Krypton (the element, not Superman’s home planet)

Crystal Gaulton
15 December 2014

Name: Krypton

Symbol: Kr
Atomic Number: 36
Relative Atomic Mass: 83.798
Category: Noble gas (Group 18)
Appearance: Colourless and Odourless gas

Above: Image © istockphoto.com/3dalia

It’s a bird, it’s a plane, it’s Superman! He is the superhero who can move faster than a speeding bullet and leap tall buildings in a single bound. Aside from Lois Lane, he has only one weakness: kryptonite. This bright green radioactive substance was formed during the destruction of Superman’s home planet, Krypton. But did you know that krypton is also a real element in our universe?

Krypton was accidentally discovered by Sir William Ramsay and Morris M. Travers in 1898. These two chemists were boiling liquid air and when almost all of it was boiled away, they found krypton in the residue that was left behind. You may be wondering: “Does that mean krypton is in the air I breathe?”.

Did you know? The length of the metre used to be determined using the orange-red wavelengths of the isotope krypton-86.

The answer is yes! Earth’s atmosphere is about 1 parts per million (or 0.0001%) krypton. In fact, the element is only found in the air.

In temperatures above -153.2 degrees Celsius, Krypton is a colourless, odourless gas. In temperatures below -157.3 degrees Celsius, it is a white, crystalline solid.

Like the other noble gases in group 18, krypton is an incredibly stable element that very rarely reacts with others to form compounds because of its full outer shell of eight valence electrons.

Did you know? Isotopes are different atoms of the same element that have the same number of protons but a different number of neutrons.

Nevertheless, Krypton can form certain compounds, the most stable of which is krypton difluoride, first synthesized in 1963. Krypton has 31 different isotopes but only six of those are stable and naturally occurring.

Because krypton is so rare and very expensive to obtain from the air, its applications are limited. The main use for Krypton is in lighting. When the gas is ionized (removing electrons from the atoms to create electrically charged ions), it turns into plasma and glows white. This makes it very useful in light bulbs for photography and studio lighting.

Did you know? Like krypton, most noble gases are used as light sources. For example, neon is used in neon lights and xenon is used in the lamps that project IMAX movies.

So while you are constantly breathing in minute amounts of krypton, there is a good chance you have never actually seen it. That is, unless you live in a comic book universe, spend a lot of time boiling liquid air, or work in a photography studio. Appropriately enough, the name krypton actually comes from the Greek word kryptos, which means hidden!

Learn more!

Basic information on krypton, including discovery and history, appearance and characteristics, compounds and isotopes, applications, and related research.

Facts About Krypton (2014)
Stephanie Pappas, LiveScience

Chemistry of Krypton
Megan Meadows, UC Davis ChemWiki

Krypton Element Facts
Doug Stewart, Chemicool

Crystal Gaulton

I am currently completing my Bachelor of Science (Honours) in Psychology at Memorial University in Newfoundland.  When I'm not studying I love hanging out with my boyfriend, hand-painting glasses, exercising, and playing volleyball.  After my studies my aspiration is to become a doctor and help the mentally ill live the best quality of life they possibly can!  Growing up I had a lot of questions as to why or how something happened and science answered most of those questions!


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