Chemistry of Gases and Applications

Argon is the most abundant and most used of the noble gases. Its chief uses are in metallurgy, where it provides an inert atmosphere in which hot metals can be worked. Because argon is so very unreactive, it prevents chemical reactions of the very hot metal being welded or forged.

Nitrogen constitutes nearly 78% of the atmosphere.

Xenon is a noble gas present in the Earth's atmosphere in extremely low concentrations (about 0.087 ppm). While neon, helium, and argon are also inert, xenon is significantly rarer than the others listed.

Air consists of active and inactive components. This was proposed by Mayow in the year 1674.

The abundances of the noble gases decrease as their atomic numbers increase. Helium is the most plentiful element in the universe except hydrogen. All the noble gases are present in Earths atmosphere and, except for helium and radon, their major commercial source is the air, from which they are obtained by liquefaction and fractional distillation.

An inert gas is a gas that is generally non-reactive with other substances. The term inert means non-reactive. We refer to gases as being chemically inert if their atoms don't combine with other atoms in chemical reactions.

When we refer to inert gases, we are usually referring to six primary ones, also called the noble gases. Meet the most common inert gases: helium $\left(He\right)$, argon $\left(Ar\right)$, neon $\left(Ne\right)$, krypton $\left(Kr\right)$, xenon $\left(Xe\right)$, and radon $\left(Rn\right)$.

Most atoms do not have 8 electrons in this outer orbital so they react with other atoms to form bonds to fill their outer electron orbital. The atomic structure of the noble gases is different from the structure of most atoms because they have a filled outer orbital.

Helium is used in balloons and airships. It is much less dense than air, so balloons filled with it float upwards.

$ { { (NH } _{ 2 }) } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { Cr } _{ 2 }{ O } _{ 3 }+{ N } _{ 2 }+4{ H } _{ 2 }O\ N{ H } _{ 4 }{ NO } _{ 2 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { N } _{ 2 }+2{ H } _{ 2 }O\ 2{ NaN } _{ 3 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } 2Na+3{ N } _{ 2 } $ 

Main constituent in air is nitrogen.
The proportion of nitrogen in the open air is 78% by volume.
Note:
Air is a mixture of gases. The volume percent of nitrogen and oxygen are 78%and 21% respectively. Air also contains tiny amounts of carbon dioxide, argon, methane, ozone and water vapour.

Argon is used in light bulbs. The very thin metal filament inside the bulb would react with oxygen and burn away if the bulb were filled with air instead of argon. Argon stops the filament burning away because it is unreactive.

A mixture of nitrogen and carbon dioxide can be distinguished by passing it through lime water. Because nitrogen does not turn lime water milky and carbon dioxide forms carbonate with lime which makes lime water milky. From this we can conclude that nitrogen gas does not react with lime water, hence, it is most useful in removing nitrogen from air.

$ N{ H } _{ 4 }{ NO } _{ 2 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { N } _{ 2 }+2{ H } _{ 2 }O $

Inert gases are also known as zero-valent gases, zero group elements or noble gases. They have completely filled valence shell and are chemically unreactive.