argon

Argon is a chemical element with the symbol Ar and atomic number 18. It is a colourless, odourless, and inert gas. Argon is the third most abundant gas in Earth's atmosphere, after nitrogen and oxygen.

Argon is a noble gas, which means that it is chemically nonreactive. This is because argon has a full outer electron shell, which makes it stable.

Argon is used in a variety of applications, including:

• Lighting: Argon is used in fluorescent lights and arc lamps.
• Welding: Argon is used as a shielding gas in welding.
• Cryogenics: Argon is used to cool objects to very low temperatures.
• Laboratory equipment: Argon is used to fill laboratory equipment, such as vacuum chambers and gas chromatographs.

Argon is a safe and inert gas, and it is not harmful to humans. However, it can be asphyxiating if it is breathed in at high concentrations.

Argon is a colourless, odourless, and inert gas that is the third most abundant gas in Earth's atmosphere.