Discovered | Name | Characteristics | Uses

Krypton is in the 4th period of Group VIIIA (Group 18), the rare gases. Other members of the group are helium (He), neon (Ne), argon (Ar), xenon (Xe), and radon (Rn).

The colorless gas - a member of the rare gas family - was discovered in 1898 by Ramsay and Travers in the residue left after liquid air had nearly boiled away.

The name is derived from the Greek word, kryptos, meaning hidden. The symbol Kr is an abbreviation of the name.

Krypton is present in the atmosphere in extremely minute quantities (about 1 part per million) and is produced commercially as a byproduct in the preparation of liquid air. One of the rare gases, it is characterized by its whitish color, similar to helium, when excited in a discharge tube, and by its brilliant green and orange spectral lines. In the solid state, the element has a face-centered cubic structure.

Krypton has been used as a gas to fill small bright lamps, such as used by miners; to fill bactericidal lamp-starter tubes and special electron tubes; and is used in electron etching and ion engines. Fluorescent lamps are filled with a krypton-argon mixture.

Krypton--85, one of the 19 known isotopes of krypton and an isotope that holds its radioactivity longer than other gases, is used to stabilize the starting potential of gas-filled electronic tubes by providing free electrons. It is used to detect leaks in sealed containers and in medicine to detect abnormal heart openings.

In 1960 the wave length of the orange-red line of krypton-86 became the international standard of length.