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Facts About Krypton

Krypton
Electron configuration and elemental properties of krypton.
Credit: Greg Robson/Creative Commons, Andrei Marincas | Shutterstock
Atomic Number: 36
Atomic Symbol: Kr
Atomic Weight: 83.798
Melting Point: 315.28 F (157.38 C)
Boiling Point: 307.80 F (153.22 C)

Word origin: The term krypton comes from the Greek word kryptos, which means hidden.

Discovery: The element was discovered by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, in 1898. They were studying liquefied air and saw a small amount of liquid krypton after the air had boiled away.

History: In 1960, the length of the meter was defined in terms of the orange-red spectral line of krypton-86. The definition of the meter was again redefined in 1983 as being the length light travels in a vacuum during a time interval of 1/299,792,458 of a second.

As most people know, the comic book character Superman is from the planet Krypton. Superman's creators, Jerry Siegel and Joe Shuster, may have chosen the name because the word derives from the Greek word for hidden or unknown. Kryptonite is a radioactive mineral from the doomed planet. Exposure to it weakens and would eventually kill Superman. This is a fictional mineral, of course, and doesn't really exist. Krypton is a gas.

vial of krypton gas
A small vial (1-by-5 centimeters) of glowing ultrapure krypton.
Credit: Jurii/Creative Commons

Properties of krypton

The element is one of the noble gases, a category of chemical elements that all have similar properties. [See Periodic Table of the Elements]

Solid krypton is a milky-white crystalline substance with atoms arranged at the corners and points of cubes in its structures. This is called a face-centered cube structure that is common to most noble gases. Krypton gas has bright green and orange spectral lines.  These spectral lines are easy to produce and can look quite beautiful.

Elemental krypton contains six stable isotopes. There are 17 other stable isotopes. Scientists have identified molecule-ions of ArKr+ and KrH+, and provided evidence of KrXe or KrXe+.

Sources of krypton

Krypton is a rare gas. The earth's atmosphere contains about 0.0001 percent krypton. Scientists have found the atmosphere of Mars contains 0.0003 percent of krypton.

Uses of krypton

As it is quite rare, krypton is not commonly used for many purposes. It is used in combination with argon in some fluorescent light bulbs. It is also used in some photographic flash lamps for high-speed photography.

Some krypton compounds do exist, including krypton difluoride, krypton clathrates, kryptonates and a salt of an oxyacid of krypton. Krypton clathrates are produced by using hydroquinone and phenol. Krypton difluoride can be made easily by several methods and some gram amounts of it have been produced.

(Source: Los Alamos National Laboratory)

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