 decay.ArF*
Argon Fluoride ExcimerExcited-state species used in 193 nm excimer lasers for photolithography and LASIK.HArF
Argon FluorohydrideA rare argon compound stable only at extremely low temperatures.- Inert shielding gas for welding and metal cutting
- Filling incandescent and fluorescent lamps
- Insulating gas in double-glazed windows
- Protective atmosphere for producing reactive metals and semiconductor crystals
- Argon lasers and plasma applications
Argon has no known biological role. It is generally chemically inert and non-toxic, but like other inert gases it can displace oxygen in confined spaces.
- Argon is the third most abundant gas in Earth’s atmosphere after nitrogen and oxygen.
- Most atmospheric argon is argon-40 from the decay of potassium-40 in rocks.
- Potassium-argon dating uses the buildup of argon-40 to estimate the age of rocks and minerals.
- The name argon reflects its low chemical reactivity.
- Argon has atomic number 18 and belongs to group 18, the noble gases.
- Its electron configuration is [Ne] 3s² 3p⁶, giving argon a full valence shell.
- Argon is monatomic under ordinary conditions because it is very inert.
- Argon is the most abundant noble gas in Earth’s atmosphere.
What is the atomic number of argon?
The atomic number of argon is 18.
What is the electron configuration of argon?
Argon has the electron configuration [Ne] 3s² 3p⁶.
Is argon a noble gas?
Yes. Argon is a group 18 noble gas.
How much argon is in the atmosphere?
Argon makes up about 0.93-0.94% of Earth’s atmosphere, making it the most abundant noble gas in air.
What is potassium-argon dating?
Potassium-argon dating estimates rock and mineral ages from the buildup of argon-40 produced by potassium-40 decay.
What is argon used for?
Argon is used in welding, light bulbs, insulated windows, semiconductor production, lasers and inert-atmosphere applications.