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argon (Ar)

Term: argon (Ar)
Literally meaning: “slow”
Origin: Anc Greek
'áργüς < εργüς(=lazy, idle, not working the ground, living without labor)

William Ramsey (1852-1916) 
The name is a reference to the fact the element is very stable and inactive (8 electrons in the outer atomic shell). The element discovered in 1785 by English chemist Sir Henry Cavendish (17310-1810) when tried to distinguish nitrogen and oxygen from air using  electrical sparks. He noticed then that” air is at least 99.3 percent nitrogen/oxygen/carbon dioxide with a maximum 0.7 percent of something else.” The experiment was ignored until repeated by Scottish chemist (sir) William Ramsey (1852-1916)  who is credited with the isolation of Argon. Ramsey  in 1984 attended a lecture given by Lord Rayleigh  who had noticed that the density of nitrogen of the air (1,2572) was always larger than the density of the density of the nitrogen present in compounds (1,2506). This observation lead Rayleigh to conclusion that the atmosphere had to contain an heavier inert substance.  Ramsey discussed the “unsolved problem” with Rayligh and he decide to repeated Cavendish experiment in 1894 removing the nitrogen with heated magnesium. The residue revealed an unknown spectrum which called  “argon”
Argon is a chemical element with atomic number 18 and atomic mass 39.948. Argon is colorless and belongs to noble gases. It makes up 0.93% of the atmosphere , making it the third most abundant gas.

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