Isotopes. As befits an element that flies under the chemical and physical radar unless provoked, it is colorless, odorless and tasteless. Classified as a noble gas, Argon is a gas at room temperature. Argon was suspected to be present in air by Henry Cavendish in the year 1785. Certain Facts About Argon. But in the year 2000, chemists at the University of Helsinki led by Markku Räsänen announced the first ever compound: argon fluorohydride. Argon, abbreviated Ar, is element number 18 on the periodic table, making it the third-lightest of the six noble gases behind helium (atomic number 2) and neon (number 10). In the above, the most intense ion is set to 100% since this corresponds best to the output from a mass spectrometer. Although the stable isotopes argon-36 and argon-38 make up all but a trace of this element in the universe, the third stable isotope, argon-40, makes up 99.60 percent of the argon found on Earth. That is why argon laser is the most popular type of ion lasers. It was isolated by examination of the residue obtained by removing nitrogen, oxygen, carbon dioxide, and water from clean air. It is characterised by same solubility level in water as that of oxygen. Argon was discovered by Sir William Ramsay, a Scottish chemist, and Lord Rayleigh, an English chemist, in 1894. The main isotopes of argon found on Earth are Ar-40, Ar-36, and Ar-38. Argon was discovered by Lord Rayleigh and Sir William Ramsay in 1894. Where did argon get its name? Argon's name comes from the Greek word argos meaning lazy and indeed for more than a hundred years after its discovery chemists were unable to get it to combine with any other elements. This is not to be confused with the relative percentage isotope abundances which totals 100% for all the naturally occurring isotopes. Argon will form positive ions. Because it's outer shell is Argon Argon is a chemical element with symbol Ar and atomic number 18. When we write the configuration we'll put all 18 electrons in orbitals around the nucleus of the Argon atom. Naturally occurring K-40 with a half-life of 1.250 x 10 9 years, decays to stable Ar-40 (11.2%) by electron capture and by positron emission, and also decays to stable Ca-40 (88.8%) by negatron emission. The argon laser is a special, green-wavelength laser that is often used for retinal therapy. In cosmic abundance, argon ranks approximately 12th among the chemical elements. The argon laser active medium consists of this gas, where the lasing takes place due to ions of argon gas. In writing the electron configuration for Argon the first two electrons will go in the 1s orbital. In order to write the Argon electron configuration we first need to know the number of electrons for the Ar atom (there are 18 electrons). In order to write the Argon electron configuration we first need to know the number of electrons for the Ar atom (there are 18 electrons). Start studying Elements and their Ions. Isotopes Argon has three isotopes that are stable including argon-36, 38, and 40. Learn vocabulary, terms, and more with flashcards, games, and other study tools. It is nearly impossible to get Argon to form ions, as it has a. complete electron shell and a noble gas electron configuration.