Argon
Definition and meaning of Argon in chemistry.
![Argon element card: symbol Ar, atomic number 18, atomic mass 39.95, electron configuration [Ne] 3s² 3p⁶, Noble gas, group 18, period 3, gas at room temperature.](/assets/images/terms/argon-chemical-element.webp)
Argon is a noble gas with the symbol Ar and atomic number 18. It makes up about 0.93 percent of Earth's atmosphere. Argon is colorless, odorless, and does not react under normal conditions.
In more detail
Argon's outer electron shell already holds a full set of 8 electrons. This gives it excellent stability and almost no tendency to form chemical bonds. Because of this, argon stays chemically inert under everyday conditions on Earth.
This inertness makes argon extremely useful whenever a protective, non-reactive atmosphere is needed. Factories extract argon commercially from ordinary air. The process is called fractional distillation of liquid air.
Air is cooled until it turns to liquid, then slowly warmed back up. Nitrogen, oxygen, and argon boil off at slightly different temperatures, which lets them be collected separately. Argon has many uses across different industries.
Welders use argon gas to shield hot metal from oxygen in the air, which would otherwise cause unwanted reactions. Argon also fills certain light bulbs, and it is used in some food packaging and scientific research. Because argon is heavier than air, it can displace oxygen and protect materials that would otherwise react with it.
Scientists first isolated argon in 1894. Its name comes from a Greek word meaning lazy or inactive, fitting its unreactive nature. Argon is also used in some window insulation.
There it fills the gap between panes of glass to reduce heat loss. Divers sometimes use argon to inflate a dry suit, since it insulates the body better than ordinary air.
Key facts
| Chemical symbol | Ar |
|---|---|
| Atomic number | 18 |
| Atmospheric abundance | About 0.93 percent |
| Field | Inorganic Chemistry |
| Extraction method | Fractional distillation of liquid air |
Argon gas fills incandescent light bulbs to create an inert atmosphere inside the glass. This prevents the hot tungsten filament from reacting with oxygen and burning out. As a result, the bulb lasts much longer than it would in ordinary air.
Frequently asked questions
Why is argon so unreactive?
Argon has a complete outer electron shell of 8 electrons. This full shell makes it very stable, so it has almost no tendency to form chemical bonds with other elements.
How is argon extracted from the atmosphere?
Argon is separated from ordinary air by fractional distillation of liquid air. Nitrogen, oxygen, and argon each boil off at a slightly different temperature, allowing them to be collected one at a time.
What is argon commonly used for?
Argon is widely used in welding, where it shields hot metal from reacting with air. It also fills certain light bulbs and is used in food packaging and scientific research.
Related terms
Sources & references
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