Krypton is a colorless, odorless noble gas with the chemical symbol Kr and atomic number 36, existing as single atoms rather than molecules under normal conditions. Discovered in 1898 by Scottish chemist William Ramsay and English chemist Morris Travers through the fractional distillation of liquid air, krypton gets its name from the Greek word “kryptos” meaning “hidden,” reflecting its secretive nature. Despite Superman making it famous as his home planet’s namesake, real krypton is far from fictional – this rare gas makes up just 1 part per million of Earth’s atmosphere but plays crucial roles in high-performance lighting, laser technology, and even defining the fundamental unit of length. Long considered completely inert, krypton surprised scientists in 1963 by forming compounds with fluorine under extreme conditions, proving that even noble gases aren’t entirely aloof from chemical bonding.

Find out about the noble gasses as a group here [Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn), Oganesson (Og)]. Find a review of the 50 most important industrial gases here.

20 Fun Facts About Krypton

Beyond the basics above, what else should we know about Krypton? Check out the 20 fun facts below!

1. Krypton-86’s orange-red spectral line defined the meter from 1960-1983 as exactly 1,650,763.73 wavelengths.
2. The gas glows brilliant white in electric discharge tubes, producing twice the light output of argon-filled bulbs.
3. Krypton costs about $30 per liter, making it 100 times more expensive than argon despite similar properties.
4. Airport runway lights use krypton because its white light penetrates fog better than yellow sodium lamps.
5. The gas becomes a metal under 350 GPa pressure, conducting electricity like copper at these extreme conditions.
6. Krypton-85, a radioactive isotope from nuclear reactors, is used to detect clandestine nuclear reprocessing globally.
7. Double-pane windows filled with krypton insulate 50% better than air-filled ones due to lower thermal conductivity.
8. The element forms a clathrate hydrate at 0°C that looks like ice but releases bubbles when melting.
9. Krypton difluoride (KrF₂) decomposes explosively at -10°C, making it one of the most powerful oxidizers known.
10. MRI machines use krypton-83 to image lung airspaces because it’s safer than radioactive xenon alternatives.
11. The gas liquefies at -153°C forming a clear liquid denser than water at 2.4 g/cm³.
12. Ion propulsion spacecraft use krypton instead of xenon when cost matters more than efficiency.
13. Krypton fluoride lasers produce ultraviolet light at 248 nm, used for eye surgery and semiconductor manufacturing.
14. Earth’s atmosphere contains about 15 billion tons of krypton, but extraction yields only 8,000 tons annually.
15. The gas narcotizes divers at 4 times atmospheric pressure, causing symptoms similar to nitrogen narcosis.
16. Krypton atoms are perfectly spherical with a van der Waals radius of exactly 202 picometers.
17. Some nuclear weapon designs use krypton-85 switches that conduct electricity when exposed to radiation.
18. The International Space Station uses krypton flashlights because they work in vacuum without oxygen.
19. Krypton forms van der Waals molecules with fluorine at -196°C that exist for nanoseconds before decomposing.
20. Stars produce krypton through slow neutron capture, taking millions of years to build up from lighter elements.

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