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Argon By Lauren Ciocca, Cynthia Gagliardi, and Dana Civitello Basic Information Atomic Number:18 Atomic Mass: 39.948(1) amu Symbol: Ar Subatomic Particles: 18 electrons, 18 protons, 22 neutrons Isotopes: Ar-36 Ar-38 Ar-40 Electron Configuration: [Ne]3s23p6 Pure Form: Colorless odorless tasteless nontoxic gas Physical State at Room Temperature: gas Common in Nature: makes up 0.93 % of the earth’s atmosphere third most abundant. It has increased since the earth was created because Potassium that is radioactive decays and forms Argon. Where found in Nature: In the air as a by product of Nitrogen and Oxygen. How to make pure samples: from fractional distillation of liquid air Does not form compounds Common Uses Used in electric light bulbs, and florescent tubes Filling phototubes, and glow tubes Used as an inert gas shield for arc welding and cutting Crystals in the semiconductor industry are grown in argon atmospheres A blanket for the production of radioactive elements Makes argon lasers that are used in holography, eye surgery, spectrochemistry, optical image processing, semiconductor processing, and laser light shows History From the Greek word argon meaning inactive. It was discovered in 1894 by Sir William Ramsay, a Scottish chemist, and Lord Rayleigh, an English chemist. Lord Rayleigh noticed that a liter of pure nitrogen from air weighed more than a liter of nitrogen from a compound He concluded another gas was present Many gases were present such as helium, neon, krypton, xenon, as well as argon Eventually Ramsey obtained argon by examining the left over elements in air after removing nitrogen, oxygen, carbon Lord Rayleigh (above), dioxide and water William Ramsay (left) Air has 0.93% argon Argon in Light Bulbs Incandescent bulbs • Vacuum or inert gas must be used in the bulb • Argon- inert gas, inexpensive, does not conduct a lot of heat • Replaces air that causes bulbs to blacken and burn out by preventing the metal from hitting air • Sometimes mixed with nitrogen • Sometimes replaces nitrogen (very inert) • Use of gas makes it possible for the filament to be at a higher temperature • Light more visible • Argon filled light bulbs usually last longer • 120 watt bulbs (over 60 watts) contain gases like argon • Gas Discharge Tubes (Neon Bulbs) and Florescent Lighting • Mixed with neon or mercury • Produces a blue or violet glow Argon Lasers Click for video An ion laser (popular) •Discharge tube- normally made of materials with low heat conductivity Used for scientific and medical purposes, artistic/light shows •Emits 1 to 20 Watts of flux Produces nine different wavelengths •Advantages include: little noise, easy to aim Blue spectrum wavelength- common beam, cost, long lasting Large amount of power necessary Argon atoms become ionized and excited •Used often for eye surgery, holography, Magnetic field around laser tube spectrochemistry, optical imaging, and semiconductor processing, printing, copying, Prevents loss of electrons scanning Glossary Arc Welding- welding that uses an electrical arc to provide heat Discharge Tube- a closed insulating vessel containing a gas at low pressure through which an electric current flows when sufficient voltage is applied to its electrodes Distillation- the evaporation and subsequent collection of a liquid by condensation as a means of purification Holography- a method of producing a three-dimensional image of an object by recording on a photographic plate or film the pattern of interference formed by a split laser beam and then illuminating the pattern either with a laser or with ordinary light Inert- not readily reactive with other chemical elements; forming few or no chemical compounds Glossary cont. Ionized- converted totally or partly into ions Filament- A fine wire heated electrically to incandescence in an electric lamp Flux- radiant energy in the visible-wavelength range Liquid air- air in its liquid state, intensely cold and bluish, obtained by cooling and compression. Spectrochemistry- a branch of chemistry based on a study of the spectra of substances Bibliography Dictionary.com. 2005. Lexico Publishing Group, LLC. <www.dictionary.com> Element Displays. 2004. The Red Green & Blue Company. <http://www.theodoregray.com/PeriodicTableDisplay/Elements/018/index.s12.html> Chem4Kids. 1997-2005. Andrew Rader Studios. <http://www.chem4kids.com/files/elements/018_shells.html> http://vcs.abdn.ac.uk/ENGINEERING/lasers/gas.html Bulbs.com. 2005. Illuminating Engineering Society of North America. <http://www.bulbs.com/lightingguide/tech_incandescentdiagram.asp> Boyer, Matt. Argon Laser. 1992-2000. Matt Boyer. <http://www.angelfire.com/la3/lasers/argonlaser.html> www.en.wikipedia.org/Wiki/Argon http://www.ucl.ac.uk/news/library/images/ramsay.jpg Goldwasser, Samuel M. Argon/Krypton Lasers. 1994-2005. Samuel M. Goldwasser. <http://repairfaq.ece.drexel.edu/sam/laserarg.htm> www.Pearll.lanl.gov/periodic/elements/18.html Chemistry Web Elements. 1993-2005. Mark Winter. <www.webelements.com/webelements/scholar/elements/argon/history.html> www.Nautilus.fis.uc.pt/st2.5/scenes-e/elem/e01810.html http://www.ioa.org.uk/publications/web_articles/pioneers_of_acoustics/rayleigh/rayleigh.html
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