Noble gas is any of 7 chemical elements, which make up group 18 (villa) of periodic table, are neon (Ne), helium (He), krypton (Kr), argon (Ar), radon (Rn), xenon (Xe), and ununoctium (Uon). Noble gases are tasteless, colorless, odorless, nonflammable gases. From the earliest time, they have actually been labeled as group O. This is because it was discovered that their atoms could not actually combine with the atoms of the other elements to form the chemical bonds. They were called inert or rare gases because they were thought to be chemically inert or to be exceedingly rare. However, the term rare has been removed since a number of these elements are found on earth.
Their abundances fall as their atomic numbers rise. They are all present in the atmosphere. A number of their important uses actually depend on reluctance in them to react chemically. For instance, their indifference towards the oxygen confers utter the non- flammability. They emit and absorb electromagnetic radiation in much complex way than the other substances. Thus, this behavior is utilized in fluorescent and discharge lamps lightning devises. For example, xenon emits blue color that is beautiful and neon produces the orange red color used in advertising signs.
Noble gases have very low melting points and boiling points. These characteristics make them useful in study of matter at very low temperatures. For instance, the low solubility of the helium makes it not to dissolve in the blood. Xenon is used as anesthetic since it is readily removed from body and nonflammable. Because radon highly radioactivity it is used in radiotherapy. Xenon, radon, and krypton are the only noble gases that form stable compounds. Therefore, they are used as oxidizing agents.