What is Argon? - Facts, Properties & Uses

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  • 0:00 Discovery
  • 0:59 Properties
  • 2:24 Uses
  • 4:01 Lesson Summary
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Lesson Transcript
Instructor: Nicola McDougal

Nicky has taught a variety of chemistry courses at college level. Nicky has a PhD in Physical Chemistry.

Argon is abundant in our atmosphere but evaded discovery until the late 1800s. In this lesson, we will look at how argon was discovered, its properties and how we use it. A quiz will test our knowledge.


In 1785, a gas had been isolated by Henry Cavendish who noted that about 1% of air would not react even under the most extreme conditions. At the time, Cavendish was unable to identify what it was. That 1% was argon.

A century later, argon was identified in 1894 by British scientists, Lord Rayleigh and William Ramsay. It was discovered by separating it from liquid air. The discovery was made as a result of trying to explain why the density of nitrogen extracted from air was different from that obtained by decomposing ammonia. Ramsay removed all of the nitrogen he had extracted from the air by reacting it with hot magnesium, forming solid magnesium nitride. He was then left with a gas that would not react. He examined the gas's spectrum and saw new groups of red and green lines, confirming that this was a new element.


Argon has the atomic number 18 and is a noble gas found in group 18 in the Periodic Table. It is the third noble gas and sits below neon and above krypton. Argon is a colorless and odorless gas and does not react with other substances under normal conditions. In fact, the name is derived from the Greek, argos, meaning idle. Like all noble gases, it has a low melting point (-189.36 C, -308.848 F) and boiling point (-185.85 C, -302.53 F).

Argon has three stable isotopes; the most abundant at 99.60% is argon-40. Argon is not rare; in fact, it is the third most abundant atmospheric gas, making up 0.94% of the earth's atmosphere. Argon is produced when potassium-40, present naturally in the earth's crust, undergoes radioactive decay to Ar-40. The argon then makes its way into the atmosphere. Argon is produced commercially by fractional distillation of liquefied air.

Due to its abundance, argon is relatively inexpensive. It costs just 50 cents per 100g. It is over 65 times less expensive than neon, which is another noble gas that was discovered by Ramsay and Raleigh.


Argon is used in a variety of different ways:

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