What is the third most common gas found in the air we breathe?

The air around us is not a single substance but a mixture of several gases, each present in different proportions. The two most abundant gases in Earth’s atmosphere are Nitrogen (N₂), which makes up about 78%, and Oxygen (O₂), which accounts for around 21%. After these two, the third most common gas is Argon (Ar), a noble gas that constitutes approximately 0.93% of the atmosphere.

Argon is a colorless, odorless, and tasteless gas. It was discovered in 1894 by the British scientists Lord Rayleigh and Sir William Ramsay. Its name comes from the Greek word “argos,” meaning inactive, which refers to its chemically inert nature. Argon does not react easily with other elements or compounds because its outer electron shell is complete, making it very stable.

Despite being present in small quantities, Argon plays important roles in various scientific and industrial applications. It is commonly used in electric light bulbs, fluorescent tubes, and welding processes to provide an inert atmosphere that prevents unwanted chemical reactions. It is also used in laboratories and in the preservation of materials that can be damaged by oxygen or moisture.

The atmospheric composition by volume is approximately:

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  Nitrogen (N₂): 78.09%

  
  


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  Oxygen (O₂): 20.95%

  
  


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  Argon (Ar): 0.93%

  
  


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  Carbon Dioxide (CO₂): 0.04%

  
  


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  Other gases (Neon, Helium, Krypton, etc.): trace amounts

  
  

Argon’s presence in the air remains constant, as it is produced naturally from the radioactive decay of potassium-40 in the Earth’s crust.

In conclusion, while most people focus on oxygen and nitrogen, Argon is the third most abundant gas in the air we breathe — an important but often overlooked component of our atmosphere