Krypton's name comes from the Greek, meaning "the hidden one." Its chemical symbol is "Kr" and its atomic number is 36. An element's atomic number indicates the number of protons found in the nucleus of its atoms. The gas is inert, or nonreactive, and also colorless, harmless, odorless and tasteless. This rare gas belongs to group O of the periodic table, along with argon, helium, neon, radon and xenon. This group is also known as the noble gases.
Krypton was discovered in 1898 by Scottish chemist William Ramsay and his assistant, English chemist Morris Travers. They found the gas in the residue remaining after they boiled liquid air. Ramsay and Travers had been experimenting with nitrogen (N), which makes up about 78 percent of the Earth's atmosphere. They were puzzled about why the nitrogen obtained from air is heavier than the nitrogen obtained from chemical compounds and discovered krypton in the course of their work. For the discovery, William Ramsay was awarded the Nobel Prize for Chemistry in 1904.
Krypton has many uses. The gas has applications in the lighting industry, such as fluorescent lamps, and is also used in laser technology. There is a special krypton fluoride laser -- KrF laser -- used in the production of integrated circuits. Krypton is valuable in the production of some medicines and in the measuring of X-rays. It can be used to detect leaks in otherwise completely sealed containers and also to assist in determining the approximate age of water discovered deep underground.
Although krypton is found in trace amounts in the air, it has a negligible presence in the Earth's crust and in sea water. Unlike the other noble gases, krypton and xenon will form chemical compounds. This is because of the larger size of their atoms. However, obtaining the rare gas is an expensive process, a fact that has limited its industrial applications to some extent.