Krypton

Krypton is a chemical element with the symbol Kr and atomic number 36. It belongs to the group of gases known as noble gases—elements that do not readily combine with other elements because their outer electron shell is full. Under normal conditions, it is a colorless, odorless, and tasteless gas.

Krypton is extremely rare in Earth's atmosphere, making up only about one part per million. It is therefore most commonly obtained through fractional distillation of liquid air, making it expensive compared to nitrogen or oxygen.

Chemical and Physical Properties

Krypton has a very low boiling point and condenses easily, like other heavy gases in its group. Although it is known as a highly unreactive gas, under special conditions it can form compounds with fluorine, such as krypton difluoride. This shows that the heavy noble gases are not completely inert.

Isotopes

Natural krypton consists of several stable isotopes. There are also radioactive isotopes, some produced by nuclear fission. For example, krypton-85 is found in the atmosphere as a release from nuclear fuel reprocessing plants and is used as a tracer to detect such operations.

Applications

Krypton is commonly used to fill lamps. It is employed in fluorescent lamps and specialized high-intensity light sources, such as aircraft landing lights. When an electric current passes through it, it produces light ranging from white to blue-green. It is also used in certain lasers (such as the krypton fluoride laser) and in double-pane windows to reduce heat loss.

Discovery

Krypton was discovered in the late 19th century through examination of the residue left when liquefied air is boiled off. Its name comes from the Greek word meaning 'hidden', reflecting how rare and difficult it is to detect.