Krypton: Chemical element with symbol Kr and atomic number 36; rare gas

It has an atomic number of 36. The name krypton comes from the Greek word kryptos meaning hidden. It is used in fluorescent lamps, flashbulbs, and as a wavelength standard. The metre used to be defined as 1,650,763.73 wavelengths in a vacuum of krypton gas.

The Simple English Wiktionary has a definition for: krypton.

Because it is a gas, it does not react with many elements. It is clear and has no taste or smell. The atmosphere is only about one millionth part krypton. Krypton has very few compounds.

The main use for krypton is to make light. There is one main type of krypton light bulbs. This is called a gas discharge lamp. There are three main types of these. First is a low energy gas discharge lamp or "neon light". Low energy gas discharge lights made from krypton are near white to green. Second is a high energy short length of time gas discharge light or "flash bulb". These are mostly used for photography. They are bright blue-white. Third is a high energy gas discharge light. This third kind is mostly used to light airport runways. They are also bright blue-white.

Krypton was found by Sir William Ramsay and Morris Travers in Great Britain in 1898. Ramsay was given the 1904 Nobel Prize in Chemistry for his work on noble gases. It was a difficult gas to discover; Ramsay suspected it existed but only found it by removing other gases. This is why he gave it the name Krypton. There is no mineral called Kryptonite or planet called Krypton, which both feature in the Superman comics by Jerry Siegel and Joe Shuster. The fictional planet is probably better known than the real chemical element called Krypton.

• List of common elements
• Periodic table