The noble gases are the six elements that make up Group 18 on the periodic table. These elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). All noble gases contain eight valence electrons and have completely full outer shells. Due to this chemical property, the noble gases display many unique properties.
All the elements in the noble gas group are located on the far right of the periodic table. This means they are all nonmetals at room temperature. All noble gasses are odourless and colourless. In addition, noble gases fluoresce, which means they emit visible light.
Most of the noble gas elements are inert because they have full valence electron shells. Thus, they have no spaces available to accept electrons and from bonds. This makes them extremely stable and unreactive. Overall, the noble gases form only a few compounds. Helium, neon and argon do not form any documented compounds. Even though the majority of the noble gases are not reactive, they are excellent conductors of electricity.
Occurrence and Extraction
The noble gases are rare in nature, found only in minuscule quantities. The only noble gas available in large natural quantities is helium, which forms through radioactive decay and develops natural gas wells.
All the noble gases have only one atom. They also have relatively low boiling temperatures because they only have dispersion forces and cannot create bonds between atoms. Noble gas densities increase with increasing molecular mass. Thus, helium, which is at the top of Group 18, has a lower density than air and can be used to inflate balloons that float. Xenon, however, is near the bottom of the column and has a density approximately five times the density of air.
The noble gases have many important industrial and practical uses. For example, deep sea divers use helium in their air tanks. The helium dilutes the oxygen that they breathe while underwater. Neon and argon are used to fill the discharge tubes in neon lighting. Xenon is a main component of electronic flashes used in cameras.
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