Krypton is the chemical element named after the Greek word for “hidden one” and has atomic number 36.
Krypton is a colorless, odorless noble gas. Its name comes from the Greek kryptos, meaning “hidden,” because the element was difficult to detect in the small residue left after other components of liquid air had been removed. British chemists William Ramsay and Morris Travers discovered krypton in 1898.
Krypton atoms have 36 protons, and a complete outer electron shell makes the element relatively unreactive. Krypton is present in Earth’s atmosphere only in trace amounts. It has been used in specialized lighting, including some flash lamps and high-performance lamps, and in certain insulating gas mixtures for windows.
Krypton is often mixed up with xenon because both are noble gases used in lighting. Xenon has atomic number 54, while krypton has atomic number 36. Krypton is also different from the fictional planet Krypton in name and spelling history: the element’s name was established from Greek, whereas the comic-book planet was created later.