argon

Also known as Ar, element 18, 18Ar

Argon is a chemical element; it has 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 abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv). Argon is the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust.

AI overview

Argon is a chemical element and noble gas that makes up about 0.934% of Earth's atmosphere, making it the third most abundant gas in the air we breathe. It is notably more plentiful than other gases like carbon dioxide and water vapor, and is the most abundant noble gas found in Earth's crust.

AI-generated from the Wikipedia summary — may contain errors.

Chemical data

Formula: Ar
Molecular weight: 39.9 g/mol
IUPAC name: argon
SMILES: [Ar]
InChIKey: XKRFYHLGVUSROY-UHFFFAOYSA-N
Polar surface area: 0 Å²
H-bond donors: 0
H-bond acceptors: 0
Formal charge: 0

via PubChem

Research

21,127 papers

Argon neuroprotection in ischemic stroke and its underlying mechanism.ReviewBrain research bulletin · 2024Bao L, Liu Y, Jia Q et al.DOI: 10.1016/j.brainresbull.2024.110964
Argon pharmacokinetics: a solubility measurement technique.Medical gas research · 2023Lemaire J, Heninger M, Louarn E et al.DOI: 10.4103/2045-9912.351106
Xenon and Argon as Neuroprotective Treatments for Perinatal Hypoxic-Ischemic Brain Injury: A Preclinical Systematic Review and Meta-Analysis.Anesthesia and analgesia · 2025Barros M, Liang M, Iannucci N et al.DOI: 10.1213/ANE.0000000000007223
Argon neuroprotection.Critical care (London, England) · 2010Sanders RD, Ma D, Maze MDOI: 10.1186/cc8847
Argon: The Future Organ Protectant?Annals of cardiac anaesthesia · 2019Nair SGDOI: 10.4103/aca.ACA_180_18
Argon: systematic review on neuro- and organoprotective properties of an "inert" gas.International journal of molecular sciences · 2014Höllig A, Schug A, Fahlenkamp AV et al.DOI: 10.3390/ijms151018175
The Molecular Pathway of Argon-Mediated Neuroprotection.ReviewInternational journal of molecular sciences · 2016Ulbrich F, Goebel UDOI: 10.3390/ijms17111816
Argon-stimulated nitric oxide production and its function in alfalfa cadmium tolerance.Environmental pollution (Barking, Essex : 1987) · 2023Wang J, Liu B, Jin Z et al.DOI: 10.1016/j.envpol.2023.122009

via PubMed

Wikidata facts

Mass: 39.95
Image: ArTube.jpg

Show 14 more facts

element symbol: Ar
Commons category: Argon
atomic number: 18
speed of sound: 813
Commons gallery: Argon
canonical SMILES: [Ar]
chemical formula: Ar
time of discovery or invention: 1894-00-00
standard molar entropy: 154.8
dynamic viscosity: 22.7
Unicode character: 氬
electron configuration: [Ne] 3s² 3p⁶
melting point: -189.34
boiling point: -185.85

Sources (6)

via Wikidata · CC0

~19 min read

Article

19 sections

Contents

Characteristics
History
Occurrence
Isotopes
Compounds
Production
Applications
Industrial processes
Scientific research
Preservative
Laboratory equipment
Medical use
Lighting
Miscellaneous uses
Safety
See also
References
Further reading
External links

Nearly all argon in Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most easily produced by stellar nucleosynthesis in supernovas.