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( Argon)
Argon (pronounced /'?rg?n/) is a chemical element designated by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table (noble gases). Argon is present in the Earth's atmosphere at 0.94%. Terrestrially, it is the most abundant and most frequently used of the noble gases. Argon's full outer shell makes it stable and resistant to bonding with other elements. Its triple point temperature of 83.8058&_160;K is a defining fixed point in the International Temperature Scale of 1990. Argon has approximately the same solubility in water as oxygen gas and is 2.5 times more soluble in water than nitrogen gas. Argon is colorless, odorless, tasteless and nontoxic in both its liquid and gaseous forms. Argon is inert under most conditions and forms no confirmed stable compounds at room temperature. Although argon is a noble gas, it has been found to have the capability of forming some compounds. For example, the creation of argon hydrofluoride (HArF), a metastable compound of argon with fluorine and hydrogen, was reported by researchers at the University of Helsinki in 2000.[1] Although the neutral ground-state chemical compounds of argon are presently limited to HArF, argon can form clathrates with water when atoms of it are trapped in a lattice of the water molecules.[2] Also argon-containing ions and excited state complexes, such as ArH+ and ArF, respectively, are known to exist. Theoretical calculations have shown several argon compounds that should be stable but for which no synthesis routes are currently known. Argon (Greek meaning "inactive," in reference to its chemical inactivity)[3][4][5] was suspected to be present in air by Henry Cavendish in 1785 but was not discovered until 1894 by Lord Rayleigh and Sir William Ramsay in Scotland in an experiment in which they removed all of the oxygen and nitrogen from a sample of air.[6][7] They had determined that nitrogen produced from chemical compounds was one-half percent lighter than nitrogen from the atmosphere. The difference seemed insignificant, but it was important enough to attract their attention for many months. They concluded that there was another gas in the air mixed in with the nitrogen.[8] Argon was also encountered in 1882 through independent research of H.F. Newall and W.N. Hartley. Each observed new lines in the color spectrum of air but were unable to identify the element responsible for the lines. Argon became the first member of the noble gases to be discovered. The symbol for argon is now Ar, but up until 1957 it was A.[9]
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Argon Articles
NLP Jargon - What Is Uptime? by Steve Bauer
I'm starting a new line of articles: NLP Jargon. These articles will help you figure out the myriad of terms used by NLP gurus in seminars and seminal books such as Frogs Into Princes. Our NLP term for today is uptime. You'll find the...
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