The Element Krypton: History, Facts, Uses & Properties

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  • 0:03 What Is Krypton?
  • 0:52 The Discovery of Krypton
  • 1:42 Properties of Krypton
  • 2:49 Uses of Krypton
  • 3:47 Facts About Krypton
  • 4:32 Lesson Summary
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Lesson Transcript
Instructor: Mary Ellen Ellis
Krypton is an element on the periodic table and belongs to the family of unreactive noble gases. Learn about this gaseous element's history, uses and chemical properties, as well as some fascinating facts.

What Is Krypton?

Yes, Krypton is the name of Superman's home planet, and kryptonite is a radioactive mineral that can destroy the famous superhero. But these are fictional, and krypton exists outside the world of comic books and movies. The real krypton is a member of the noble, or inert, gases in column 18 of the periodic table of the elements. A small amount is found naturally in the earth's atmosphere and it is not harmful to anyone, superhero or human.

As a member of the noble gases on the periodic table, krypton has a full outer electron shell with eight valence electrons. All other elements strive for the stability of this electron arrangement and when they reach it, stop reacting. Krypton and the other noble gases rarely react with each other or with other elements because of their naturally stable valence electron configurations.

The Discovery of Krypton

Two chemists, William Ramsay and Morris William Travers, working at the University College, London, discovered krypton on May 30th, 1898. They had previously found argon, the first noble gas to be discovered, when they extracted it from a sample of air. In examining argon the chemists believed they had found a new family of elements, and they were right. With its amazing chemical stability, argon didn't fit with any of the other known family of elements.

Ramsay and Travers believed there must be more elements related to argon. They assumed that other similar gases were 'hidden' in the sample of argon. Sure enough, they separated out another element and called it krypton. The name comes from the Greek word kryptos, which means 'hidden.' Ramsay and Travers also worked together to isolate neon and xenon, two more noble gases.

Properties of Krypton

Krypton's symbol is Kr and it has the atomic number 36, which means that it has 36 protons in its nucleus. The number of neutrons in the nucleus varies by isotope. The atomic mass of krypton is 83.79. This is an average of all naturally occurring isotopes, which include Kr-78, Kr-80, Kr-82, Kr-83, Kr-84, and Kr-86.

Krypton-84 is the most abundant isotope. Every isotope of krypton has 36 protons, and the mass number represents the total number of protons and neutrons. If you subtract 36 from 84, you will find that Kr-84 has 48 neutrons in its nucleus.

Krypton is a gas at room temperature and has low melting and boiling points. To get this element to be a liquid or a solid requires that it be very, very cold, around -244 °F and -251 °F respectively. Krypton rarely reacts with other elements, but it can form a compound with fluorine, called krypton difluoride.

Uses for Krypton

Krypton is a pretty rare element. It represents a tiny component of our atmosphere here on Earth. Because of its rarity, krypton has fewer practical uses than some of the other, more abundant noble gases like argon or neon.

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