Argon

Argon is a chemical element with the 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 the Earth's atmosphere, at 0.934%. It is more than twice as abundant as water vapor, 23 times as abundant as carbon dioxide, and more than 500 times as abundant as neon. Argon is the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust. Nearly all of the argon in the Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the 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. The name "argon" is derived from the Greek word ἀργόν, neuter singular form of ἀργός meaning 'lazy' or 'inactive', as a reference to the fact that the element undergoes almost no chemical reactions.

Read more in the app