an inert gaseous element occurring in trace amounts in air and used in fluorescent lights and lasers. Symbol: Kr; atomic no: 36; atomic wt: 83.80; valency: 0; density: 3.733 kg/m³; melting pt: –157.37°C; boiling pt: –153.23±0.10°C
inert gaseous element, 1898, coined by its discoverers (Sir William Ramsay and Morris W. Travers) from Greek krypton, neuter of adjective kryptos "hidden" (see crypt); so called because it was so difficult to find.
A colorless, odorless element in the noble gas group. It is used in certain fluorescent lamps and photographic flash lamps. Atomic number 36; atomic weight 83.80; melting point -156.6°C; boiling point -152.30°C; density 3.73 grams per liter (0°C). See Periodic Table.