ARGON
...mstances. This is because none of their valence electrons spots are open, as all of their energy levels are full. Argon has eight electrons in its third, and outermost, energy level. Argon’s atomic weight is 39.48 amus. Argon is a colorless gas; it also has no odor or taste. Argon, when not in it’s normal state will melt at -189.3 degrees C, and will boil at -185.8 degrees C. It is a very dense gas as its density at 293K is 1.784 g/cm^3. Argon is twice as soluble in water as nitrogen, and has six isotopes. Now for the history of Argon, Sir William Ramsey and Lord Rayleigh discovered it in 1894. ‘Argon’ come comes from the Greek word argos meaning inactive. Cavendish had suspected argon’s presence in air since 1785, because after removing all the traces of oxygen, nitrogen, carbon dioxide, moisture and dust from the air, there was still some gas present. It was Argon, which makes up 0.934% of earth’s atmosphere, making it the most abundant of the noble gases. Argon is recovered from the atmosphere by fractional distillation. Removing each fraction of the atmosphere by itself, carbon dioxide, oxygen, etc., then whatever is left is argon. Argon is also constantly being formed from the radioactive decay of K-40, which is an isotope of potassium. Argon is most commonly used for lighting. It is used in incandescent light bulbs; a low-pressure argon atmosphere prevents oxidative destruction of the filament at high operating temperatures because argon does not react with the filament. This prolongs the filament life. If argon were not used in this procedure, a vacuum would be needed, which would raise production costs and would require a much stronger light bulb. It is also used in fluorescent light tubes and different types of gas discharge glow tubes. When combined with other gases, argon lends a bluish hue. Electricity in the bulbs and signs excite the electrons, causing them to emit energy in the form of light. Argon is also used as a shield gas when welding of reactive metals such as titanium, aluminum and stainless steel, and during the processing of silicon and silicone. When welding a reactive metal, such as aluminum, a hard oxide layer will form on the hot metal, which would prevent adhesion of the weld. It is important to exclude nitrogen in the welding of titanium, since titanium will just burn in nitrogen. Therefore, an argon blanket will exclude oxygen and nitrogen from the weld area and prevent the formation of an oxide, or the destruction of the metal. The argon is in a pressurized tank, which is linked to the welding gun by a rubber hose. This hose allows the argon to flow from the tank and disperses it around the weld when there is electricity flowing. Argon is most commonly used in TIG, (tungsten- inert gas), welding because this welding process is used for aluminum, stainless steel and titanium, argon, because of its density excludes all the other environmental gases which could have adverse side effects on the quality of the weld. A mixture of helium is most commonly used in GMAW, (gas, metal, and arc welding), wire and metal melting with an electric arc, fusing together. Argon’s high density allows it to be in an open container with little to no diffusion of oxygen or nitrogen into it. This also causes it to be quite the health hazard. Because of its density, caution should be used to prevent accumulation in closed work areas. It can exc...