Kr

Krypton

Krypton was discovered in 1898 by William Ramsay and Morris Travers, who found it while studying liquid air. They had already discovered neon and xenon, and then noticed another new element with a distinctive green and orange spectral signature. They named it krypton from the Greek word “kryptos,” meaning hidden.

In 1960 krypton was chosen to help define the international standard for the meter. From 1960 to 1983, the meter was officially defined by the wavelength of a specific orange spectral line of krypton-86. This definition was later replaced by the current definition based on the speed of light.